Academic literature on the topic 'Propylene polymer'

The research features a comprehensive study aimed at increasing the technological compatibility of multilayer packaging materials. The paper describes a recycling technology with the prospect of returning the resulting secondary raw materials to the production cycle. The research included the following tasks: to conduct a comprehensive study of polyolefin mixtures modified by ethylene propylene copolymer; to study the effect of the copolymer on the rheological and physicomechanical properties of polymer compositions; to propose a technology for the recycling of secondary polyolefin mixtures. The research involved the following methods: the capillary viscometry method was used to determine the rheological properties of polymer compositions; the tensile test method was employed to define the physicomechanical properties of the compositions; the pycnometric method was used to assess the density of the mixtures. The study featured such polymers as polyethylene, polypropylene, and ethylene-propylene copolymer, which was chosen as a link between the polymers. The authors obtained polymer compositions in various ratios of polyethylene, polypropylene, and ethylene-propylene copolymer: 70:30:0; 68.5:28.5:3; 65:25:10; 30:70:0; 28.5: 68.5: 3; 25:65:10. The article describes the process of modifying polyolefin compositions based on polyethylene and polypropylene by ethylene-propylene copolymer on a single-screw extruder. The authors defined the rheological properties and the deformation-strength characteristics of the polymer mixtures. Repeated processing proved to lead to a decrease in the physicomechanical properties of polyolefin mixtures, with the exception of compositions based on polyethylene and polypropylene in the ratio of 30:70, where the breaking stress increased. The number of processing cycles increased the melt flow rate of the mixtures. The proposed technology is meant for producing multilayer packaging materials using packaging waste in the middle layer for contact with food.

Propane dehydrogenation is a promising route for producing propylene to replace traditional cracking methods. A membrane reactor offers a possibility to produce not only chemical grade but also polymer grade of propylene. The purpose of the present study is to evaluate the performance of a Modified Porous Membrane Reactor (MPMR) in producing these two propylene grades simultaneously. The study involves evaluations based on thermodynamics and process flow sheeting. The performance of this reactor is compared to that of conventional reactor. At first, the thermodynamics is conducted using minimum Gibb's Energy approach. Then the process flow sheeting evaluation is built using the HYSYS simulator. The effect of inert gas (steam) concentration in both sweep and feed sides is investigated. The thermodynamics study results optimum temperature and inert gas concentration to obtain these two grades of propylene simultaneously. The propylene with polymer grade above 99% is produced from the sweep side outlet. The propylene with chemical grade is produced from the feed side outlet. The simultaneous production of these two grades of propylene has benefit in vanishing propane-propylene splitter. Keywords: Membrane reactor, porous membrane, propane dehydrogenation, propylene production, and process simulation.

Abstract Polymer blends of ethylene-propylene elastomers and polypropylene plastics, referred to as thermoplastic olefins, are finding increasing use in automotive applications. The combination of attractive mechanical properties, low raw material cost and recyclability make these materials ideal substitutes for expensive engineering thermoplastics (polycarbonate/polybutylene terephthalate alloys) and nonrecyclable polyurethane systems. The primary application is in automotive bumper fascia. This paper describes the addition of long chain branched ethylene-propylene elastomers in thermoplastic olefin compounds containing a high flow polypropylene resin matrix. In such compounds, the modifier molecular architecture plays an important role in impact toughening. The results clearly indicate that linear modifiers such as traditional ethylene-propylene copolymers are ineffective in impact toughening, while long chain branched polymers provide enhanced impact resistance with a ductile failure mode in high flow polypropylenes.

Purpose This study aims to demonstrate for the first time that the cheap, commodity polymer, poly(propylene), can be successfully processed using high speed sintering, and that it can be recycled several times through the process, with little to no detriment to either the polymer itself or the parts obtained. This is significant as a step towards the realisation of high speed sintering as a technology for high-volume manufacturing. Design/methodology/approach A poly(propylene) powder designed for laser sintering was used to build parts on a high speed sintering machine. The unsintered powder was then collected and reused. Repeating this process allowed creation of seven generations of aged powder. A variety of characterisation techniques were then used to measure polymer, powder and part properties for each generation to discern any effects arising from ageing in the machine. Findings It was found that poly(propylene) could be used successfully in high speed sintering, albeit with a low build success rate. Increased powder age was found to correlate to an increase in the build success rate, changes in microscopic and bulk powder properties and improvement to the dimensional accuracy of the parts obtained. By contrast, no discernible correlations were seen between powder age and polymer molecular weight, or between powder age and the tensile properties of parts. Originality/value This is the first report of the use of poly(propylene) in high speed sintering. It is also first study regarding powder recyclability in high speed sintering, both in general and using poly(propylene) specifically.

Abstract Polyolefin elastomers based on ethylene, propylene, and isobutylene plus other monomers are now widely used in many diverse applications. Major research and development efforts have led to thermoplastic polyolefin soft automobile bumpers, modifiers for lubricating oils, and fast extrusion grades of ethylene–propylene–diene terpolymers. These and other successful commercial innovations depend on the tools of the basic science of structure–property relationships, proper needs assessments, sound engineering, and good management. These tools have been largely provided by my colleagues at ExxonMobil Chemical, customers, and universities and I thank them profoundly. Several historical commercial developments are discussed, including thermoplastic polyolefin elastomers based on ethylene–propylene copolymer–isotactic–polypropylene blends, shear stable viscosity modifiers based on ethylene–propylene copolymers, bimodal molecular weight and compositional distribution EPDM to control rheological characteristics, and diene structure and interchain distribution. In addition, the ongoing research on nanocomposites for tire innerliners based on isobutylene polymers and clay is reviewed. The roles of polymer science, serendipity, and lost opportunity costs on innovation are also discussed.

A set of 16 inexpensive and commercially available polymer precipitants were tested for protein crystallization. Eight of them were found suitable: polyethylene glycol dimethyl ether of molecular weight (MW) 500, 1000 and 2000; di[poly(ethylene glycol)] adipate, MW 900; poly(ethylene glycol-ran-propylene glycol), MW 2500 and 12000; poly(acrylic acid) sodium salt, MW 2100; and polyethylene glycol methyl ether methacrylate, MW 1100. Two new crystallization screens, PolyA and PolyB, were formulated using these eight polymers, each containing 96 solutions – four polymers in combination with 24 common salts and buffers, covering pH values from 4.5 to 9.0. The screens were tested on 29 proteins, 21 of which were crystallized. The tests confirmed the applicability of the eight polymers as precipitants for protein crystallization.

