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When oppositely-charged polymers are mixed in water they self-assemble into polyelectrolyte complexes (PECs). These complexes have numerous technological applications that require control over their shape. To this end, we show how PEC geometry can be tailored through photodirected assembly. A commonly-used weak polycation, poly(allylamine) (PAH), was co-dissolved in a basic solution (significantly...
Results of measurements of dynamic mechanical and physical properties of the ionic polymer, based on carboxylated nitrile rubber (XNBR) neutralized by zinc oxide (ZnO), reveal that ammonia works as an ionic plasticizer. Accordingly, the main chain transition is little affected but the high temperature transition due to ionic aggregates, as observed in dynamic mechanical measurements, disappeared after...
Precipitated silica improves the physical properties of a zinc-sulfonated ethylene-propylene-diene terpolymer (SEPDM) of high (i.e. 75 wt%) ethylene content. The properties studied include hardness, stress-strain characteristics, tear strength, abrasion resistance and hysteresis. Processability studies carried out by using the Monsanto Processability Tester (MPT) show that silica increases the melt...
Zinc sulfonated EPDM of high (75 wt%) ethylene content behaves as an ionic thermoplastic elastomer. Diethylene glycol plasticizes the ionic domains of zinc sulfonated EPDM, without affecting the hydrocarbon backbone. Studies include measurement of physical properties, processability studies in a Monsanto processability tester (MPT), dynamic mechanical analyses (d.m.a.) and dielectric thermal analyses...
Blends of the zinc salt of poly(ethylene-co-methacrylic acid) (ZnEMA) and the zinc salt of sulfonated ethylene-propylene-diene monomer rubber (SEPDM), show thermoplastic elastomeric behaviour. The physical properties of the blends are greater than that predicted by the additivity rule. Results of dynamic mechanical analyses show ionic transitions in addition to T g in the case of neat polymers...
Incorporation of up to 30 phr of high abrasion furnace (HAF) carbon black into a thermoplastic elastomer of composition 100 phr maleated EPDM rubber, 10 phr ZnO, 1 phr stearic acid and 30 phr zinc stearate, improves its physical properties like modulus and tear resistance. While the glass-rubber transition temperature (T g ) of the thermoplastic elastomer occurring around -37°C remains unaltered...
Results of dynamic mechanical studies and measurements of physical properties of the ionic polymer based on carboxylated nitrile rubber (XNBR) and zinc oxide (ZnO) reveal that dioctylphthalate (DOP) plasticizes the backbone chain of the polymer, while dimethylsulfoxide (DMSO) plasticizes the hard phase arising from the ionic aggregates. Accordingly, the high-temperature ionic transition in the plot...
Epoxy networks based on N,N,N ,N -tetraglycidyl-4,4 -diamino diphenylmethane (TGDDM) prepolymer were prepared with cis-1,2,3,6-tetrahydrophthalic anhydride (THPA) curing agent at anhydride/epoxy group ratios varying from 0.3 to 1.0. For post-cured mixtures, dynamic mechanical tests show that the glass transition temperature reaches the maximum value at stoichiometric ratios between 0.8 and 0.9...
Zinc sulfonated ethylene-propylene-diene terpolymer (EPDM) behaves as an ionic thermoplastic elastomer. Both paraffin oil and dimethyl sulfoxide (DMSO) act as plasticizers for this polymer; while paraffin oil plasticizes the hydrocarbon backbone, DMSO plasticizes the ionic domains. Results obtained from dynamic mechanical analysis (d.m.a.) show that DMSO does not affect the glass-rubber transition...
An unsaturated polyester resin was cured with different catalyst contents. The crosslinking process was followed by static and dynamic viscosimetry and by differential scanning calorimetry (d.s.c.). Activation energies were determined from the gel times obtained by viscosimetry and from the variation in the maximum exotherm temperature obtained by d.s.c. at different heating rates. The existence...
Incorporation of up to 20 phr of precipitated silica filler into a thermoplastic elastomer of composition 100 phr maleated EPDM rubber, 10 phr zinc oxide, 1 phr stearic acid, 30 phr zinc stearate, results in an improvement of physical properties such as modulus, tensile strength and tear resistance. While the glass-rubber transition temperature (T g ) of the thermoplastic elastomer occurring...
Interactions of carbon black with nitrile rubber (NBR) and carboxylated nitrile rubber (XNBR) were studied by measurements of bound rubber, physical and dynamic mechanical properties of the vulcanizates and Monsanto rheometric studies on the rubber-filler mixes. Compared with NBR, XNBR shows a higher degree of interaction with the filler and oxidation of the filler surface increases the extent of...
High abrasion furnace carbon black improves the physical properties of zinc sulfonated ethylene-propylene-diene terpolymer of high (75 wt%) ethylene content. Properties studied include hardness, stress-strain characteristics, tear strength, hysteresis and abrasion resistance. Scanning electron photomicrographs of the tear fractured and abraded surfaces show changes in failure mode of the polymer...
Blends of polychloroprene (CR) and epoxidized natural rubber (ENR) are crosslinked during high temperature moulding for a prolonged time. As studied by dynamic mechanical spectroscopy, the 30 CR/ENR-50 blend is miscible and its miscibility is unaffected by the incorporation of high abrasion furnace carbon black filler. The 50 CR/ENR-50 blend is miscible, but its miscibility is adversely affected...
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