Styrene copolymers, thermal properties

SAN gives improved toughness, resistance to solvents and crazing, good thermal properties, while retaining the transparency of the polymer. Upon increasing the concentration of acrylonitrile in styrene copolymer some properties are enhanced except for workability. SAN is more improved in properties than PS and hence competes (in price or performance) with acrylics and cellulose-acetate (except for weatherability). 

Styrene is a colorless Hquid with an aromatic odor. Important physical properties of styrene are shown in Table 1 (1). Styrene is infinitely soluble in acetone, carbon tetrachloride, benzene, ether, / -heptane, and ethanol. Nearly all of the commercial styrene is consumed in polymerization and copolymerization processes. Common methods in plastics technology such as mass, suspension, solution, and emulsion polymerization can be used to manufacture polystyrene and styrene copolymers with different physical characteristics, but processes relating to the first two methods account for most of the styrene polymers currendy (ca 1996) being manufactured (2—8). Polymerization generally takes place by free-radical reactions initiated thermally or catalyticaHy. Polymerization occurs slowly even at ambient temperatures. It can be retarded by inhibitors. 

It has been found that the incorporation of a MMBS polymer into a composition containing a PC resin and a copolymer of MA and styrene facilitates the production of molded articles over a wide range of molding conditions without deleteriously affecting the strength or the thermal properties of the molded articles (4). 

Each set of experiments was carried out under the same reaction condition except using different comonomers, i.e. p-methylstyrene, o-methylstyrene, m-methylstyrene and styrene, respectively. The compositions of copolymers were determined by H NMR spectra, and the thermal properties (melting point and crystallinity) were obtained by DSC measurements. Overall, all comonomers show no retardation to the catalyst activity. In fact, the significantly higher catalyst activities were observed in all copolymerization reactions (runs 2-5), comparing with that of ethylene homopolymerization (run 1). Within each set (runs 2-5 and 6-9) of comparative experiments, p-methylstyrene consistently shows better incorporation than the rest of comonomers, i.e. o-methylstyrene, m-methylstyrene and styrene. Both catalysts with constrained mono- and di-cyclopentadienyl ligands are very effective to incorporate p-methylstyrene into polyethylene backbone. In runs 2 and 6, more than 80 % of p-methylstyrene were converted to copolymer within one hour under constant (- 45 psi) ethylene pressure. On the other hand, only less than half of styrenes (runs 5 and 9) were incorporated into ethylene copolymers under the same reaction conditions. The significantly... 

Thermal properties of some butadiene-styrene copolymers. J. 

Incorporation of monofunctional epoxy POSS into an amine-cured epoxy network increased and broadened the Tg without changing the crosslink density and enhanced the thermal properties. Additionally, it was found that the thermal and thermal-mechanical properties of resultant styrene-POSS vinylester resin nanocomposites were dependent on the percentage of POSS incorporated into the resin [171]. Over a range of POSS incorporations, the Tg of the copolymers changed very little, but the flexural modulus increased with increasing POSS content. 

Some other interesting copolymers having properties of PVC thermal stabUizers, like poly[Af-(a-benzothiazolonylmethyl)methacrylate-co-methyl methacrylate] [45], of flame retardants like a terpolymer of styrene, acrylonitrile and a polymerizable perbrominated phenol [76] or poly[4-methacryloyloxy-2,3,5,6-tetrabromobenzyldi-phenyl phosphonate-co-methyl methacrylate] [104] (93), bioddes, mostly copolymers of monomers containing tris(n-butyl tin) or triphenyl tin moieties and alkyl acrylates, methacrylates, vinyl acetate, acrylonitrile, styrene or A-vinylpyrrolidone [105], e.g. a terpolymer of styrene, MMA and tri(n-butyl tin) itaconate [106] (94),... 

