Academic literature on the topic 'Chitin nanowhiskers'

This article provides insights into nanowhisker nanofiller particles, different categories of polymer/nanowhisker nanocomposites, and broad span of applications. Nanowhiskers are hierarchical needle-like elementary crystallites, often used as nanofillers in polymers. Cellulose, chitin, zinc oxide, fullerene, and aluminum nitride-based nanowhiskers have been employed in matrices. Inclusion of organic and inorganic nanowhiskers in polymers has enhanced thermal conductivity, electrical conductivity, thermal stability, water resistance, and other physical properties of nanocomposites. Polymer/nanowhisker nanocomposites have found technical applications in supercapacitors, sensors, anticorrosion agents, antibacterial agents, and drug delivery systems. Future research directions for potential applications rely on material design, nanowhisker functionalization, better dispersion, better reinforcement, and better processing techniques.

This study details the fabrication and foaming of melt-blended polylactide (PLA) and chitin composites. The chitin used for compounding was as-received, as chitin nanowhiskers and as chitin nanowhiskers with a compatibilizing agent. The chitin nanowhiskers were produced by an acid-hydrolysis technique and their morphology was examined with transmission electron microscopy. The composite morphology was characterized with scanning electron microscopy and was related to the observed thermal, rheological, and mechanical behaviors of the composites. Chitin was found to decrease the thermal stability of the composites. Addition of chitin was also found to reduce the viscosity of the composites, which is believed to be because of the hydrolysis of PLA during melt blending of chitin in suspension. The stiffness of the composites was found to increase with increasing chitin content while the strength was found to decrease. Porous PLA—chitin composites were produced by a two-step batch-foaming technique, and the expansion behavior was correlated with the visco-elastic observations. The statistical significance of chitin type and composition dependence on the mechanical properties and foam morphologies were evaluated.

A green adsorbent was evaluated to remove the carmine dye. Chitin nanowhiskers were synthesized via acid hydrolyzed method. The diameter of the synthesized chitin whiskers was about 20 nm and had 200 to 400 nm length. The morphology and chemical structure of the synthesized adsorbent were investigated by Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FT-IR), X- Ray Diffraction (XRD). The adsorption process parameters of the carmine dye removal were optimized as follow: adsorption time (3 h), initial carmine dye solution concentration (100 ppm), mass loaded of the chitin whiskers suspension 1% weight of chitin nanowhiskers, as an adsorbent (1.4 g). The removal efficiency of the carmine dye adsorption was about 85% which is modified 15% better than the previous researches. The results indicated that carmine dye molecules were absorbed by hydrogen bonding mechanism due to the N-H bond in the chitin nanowhiskers structure.

Nanochitin and nanochitosan are nanowhiskers combining the structural strength of nanocellulose with the versatile chemistry of chitin/chitosan. We review their fabrication, properties and uses, with a focus on recent progress.

The market share of biodegradable polymers from renewable sources has grown rapidly in the plastic industry. Properties of the polymers from renewable resources can be enhanced through blending and composite formation. Fermented chitin is a by-product in a bacterial prawn waste fermentation for protein recovery which has undergone mild chemical treatment producing treated fermented chitin (TFC). TFC was further acid hydrolysed to produce chitin nanowhiskers (TFCNW). The chitin nanowhiskers was used as filler in polylactic acid (PLA) through solution casting method. Atomic Force Microscopy showed TFCNW particles are uniformly dispersed in PLA matrix but tends to agglomerate as TFCNW loading increased. Tensile strength of the biocomposite film increased up to 12.4 MPa at 2 phr TFCNW which it decreased with further addition of TFCNW. The Young’s modulus increased with increasing of TFCNW content up to 3.69 GPa. However, elongation at break of the biocomposite film decreased by 66 % upon addition of TFCNW when compared to pure PLA.

