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Styrene Content (styrene + content)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Copolymerization of norbornene and styrene catalyzed by a novel anilido,imino nickel complex/methylaluminoxane system

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2006
Haiyang Gao
Abstract Copolymerizations of norbornene with styrene were carried out with a catalytic system of anilido,imino nickel complex (ArNCHC6H4NAr)NiBr (Ar = 2,6-dimethylphenyl) and methylaluminoxane in toluene. The influence of the comonomer feed content and polymerization temperature on the conversion and composition of the copolymers with (ArNCHC6H4NAr)NiBr/methylaluminoxane was investigated. An increase in the initial styrene feed content led to an increase in the incorporated styrene content of the resulting copolymer. The determination of the reactivity ratios showed a much high reactivity for norbornene (reactivity ratio for styrene = 0.26, reactivity ratio for norbornene = 20.78), which was consistent with a coordination mechanism. NMR analysis of the end groups further confirmed that the chain was initiated through a styrene secondary insertion or a norbornene insertion into NiH and terminated through ,-H elimination from an inserted styrene unit. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5237,5246, 2006 [source]

Copolymerization of ethylene with styrene catalyzed by a linked bis(phenolato) titanium catalyst

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2006
Carmine Capacchione
Abstract Copolymerization of ethylene with styrene, catalyzed by 1,4-dithiabutanediyl-linked bis(phenolato) titanium complex and methylaluminoxane, produced exclusively ethylene,styrene copolymers with high activity. Copolymerization parameters were calculated to be rE = 1.2 for ethylene and rS = 0.031 for styrene, with rErS = 0.037 indicating preference for alternating copolymerization. The copolymer microstructure can be varied by changing the ratio between the monomers in the copolymerization feed, affording copolymers with styrene content up to 68%. The copolymer microstructure was fully elucidated by 13C NMR spectroscopy revealing, in the copolymers with styrene content higher than 50%, the presence of long styrene,styrene homosequences, occasionally interrupted by isolated ethylene units. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1908,1913, 2006 [source]

Tailoring viscoelastic and mechanical properties of the foamed blends of EVA and various ethylene-styrene interpolymers

POLYMER COMPOSITES, Issue 3 2003
I-Chun Liu
Foamed materials (EVA/ESI) have been prepared from blends of ethylene-vinyl acetate copolymer (EVA) and ethylene-styrene interpolymers (ESI) in the presence of various amounts of dicumyl peroxide (DCP). Four ESIs of different compositions were employed in this study; their styrene contents ranged from 30 to 73 wt% and their Tg ranged from ,2 to 33°C. It has been found that microcellular morphology, degree of crosslinking and expansion ratio were strongly affected by the DCP concentration and the type of ESI employed. A minimum degree of crosslinking was required for making good foams and the same degree of crosslinking could be achieved by employing a smaller amount of DCP for an EVA/ESI blend having a higher styrene content. In contrast to other EVA blends, such as EVA/LDPE, these EVA/ESI blends exhibited no existence of any optimum DCP concentration, and the , glass transition temperatures of the foams varied with the ESI type, covering a wide span from 0°C to 37°C. Therefore, it was possible to tailor the Tg of an EVA/ESI blend by choosing an appropriate type of ESI. Furthermore, by correctly tailoring the Tg, the EVA/ESI foam could be made into a rubbery material with a custom-designed damping factor. Tensile strength and modulus of the EVA/ESI foams increased generally with an increase in the styrene content, with the exception that ESIs with very low styrene content will confer on the blend a high modulus at small strain and a large elongation at break. [source]

Effects of rubber type on the curing and physical properties of silica filled rubber compounds

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2008
Chung Ho Shin
Abstract As environmental regulations are getting stricter, tire industries for automobiles have shown much interest in substituting silica for conventional carbon black partially or entirely. To take full advantage of silica as fillers for rubbers, it is essential to find a reasonable rubber system that shows an excellent performance with silica reinforcement. Therefore, in this study, several different rubber compounds comprising the same amount of silica were prepared with several different rubber systems, respectively. The processability, curing characteristics, and mechanical and viscoelastic properties of the rubber compounds were investigated to analyze the performance of the rubber compounds as tire tread materials. Among the rubber compounds studied, SBR1721 compound comprising natural rubber (NR) and styrene butadiene rubber (SBR) with high styrene content was considered the most appropriate for application to tire tread materials. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Preparation and Characterization of Styrene Butadiene Rubber Based Nanocomposites and Study of their Mechanical Properties

ADVANCED ENGINEERING MATERIALS, Issue 9 2004
S. Sadhu
Nanocomposites were prepared from styrene butadiene rubber (SBR) having different styrene contents and octadecyl amine modified Na-montmorillonite clay (OC). The modified and the unmodified clays were characterized with the help of X-ray diffraction technique (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Transmission Electron Microscopy (TEM). All these nanocomposites were then subjected to tensile testing. The modified clay-rubber nanocomposites showed improved tensile strength (55% increase) and elongation at break (76% increase) compared to those of the gum vulcanizates. [source]