Journal articles: 'Oxidised polyethylene wax'

1

Al-Sammerrai, Dhoaib, and Wejdan Selim. "The thermal decomposition of oxidized polyethylene wax." Polymer Degradation and Stability 15, no. 2 (January 1986): 183–87. http://dx.doi.org/10.1016/0141-3910(86)90072-8.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Fa, Wenjun, Changjun Yang, Chuqing Gong, Tianyou Peng, and Ling Zan. "Enhanced photodegradation efficiency of polyethylene-TiO2nanocomposite film with oxidized polyethylene wax." Journal of Applied Polymer Science 118, no. 1 (May 19, 2010): 378–84. http://dx.doi.org/10.1002/app.32413.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Shagov, V. S., and N. S. Domnina. "Modified oxidized polyethylene wax as a lube oil additive." Chemistry and Technology of Fuels and Oils 28, no. 7 (July 1992): 374–75. http://dx.doi.org/10.1007/bf00727031.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Radecka, Iza, Victor Irorere, Guozhan Jiang, David Hill, Craig Williams, Grazyna Adamus, Michal Kwiecień, et al. "Oxidized Polyethylene Wax as a Potential Carbon Source for PHA Production." Materials 9, no. 5 (May 13, 2016): 367. http://dx.doi.org/10.3390/ma9050367.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Wang, Wenxue, Yujue Wang, Ziliang Liu, Yuying Han, and Chuanxing Wang. "Study on application performance of oxidized polyethylene wax in powder coatings." Progress in Organic Coatings 136 (November 2019): 105294. http://dx.doi.org/10.1016/j.porgcoat.2019.105294.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Wang, Wenxue, Yujue Wang, Yuying Han, Ziliang Liu, and Chuanxing Wang. "Effect of Oxidized Polyethylene Wax on Curing Process of Powder Coatings." IOP Conference Series: Materials Science and Engineering 768 (March 31, 2020): 022034. http://dx.doi.org/10.1088/1757-899x/768/2/022034.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Ahn, Ho Geun. ""Study on Preparation of Anticaking Agent for Fertilizer Using Oxidized Polyethylene Wax"." Journal of the Korean Society for Environmental Technology 19, no. 4 (August 30, 2018): 383–89. http://dx.doi.org/10.26511/jkset.19.4.10.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

KIM, M., and A. L. POMETTO. "Food Packaging Potential of Some Novel Degradable Starch-Polyethylene Plastics1." Journal of Food Protection 57, no. 11 (November 1, 1994): 1007–12. http://dx.doi.org/10.4315/0362-028x-57.11.1007.

Full text

Abstract:

The food-packaging potential of 12 degradable starch-polyethylene films containing cornstarch, low- or high-molecular-weight oxidized polyethylene and pro-oxidant was evaluated. Mechanical properties of the films were affected more by acids than by alkali, but the film was stable in paraffin oil. Starch in the films did not impair heat-sealing ability. Water vapor transmission increased with increasing starch content but was not affected by oxidized polyethylene. Oxygen and carbon dioxide permeability were not affected by starch or oxidized polyethylene, but nitrogen permeability was affected by starch. Oil oxidation was stimulated by pro-oxidant and high-molecular-weight oxidized polyethylene in films. Film starch content, oxygen permeability, and water permeability did not accelerate microbial growth, and the mechanical properties of most films were not reduced after use. These results suggest that these degradable starch-polyethylene films have some potential use as primary food containers for some food products and storage requirements.

APA, Harvard, Vancouver, ISO, and other styles

9

Geethamma, V. G., and Adriaan S. Luyt. "Oxidized Wax as Compatibilizer in Linear Low-Density Polyethylene-Clay Nanocomposites: X-ray Diffraction and Dynamic Mechanical Analysis." Journal of Nanoscience and Nanotechnology 8, no. 4 (April 1, 2008): 1886–94. http://dx.doi.org/10.1166/jnn.2008.18254.

Full text

Abstract:

Oxidized paraffin wax was used as a compatibilizer in composites of linear low-density polyethylene and layered nano silicate clays. X-ray diffraction analyses were carried out to investigate the crystalline morphology of five types of clays, oxidized wax, and their composites with LLDPE. The composites exhibited different X-ray diffraction and dynamic mechanical behaviour in the presence of different clays. Generally, the composites retained the partially crystalline behaviour of LLDPE, and no exfoliation was observed. Increased amount of wax did not change the morphology in most cases. The incorporation of clay resulted in an observable increase in the storage modulus of LLDPE. These values also increased with the addition of oxidized wax for most of the composites. The loss modulus increased with the amount of clay, irrespective of its nature. In most cases these values also increased with the incorporation of wax. The composites with 10% clay and 10% oxidized wax showed the highest storage and loss moduli, irrespective of the nature of the clay. The tan δ values did not change considerably with the addition of clay or wax.

APA, Harvard, Vancouver, ISO, and other styles

10

Choi, Seung-Hyun, Jae-Min Kim, Sun-il Choi, Tae-Dong Jung, Bong-Yeon Cho, Jin-Ha Lee, Gunyoung Lee, Ho Soo Lim, Sang Soon Yun, and Ok-Hwan Lee. "Study on the Analytical Method and Monitoring of the Oxidized Polyethylene Wax in Foods." Journal of Food Hygiene and Safety 32, no. 4 (August 31, 2017): 284–89. http://dx.doi.org/10.13103/jfhs.2017.32.4.284.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Mtshali, T. N., C. G. C. E. Van Sittert, V. Djokovi?, and A. S. Luyt. "Binary mixtures of polyethylene and oxidized wax: Dependency of thermal and mechanical properties upon mixing procedure." Journal of Applied Polymer Science 89, no. 9 (June 13, 2003): 2446–56. http://dx.doi.org/10.1002/app.12466.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Boldyreva, E. V., U. A. Chus, and V. A. Klushin. "Synthesis of 2,5-Furandicarboxylic Acid from Natural Raw Materials." Materials Science Forum 945 (February 2019): 488–92. http://dx.doi.org/10.4028/www.scientific.net/msf.945.488.

Full text

Abstract:

2,5-Furandicarboxylic acid (FDCA) and polyethylene furanoate are now considered as an alternative to terephthalic acid and polyethylene terephthalate (PET), which are produced from fossil sources. FDCA can be obtained by dehydration of polysaccharides and biomass feedstock to 5-hydroxymethylfurfural (5-HMF) with its following catalytic oxidation. A procedure for obtain 2,5-furandicarboxylic acid with using jerusalem artichoke rhizomes as raw materials for the 5-HMF preparation without prior isolation of inulin has been shown. In first step jerusalem artichoke rhizomes dehydration in a two-phase system of «aqueous solution of Na2SO4 · 10 H2O – methyl isobutyl ketone» 40% 5-HMF yield has been achieved. In second step 5-HMF was oxidized by KMnO4 in alkaline medium to FDCA with 100% yield according to HPLC and 89% yield (99% purity) after isolation. The optima time of intervals and amount of oxidizer - potassium permanganate and importance of maintaining the exact pH= 10.5 ± 0.5 of the reaction mixture have been shown. A perspective of using this approach to create the FDCA synthesis technology by oxidizing the product from 5-HMF raw material with 60% main product content, avoiding expensive and long-term 5-HMF purification steps have been proved.

APA, Harvard, Vancouver, ISO, and other styles

13

Park, Sang-Yul, Hyo-Sun Kim, Jeseung Yoo, and Young-Soo Seo. "Fabrication of Hollow Silica Particles Using a Self-Assembled Polyethylene Granule as a Template." Journal of Nanomaterials 2018 (June 4, 2018): 1–9. http://dx.doi.org/10.1155/2018/4979260.