Thesis (PhD)--Stellenbosch University, 2002.
ENGLISH ABSTRACT: Most polypropylene copolymers commercially available have ethylene, and to a lesser degree t-butene as comonomers. Commercially available higher a-olefins, mostly even-numbered, are seldom used for the production of pp copolymers, probably due to cost. Sasol's Fischer- Tropsch oil-from-coal process produces many linear and branched a-olefins as by-products that can be isolated and purified by a relatively cheap refinery process, including the odd-numbered 1- pentene olefin. Sasol's gas-phase Novolen pp plant at Secunda, South Africa is ideally suited to the manufacture of high quality pp random copolymers. As such an opportunity was identified to research the use of higher a-olefins, and more specifically 1-pentene, in the gas-phase production of pp random copolymers. Different methods to produce propylene / 1-pentene random copolymers in the slurry phase on bench-scale were investigated. A procedure was subsequently developed to produce propylene / 1-pentene random copolymers in the gas-phase in 10 litre autoclaves. It was found that commercially available fourth generation supported catalysts successfully incorporated the bulky 1-pentene monomer into the propylene backbone, both during slurry and gas-phase polymerisations. Software modelling was employed to determine the dew points of selected gas mixtures typically found during the production of pp random copolymers. The results indicated that typical process conditions could be employed during the gas-phase polymerisation of propylene and 1-pentene without the risk of condensation taking place inside the reactor. Propylene / 1-pentene random copolymers were subsequently successfully produced on the 800 litre BASF pilot plant in Germany followed by the first commercial production of the copolymer on Sasol's 50m3 Novolen gas-phase plant at Secunda. Using commercially available software the impact of introducing 1-pentene as comonomer during the production of random copolymers on the condenser cooling capacity was evaluated. Feasible and safe plant operating conditions were established for the production of propylene / 1-pentene random copolymers. The relationship between operating pressure and powder morphology was investigated to optimise process conditions. Operating at higher pressure in the gas-phase increases the monomer concentration in the reactor and as such improves the space/time/yield ratio of the 50m3 reactors. It was shown that higher operating pressures could be employed through the introduction of 1-pentene as comonomer during the production of PP random copolymer. The dramatic increase in catalyst productivity observed during the 800 litre pilot plant trials, up to a comonomer ratio of about 5%, supported the results obtained from a kinetic study carried out in bench-scale autoclaves. A comprehensive study was undertaken to compare the rheological, thermal, crystallisation, physical and mechanical properties of propylene / 1-pentene random copolymers with those of commercially available pp random copolymers. A series of propylene homo- and random copolymers with 1-pentene and ethylene as comonomers respectively, was prepared. NMR and IR techniques were developed to facilitate the determination of copolymer composition for the new family of 1-pentene random copolymers. The effect of comonomer content, molecular weight and temperature on the properties of the series of polymers was investigated. The propylene / 1-pentene random copolymers show unique rheological behaviour associated with the short propyl branches in the polymer backbone with minimum zero shear viscosity at about 2% 1-pentene content. The effect of molecular structure changes with comonomer content were analysed by the calculation of square average end-toend distance, packing length, tube diameter, molecular mass between entanglements and critical molecular mass. The viscosity of the 1-pentene random copolymers shows higher shear and temperature sensitivity compared to propylene homo- and ethylene random copolymers. The thermodynamic melting point of the propylene / 1-pentene random copolymers showed a significant decrease with increasing comonomer content in the 0 to 5% range. A wider melting range and higher peak melting point depression rate was observed compared to ethylene random copolymers at similar and increasing comonomer content measured on a weight % basis. It was found that the crystal structure of the propylene / 1-pentene random copolymers contains both the Q- and the y-modifications with the ratio of the respective crystal forms a function of both comonomer content and crystallisation temperature. The glass temperature decreased slightly with increasing comonomer (1-pentene) content. It is proposed that the short branch (propyl) "defects" in the polymer backbone are .incorporated into the crystal lattice resulting in increased rate of melting point depression with increasing (wt%) comonomer content compared to other random copolymers while maintaining relative high stiffness. The propylene / 1-pentene random copolymers exhibit the lowest haze values compared to all commercially available pp random copolymers at corresponding levels of comonomer content on a wt% basis. The stiffness to haze ratio of propylene / 1-pentene random copolymers are unique for all the members of the pp family. An inverse relationship between comonomer content and the measured tensile yield strength and modulus is observed. Application studies conducted on the propylene / 1-pentene random copolymers highlighted several interesting characteristics. Films produced from these copolymers exhibited very low haze and xylene soluble values while maintaining mechanical integrity. In the BOPP application the combination of processability and premium film properties presents a unique opportunity for the family of propylene / 1-pentene random copolymers. Blow moulding and injection moulding trials highlighted several advantages of product properties manufactured with propylene / 1-pentene random copolymers if compared to other commercially available random copolymers. The 1-pentene randoms presented lower in-mould as well as total shrinkage than ethylene based random copolymers. Stabilisation and nucleation studies conducted on the propylene / 1-pentene random copolymers showed that a typical combination antioxidant package and nucleating agent, at normal loading levels, could be used. In the larger pp random copolymer family 1-pentene imparts a better balance of properties than other comonomers. The combination of low melting point and xylene solubles with high stiffness and clarity is unique to propylene / 1-pentene random copolymers.
AFRIKAANSE OPSOMMING: Die oorgrote meerderheid van kommersieel beskikbare polipropileen (PP) kopolimere het etileen, en tot 'n mindere mate buteen, as komonomeer. Die relatief hoë koste van kommersieel beskikbare hoër alfa-olefiene is moontlik die rede waarom hulle selde gebruik word vir die vervaardiging van PP kopolimere. Die Sasol Fischer-Tropsch proses, waartydens olie uit steenkool vervaardig word, lewer verskeie liniêre en vertakte alfa-olefiene as neweprodukte wat geïsoleer en gesuiwer kan word in 'n relatiewe goedkoop rafineringsproses. Dit sluit ook die onewe-koolstofgetal 1-penteen-olefien in. Sasol se gasfase Novolen PP aanleg in Secunda, Suid-Afrika, is besonder geskik vir die vervaardiging van hoë standaard PP statistiese kopolimere. Voortvloeiend hieruit is die geleentheid geidentifiseer om die gebruik van hoër alfa-olefiene, en meer spesifiek 1-penteen, na te vors tydens die gasfaseproduksie van PP statistiese kopolimere. Verskeie metodes om propeleen / 1-penteen statistiese kopolimere in 'n koolwaterstofoplosmiddel op laboratoriumskaal te produseer, is ondersoek. 'n Prosedure is daarna ontwikkel om propileen / 1-penteen statistiese kopolimere ook in die gasfase te vervaardig in 10-liter drukvate. Die bevinding was dat kommersieel beskikbare vierde-generasie ondersteunde kataliste die swaarder 1-penteenmonomeer suksesvol geïnkorporeer het in die propileenketting tydens beide die koolwaterstof oplosmiddel- en gasfase polimerisasiereaksies. Rekenaargebaseerde modellering is gebruik om die kondensasiekondisies van tipiese gasmengsels, teenwoordig tydens die produksie van PP statistiese kopolimere, te bepaal. Die resultate het aangedui dat normale proseskondisies tydens die gasfasepolimerisasie van propileen en 1-penteengeen risiko van kondensasie in die reaktor inhou nie. Propileen / 1-penteen statistiese kopolimere is gevolglik met groot sukses vervaardig by die 800-liter BASF loodsaanleg in Duitsland, gevolg deur die eerste kommersiële vervaardiging van die kopolimeer op die Sasol50m3 Novolen gasfase-aanleg in Secunda. Deur gebruik te maak van kommersieel beskikbare sagteware, is die impak van 1-penteen as komonomeer tydens die vervaardiging van statistiese kopolimere op die verkoelingskapasiteit van die kondensator bepaal. Veilige en uitvoerbare aanlegkondisies is uitgestip vir die vervaardiging van propileen /1-penteen statistiese kopolimere. Die verhouding tussen die reaktordruk en poeiermorfologie is ondersoek om die prosestoestande te optimiseer. Vervaardiging van kopolimere in die gasfase by hoër drukke lei tot verhoogde monomeerkonsentrasie in die reaktor en gevolglik hoër produksiedeursette. Daar is bewys dat tydens die produksie van PP statistiese kopolimere, met 1-penteen as komonomeer, hoër reaktordruk ingespan kan word. Die dramatiese toename in katalisproduktiwiteit waargeneem tydens die 800- liter loodsaanleg proefloop, tot en met 'n komonomeer inhoud van ongeveer 5%, word ondersteun deur die resultate van 'n kinetiese studie uitgevoer in laboriumskaal drukvate. 'n Omvattende studie, om die reologiese, termiese, kristallyne, fisiese en meganiese eienskappe van propileen / 1-penteen statistiese kopolimere te vergelyk met kommersieel beskikbare PP statistiese kopolimere, is uitgevoer. 'n Reeks propileen homo- en statistiese kopolimere, met 1-penteen en etileen as komonomere onderskeidelik, is berei. KMR- en IR- tegnieke is ontwikkel om die bepaling van komonomeersamestelling vir die nuwe familie van 1- penteen statistiese kopolimere te fasiliteer. Die invloed van komonomeersamestelling, molekulere gewig en temperatuur op die eienskappe van die reeks polimere is ondersoek. Die propoleen / 1- penteen statistiese kopolimere toon unieke reologiese eienskappe wat geassosieer kan word met die propielsykettings in die polimeerruggraat. Die viskositeit van die propileen / 1-penteen statistiese kopolimere toon 'n hoër wrywings- en temperatuursensitiwiteit in vergelyking met propileen homo- en etileen statistiese kopolimere. 'n Drastiese verlaging in die termodinamiese smeltpunt van die propileen / 1- penteen statistiese kopolimere met 'n toename in komonomeerinhoud is waargeneem tot en met 'n 5% komonomeerinhoud. Die propileen / 1-penteen statistiese kopolimere toon 'n breër smeltgebied en 'n hoër tempo in die piek smeltpuntafname in vergelyking met etileen statistiese kopolimere met soortgelyke komonomeer inhoud, gemeet op 'n massabasis. Daar is bewys dat die kristalstruktuur van die propileen / 1-penteen statistiese kopolimere beide die alfa en gamma modifikasies bevat. Die verhouding van die onderskeie kristalvorms is 'n funksie van komonomeerinhoud en kristalisasietemperatuur. 'n Afname in die glastemperatuur met verhoogde komonomeer inhoud is waargeneem. Die aanname dat die kort propielsykettings in die polimeerruggraat in die kristalstruktuur geïnkorporeer word, is gemaak. Dit verklaar die hoë afname in die tempo van die smeltpunt met toenemende komonomeer inhoud relatief tot ander statistiese kopolimere, met die handhawing van hoë moduluswaardes. Die besondere deursigtigheid van die propileen / 1-penteen statistiese kopolimere tesame met relatief hoë modulus waardes is uniek. 'n Omgekeerde verhouding tussen komonomeer inhoud en treksterkte asook moduluswaardes is waargeneem. 'n Toepassingstudie uitgevoer met die propileen / 1-penteen statistiese kopolimere het verskeie interessante resultate gelewer. Films vervaardig van hierdie kopolimere toon besonderse deursigtigheid en lae waarde van xileenoplosbaarheid, terwyl meganiese integriteit gehandhaaf word. Voordele in die vervaardigingsproses van BOPP-films asook bogemiddelde filmeienskappe hou unieke moontlikhede vir propileen / 1-penteen statistiese kopolimere in. Verskeie voordele tydens blaas- en spuitvormingsprosesse is waargeneem relatief tot ander beskikbare statistiese kopolimere. Die 1-penteen statistiese kopolimere toon 'n laer in-vorm sowel as totale krimping relatief tot etileen- gebaseerde kopolimere. 'n Studie het aangetoon dat tipiese bymiddelpakette by normale toevoegingsvlakke geskik is vir propileen / 1-penteen statistiese kopolimere. Gesien in die groter pp statistiese kopolimeer familie toon 1-penteen 'n beter balans van eienskappe as ander komonomere. Die kombinasie van laer smeltpunt en xileen-oplosbares met hoë moduluswaardes en helderheid is uniek aan propileen /1-penteen statistiese kopolimere.