Predesigned particles of impact modifiers are based on core-shell technology. Core is involved in impact modification and shell improves adhesion between PVC and impact modifier particles.Three major combinations are used methacrylate-butadiene-styrene, MBS, which has a core made out of butadiene-styrene copolymers and shell made out of methylmethacrylate-styrene copolymer, acrylic impact modifiers, AIM, which have a core made out of acrylic and shell from polymethylmethacrylate, and silicone-acrylic have multilayer structures with silicone-acrylic in the core. MBS has excellent compatibility with PVC, similar to ABS, which is used as an impact modifier of PVC, as well. In both cases of ABS and MBS, weather resistance is lacking, therefore they are used for indoor applications only. At the same time, MBS gives translucent to crystal clear products, whereas with AIM, only translucent products are possible. In order to improve optical properties of AIM, it has to be reformulated. For transparent products, the core is made out of acrylic-styrene copolymers. Comparing silicone and all acrylic impact modifiers, PVC containing silicone-based products has superior low temperature impact properties. The incorporation of silicone into an acrylic impact modifier provides excellent weatherability, and thermal stability. It has shown improved retention of impact after outdoor weathering in PVC. ... 

Chem. Descrip. 2-Hydroxy-4-n-octyloxybenzophenone CAS 1843-05-6 EINECS/ELINCS 217-421-2 Uses UV absorber, light stabilizer for rigid and flexible PVC, PS, styrenic copolymers, olefin copolymers, epoxy resins, polyesters, LDPE, HOPE, propylene, adhesives, coatings Regulatory DOT nonregulated SARA 313 nonreportable Properties SI. yish. ctyst. powd. odorless insol. in water dens. 1.16 g/ ml vapor pressure 5.6 x 10 mm Hg (20 C) m.p. 47 C flash pt. > 200 C thermal decomp. > 350 C 99-100% act. 

Before irradiating a polymer, two kinds of additives could be incorporated. The first kind is that of radical scavengers (like hydroquinone, and more generally aromatic additives). Chen et al. studied the effect of four different aromatic additives on the radiation resistance of 60/40 styrene-ethylene/ butylene-styrene copolymer (SEBS)-PS blends. Considering the changes in mechanical properties, thermal stability and volume resistivity, pyrene was found the most efficient additive and diphenylacetylene (DPA) the worst. The authors concluded that the best protection effect could be attributed to... 

F-2016 is a brominated epoxy oligomer with around 50% bromine and a molecular weight of 1600 designed to ensure optimal properties in styrenic copolymers. Brominated epoxy oligomers offer a combination of high flame retardant efficiency, UV stability, good mechanical properties and thermal stability. They are non-blooming due to their physicochemical properties and polymeric... 

PPE is not miscible with SMA containing as much as 28 % MA (Witteler et al. 1993). To compatibilize these two resins, Koning et al. (1993b, 1996) have added a monoamine-terminated PS that can form a graft copolymer with SMA. Since the amine-terminated PS is miscible with PPE, compatibilized PPE-SMA blends are obtained. Specifically, 30 parts of unfunctionalized PPE was blended (internal mixer at 220 °C, or mini-SSE at 280 °C, or TSE at 326 °C) with 56 parts SMA (28 % MA) and 14 parts amine-functionalized PS. The blend was characterized by TEM, SEM, mechanical and thermal properties, DMA, and GPC copolymer detection. The effect of pre-reacting amine-terminated PS with SMA was studied. The blend properties were compared to those for uncompatibilized blends. Blends were also made containing ABS -i- SEBS. Eurther examples of compatibilizing copolymer formation in PPE-styrene copolymer blends are shown in Table 5.43. 

It was reported that styrenic copolymer/poIyacetal/TPU systems also have good processability and a beneficial combination of physical and chemical properties, including thermal/dimensional stability, impact resistance, chemical resistance, and creep resistance. The polymer blends are suitable for use in the preparation of a variety of molded utilitarian articles having good appearance and printability [39]. TPU/PS blends have found suitable applications as adhesive [40]. 

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