Full text

Abstract:

We developed a novel method preparing nonspherical hollow silica particles (HSP) using a micron-sized granule self-assembled from partially oxidized PE wax. The morphology of the granule was closely investigated in terms of concentration and acid value of PE wax and cooling rate. Due to the oxidized unit in PE wax, magnetic nanoparticle was incorporated into the granule during the self-assembly, and silica was coated on the granule surface via the self-assembly. Silica-coating condition was studied by varying water content and reaction time. After the PE wax was removed by calcination, nonspherical HSP or magnetic HSP was obtained. This cost-effective HSP is expected to be useful for practical applications.

APA, Harvard, Vancouver, ISO, and other styles

14

Rosa, Derval dos Santos, Flávia Gaboardi, Cristina das Graças Fassina Guedes, and Maria Regina Calil. "Influence of oxidized polyethylene wax (OPW) on the mechanical, thermal, morphological and biodegradation properties of PHB/LDPE blends." Journal of Materials Science 42, no. 19 (October 2007): 8093–100. http://dx.doi.org/10.1007/s10853-007-1701-z.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Mikulíková, Regina, Kateřina Kolářová, Václav Švorčík, Barbora Dvořánková, and Tomáš Sopuch. "Surface Structure and Cells Adhesion on Doped Polyethylene." Materials Science Forum 567-568 (December 2007): 253–56. http://dx.doi.org/10.4028/www.scientific.net/msf.567-568.253.

Full text

Abstract:

The properties of polyethylene doped with Ca2+ salt of oxidized cellulose was studied by different techniques. FTIR spectroscopy was used for the determination of crystalline phase in polymer film, surface wettability was determined by standard goniometry and surface morphology was examined by SEM microscopy. Adhesion of mouse 3T3 fibroblasts on the doped polymer was studied in vitro. It was found that the polyethylene doped with the cellulose derivative can be sterilized in boiling water. The number and homogeneity of adhering cells were shown to depend on the surface wettability and morphology.

APA, Harvard, Vancouver, ISO, and other styles

16

Luyt, A. S., and V. G. Geethamma. "Effect of oxidized paraffin wax on the thermal and mechanical properties of linear low-density polyethylene–layered silicate nanocomposites." Polymer Testing 26, no. 4 (June 2007): 461–70. http://dx.doi.org/10.1016/j.polymertesting.2006.12.015.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Shevchenko, T. V., Yu V. Ustinova, A. M. Popov, and E. D. Mel’nikova. "Biodegradable Composite Polyethylene Film." Ecology and Industry of Russia 23, no. 2 (February 8, 2019): 24–29. http://dx.doi.org/10.18412/1816-0395-2019-2-24-29.

Full text

Abstract:

The results of research on the creation of biodegradable polymer films using porous materials of various chemical nature - porous aluminosilicate microspheres extracted from fly ash formed during the combustion of coal and porous oxidized coal, which are pre-saturated with sugar solutions, are presented. Laboratory technology is based on a hot-mix of two films, between which a filler pre-impregnated with a solution of sugar was previously placed. The proposed technology for obtaining biodegradable films involves the use of industrial devices, such as an extruder, calender, etc. With the help of field tests, a sharp decrease in the time of their destruction under natural conditions due to the activation of soil bacteria capable of destroying polymer compositions has been proved. A version of the industrial technology of accelerated destruction of used films by the microbiological method at special test sites is proposed.

APA, Harvard, Vancouver, ISO, and other styles

18

Novák, I., I. Krupa, and A. S. Luyt. "Improvement of the polarity of polyethylene with oxidized Fischer-Tropsch paraffin wax and its influence on the final mechanical properties." Journal of Applied Polymer Science 95, no. 5 (January 11, 2005): 1164–68. http://dx.doi.org/10.1002/app.21283.

Full text

APA, Harvard, Vancouver, ISO, and other styles

19

Zhang, Kui, Mingquan Ye, Aijun Han, and Xin Chen. "Preparation and properties of Styrene‐Butyl Acrylate resin co‐encapsulated Pigment Red 48:2 and Oxidized Polyethylene wax composite nanoparticles." Journal of Applied Polymer Science 137, no. 38 (February 29, 2020): 49150. http://dx.doi.org/10.1002/app.49150.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Carli, Alberto V., Anay R. Patel, Michael B. Cross, David J. Mayman, Kaitlin M. Carroll, Paul M. Pellicci, and Seth A. Jerabek. "Long-term performance of oxidized zirconium on conventional and highly cross-linked polyethylene in total hip arthroplasty." SICOT-J 6 (2020): 10. http://dx.doi.org/10.1051/sicotj/2020010.

Full text

Abstract:

Introduction: Polyethylene wear and subsequent osteolysis remain obstacles to the long-term survivorship of total hip arthroplasty (THA). Highly cross-linked polyethylene (XLPE) with radical quenching represents a massive leap forward with dramatically improved wear rates compared to ultra-high molecular weight polyethylene (UHMWPE). In this study we evaluate the wear of UHMWPE and XLPE coupled with oxidized zirconium (OxZr) femoral heads. Methods: A longitudinal, retrospective analysis was performed identifying consecutive patients who received a 28-mm OxZr-on-polyethylene primary THA from 2003 to 2004 by a single, high-volume arthroplasty surgeon. Patients were divided into two groups: those that received (1) UHMWPE liner and (2) a highly XLPE liner. Patients were included if clinical follow-up was complete to 2014 or later. Radiographic analysis was performed by two blinded observers. Measures included cup position, annual linear wear rate, and presence of osteolysis. Pairwise comparisons, correlations, and inter-rater reliability were calculated. Results: Eighty patients were in the UHMWPE group with an average follow-up of 10 ± 1.23 years and 88 patients in the XLPE group with an average of 10 ± 1.03-year follow-up. Average age (68) was similar between groups (p = 0.288). Observer reliability was excellent for cup abduction (ICC = 0.940), anteversion (ICC = 0.942), and detection of osteolysis (ICC = 0.811). Annual linear wear rates were significantly higher (p = 1 × 10−19) with UHMWPE (0.21 ± 0.12 mm/year) compared to XLPE (0.05 ± 0.03 mm/year). Linear wear rate was significantly correlated to decreasing acetabular abduction (p = 0.035). Osteolysis was noted only in the UHMWPE group, with 17 patients (21.2%) exhibiting acetabular osteolysis and 37 (46.3%) patients exhibiting femoral osteolysis. Conclusions: OxZr coupled with XLPE showed minimal wear and no osteolysis at 10-year follow up. The yearly linear penetration rate is similar to that seen in other studies of XLPE THA. A careful longitudinal follow-up will be required to determine if advanced bearings such as OxZr or ceramic can show improved performance in the second decade of implantation.

APA, Harvard, Vancouver, ISO, and other styles

21

Kennedy, F. E., J. H. Currier, S. Plumet, J. L. Duda, D. P. Gestwick, J. P. Collier, B. H. Currier, and M.-C. Dubourg. "Contact Fatigue Failure of Ultra-High Molecular Weight Polyethylene Bearing Components of Knee Prostheses." Journal of Tribology 122, no. 1 (June 30, 1999): 332–39. http://dx.doi.org/10.1115/1.555364.

Full text

Abstract:

The objective of this work has been to study the origin of surface failures in UHMWPE tibial bearings of total knee replacements. Earlier examination of hundreds of retrieved prostheses, along with analysis of the properties of UHMWPE material from retrieved bearings, had shown that a large number of the bearings suffered from subsurface oxidation. This oxidation was related to the gamma irradiation used to sterilize the tibial bearings. Mechanical properties of the polymer were significantly deteriorated in the oxidized region, with the most severe reduction of strength and ductility occurring about 1 mm beneath the contact surface. In this work the contact stress distribution in the bearings was analyzed, and tribotesting of the bearing materials was carried out under simulated service conditions. Fatigue cracks and delamination developed in bearings tested in a knee simulator and in rolling/sliding test specimens, and the damage was similar to that found in retrieved tibial bearings. The fatigue cracks invariably initiated in the embrittled oxidized layer, and the depth of that layer determined the depth at which the cracks began. The stress analysis showed that the maximum shear stress and von Mises equivalent stress reached high levels in the subsurface oxidized zone where the delamination and contact fatigue failures initiated. [S0742-4787(00)04401-5]

APA, Harvard, Vancouver, ISO, and other styles

22

Yusof, Farazila, Yoshiharu Mutoh, and Yukio Miyashita. "Effect of Pre-Oxidized CuO Layer in Joining between Polyethylene Terephalate (PET) and Copper (Cu) by Using Pulsed Nd:YAG Laser." Advanced Materials Research 129-131 (August 2010): 714–18. http://dx.doi.org/10.4028/www.scientific.net/amr.129-131.714.