Thesis (PhD)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: From the Sasol Fischer- Tropsch process, a variety of different a-olefins are produced. Sasol recently started presenting these a-olefins to polymer producers. To demonstrate the application possibilities of these a-olefins as comonomers for ethylene and propylene polymerization, it was necessary to first synthesize catalysts having a combination of high activity and good comonomer incorporation, and in the case of propylene copolymers, also sufficient stereospecificities. Different methods to produce catalysts conforming to these requirements were investigated and it was found that catalysts produced from a MgCb-support activated by a combination of chemical and mechanical means produced suitable catalysts. The amount of alcohol used during the support activation step and the time allowed for alkylation of the active centers were important. No clear correlation between total titanium content and activity was observed. The degree to which active sites are protected was evaluated from the amount of comonomer present in the final copolymer based on the amount added to the reaction. Cyclopentadiene was used to selectively deactivate the unprotected active sites to determine the ratio between protected and "open" active sites. High activity catalysts are not suitable for gas-phase copolymerization and were consequently "diluted" by dispersion in a pre-formed polymer powder and by prepolymerization. Catalyst activity based on titanium content was substantially decreased, but comonomer incorporation was not. Catalysts for producing crystalline polypropylene require the presence of both an internal and external electron donor. It was shown that isotacticity increased linearly with an increase in external modifier at the expense of catalyst activity and that a double treatment of the support or catalyst before the final TiCl4 fixation was more effective at increasing stereospecificity. The less stereospecific sites are more capable of accepting bulky comonomers in the coordination complex and thus by decreasing the amount of less-stereospecific active sites, the overall capability of the catalyst to incorporate comonomer was decreased. Comonomer sequence distributions and average lamellar thicknesses of different ethylene / a-olefin copolymers were calculated from CH2 dyad concentrations determined by I3C NMR spectroscopy. Ethylene sequences in the I-butene containing copolymers are generally longer than those where a higher a-olefin was used as comonomer which indicates that a more random comonomer distribution is obtained when the higher u-olefins are used. It was shown that an inverse relationship exists between branch size and density. For density, no effect resulting from the comonomer type was observed. This same inverse relationship was also observed for tensile strength. Modulus, hardness and impact strength, on the other hand, did show an effect resulting from the comonomer type. Modulus and hardness were not depressed as much and impact strength improved more than what was expected from calculations based on branch size. Homogeneous copolymers have broad melting peaks. It was shown that at sufficiently high comonomer content, peak broadening occurs when the higher cc-olefins are used as comonomer, which also indicates that more random comonomer distributions are obtained with the higher aolefins. From the chain propagation probabilities calculated it was observed that two types of active sites are present. Those responsible for producing mainly polyethylene have an alternating character while the sites capable of incorporating comonomer have a blocky character. It was expected that the additional introduction of a third a-olefin during ethylene / 1- pentene copolymerization will produce a terpolymer with density and related properties similar to the mathematical average between those of the relevant copolymers. This was only observed for the terpolymers containing l-heptene, 1- octene and l-nonene. The I-butene containing terpolymers have densities well below the expected values while the I-hexene containing terpolymers have values very similar to that of the ethylene / l-hexene copolymer densities, but still below the expected values. Properties related to density, such as tensile strength and modulus, follow this same trend. It is believed that the presence of l-pentene breaks up the tendency of the lower c-olefins to cluster which results in improved randomness. Compared to the copolymers, I-butene and l-hexene containing terpolymers seem to reach the impact strength maximum at a lower total comonomer content than that of the I-pentene copolymers which also indicates an enhanced effect from the combined use of I-pentene with these o-olefins. No substantial difference between impact strengths of co- and terpolymers prepared with higher a-olefins was observed. In general, the melting temperatures of the terpolymers are slightly lower and spread over a wider temperature range than those of the copolymers which can be realized if the comonomer units are less clustered and thus more randomly distributed. Decrease in melting temperature was, however, not as much as for the metallocene catalyzed terpolymers. From sequence length calculations from l3C NMR spectroscopy it was found that the crystallizable ethylene sequences of l-butene containing terpolymers were shorter than those of the corresponding copolymers, which confirms the notion that the introduction of a third comonomer resulted in an increase in randomness. Crystallizable sequence lengths became gradually shorter when higher cc-olefins were used in co- and terpolymers and those of the terpolymers are generally shorter. From the different types of active centers present on a Ziegler-Natta catalyst, it was reasoned that three main types of polymer chains can be present in the terpolymers: (a) ethylene homopolymer, (b) ethylene / lower a-olefin copolymer and (c) ethylene / lower a-olefin / higher a-olefin terpolymer. The ratio between these components in the final terpolymer depends primarily on the size of the higher a-olefin. The larger the third a-olefin becomes, the more active sites will reject it, resulting in a higher amount of ethylene / lower a-olefin copolymer. It was thus suggested that the large decrease in density and the associated change in related properties observed for ethylene / l-pentene / l-butene terpolymers can be related to the combined result of improved random comonomer incorporation together with the decrease in the amount of ethylene homopolymer. The possibilities of using the higher a-olefins having uneven carbon numbers were investigated in random propylene copolymers. Similar to that observed for the ethylene copolymers, less of the higher a-olefins was necessary to achieve a certain level of crystallinity. A good agreement was observed between tensile properties and comonomer type and content and the size of the branch and the resulting defect it causes in the crystal structure is the primary factor affecting tensile strength. For impact strength a close correlation between the size of the comonomer side chain and comonomer content was observed. It was shown that the effect of the heptyl branch derived from a l-nonene unit was 2.3 times that of the propyl group derived from the I-pentene unit. Properties of block copolymers can not be related directly to l-pentene content as is the case with random copolymers, mainly due to the heterogeneity of the block copolymers. The activating effect of hydrogen on catalyst activity was observed. It was also observed that the amount of l-pentene incorporated in the copolymer as well as the copolymer yield were higher in the presence of hydrogen than when the reaction was carried out in the absence of hydrogen. By using DSC it was possible to identify different crystalline phases in the propylene / I-pentene block copolymers due to the differences in their crystallization kinetics. A connection between the low-temperature peak and impact strength was observed. It was found that the presence of the low-temperature peak resulting from thin lamellae formed by chain containing many defects was undesirable when high impact strength is required. It was not possible to quantify the extent to which the intensity of this peak affected mechanical properties of the block copolymers. However, from sequence length calculations it was found that the ratio between the propylene and 1- pentene sequence lengths could be related quantitatively to impact strength, modulus, hardness and tensile strength of the polymers investigated.
AFRIKAANSE OPSOMMING: 'n Verskeidenheid van verskillende «-olefiene word in die Sasol Fischer- Tropsch proses vervaardig. Sasol het onlangs begin om hierdie a-olefiene aan polimeervervaardigers te bied. Om die toepassingsmoontlikhede van hierdie aolefiene as komonomere vir etileen en propileen polimerisasie te demonstreer was dit nodig om eerstens 'n katalis met 'n kombinasie van hoë aktiwiteit en goeie komonomeer invoeging te sintetiseer. In die geval van propileen word voldoende stereospesifisiteit ook vereis. Verskillende metodes om kataliste wat aan hierdie vereistes voldoen te vervaardig is ondersoek. Daar is gevind dat kataliste waarvan die MgCb basis deur 'n kombinasie van chemiese- en meganiese metodes geaktiveer is, die vereiste eienskappe besit. Die hoeveelheid alkohol gebruik tydens die basis aktivering stap en die tyd toegelaat vir die alkilering van die aktiewe spesies was belangrik. Geen duidelike verband tussen totale titaan inhoud en aktiwiteit is waargeneem nie. Die mate waartoe aktiewe spesies beskerm is, is bepaal vanaf die hoeveelheid komonomeer teenwoordig in die finale kopolimeer in verhouding met die hoeveelheid bygevoeg tydens die reaksie. Siklopentadieen is gebruik om onbeskermde aktiewe spesies selektief te deaktiveer om die verhouding tussen beskermde en oop aktiewe spesies te bepaal. Hoëaktiwiteit kataliste is nie geskik vir gasfase kopolimerisasie nie en is gevolglik verdun deur dit te versprei in 'n voorafgevormde polimeer poeier en deur prepolimerisasie. Katalis aktiwiteit gebaseer op titaan inhoud was aansienlik laer maar komonomeer invoeging was nie merkbaar beinvloed nie. Kataliste VIr die vervaardiging van kristallyne polipropileen vereis die teenwoordigheid van beide interne- en eksterne elektron donors. Daar is gewys dat isotaktisiteit liniêr verhoog met 'n toename in eksterne modifiseerder ten koste van katalis aktiwiteit en dat 'n dubbele behandeling van die basis of katalis, voor die finale titaan fiksering, meer effektief was om stereospesifisiteit te verhoog. Die spesies met laer stereospesifisiteit is meer bevoeg om bonkige komonomere in die koërdinasie kompleks toe te laat en deur dus die konsentrasie van hierdie spesies te verlaag is die bevoegdheid van die katalis om bonkige komonomeer te inkorporeer, verlaag. Komonomeer reeksverspreiding en gemiddelde lamellêre dikte van verskillende etileen / o-olefien kopolimere is bereken vanaf CH2 diad konsentrasie bepaal deur KMR spektroskopie. Etileen reekse in die kopolimere wat l-buteen bevat is oor die algemeen langer as dié waarin 'n hoër a-olefien as komonomeer gebruik was, wat aandui dat 'n meer egalige komonomeer verspreiding verkry word as hoër «-olefiene gebruik word. Daar is getoon dat 'n inverse verhouding tussen die grootte van die vertakking en digtheid bestaan. Geen effek komende van die komonomeer tipe kon waargeneem word nie. Hierdie soortgelyke inverse verhouding was ook waargeneem vir treksterkte. Modulus, hardheid en impaksterkte aan die ander kant, hét 'n effek komende van die komonomeer tipe getoon. Modulus en hardheid was nie soveel verlaag, en impak sterkte soveel verhoog as wat verwag is vanaf berekeninge gebaseer op vertakking grootte nie. Homogene kopolimere toon breë smeltpieke. Daar is gewys dat by voldoende komonomeer inhoud 'n verbreding van die pieke voorgekom het wanneer hoër a-olefiene as komonomere gebruik is, wat ook aandui dat 'n meer egalige komonomeer verspreiding met hierdie c-olefiene verkry kan word. Vanaf berekening van die ketting voortplantingsmoontlikhede is waargeneem dat twee tipes aktiewe spesies teenwoordig is. Die verantwoordelik vir die vorming van polietileen het 'n alternerende karakter terwyl die sentra wat komonomeer kan inkorporeer 'n blokagtige karakter het. Daar is verwag dat die addisionele byvoeging van 'n derde o.-olefien tydens etileen / I-penteen kopolimerisasie, 'n terpolimeer met digtheid en verwante eienskappe soortgelyk aan die wiskundige gemiddelde tussen dié van die relevante kopolimere tot gevolg sal hê. Dit was egter slegs waargeneem vir terpolimere wat I-hepteen 1- okteen en l-noneen bevat. Die I-buteen bevattende terpolimere het digthede ver onder die verwagte waardes terwyl die I-hekseen bevattende terpolimere waardes soortgelyk aan die etileen / l-hekseen kopolimeer digthede het' wat steeds onder die verwagte waardes is. Eienskappe verwant aan digtheid, soos treksterkte en modulus, volg dieselfde neiging. Dit word geglo dat die teenwoordigheid van l-penteen die neiging van die laer a-olefiene om saam te bondelopbreek wat 'n verbeterde egaligheid in komonomeerverspreiding tot gevolg het. Vergeleke by die kopolimere blyk dit dat die terpolimere wat l-buteen en I-hekseen bevat, die impaksterkte maksimum by 'n laer totale komonomer inhoud bereik as dié van die 1-penteen polimere. Dit dui ook op 'n verbeterde effek as gevolg van die gekombineerde gebruik van l-penteen met ander a-olefiene. Geen duidelike verskil tussen die impaksterktes van ko- en terpolimere, wat met die hoër a-olefiene berei was, is waargeneem me. In die algemeen is die smeltingstemperature van die terpolimere effens laer, en versprei oor 'n wyer temperatuurgebied as dié van die kopolimere wat verklaar kan word as komonomere minder saamgebondel is en dus meer homogeen versprei is. Die afname in smelt temperatuur was egter nie soveel as dié van die metalloseengekataliseerde terpolimere nie. Vanaf reekslengte berekeninge met behulp van KMR spektroskopie is daar gevind dat die kristalliseerbare etileen reekse van die l-buteen bevattende terpolimere korter was as dié van die ooreenkomstige kopolimere, wat die gevoel dat die byvoeging van 'n derde komonomeer 'n verbeterde komonomeerverspreiding tot gevolg het, bevestig. Vanaf die verskillende aktiewe spesies teenwoordig in 'n Ziegler-Natta katalis is daar geredeneer dat drie hooftipes polimeerkettings in die terpolimere teenwoordig kan wees: (a) etileen hompolimeer, (b) etileen / laer a-olefien kopolimeer en (c) etileen / laer a-olefien / hoër a-olefien terpolimeer. Die verhouding tussen hierdie komponente in die finale terpolimeer hang primêr van die grootte van die hoër aolefien af. Hoe groter die derde a-olefien is, deur hoe meer van die aktiewe spesies sal dit verwerp word wat 'n groter hoeveelheid etileen / laer a-olefien kopolimeer tot gevolg sal hê. Daar word dus voorgestel dat die groot afname in digtheid en die geassosieerde veranderings in die toepaslike eiensappe waargeneem vir etileen / 1- penteen / I-buteen terpolimeere, herlei kan word na die gekombineerde effek van verbeterde komonomeerverspreiding tesame met die afname lil die hoeveelheid etileen homopolimeer. Die moontlikheid om hoër cc-olefiene met onewe koolstofgetalle te gebruik in homogene propileen kopolimere is ondersoek. Soortgelyk aan dit wat waargeneem is vir die etileen kopolimere, was minder van die hoër cc-olefiene nodig om 'n spesifieke vlak van kristalliniteit te bereik. 'n Goeie ooreenkoms tussen trek-eienskappe en . komonomeer tipe- en inhoud is waargeneem en die grootte van die vertakking en die gevolglike defek wat dit veroorsaak in die kristal struktuur is die primêre faktor wat treksterkte beinvloed. Vir impaksterkte is 'n noue verband tusssen die grootte van die vertakking en komonomeer inhoud waargeneem. Daar is aangetoon dat die effek van die heptiel vertakking vanf die l-noneen eenheid 2.3 keer dié van die propiel groep van die l-penteen eenheid is. Eienskappe van blok kopolimere kan nie direk na l-penteen inhoud herlei word soos die geval met die homogene kopolimere was nie, hoofsaaklik as gevolg van die heterogeniteit van die blok kopolimere. Die aktiverende effek van waterstof op katalis aktiwiteit is waargeneem. Daar is ook gesien dat die hoeveelheid l-penteen geïnkorporeer in die kopolimeer, sowel as die kopolimeer opbrengs, hoër was in die teenwoordigheid van waterstof as wanneer die reaksie sonder waterstof uitgevoer is. Deur DSC te gebruik was dit moontlik om verskillende kristallyne fases in die propileen / l-penteen blok kopolimere vanaf die verskille in hulle krisallisasie kinetika, te identifiseer. 'n Verbintenis tussen die lae-temperatuur piek en impaksterkte is waargeneem. Daar is gevind dat die teenwoordigheid van die laetemperatuur piek, komende van die dun lamellas gevorm, deur kettings wat baie defekte bevat, ongewens is wanneer hoë impaksterkte vereis word. Dit was nie moontlik om die bereik waartoe die intensiteit van hierdie piek die meganiese eienskappe van die blok kopolimere affekteer, te kwantifiseer nie. Vanaf reekslengte bepalings is daar gevind dat die verhouding tussen die propileen en I-penteen reekslengtes kwantitiatief herlei kan word na impaksterkte, modulus, hardheid en treksterkte van die ondersoekte polimere.