This study investigates the use of chitin nanowhiskers (CHW) from different chitin sources to develop CHW reinforced polylactic acid (PLA) nanocomposite. Chitin sources used in this study were commercial chitin (CC), fermented chitin (FC) and treated fermented chitin (TFC) whereby FC and TFC were obtained from fermentation of prawn waste. The chitin was then undergoes acid hydrolysis to produce commercial chitin nanowhiskers (CCHW), fermented chitin nanowhiskers (FCHW) and treated fermented chitin nanowhiskers (TFCHW). PLA was chosen due to several advantages such as biodegradability, good mechanical strength and in line with global pressure to improve environmental pollution aspects. Tensile strength for PLA/FCHW, PLA/TFCHW and PLA/CCHW increased with increasing filler content until it reached optimum value at 1 phr, 2 phr and 3 phr, respectively. Young’s modulus for the nanocomposites increased with increasing filler content but elongation at break decreased significantly with increasing filler content for all types of nanocomposites. TGA results indicated that PLA/CHW nanocomposites displayed better thermal stability as compared to pure PLA. The biodegradability and water absorption of nanocomposites increased with increasing filler content.The overall results confirm that PLA nanocomposites from FC are not inferior than PLA nanocomposites from CC and therefore has similar potential to be used in packaging applications. ABSTRAK: Kajian ini menyelidik penggunaan nanowisker kitin (CHW) dari sumber kitin yang berbeza untuk membangunkan komposit poli(asid laktik) (PLA) bertetulang CHW. Sumber-sumber kitin yang digunakan dalam kajian ini terdiri daripada kitin komersial (CC), kitin ditapai (FC) dan kitin ditapai yang dirawat (TFC) di mana FC dan TFC diperoleh daripada penapaian sisa udang. Kitin kemudiannya menjalani proses hidrolisis asid untuk menghasilkan nanowisker kitin komersial (CCHW), nanowisker kitin ditapai (FCHW) dan nanowisker kitin ditapai yang dirawat (TFCHW). PLA dipilih kerana kelebihannya misalnya kebolehan pereputan-bio, kekuatan mekanikal yang baik dan sesuai dengan tekanan global untuk memperbaiki aspek pencemaran alam sekitar. Kekuatanreganganuntuk PLA/FCHW, PLA/TFCHW dan PLA/CCHW meningkat dengan peningkatan kandungan pengisi sehingga mencapai nilai optimum masing-masing pada 1 phr, 2 phr dan 3 phr. Modulus Young bagi komposit nano meningkat dengan peningkatan kandungan pengisi tetapi ciri pemanjangan takat putus menurun dengan ketara dengan peningkatan kandungan pengisi bagi semua jenis komposit nano. Keputusan TGA menunjukkan bahawa komposit nano PLA/CHW memaparkan kestabilan terma yang lebih baik berbanding dengan PLA tulen. Kadar pereputan-bio dan penyerapan air komposit nano meningkat dengan peningkatan kandungan pengisi. Hasil keseluruhan mengesahkan bahawa komposit nano PLA daripada FC tidak lebih rendah daripada komposit nano PLA dari CC dan berpotensi serupa untuk digunakan dalam aplikasi pembungkusan.

Thesis (MSc)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: Polymer composites have been gaining more importance in our daily lives because of the favorable properties that can be provided by these types of material. A polymer composite consists of improved properties when compared to the individual polymers that it is compiled of. The reason that composites are better than the individual polymers is mainly because composites are a combination of all the bene cial properties from the individual materials that was used to make the polymer composite. High impact polypropylene (HiPP) is a complex copolymer that was developed to overcome the restrictions of polypropylene (PP). Although PP have excellent properties at lower temperatures, it loses these advantages at elevated temperatures. High impact polypropylene has a much better impact strength and is processable at high temperatures. High impact polypropylene has been studied in depth for its applications and its superior properties such as an improved impact strength. The tensile properties, after the incorporation of a nano ller, have however not been investigated to our knowledge. Nano llers have reinforcing abilities due to the nano-scale diameters. Particles that have sizes on a nanometer range are mostly devoid of defects. Nano llers that are biopolymers have additional advantages such that can consist of antimicrobial abilities, renewability, biocompatibility and biodegradability. Composites reinforced with chitin nanowhiskers (chnw) have shown to have valuable applications in the latest medical, industrial and environmental developments. Di erent loadings of chnw were incorporated into a HiPP matrix in order to investigate the e ects that this nano ller will have on the tensile properties of HiPP. There were two challenges that required attention during the incorporation of chnw into HiPP. The rst major challenge was the poor interaction that exist between chnw and HiPP due to the hydrophobic nature of the HiPP matrix and the hydrophilic nature of chnw. The second problem was the agglomeration that can occur because of the hydrogen bonding between the chnw that is caused by the structure of the chnw chains. In order to gain the best dispersion of chnw within the HiPP matrix it was necessary to use compatibilizers and di erent methods of incorporation. The two types of compatibilizers that were chosen to improve the compatibility between the HiPP matrix and chnw were polypropylenegraft- maleic anhydride (PPgMA) and poly(ethylene-co-vinyl alcohol)(EVOH). Injection molding is typically used to process HiPP and was chosen as one of the methods for incorporating chnw into the HiPP matrix. A second method of incorporation was used speci cally for the nancomposites containing EVOH known as electrospinning combined with meltpressing. Tensile testing, DSC, TGA and FTIR were used to investigate the changes in the mechanical and thermal properties of the nanocomposites. SEM and TEM were employed to investigate the morphology of the electrospun ber mats and to characterize the chnw. FTIR as well as TGA were used to characterize the chitin nanowhiskers and to identify the individual components within the nanocomposites after incorporation took place. The incorporation of chnw along with the compatibilizer did show improvement in some mechanical properties of the polymer matrix. However, the in uence that each type of compatiblizer had on this e ect varied depending on the content of the chnw and compatibilizer with regards to the polymer matrix.

Biobased polymers are a critical research topic as they may serve as replacement to traditional unsustainable petro-chemical polymers. It is vital to widen its range of applications by improving its physical and mechanical properties via light weighting and strength improvements. Light weighting can be accomplished by introducing foam morphology to the material while mechanical strength improvements can be achieved by inserting stiff filler material to the base polymer to form a composite. This study explores the physical, mechanical, thermal, rheological and morphological properties of blends, foams and composites between biobased PLA and PHBV matrix polymers and biobased chitin nanowhisker filler. It was found that foams produced from PLA and PHBV blends exhibits refined cellular morphology which leads to light weighting and good strength preservation while chitin nanowhiskers was determined to be a very effective filler for mechanical property improvements in both solid and porous materials.