Full text

Abstract:

In the present study, effect of pre-oxidized (PO) CuO layer in the joining between polyethylene terephalate (PET) and copper (Cu) by using pulsed Nd:YAG laser was investigated. The experimental result for PET/PO Cu (with pre-oxidized layer) and PET/Cu (without pre-oxidized layer) were presented in this paper. The results showed the pre-oxidation surface improved the welding efficiency. The welded area and tensile shear failure load (TSFL) of PET/PO Cu joint were increased when pre-oxidized layer was introduced. This indicates that high heat was absorbed during laser irradiation of PET/PO-Cu joint compare to PET/Cu joint. On the other hand, the fracture surface of PET/PO-Cu showed the presence of Cu and Cu oxide particles in the PET side. While in case of PET/Cu, no occurrence of Cu particles can be observed. The presence of Cu oxide particles and Cu particles were believed may increase PET/PO Cu joint shear force. From the cross-sectional observation of PET/PO Cu joint interface, it was found that an oxide layer in the laser irradiation area was removed and PET seemed to have intimate contact with Cu surface.

APA, Harvard, Vancouver, ISO, and other styles

23

Bozeya, Ayat, Yahia F. Makableh, Rund Abu-Zurayk, Aya Khalaf, and Abeer Al Bawab. "Thermal and Structural Properties of High Density Polyethylene/Carbon Nanotube Nanocomposites: A Comparison Study." Chemosensors 9, no. 6 (June 11, 2021): 136. http://dx.doi.org/10.3390/chemosensors9060136.

Full text

Abstract:

The effects of functionalization of carbon nanotubes on the properties of nanocomposite sheets prepared from high-density polyethylene (HDPE) and carbon nanotubes (CNTs) were investigated. Carbon nanotubes were first oxidized, followed by amine group functionalization. The Fourier transform-infrared (FTIR) spectroscopy results confirm the presence of oxygenated and amide groups at the surface of the CNTs after each treatment. The HDPE/CNT nanocomposites sheets were prepared using a melt compounding method. Six types of CNTs were used; pristine Single-walled Carbon nanotubes (SWCNT) and pristine Multi-walled Carbon nanotubes (MWCNT), oxidized (O-SWCNT and O-MWCNT) and amide (Amide-SWCNT and Amide-MWCNT). All prepared nanocomposite sheets were characterized using Thermal gravimetric analysis (TGA), Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and scanning electronic microscope (SEM). TGA results measured increased thermal stability of the polymer with the addition of CNTs, O-MWCNT showed the best enhancement. XRD measurements confirmed that the addition of CNTs did not change the crystal structure of the polymer, although the crystallinity was decreased. The maximum crystallinity decrease resulted from O-SWNTs addition to the polymer matrix. SEM imaging showed that oxidized and functionalized CNTs have more even dispersion in the polymer matrix compared with pristine CNTs.

APA, Harvard, Vancouver, ISO, and other styles

24

Nadeem, Muhammad, Asif Anwar, Rahman Ullah, Shakeel Ahmad, and Masroor Ellahi Babar. "Photo-oxidation of Pasteurized Milk in Polyethylene Pouch Packs." Biological Sciences - PJSIR 60, no. 1 (April 1, 2017): 46–48. http://dx.doi.org/10.52763/pjsir.biol.sci.60.1.2017.46.48.

Full text

Abstract:

In the present study photo-oxidative stability of pasteurized milk packaged in polyethylenepouches was investigated. Milk packaged in three layer polyethylene pouch packs was exposed to 400,600 and 800 l´ florescent light at 4 °C for 6 days, compared with a control (stored in dark). Light had apronounced effect on fat content of milk with no effect on protein, lactose and ash content. Photo-oxidativestability of milk decreased as the intensity of light increased, peroxide value, anisidine value and conjugateddienes increased during the storage period of 6 days, higher values were observed in samples exposed to800 l´ florescent light. After 6 days of storage period, milk exposed to 400 l´ florescent light did not revealany oxidized flavour. The results of this study depicted that polyethylene pouches have the capability toresist photo-oxidation up to 400 l´ light.

APA, Harvard, Vancouver, ISO, and other styles

25

Rocha, Magda F. G., Alexandra A. P. Mansur, Camila P. S. Martins, Edel F. Barbosa-Stancioli, and Herman S. Mansur. "Macrophage Response to UHMWPE Submitted to Accelerated Ageing in Hydrogen Peroxide." Open Biomedical Engineering Journal 4, no. 1 (June 10, 2010): 107–12. http://dx.doi.org/10.2174/1874120701004010107.

Full text

Abstract:

Ultra-high molecular weight polyethylene (UHMWPE) has been the most commonly used bearing material in total joint arthroplasty. Wear and oxidation fatigue resistance of UHMWPE are regarded as two important properties to extend the longevity of knee prostheses. The present study investigated the accelerated ageing of UHMWPE in hydrogen peroxide highly oxidative chemical environment. The sliced samples of UHMWPE were oxidized in a hydrogen peroxide solution for 120 days with their total level of oxidation (Iox) characterized by Fourier Transformed Infrared Spectroscopy (FTIR). The potential inflammatory response, cell viability and biocompatibility of such oxidized UHMWPE systems were assessed by a novel biological in vitro assay based on the secretion of nitric oxide (NO) by activated murine macrophages with gamma interferon (IFN-γ) cytokine and lipopolysaccharide (LPS). Furthermore, macrophage morphologies in contact with UHMWPE oxidized surfaces were analyzed by cell spreading-adhesion procedure using scanning electron microscopy (SEM). The results have given significant evidence that the longer the period of accelerated aging of UHMWPE the higher was the macrophage inflammatory equivalent response based on NO secretion analysis.

APA, Harvard, Vancouver, ISO, and other styles

26

WU, Hsiao-Huei, James A. THOMAS, and Jamil MOMAND. "p53 protein oxidation in cultured cells in response to pyrrolidine dithiocarbamate: a novel method for relating the amount of p53 oxidation in vivo to the regulation of p53-responsive genes." Biochemical Journal 351, no. 1 (September 26, 2000): 87–93. http://dx.doi.org/10.1042/bj3510087.

Full text

Abstract:

A novel method was developed to determine the oxidation status of proteins in cultured cells. Methoxy-polyethylene glycol-maleimide MW 2000 (MAL-PEG) was used to covalently tag p53 protein that was oxidized at cysteine residues in cultured cells. Treatment of MCF7 breast cancer cells with pyrrolidine dithiocarbamate (PDTC), a metal chelator, resulted in a minimum of 25% oxidation of p53. The oxidized p53 had an average of one cysteine residue oxidized per p53 protein molecule. The effect of PDTC treatment on downstream components of the p53 signal-transduction pathway was tested. PDTC treatment prevented actinomycin D-mediated up-regulation of two p53 effector gene products, murine double minute clone 2 oncoprotein and p21WAF1/CIP1 (where WAF1 corresponds to wild-type p53-activated fragment 1 and CIP1 corresponds to cyclin-dependent kinase-interacting protein 1). Actinomycin D treatment led to accumulation of p53 protein in the nucleus. However, when cells were simultaneously treated with PDTC and actinomycin D, p53 accumulated in both the nucleus and the cytoplasm. The data indicate that an average of one cysteine residue per p53 protein molecule is highly sensitive to oxidation and that p53 can be efficiently oxidized by PDTC in cultured cells. PDTC-mediated oxidation of p53 correlates with altered p53 subcellular localization and reduced activation of p53 downstream effector genes. The novel method for detecting protein oxidation detailed in the present study may be used to determine the oxidation status of specific proteins in cells.