Thermoplastic elastomer is one of the priority polymeric compound identified for promotion and further development, given the growing demand for a number of commercial industries such as automobile, construction, footwear, healthcare, medical and food packaging sectors. In this study polypropylene (PP)/ethylene propylene diene monomer (EPDM) based thermoplastic elastomers are preferred for improving their properties as it can serve as a good replacement for PP or EPDM material, bridging the gap between thermoset and thermoplastic materials. This study focuses to develop PP/EPDM which can resist changes or improve properties when exposed to E-beam radiation, as E-beam also offers sustainable sterilization at low cost. The PP/EPDM blends with mixing ratios of 80/20, 50/50 and 20/80 were melt blended with the process parameters optimized using Design of experiments (DOE). The effect of E-beam on mechanical properties, thermal stability, crystallization and dynamic mechanical properties over the dose of 0 to 100 kGy were studied. The blends with high EPDM content (20PP/80EPDM) showed improvement in tensile strength up to 36% (at 40kGy and 60kGy) and resistant to impact strength up to 100 kGy, at the expense of elongation at break. On the other hand, the blends with high PP content (80 PP/20 EPDM and 50 PP/50 EPDM) showed detrimental effects on mechanical properties at all radiation dose studied and found to be not compatible for E-beam sterilization. Further, ethylene vinyl acetate (EVA) was incorporated to PP/EPDM blends at 10EVA/40EPDM/50PP, 20EVA/30 EPDM/50PP, 30EVA/20 EPDM/50PP and 40EVA/10 EPDM/50PP ratios. The gel content analysis showed that the efficiency of crosslinking decreased with increase in EVA loading. However, the presence of EVA in ternary blend especially facilitated the induction of sufficient crosslinks leading to improvement in tensile strength (up to 29% at 60 kGy), impact strength (up to 15% at 80 kGy) and retention of stiffness and thermal properties under radiation at the expense of elongation at break. In order to develop antibacterial ternary blends, silver nanoparticles (AgNP) were added by varying the loading from 0.3wt% to 1wt%. The Ag-ternary blends showed enhancement in impact properties (up to 9%) at the expense of decrement in tensile properties due to the agglomeration of AgNP. When, exposed to E-beam radiation, the mechanical and thermal properties exhibited similar trend of increment and decrement across radiation dose similar to the blends without AgNP. While, 1% Ag blend composites showed bacteriostatic effect on Staphylococcus aureuson, no significant reduction of Pseudomonas aeruginosa bacteria was observed. All the blends, before and after sterilization showed no significant toxicity on HaCaT cells investigated using in vitro analysis. Thus, the blends showed an instinct that their application could be extended to manufacturing of healthcare products and food packaging sector, as they are biocompatible and can withstand E-beam sterilization as demanded by the respective application. Among all the blends ternary blends studied (that exhibited biocompatibility even after radiation), 20EVA/30EPDM/50PP without AgNP showed the highest tensile strength of 18.41 MPa and impact strength of 43.64 J/m. Only a slight increase in tensile and impact properties was witnessed upon addition of 20% EVA to PP/EPDM blend in comparison to the binary blend (50PP/50EPDM blend). However, unlike the binary blend (whose properties decreased upon radiation), the ternary blend (20EVA/30EPDM/50PP) showed improvement in tensile strength up to 29% at 60kGy and up to 15% increase in impact strength at 80kGy.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2006.
Propylene/1-pentene random copolymers are a relatively new family of random copolymers being prepared by Sasol Polymers and reveals high impact strength, good tensile properties, excellent optical properties, good rheological properties and a large pool of processing possibilities. These commercial copolymers are being prepared with stereospecific heterogeneous Ziegler-Natta catalytic systems containing multiple active sites and therefore producing copolymers with a varying degree of stereoregularity. Two different groups of propylene/1-pentene random copolymers were received by Sasol Polymers and investigated in this project. The first group (Group 1, Polymers A - F) consisted of six totally different batches of commercial propylene/1-pentene copolymers which were produced by different catalyst systems. All had different melt flow indices (MFIs) and different 1-pentene contents and all of the copolymers, except for one, were nucleated. The second group (Group 2, Polymers G - J) were produced by the same catalyst, but with varying donor:catalyst ratios and also differing in their 1-pentene content. Investigation of the Group 1 copolymers was used in order to construct a “molecular toolbox” which was then used to study the Group 2 copolymers. The original commercial copolymers were all studied by various analytical techniques: high-temperature carbon thirteen nuclear magnetic resonance spectroscopy (13C-NMR), high-temperature gel permeation chromatoghraphy (HT-GPC), crystallization analysis fractionation (CRYSTAF), differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and positron annihilation lifetime spectroscopy (PALS). The random copolymers were all fractionated by preparative TREF and the fractions analyzed utilizing the following analytical techniques: 13C-NMR, HT-GPC, CRYSTAF and DSC. The results of these analyses were used to investigate inter alia the distribution of 1-pentene in the copolymers. In order to investigate the low molecular weight material of the copolymers, which were part of the room temperature fraction during TREF, solvent extractions were carried out using different solvents and different extraction techniques. A complete structural analysis study was carried out on the extracts. The percentages of xylene-solubles were also determined during the quantitative xylene extraction study of the copolymers. Characterization of the xylene non-soluble material was carried out using 13C-NMR, HT-GPC, CRYSTAF, DSC and WAXD in order to compare the properties of the unextracted copolymers with the material after removal of the xylene soluble fraction. Positron annihilation lifetime spectroscopy (PALS) was used as an alternative investigation method for the Group 1 copolymers and their XNS fractions in order to determine what type of information this novel analytical method could generate and how the results compared with those of previous PALS studies on poly-olefins. A new fractionation technique, preparative solution fractionation (SF), was developed and evaluated. The commercial propylene/1-pentene copolymers were fractionated using this novel technique, the fractions were analyzed by 13C-NMR, HT-GPC, CRYSTAF and DSC and the results were compared with previously existing fractionation methods, namely TREF and CRYSTAF. A final study was done on the random copolymers by blending one of the commercial Ziegler-Natta catalyzed propylene/1-pentene copolymers with a tailored, low 1-pentene content, metallocene propylene/1-pentene copolymer in different ratios. The blends were analyzed by molecular weight, thermal and crystal phase analysis in order to investigate the effect of the tailored, highly isotactic propylene/1-pentene copolymer on the properties the commercial random copolymers. Throughout the project the influence of the 1-pentene as well as the donor:catalyst ratio on the copolymers was investigated. This study, in its entirety, therefore allow a better understanding of the effects that the commercial, heterogeneous, transition metal catalysts have on the make up of the copolymers and, by extension, the ultimate properties of the materials.

