Polystyrene or styrene copolymer blends

Table 5.52. Crosslinked copolymer formation in PO/polystyrene or styrene copolymer blends...

Polyolefin + Polystyrene or Styrene Copolymer Blends (Including Polypropylene)... 

Examples of photothermoplasts include polyacrylates, polyacrylamides, polystyrenes, polycarbonates, and their copolymers (169). An especially well-re searched photothermoplast is poly(methyl methacrylate) (PMMA), which is blended with methyl methacrylate (MMA) or styrene as a monomer, and titanium-bis(cyclopentadienyl) as a photoinitiator (170). 

PVC can be blended with numerous other polymers to give it better processability and impact resistance. For the manufacture of food contact materials the following polymerizates and/or polymer mixtures from polymers manufactured from the above mentioned starting materials can be used Chlorinated polyolefins blends of styrene and graft copolymers and mixtures of polystyrene with polymerisate blends butadiene-acrylonitrile-copolymer blends (hard rubber) blends of ethylene and propylene, butylene, vinyl ester, and unsaturated aliphatic acids as well as salts and esters plasticizerfrec blends of methacrylic acid esters and acrylic acid esters with monofunctional saturated alcohols (Ci-C18) as well as blends of the esters of methacrylic acid butadiene and styrene as well as polymer blends of acrylic acid butyl ester and vinylpyrrolidone polyurethane manufactured from 1,6-hexamethylene diisocyanate, 1.4-butandiol and aliphatic polyesters from adipic acid and glycols. 

When only spectroscopic methods are used, they are able to identify polymer components with respect to their chemical nature. However, in many cases, they are unable to answer the question whether two chemical structures are combined to yield a copolymer or a blend or both. For example, analyzing a rubber mixture one is able to identify styrene and butadiene as the monomer units. However, using FTIR or NMR it is impossible to decide if the sample is a mixture of polystyrene (PS) and polybutadiene (PB),or a copolymer of styrene and butadiene, or a blend of a styrene-butadiene copolymer and PB. For the latter case, even the copolymer composition cannot be determined just by running a FTIR or NMR spectrum. 

Polystyrene is one of the most widely used thermoplastic materials ranking behind polyolefins and PVC. Owing to their special property profile, styrene polymers are placed between commodity and speciality polymers. Since its commercial introduction in the 1930s until the present day, polystyrene has been subjected to numerous improvements. The main development directions were aimed at copolymerization of styrene with polar comonomers such as acrylonitrile, (meth)acrylates or maleic anhydride, at impact modification with different rubbers or styrene-butadiene block copolymers and at blending with other polymers such as polyphenylene ether (PPE) or polyolefins. 

Halogenated styrenes can form a number of copolymers, some used in blends with polystyrenes or other polymers. Examples of such copolymers are poly(o-chloro-styrene-co-p-chlorostyrene), polystyrene-co-poly(2-chlorostyrene) [14], poly(methyl acrylate-co-4-chlorostyrene), etc. A few studies on thermal behavior of these polymers are available [15, 16]. 

REDOR was also applied to examine the structure and dynamics of interfaces of heterogeneous polymer blends. A heterogeneous blend was prepared from [carbonyl- C]polycarbonate and poly(p-fluorostyren-co-styrene) copolymer of p-fluorostylene. The blend was formed by coprecipitation from chloroform into methanol. A fluorine dephased REDOR signal indicates that the 1 polycarbonate chain in 20 exists at the interface, suggesting that the polycarbonate phase is embedded in a continuous polystyrene matrix which is 200 A thick or 400 A in diameter [54],... 

Styrene-butadiene copolymers are often blended with other polymers. Transparent blends can be made with styrene, styrene-acrylonltrlle copolymers, or styrene-methyl methacrylate copolymers. Blends with styrene have low impact strength even at low styrene levels, while blends with styrene-methyl methacrylate copolymers can have greatly Improved impact strength. Blends with high impact polystyrene, polypropylene, and polycarbonate are opaque. 

Summary. Copolymers based on ethylene and styrene are a novel class of polymers exhibiting unique combinations of material attributes that are not found in polyethylenes, polystyrenes, or their blends. These copolymers offer unique opportunities for innovative developments in basic polymer chemistry, catalyst and process development, materials science and engineering, and application technology. 

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