APA, Harvard, Vancouver, ISO, and other styles

27

Akter, Sharmin, Md Golam Rasul, Mohammad Zakaria, Md Mahathir Sarker, Irin Sultana Nila, Sudipta Dutta, Md Masudul Haque, and Md Motiar Rohman. "Effect of Polyamine on Pigmentation, Reactive Oxidative Species and Antioxidant under Drought in Maize (Zea mays L.)." Turkish Journal of Agriculture - Food Science and Technology 6, no. 7 (May 31, 2019): 799. http://dx.doi.org/10.24925/turjaf.v6i7.799-811.1493.

Full text

Abstract:

To examine polyamines (PAs) effect in modulating the drought induced by polyethylene glycol (PEG) in maize (Zea mays L.) seedlings (variety Khoibhutta, 8 day seedlings grown in petri dish in incubator) were subjected to 20% PEG (polyethylene glycol) followed by 20 µmol PAs, Putrescine (Put), Spermidine (Spd) and Spermine (Spm) with PEG solution for 48 hours. Sharp decrease in Relative Water Content (RWC), Chl a, Chl b, carotenoid (Car) and total pigment content was observed under drought compared to control condition, while PAs application reversed their decreasing trends. PEG significantly increased Reactive Oxidative Species (ROS) [superoxide (O2•−) and H2O2], Methyl Glyoxal (MG), Melondialdehyde (MDA) and Lipoxigenase (LOX) activity, while Pas decreased the contents considerably (except MG) as compared to those under drought. Drought increased proline content, which was further augmented in PA treatments. PAs failed to incline glyoxalase’s (Gly-I and Gly-II) activities, reduced under PEG. The activity and western blot confirmed the accumulation of Glutathione S-Transferase (GST) under drought, but PAs failed to augment the activity. Ascorbic Acid (AsA) and Glutathione (GSH) got oxidized into Dehydroascorbate (DHA) and oxidized Glutathione (GSSG) under drought but PAs effectively maintained homeostasis. Superoxide Dismutase (SOD), Peroxidase (POD), Ascorbate Peroxidase (APX), Glutathione Peroxidase (GPX), Monodehydroascorbatereductase (MDHAR), Dehydroascorbatereductase (DHAR), and Glutathione Reductase (GR) inclined in drought stressed seedlings, while Catalase (CAT) activity decreased under drought. PAs addition increased SOD, POD, GPX, CAT, MDHAR, and GR activities, but declined DHAR activity. These findings suggested important role of PAs in increasing tolerance under short term drought by modulating antioxidant effect.

APA, Harvard, Vancouver, ISO, and other styles

28

Bai, Fu Chen, Chun Xiao Zhang, Xi Yao Zhang, Jian Liu, and Wei Tian. "Photo-Oxidative Degradation of Metallocene Linear Low-Density Polyethylene." Materials Science Forum 610-613 (January 2009): 243–47. http://dx.doi.org/10.4028/www.scientific.net/msf.610-613.243.

Full text

Abstract:

Films of linear-low density polyethylenes, made from metallocene catalyst and Ziegler-Natta catalyst , were exposed to accelerate photo-oxidation conditions. The investigations were focused on the changes of the physical and chemical structures and elongation at break occurring in the photo-oxidation process. The results showed that ethylene-hexene m-LLDPE was more favorer to photo-oxidize than ethylene-octene LLDPE. The other two ethylene-ocetene m-LLDPEs were comparable to LLDPE with the same comonomer. The oxidation rate of LDPE is slower than those of all the LLDPEs.

APA, Harvard, Vancouver, ISO, and other styles

29

Švorčik, Václav, Vladimír Rybka, Oleg Jankovskij, Vladimír Hnatowicz, and Jiří Kvítek. "Electrical resistivity of carbon black loaded polyethylene modified by ion implantation." Journal of Materials Research 9, no. 3 (March 1994): 643–47. http://dx.doi.org/10.1557/jmr.1994.0643.

Full text

Abstract:

Different properties of the mixtures of polyethylene with carbon black modified by the implantation of Sb+ ions were studied. Chemical changes of polymer were examined by IR- and UV-visible spectroscopy. Sheet resistivity as a function of sample temperature was studied. Depth profiles of implanted Sb atoms and incorporated oxygen were determined by the Rutherford backscattering technique. The percolation threshold of unimplanted mixtures is found at 4.5 and 5 wt. % of carbon black. As a result of ion implantation, the polymer is oxidized and conjugated double bonds are produced. The mixtures with carbon black concentration above percolation threshold exhibit metal-like conductivity. For the mixtures below percolation threshold, the measurements of resistivity versus temperature dependence indicate semiconductor type conductivity and charge transport via a variable range-hopping mechanism.

APA, Harvard, Vancouver, ISO, and other styles

30

Zaman, Haydar U., and Dalour Hossen Beg. "Influence of two novel compatibilizers on the properties of LDPE/organoclay nanocomposites." Journal of Polymer Engineering 34, no. 1 (February 1, 2014): 75–83. http://dx.doi.org/10.1515/polyeng-2013-0144.

Full text

Abstract:

Abstract In the present investigation, low density polyethylene (LDPE)/organoclay nanocomposites with various clay contents (1–7 wt%) were prepared via a melt mixing technique, using two different compatibilizers with various contents; low molecular weight trimethoxysilyl-modified polybutadiene (Organosilane) and low molecular weight oxidized polyethylene (OxPE). The effects of incorporation of compatibilizers and clay contents on the mechanical and thermal properties of the nanocomposites were investigated. The dispersibility of silicate clay in the nanocomposites was investigated by transmission electron microscopy (TEM). It was found that organosilane yielded better clay dispersion and a more exfoliated structure compared with the OxPE. Rheological behavior of the samples was examined by a dynamic oscillatory rheometer in the linear viscoelastic region. The organosilane compatibilized system conferred higher tensile strength, yield strength and tensile modulus than those of an uncompatibilized system, and even higher than those of the OxPE compatibilized case. The crystallization behaviors of uncompatibilized and compatibilized nanocomposites were investigated using differential scanning calorimetry (DSC). DSC results indicated that the addition of compatibilizers increased the crystallization temperature (Tc) as a result of heterogeneous nucleation effect of clay on LDPE.

APA, Harvard, Vancouver, ISO, and other styles

31

Xu, Shuang, Song Nuan, and Chang Li Qiu. "Morphology Affects the Stability and Surface Photovoltage of Cu₂O." Advanced Materials Research 534 (June 2012): 160–63. http://dx.doi.org/10.4028/www.scientific.net/amr.534.160.

Full text

Abstract:

The effect of morphology on the stability of Cu2O remains a great challenge. We have synthesized two types of samples in cube crystal structure with about 700 nm by a facile reduction route, which were investigated by X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), Energy- dispersive X-ray (EDX) and surface photovoltage spectroscopy (SPS). It is noteworthy that one sample prepared using polyethylene glycol (PEG) as template was oxidized in air, but another template with glucose was stable in air. The testing results demonstrate that the differences of Cu2O morphology apparently affect its stability. In addition, we analyzed the effect of surface oxidation on the SPV signal of the two samples.

APA, Harvard, Vancouver, ISO, and other styles

32

Matyašovský, Ján, Ján Sedliačik, Peter Šimon, Igor Novák, Peter Jurkovič, Peter Duchovič, Mariana Sedliačiková, Zuzana Cibulková, Matej Mičušík, and Angela Kleinová. "Antioxidation Activity of Cysteine and Cystine Prepared from Sheep Wool." Journal of the American Leather Chemists Association 115, no. 5 (May 1, 2020): 166–75. http://dx.doi.org/10.34314/jalca.v115i5.3810.