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: Impact polypropylene copolymers (IPPC) are important commercial materials, but their morphology and molecular architecture are not yet fully understood. In this study the focus was on selectively removing specific fractions from the original IPPC, recombining the remaining fractions, and studying the properties of these recombined polymers. It was found that some properties of the samples changed remarkably, depending on the fraction of material that was removed before recombination. For example, the degree of phase separation and the crystalline morphology of the recombined materials varied noticeably. During the study an effective way of staining samples for transmission electron microscopy (TEM) was developed. Furthermore, a comparison of fourier transform infrared spectroscopy (FTIR), with TEM and scanning electron microscopy (SEM) results, revealed a hitherto unreported relationship between phase separation. Absorption bands appeared at 1100 cm-1 and 1080 cm-1 in the FTIR spectra and appear to be an indication of phase separation. It was further established that specific copolymer fractions present in the original polymer affect not only the morphology of the final polymer, but also the hardness and impact resistance.
AFRIKAANSE OPSOMMING: Impak polipropileen kopolimere (IPPK) is belangrike kommersïele materiale, maar die kennis met betrekking tot die morfologie en molekulere argitektuur van die materiale is nog gebrekkig. Tydens hierdie studie was die fokus op die selektiewe verwydering van spesifieke fraksies van die oorspronklike IPPK, herkombinering van die oorblywende fraksies, en die studie van die eienskappe van hierdie herkombineerde polimeriese materiale. Daar is gevind dat sommige van die eienskappe van die herkombineerde materiale daadwerklik verskil van die oorspronklike materiaal, en dat die verskille direk verband hou met die spesifieke fraksie wat uit die oorspronklike materiaal verwyder is. Die mate van fase-skeiding asook die kristal-morfologie van die herkombineerde materiaal het opmerklik verskil van die oorspronklike. Tydens die studie is n effektiewe manier ontwikkel om die materiale te vlek vir transmissie elektron-mikroskopie (TEM). Verder is daar ‘n verband tussen die resultate verkry deur Fourier Transform infrarooi spektroskopie (FTIS) en die verkry met TEM en skandeer elektron mikroskopie (SEM) vasgestel. Die verwantskap tussen FTIS en fase-skeiding is tot dusver nie in die wetenskaplike literatuur vermeld nie. Meer spesifiek is daar gevind dat absorbsie-bande sigbaar by 1100 cm-1 en 1080 cm-1 in die FTIS spektra ‘n aanduiding van fase skeiding kan wees. Dit was verder vasgestel dat spesifieke kopolimeer fraksies wat teenwoordig is in die oorspronklike IPPK, nie alleen die morfologie van die materiaal beinvloed nie, maar ook die hardheid en impak-weerstand van die materiaal.