Full text

Abstract:

Amino acid cysteine and its oxidized dimer form,?cystine, can be found in hair, nails, hoofs, feather, wool, etc. The main focus of this research was the preparation of cysteine and cystine from wool and testing of its antioxidation properties in the reduced and oxidized forms. Preparation technology was optimized on a laboratory scale and the samples were characterized by FTIR-ATR spectroscopy and X-ray photoelectron spectroscopy (XPS). Antioxidation activity of cysteine and cystine was studied in a?polyethylene glycol (PEG) matrix employing the non-isothermal differential scanning calorimetry (DSC). In the data treatment, the Berthelot-Hood equation was chosen as the temperature function. The kinetic parameters enabled the assessment of the induction period of oxidation for application temperatures. For the comparison of the stabilizing effect, the protection factors and antioxidant efficiency were calculated. The results show that the antioxidant activity of the samples depends on the preparation procedure, purity, etc. Protection factors decreased with increasing temperature and decreasing concentration. In the second part of the study, cysteine was tested in its reduced and oxidized form for the model polycondensation system of the urea-formaldehyde formulations. The quality parameters of these adhesive mixtures were verified on wood-based panels to determine formaldehyde emission and physical and mechanical properties. The results showed ca. 44% decrease of formaldehyde emission and increase of the shear strength of glued joint for all modifications in comparison with?the reference sample.

APA, Harvard, Vancouver, ISO, and other styles

33

Svirko, L., I. Bashtan-Kandybovich, and D. Karamanev. "Experimental Study of Ferrous Iron Biooxidation by Leptospirillum Ferriphilum in Different Biofilm Reactors." Advanced Materials Research 71-73 (May 2009): 263–66. http://dx.doi.org/10.4028/www.scientific.net/amr.71-73.263.

Full text

Abstract:

The process of biological oxidation of ferrous iron by the microorganism Leptospirillum ferriphilum was studied in different types of biofilm reactors. A total of 12 bioreactor types with both fixed and mobile support were used. The biofilm supports used had different shapes and were made of: polyethylene, nylon, polystyrene, polyvinylidene difluoride, polyester, ceramics, carbon and PVC. The pH of the microbial medium was maintained around 1.0, the temperature was 40°C while the influent ferrous iron concentration was 20 g/L. Iron oxidation rates of up to 4.5 g/L/h were obtained. The most efficient were the bioreactors with polyethylene and nylon woven fabric support. However, they oxidized ferrous iron at high rate for relatively short time periods - 40 to 60 days. While the bioreactor with a fixed bed of Raschig rings support had lower iron oxidation rate, their long-term stability was much higher. Of all the biofilm support materials tested, it was found that only polyvinylidene difluoride did not allow the formation of biofilm. Since no significant amounts of jarosite were formed at pH of 1.0 and below, the biofilm formed was very weak mechanically. For that reason the moving support, such as inverse fluidized bed, was not very appropriate because of the high shear stress.

APA, Harvard, Vancouver, ISO, and other styles

34

Zhang, Zhen Ming, Run Lai Li, Shuan Li, Pei Liu, and Kai Kai Song. "Synthesis of 2-Pyridyl Tribromomethyl Sulfone." Advanced Materials Research 781-784 (September 2013): 272–75. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.272.

Full text

Abstract:

Polyethylene glycol-400 was used as phase transfer catalyst in reaction of dichloropyridine and sodium thiomethoxide to form 2-methylthiopyridine with a yield of 97.8%. Then 2-methylthiopyridine and sodium hypochlorite were added respectively to oxidize and bromize it to synthesis 2-Pyridyl tribromomethyl sulfone, with the purity of 99.6% and yield of 93.3%. Mass ratio of dichloropyridine versus polyethylene glycol-400 is 1:0.18, and molar ratio of dichloropyridine versus sodium thiomethoxide is 1:1.2. The optimum conditions to prepare sodium hypochlorite are a temperature at-5 to 0 °C, a molar ratio of bromine versus sodium hydroxide being 1:4. Proved optimum conditions to synthesis 2-pyridyl tribromomethyl sulfone are a temperature at (80±1)°C, reaction time for 5 hours and the molar ratio of 2-methylthiopyridine versus bromine being 1:6.58. Probable mechanism of synthetizing 2-methylthiopyridine was speculated, properties with structure of resultant substances were characterized by melting point apparatus, IR spectra and magnetic resonance spectrum.

APA, Harvard, Vancouver, ISO, and other styles

35

Kamps, Sakurai, Saito, and Nagata. "Comprehensive Data Reduction for N2O/HDPE Hybrid Rocket Motor Performance Evaluation." Aerospace 6, no. 4 (April 17, 2019): 45. http://dx.doi.org/10.3390/aerospace6040045.

Full text

Abstract:

Static firing tests of a hybrid rocket motor using liquid nitrous oxide (N2O) as the oxidizer and high-density polyethylene (HPDE) as the fuel are analyzed using a novel approach to data reduction that allows histories for fuel mass consumption, nozzle throat erosion, characteristic exhaust velocity (c*) efficiency, and nozzle throat wall temperature to be determined experimentally. This is done by firing a motor under the same conditions six times, varying only the burn time. Results show that fuel mass consumption was nearly perfectly repeatable, whereas the magnitude and timing of nozzle throat erosion was not. Correlations of the fuel regression rate result in oxidizer port mass flux exponents of 0.62 and 0.76. There is a transient time in the c* efficiency histories of around 2.5 s, after which c* efficiency remains relatively constant, even in the case of excessive nozzle throat erosion. Although nozzle erosion was not repeatable, the erosion onset factors were similar between tests, and greater than values in previous research in which oxygen was used as the oxidizer. Lastly, nozzle erosion rates exceed 0.15 mm/s for chamber pressures of 4 to 5 MPa.

APA, Harvard, Vancouver, ISO, and other styles

36

Tsai, Stanley, Abraham Salehi, Patrick Aldinger, and Gordon Hunter. "Heat Generation and Dissipation Behavior of Various Orthopaedic Bearing Materials." Key Engineering Materials 309-311 (May 2006): 1281–84. http://dx.doi.org/10.4028/www.scientific.net/kem.309-311.1281.

Full text

Abstract:

It has been shown that with high interfacial temperatures in hip bearings, it is possible to precipitate proteins, greatly reduce the compressive creep properties of ultrahigh molecular weight polyethylene (UHMWPE), and change the phase content of monolithic tetragonal zirconia. These induced features may alter the wear rate of UHMWPE. It was the objective of this study to examine the interfacial temperatures of oxidized zirconium (OxZr) heads as compared with metallic and ceramic heads coupled with polyethylene in a hip simulator. The interface temperatures were measured by placing thermocouples within 0.5 mm of the interface surface of both femoral heads and acetabular liners, and then articulating the surfaces using a 12-station AMTI anatomic hip simulator. The alumina femoral heads had the lowest average interfacial temperature, followed in increasing order by OxZr, CoCr, and zirconia. The ranking corresponds to the thermal conductivity of each material. A statistically significant difference (p<0.05) was found between all four materials for the femoral head temperature. No difference was seen in liner temperature between the alumina and OxZr groups, but statistical differences were found between all other combinations. Additionally, increasing head diameter, peak load, cyclic frequency, and serum concentration all resulted in statistically significant increases in both femoral head and liner temperatures.

APA, Harvard, Vancouver, ISO, and other styles

37

Biale, Greta, Jacopo La Nasa, Marco Mattonai, Andrea Corti, Virginia Vinciguerra, Valter Castelvetro, and Francesca Modugno. "A Systematic Study on the Degradation Products Generated from Artificially Aged Microplastics." Polymers 13, no. 12 (June 18, 2021): 1997. http://dx.doi.org/10.3390/polym13121997.