Thesis (DSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006.
Commercial polyolefins degrade under the influence of light, heat, chemical and mechanical factors. They are therefore stabilised to ensure that they maintain performance characteristics during their service life. Degradation results in changes in the molar mass, molar mass distribution, chemical composition and chemical composition distribution. Classical analytical techniques only provide averaged values of these properties. Much information is available in the open literature on the changes in molar mass, molar mass distribution and chemical composition of polypropylene upon degradation, but no information was available on the changes in chemical composition distribution (CCD) during degradation. This study describes the use of the following analytical techniques to study this: temperature rising elution fractionation (TREF), crystallisation analysis fractionation (CRYSTAF) and coupled size exclusion chromatography-Fourier transform infrared analysis (SEC-FTIR). The CRYSTAF results complimented those obtained by classical techniques: there was a broadening of the crystallisation peak (CCD), an increase in the soluble fraction and a decrease in crystallisation temperatures. SEC-FTIR analysis showed that most of the degraded products were concentrated in the low molar mass regions. TREF analysis was used to separate a degraded sample into fractions of different degrees of degradation. It was then possible to study the spatial heterogeneity in a thick, degraded polypropylene sample using SEC, FTIR and CRYSTAF. The degradation behaviour of selected Sasol propylene-1-pentene random copolymers was investigated. CRYSTAF, SEC-FTIR and TREF analyses provided information on the thermo-oxidative degradation behaviour differences between unstabilised polypropylene homopolymers and these propylene-1-pentene copolymers. It was found that the pentene copolymers degraded significantly faster compared to the homopolymers, even at low levels of pentene (< 3%). The reduction in stability was virtually linear with an increase in pentene content (up to 8 mol% pentene), indicating that higher levels of primary stabilisers are needed to ensure similar life spans for the Sasol propylene-1-pentene copolymers. The extrusion stability of the propylene-1-pentene copolymers was, however, similar to that of the polypropylene homopolymers, indicating that similar processing stabiliser packages may be used.

Thesis (PhD)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Heterophasic copolymers (also known as HECO polymers) or often referred to only as impact copolymers or block copolymers comprise a polymer matrix with a dispersed rubbery copolymer phase. The polymer under investigation in this study consists of a polypropylene homopolymer matrix and ethylene-propylene copolymers (EPCs). Due to its diverse range of applications and unique properties, polypropylene is the choice of polymer for a vast array of applications. This has led to the development of an entire class of polypropylene materials known as visbroken or controlled rheology polypropylene. By adding a suitable peroxide to the polymer in the presence of heat, radicals are formed which will attack the polymer chains in a random fashion. The resultant polymers generally have a higher melt flow rate (MFR), a narrower molecular weight distribution than the parent polymer, and good impact-stiffness balance. The main focus of this investigation was to determine if there exist any differences in the molecular structure and physical properties of controlled rheology HECO polymers and if differences do exist, how they influence the physical characteristics of the polymer. Eight HECO polymers with equal ethylene contents were visbroken to varying degrees by making use of two different types of organic peroxide. The effects of the amount of visbreaking on the molecular characteristics and physical properties were subsequently studied by making use various types of fractionation techniques, including preparative temperature rising elution fractionation (PTREF) and crystallisation analysis fractionation (CRYSTAF). Subsequent offline analysis was then done on the fractionated samples that included nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), high temperature size exclusion chromatography (HT-SEC), Fourier transform infrared spectroscopy (FTIR) and deposition of the SEC fractions via the LC Transform Interface (SEC-FTIR) as well as high temperature high performance liquid chromatography (HT-HPLC), a novel technique for the characterization of olefins according to their chemical composition.
AFRIKAANSE OPSOMMING: Heterofase kopolimere, ook bekend as HECO polimere, of dikwels na verwys net as impak kopolimere of blok kopolimere bestaan uit 'n polimeer matriks met 'n verspreide rubberagtige kopolimeer fase. Die polimeer wat in hierdie studie ondersoek was het bestaan uit 'n polipropileen homopolimeer matriks en etileen-propileen kopolimere (EPCs). As gevolg van sy veelseidigheid van toepassings en unieke eienskappe is polipropileen die keuse van polimeer vir 'n wye verskeidenheid van toepassings. Hierdie veelseidigheid het gelei tot die ontwikkeling van 'n hele klas van polipropileen materiaal bekend as gevisbreekte of beheerde reologie polipropileen. Deur die byvoeging van 'n geskikte peroksied tot die polimeer in die teenwoordigheid van hitte, word radikale gevorm wat die polimeerkettings in 'n ewekansige wyse sal aanval. Die gevolglike polimere in die algemeen het 'n hoë smelt vloeitempo (MFR), 'n smaller molekulêre gewig verspreiding as die moeder polimeer, en 'n goeie impak/styfheid balans. Agt HEKO polimere met gelyke etileen inhoude was gevisbreek in wisselende hoeveelhede deur gebruik te maak van twee verskillende tipes organiese peroksiedes. Die gevolge van die hoeveelheid van visbreeking op die molekulêre eienskappe en fisiese eienskappe was vervolgens gebestudeer deur gebruik te maak van verskillende fraksionasie tegnieke, insluitend preparatiewe TREF (P-TREF) en CRYSTAF. Daaropvolgende analiese is gedoen op die gefraktioneerde monsters en sluit in kernmagnetiese resonansie spektroskopie (KMR), differensiële skandeer kalorimetrie (DSC), 'n hoë temperatuur grootte uitsluitings chromatografie (HT-SEC), Fourier transform infrarooi spektroskopie (FTIR) met deponeering van die SEC fraksies via die LC transform koppelvlak (SEC-FTIR) sowel as 'n hoë temperatuur hoë werkverrigting vloeistof chromatografie (HT-HPLC), 'n nuwe tegniek vir die karakterisering van olefiene volgens hul chemiese samestelling.