Full text

Abstract:

Most of the analytical studies focused on microplastics (MPs) are based on the detection and identification of the polymers constituting the particles. On the other hand, plastic debris in the environment undergoes chemical and physical degradation processes leading not only to mechanical but also to molecular fragmentation quickly resulting in the formation of leachable, soluble and/or volatile degradation products that are released in the environment. We performed the analysis of reference MPs–polymer micropowders obtained by grinding a set of five polymer types down to final size in the 857–509 μm range, namely high- and low-density polyethylene, polystyrene (PS), polypropylene (PP), and polyethylene terephthalate (PET). The reference MPs were artificially aged in a solar-box to investigate their degradation processes by characterizing the aged (photo-oxidized) MPs and their low molecular weight and/or highly oxidized fraction. For this purpose, the artificially aged MPs were subjected to extraction in polar organic solvents, targeting selective recovery of the low molecular weight fractions generated during the artificial aging. Analysis of the extractable fractions and of the residues was carried out by a multi-technique approach combining evolved gas analysis–mass spectrometry (EGA–MS), pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS), and size exclusion chromatography (SEC). The results provided information on the degradation products formed during accelerated aging. Up to 18 wt% of extractable, low molecular weight fraction was recovered from the photo-aged MPs, depending on the polymer type. The photo-degradation products of polyolefins (PE and PP) included a wide range of long chain alcohols, aldehydes, ketones, carboxylic acids, and hydroxy acids, as detected in the soluble fractions of aged samples. SEC analyses also showed a marked decrease in the average molecular weight of PP polymer chains, whereas cross-linking was observed in the case of PS. The most abundant low molecular weight photo-degradation products of PS were benzoic acid and 1,4-benzenedicarboxylic acid, while PET had the highest stability towards aging, as indicated by the modest generation of low molecular weight species.

APA, Harvard, Vancouver, ISO, and other styles

38

Li, Jian Xin, Jin Wang, Peng Li, Ya Jun Weng, Ling Ren, Xue Ling Fei, Hong Sun, and Nan Huang. "Ozone-Induced Immobilization of Chitosan and Heparin on Polyethylene Terephthalate Films to Improve Antithrombogenic Properties." Key Engineering Materials 342-343 (July 2007): 809–12. http://dx.doi.org/10.4028/www.scientific.net/kem.342-343.809.

Full text

Abstract:

of artificial blood catheters. This paper describes the immobilization of chitosan and heparin molecules on polyethylene terephthalate (PET) films by ozonization. The concentration of peroxide groups (-OOH) was 1.72 × 10-7 mol/cm2 on the PET surface oxidized by ozonization. The results of X-ray photoelectron spectroscopy (XPS) indicate that chains of chitosan and heparin were successfully immobilized on the PET films. The static contact angle(STA) of water decreases from 83.5° to 68.3° by immobilization of chitosan and heparin, which means that the hydrophilic properties of the modified PET is improved. The antithrombogenic property of PET surface was evaluated by a platelet-rich plasma (PRP) adhesion test. The results indicate that the number of platelet adhered on the modified-PET surface incubated with PRP for 240 min decreased significantly and platelets did not aggregate and distort.

APA, Harvard, Vancouver, ISO, and other styles

39

Oskoueian, Arshin, Khamirul Amin Matori, Saadi Bayat, Ehsan Oskoueian, Farhad Ostovan, and Meysam Toozandehjani. "Fabrication, Characterization, and Functionalization of Single-Walled Carbon Nanotube Conjugated with Tamoxifen and Its Anticancer Potential against Human Breast Cancer Cells." Journal of Nanomaterials 2018 (2018): 1–13. http://dx.doi.org/10.1155/2018/8417016.

Full text

Abstract:

In this experiment, we aimed to fabricate SWCNT conjugated with tamoxifen and evaluated its anticancer potential against human breast cancer cells (MCF-7). The results showed that SWCNT was synthetized successfully using chemical vapor deposition (CVD) method. The results of Raman spectroscopy, SEM, and TEM analyses confirmed the synthesis of highly pure SWCNT. The functionalization of SWCNT was performed by oxidizing of SWCNT, attachment of polyethylene glycol (PEG) to oxidized SWCNT, and attachment of azelaic acid to the polyethylene glycol group. As a result, the SWCNT with free functional carboxylic acid and hydroxyl groups (SWCNT-PEG) was developed. The SWCNT-PEG was then conjugated with tamoxifen (SWCNT-PEG-TAM). The FT-IR together with NMR results confirmed the conjugation of tamoxifen to functionalized SWCNT (SWCNT-PEG-TAM). The cytotoxic concentrations (CC50) of SWCNT-PEG, tamoxifen, and SWCNT-PEG-TAM were >100, 12.67±2.69, and 5.49±1.34μg/ml, respectively. Linking tamoxifen to functionalized SWCNT enhanced the cytotoxic action of tamoxifen against breast cancer cells up to 2.3 times. The results of the morphological examination and caspase-3 activity confirmed the higher cytotoxic action of SWCNT-PEG-TAM as compared to free tamoxifen. The results obtained in this study indicated that this delivery system enhanced the therapeutic effects and anticancer potential of tamoxifen against human breast cancer cells.

APA, Harvard, Vancouver, ISO, and other styles

40

Kombaya-Touckia-Linin, Erland-Modeste, Sébastien Gaucel, Moulay T. Sougrati, Lorenzo Stievano, Nathalie Gontard, and Valérie Guillard. "Elaboration and Characterization of Active Films Containing Iron–Montmorillonite Nanocomposites for O2 Scavenging." Nanomaterials 9, no. 9 (August 23, 2019): 1193. http://dx.doi.org/10.3390/nano9091193.

Full text

Abstract:

Iron particles of sizes between 6 and 20 nm forming aggregates of 57 ± 17 nm were synthesized by chemical reduction of iron precursors on the surface of montmorillonite (MMT). This active MMT-Fe powder was then uniformly distributed in a linear low-density polyethylene (LLDPE) matrix by extrusion at atmospheric conditions, as confirmed by wide-angle X-ray scattering (WAXS), which also detected a partial exfoliation of the nanoclays. Thermogravimetric analysis (TGA) did not detect any significant modification of the degradation temperature between nanocomposites and active nanocomposites. 57Fe Mössbauer spectroscopy evidenced the formation of a majority of iron boride in MMT-Fe as well as in the active film containing it. The LLDPE.Fu15.MMT-Fe3.75 and LLDPE.Fu15.MMT-Fe6.25 films had oxygen-scavenging capacities of 0.031 ± 0.002 and 0.055 ± 0.009 g(O2)/g(Fe), respectively, while the neat powder had an adsorption capacity of 0.122 g(O2)/g(Fe). This result confirms that the fresh film samples were partially oxidized shortly after thermomechanical processing (60% of oxidized species according to Mössbauer spectroscopy). No significant difference in oxygen permeability was observed when MMT-Fe was added. This was related to the relatively small film surface used for measuring the permeability. The reaction–diffusion model proposed here was able to reproduce the observed data of O2 adsorption in an active nanocomposite, which validated the O2 adsorption model previously developed for dried MMT-Fe powder.

APA, Harvard, Vancouver, ISO, and other styles

41

Li, Lijie, Wanrong Gu, Congfeng Li, Wenhua Li, Caifeng Li, Jing Li, and Shi Wei. "Exogenous spermidine improves drought tolerance in maize by enhancing the antioxidant defence system and regulating endogenous polyamine metabolism." Crop and Pasture Science 69, no. 11 (2018): 1076. http://dx.doi.org/10.1071/cp18271.