The article is devoted to the evaluation of frost resistance of a propylene-ethylene block copolymer used as an insulating material for cable products. The standard method for testing the frost resistance of a polymer material is a drop weight impact test on insulated core samples at low temperatures. To check this parameter at the stage of incoming polymer control, it is proposed to use the method of dynamic mechanical analysis (DMA). As a result of experimental studies by the DMA method, a criterion for evaluating the frost resistance of a block copolymer of propylene with ethylene was established

We report improved performance of Li-ion polymer batteries through advanced gel polymer electrolytes (GPEs). Compared to solid and liquid electrolytes, GPEs are advantageous as they can be fabricated in different shapes and geometries; also ionic properties are significantly superior to that of solid and liquid electrolytes. We have synthetized GPE in form of membranes by trapping ethylene carbonate and propylene carbonate in a composite of polyvinylidene fluoride and N-methylpyrrolidinore. By applying phase-transfer method, we synthetized membranes with micro-pores, which led to higher ionic conductivity. The proposed membrane is to be modified further to have higher capacity, stronger mechanical properties, and lower internal resistance. In order to meet those requirements, we have doped the samples with gold nanoparticles (AuNPs) to form nanoparticle-polymer composites with tunable porosity and conductivity. Membranes doped with nanoparticles are expected to have higher porosity, which leads to higher ion mobility; and improved electrical conductivity. Four-point-probe measurement technique was used to measure the sheet resistance of the membranes. Morphology of the membranes was studied using electron and optical microscopies. Cyclic voltammetry and potentiostatic impedance spectroscopy were performed to characterize electrochemical behavior of the samples as a function of weight percentage of embedded AuNPs.

The variation of the microstructure within the thickness of moulding plates of two semicrystalline polymers, an isotactic Poly-Propylene and a Poly-Butylene Terephtalate, was observed by optical microscopy technique. These observations allowed specifying the different zones of iso-microstructure within the plate thickness, commonly called “skin zone”, “shear zone”, “post filling zone ”and“ core zone”in terms of crystallite size and zone thickness. The variation of the melting temperature was then analysed by using a local thermal analysis method based on the scanning thermal microscopy technique in each of these zones. Our results show the expected link between the local microstructure and the polymer melting temperature. They also highlight a strong coupling between the microstructure, the material and its processing conditions.

It is difficult, if not impossible to quantify LCB in polymers using rheological test methods only. Most of the reported rheological methods are affected by polymer characteristics other than LCB (Molecular weight Distribution (MWD), polymer microstructure, polymer type etc…). Poly-Propylene samples having different level of LCB produced by reactive extrusion with Per-Oxi-Dicarbonate have been characterised at strain ratios between 2.5 and 10. Stress signal distortion has been found to be sensitive only to the presence and level of LCB and not to Average Molecular Weight (AMW) and MWD. Quantification of the signal distortion was performed using Fourier transform rheology. As linear visco-elasticity equations are not applicable to LAOS, the approach of Giacomin and Dealy was applied. This considers the stress signal as a Fourier series and enables the calculation of G′n and G″n. LCB has a strong effect on both G′n and G″n, on their ratio and especially on G′ from the first harmonic (G′1). Repeatability data (CV) on G′1 and G″1 shows excellent sensitivity (&lt;1%). The technique has been successfully applied to commercially available elastomers (BR and EPDM) enabling comparisons based on LCB level irrespectively of the AMW and MWD. Rapid graphical differentiation between linear and non linear polymers is achieved with stress/strain rate curves (Lissajou figure). The development of this technique provides polymer suppliers and their customers the ability to rapidly assess variations in Long Chain Branching, essential for incoming material and/or production control.