Full text

Abstract:

Drought stress is a primary abiotic constraint affecting crop production worldwide. In this study, the role of exogenous spermidine (Spd) in conferring drought-stress-tolerance in maize (Zea mays L.) seedlings was studied by analysing polyamine metabolism and the antioxidant defence system. Two maize cultivars, Xianyu 335 (drought resistant) and Fenghe 1 (drought susceptible), were subjected to drought stress (–0.8 MPa) induced by 15% polyethylene glycol 6000 with or without Spd (0.1 mm) application. Spd significantly reduced the inhibition of plant growth and decreased malondialdehyde and hydrogen peroxide contents and the generation rate of oxidised glutathione caused by drought stress, particularly in Fenghe 1. The activities of superoxide dismutase, ascorbate peroxidase and glutathione reductase further increased with the application of Spd to the stressed plants. Application of Spd significantly moderated the drought-induced reduction in activities of monodehydroascorbate reductase and dehydroascorbate and the ratio ascorbate : dehydroascorbate and reduced the ratio glutathione : oxidised glutathione. With the application of Spd, the contents of Spd and spermine and the activities of arginine decarboxylase, S-adenosyl methionine decarboxylase and diamine oxidase increased significantly in the stressed plants, and the increases were greater in Xianyu 335 than in Fenghe 1. Thus, exogenous Spd successfully reduced oxidative damage by enhancing the antioxidant components, raising the redox state of ascorbate and glutathione, and altering the polyamine pool, which play important roles in improving physiological characteristics and drought stress in maize.

APA, Harvard, Vancouver, ISO, and other styles

42

Zhang, Yuanyuan, Zongke Hou, Kangning Wu, Shihang Wang, Jianying Li, and Shengtao Li. "Influence of Oxygen Diffusion on Thermal Ageing of Cross-Linked Polyethylene Cable Insulation." Materials 13, no. 9 (April 29, 2020): 2056. http://dx.doi.org/10.3390/ma13092056.

Full text

Abstract:

Thermal ageing of cross-linked polyethylene (XLPE) cable insulation is an important issue threatening the safe operation of power cables. In this paper, thermal ageing of XLPE was carried out at 160 °C in air for 240 h. The influence of oxygen diffusion on thermal ageing of XLPE was investigated by Ultraviolet–visible spectrophotometer (UV–Vis), tensile testing, and Fourier transformed infrared spectroscopy (FTIR). It was observed that the degradation degree not only depended on ageing time but also on sample positions. The thermally aged samples were more oxidized in the surface region, presented a darker color, more carbon atoms appeared in the conjugate cluster, had smaller elongation at break and tensile strength, and a larger carbonyl index. As ageing time increased, the non-uniform oxidation of the XLPE samples became more prominent. The degree of non-uniform oxidation caused by oxygen diffusion was quantitatively studied by first order oxidation kinetic. The calculated results demonstrated that carbonyl index measured by FTIR was more sensitive to non-uniform oxidation with a shape parameter in the range of 1–2. The result shown in this paper is helpful for interpreting and predicting the non-uniform ageing behavior of high voltage XLPE cables.

APA, Harvard, Vancouver, ISO, and other styles

43

Kérouani, Samira, Ferhat Djerboua, and Tahar Sadoun. "Efficient enhancement in polyethylene biodegradation as a consequence of oxidative fragmentation promoted by pro-oxidant/pro-degradant metal stearate." Journal of Polymer Engineering 38, no. 7 (August 28, 2018): 625–34. http://dx.doi.org/10.1515/polyeng-2017-0265.

Full text

Abstract:

Abstract We report an investigation on the effect of iron and cobalt stearates as pro-degradants and their synergetic effect on the oxidation and subsequently the biodegradation behavior of low density polyethylene (LDPE) film. For this, LDPE films containing different amounts of these additives were prepared and characterized upon exposure to accelerated thermal and photo-oxidation. The analysis shows that the films underwent a significant degradation as monitored by carbonyl index, changes in the crystallinity, in the onset of decomposition temperature and hydrophobicity. The tendency to biodegradation of the oxidized LDPE, with and without pro-oxidant/pro-degradant, was then assessed through the soil burial and the aqueous medium techniques. After an incubation period of 120 days, samples were characterized by means of structural changes and cumulative CO2 emissions. During the incubation in both soil and aqueous medium, the fragmented films with pro-oxidant/pro-degradant showed a significant decrease in oxygenated moieties present initially in the polymer and formed during the accelerated ageing when compared with LDPE without pro-oxidant/pro-degradant, and the biodegradation in the different environment was highly effective following the order LDPE/Co>LDPE/Co/Fe>LDPE/Fe>LDPE and in the range of 13–45% of mineralization after 120 days in aqueous medium and 13–29% in solid medium. These results suggest the role of pro-oxidant/pro-degradant and specially their mixture and the natural environment in oxidation and degradation of LDPE samples and in the mineralization process of oxidized fragments.

APA, Harvard, Vancouver, ISO, and other styles

44

Baxter, Chance, Jena McCollum, and Scott Iacono. "Preparation and Thermal Analysis of Blended Nanoaluminum/Fluorinated Polyether-Segmented Urethane Composites." Journal of Composites Science 3, no. 1 (March 7, 2019): 25. http://dx.doi.org/10.3390/jcs3010025.

Full text

Abstract:

The thermally induced reaction of aluminum fuel and a fluoropolymer oxidizer such as polytetrafluoroethylene (via C-F activation) has been a well-studied thermite event for slow-burning pyrolants among a multitude of energetic applications. Generally, most metallized thermoplastic fluoropolymers suffer from manufacturing limitations using common melt or solvent processing techniques due to the inherent low surface energy and high crystallinity of fluoropolymers. In this report, we prepared an energetic composite utilizing the versatility of urethane-based polymers and provide a comparative thermal characterization study. Specifically, a thermite formulation comprising of nanometer-sized aluminum (nAl) fuel coated with perfluoropolyether (PFPE) oxidizer was solvent-blended with either a polyethylene glycol (PEG) or PFPE-segmented urethane copolymer. Thermal data were collected with calorimetric and thermogravimetric techniques to determine glass transition temperature and decomposition temperature, which showed modest effects upon various loadings of PFPE-coated nAl in the urethane matrix. While our application focus was for energetics, this study also demonstrates the potential to expand the ability to broadly manufacture structural metallized composites to their consideration as coatings, foams, or fibers.

APA, Harvard, Vancouver, ISO, and other styles

45

Li, Ke, Xue Gang Luo, Mian Wang, Fang Wei Qi, Pei Wu, and Qiu Feng Meng. "Low-Temperature Thermocatalytic Degradation of Polyethene Films by Nano-Titanium Dioxide in Water." Materials Science Forum 804 (October 2014): 47–50. http://dx.doi.org/10.4028/www.scientific.net/msf.804.47.

Full text

Abstract:

nanoTiO2powders were utilized as thermocatalyst for catalytic degradation of polyethylene in water. LDPE/TiO2composite films were prepared by the method of melt blending. The aging experiments were conducted in ovens under temperatures of 30 °C, 40 °C and 50 °C, respectively. The thermocatalytic degradation behavior towards the composite films was characterized by fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG) and scanning electron microscopy (SEM). Results show that both pure LDPE films and LDPE /TiO2composite films can be degraded even under low temperatures in water. After thermal degradation for 90 days at 50 °C, the composite film with 2wt% nanoTiO2was oxidized the most acutely: the quantity of branched chains decreased to some extent and lots of small molecules were detected, the decomposition temperature was also reduced by 28.2 °C. Besides, the surface of the films became rougher than that of the film before degradation.

APA, Harvard, Vancouver, ISO, and other styles

46

Currier, Barbara H., Paul J. Hecht, James A. Nunley, Michael B. Mayor, John H. Currier, and Douglas W. Van Citters. "Analysis of Failed Ankle Arthroplasty Components." Foot & Ankle International 40, no. 2 (October 8, 2018): 131–38. http://dx.doi.org/10.1177/1071100718802589.

Full text

Abstract:

Background: Although advances in joint-replacement technology have made total ankle arthroplasty a viable treatment for end-stage arthritis, revision rates for ankle replacements are higher than in hip or knee replacements. The questions asked in this study were what can retrieved ankle devices demonstrate about ankle arthroplasty failures and how can understanding the causes of these failures inform clinical decisions for current and future ankle arthroplasty patients? Methods: An IRB-approved retrieval laboratory received retrieved components and surgeon-supplied reason for revision from 70 total-ankles (7 designs, including 5 currently marketed designs) from 2002 to 2018. These retrievals were rated for clinical wear and damage. Metal components were rated by method and effectiveness of fixation. Polyethylene inserts received by the laboratory 6 months or less after retrieval (n = 45) were analyzed for oxidation using Fourier transform infrared spectroscopy. Statistical analysis was performed using IBM SPSS, version 22. Results: The ankle implants were retrieved most commonly for loosening and polyethylene fracture. Loosening occurred more frequently in fixed-bearing designs (n = 18) than in the mobile-bearing designs (n = 4) and after shorter in vivo time (mean in vivo time to retrieval for loosening: fixed bearing 3.2 ± 2.1 years, mobile bearing 9.7 ± 4.5 years). Gamma-sterilized ankle inserts oxidized at a higher rate than non-gamma (EtO or gas-plasma) sterilized ankle inserts (gamma 0.29 ± 0.22/y, non-gamma 0.07 ± 0.05/y, mean difference=0.215, 95% CI 0.128-0.303, P < .001). The presence of clinical fatigue (cracking and/or delamination) of the polyethylene insert correlated with measured oxidation (Spearman rho = 0.685, P < .001). Nine inserts, all gamma-sterilized, fractured in vivo. Conclusions: This study suggests that loosening could be more of a problem in fixed-bearing devices than in mobile bearing devices. Gamma-sterilized polyethylene inserts were found to suffer fatigue damage or fracture in vivo, resulting in the need for revision. Retrieval analysis can provide insight into implant-related reasons for revision, with the goal of understanding the implant-related causes of these failures, informing future ankle design and clinical decisions for current and future ankle arthroplasty patients. Level of Evidence: Level III, comparative series.

APA, Harvard, Vancouver, ISO, and other styles

47

Huh, Jeongmoo, Botchu V. S. Jyoti, Yongtae Yun, M. N. Shoaib, and Sejin Kwon. "Preliminary Assessment of Hydrogen Peroxide Gel as an Oxidizer in a Catalyst Ignited Hybrid Thruster." International Journal of Aerospace Engineering 2018 (December 30, 2018): 1–14. http://dx.doi.org/10.1155/2018/5630587.

Full text

Abstract:

In regard to propulsion system applications, the stability of liquid propellants in long-term storage is of increasing importance, and this had led to a greater interest in gelation technology. As part of a preliminary test to determine the feasibility of using a gel propellant in a rocket with a catalyst bed, a hybrid rocket with a catalyst reactor using a gel propellant as an oxidizer was tested for the first time in this study. Experiments were conducted with two different oxidizers: one with liquid phase hydrogen peroxide and the other with gel phase hydrogen peroxide, as well as high-density polyethylene as fuel for a 250 N class hybrid thruster performance test. The thruster was designed with the catalyst ignition system, and a catalyst was manufactured to be inserted into the catalyst reactor to facilitate oxidizer decomposition. While the test result with neat hydrogen peroxide indicated sufficient decomposition efficiency using a manganese dioxide/alumina catalyst and successful autoignition of the fuel via the decomposed product, gel hydrogen peroxide exhibited insufficient decomposition and there were difficulties in operating the thruster as a part of the catalyst was covered in the gelling agent. This preliminary study identifies the potential challenges of using a gel phase oxidizer in a catalyst ignited hybrid thruster and discusses the technical issues that should be addressed in regard to a gel propellant hybrid thruster design with a catalyst reactor.

APA, Harvard, Vancouver, ISO, and other styles

48

Zafar, Rabia, Seon Yeong Park, and Chang Gyun Kim. "Comparison of surficial modification of micro-sized polyethylene in between by UV/O3 and UVO submerged system." Environmental Engineering Research 27, no. 3 (March 29, 2021): 210028–0. http://dx.doi.org/10.4491/eer.2021.028.

Full text

Abstract:

This study examined the effects of ozonation and UV applied in series (O3+UV) or simultaneously (UVO) under four different ozone dosages from 4 to 7 mg/min to understand the surface alterations on polyethylene microplastics in aquatic environments via the photochemical oxidation process. The plastic samples were analyzed by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angle measurements. FTIR spectroscopy showed that the levels of carbonyl (ketone and esters) and vinyl groups increased gradually with increasing ozone dose injected; the highest was observed at 6 mg/min of ozone. On the other hand, the levels at 7 mg/min of ozone were slightly lower than those at 4 to 6 mg/min. This could be related to the deeper penetration into the crystalline bulk polymeric chain. The contact angle changed from 125.90˚ to the lowest value of 120.04˚ and 123.8˚ for O3+UV and UVO, respectively. Furthermore, XPS showed that C-O was only presented in the 7 mg/min sample, whereas C-O, OH, C=O, and C-C=O remained for 4 to 6 mg/min. Overall, O3+UV can oxidize the surface of the polyethylene microplastic particles more effectively than those of UVO, irrespective of the ozone dosages.

APA, Harvard, Vancouver, ISO, and other styles

49

Jiang, Qixuan, Zhongyu Li, Ziheng Cui, Ren Wei, Kaili Nie, Haijun Xu, and Luo Liu. "Quantum Mechanical Investigation of the Oxidative Cleavage of the C–C Backbone Bonds in Polyethylene Model Molecules." Polymers 13, no. 16 (August 15, 2021): 2730. http://dx.doi.org/10.3390/polym13162730.

Full text

Abstract:

Recalcitrant plastic waste has caused serious global ecological problems. There is an urgent need to develop environmentally friendly and efficient methods for degrading the highly stable carbon skeleton structure of plastics. To that end, we used a quantum mechanical calculation to thoroughly investigate the oxidative scission of the carbon-carbon (C–C) backbone in polyethylene (PE). Here, we studied the reaction path of C–C bond oxidation via hydroxyl radical in PE. The flexible force constants and fuzzy bond orders of the C–C bonds were calculated in the presence of one or more carbocations in the same PE carbon chain. By comparison, the strength of the C–C bond decreased when carbocation density increased. However, the higher the density of carbocations, the higher the total energy of the molecule and the more difficult it was to be generated. The results revealed that PE oxidized to alcohol and other products, such as carboxylic acid, aldehyde and ketone, etc. Moreover, the presence of carbocations was seen to promote the cleavage of C–C backbones in the absence of oxygen.

APA, Harvard, Vancouver, ISO, and other styles

50

Ahmad, Waqas, Bushra Jabbar, Imtiaz Ahmad, Badrul Mohamed Jan, Minas M. Stylianakis, George Kenanakis, and Rabia Ikram. "Highly Sensitive Humidity Sensors Based on Polyethylene Oxide/CuO/Multi Walled Carbon Nanotubes Composite Nanofibers." Materials 14, no. 4 (February 22, 2021): 1037. http://dx.doi.org/10.3390/ma14041037.

Full text

Abstract:

Polymer composites are favorite materials for sensing applications due to their low cost and easy fabrication. In the current study, composite nanofibers consisting of polyethylene oxide (PEO), oxidized multi-walled carbon nanotubes (MWCNT) and copper oxide (CuO) nanoparticles with 1% and 3% of fillers (i.e., PEO–CuO–MWCNT: 1%, and PEO–CuO–MWCNT: 3%) were successfully developed through electrospinning for humidity sensing applications. The composite nanofibers were characterized by FTIR, XRD, SEM and EDX analysis. Firstly, they were loaded on an interdigitated electrode (IDE), and then the humidity sensing efficiency was investigated through a digital LCR meter (E4980) at different frequencies (100 Hz–1 MHz), as well as the percentage of relative humidity (RH). The results indicated that the composite nanofibers containing 1% and 3% MWCNT, combined with CuO in PEO polymer matrix, showed potent resistive and capacitive response along with high sensitivity to humidity at room temperature in an RH range of 30–90%. More specifically, the PEO–CuO–MWCNT: 1% nanocomposite displayed a resistive rapid response time within 3 s and a long recovery time of 22 s, while the PEO–CuO–MWCNT: 3% one exhibited 20 s and 11 s between the same RH range, respectively.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Oxidised polyethylene wax'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles