Styrenic thermoplastic vulcanizates

The following TPs are the main thermoforming materials processed high-impact and high-heat PS, HDPE, PP, PVC, ABS, CPET, PET, and PMMA. Other plastics of lesser usage are transparent styrene-butadiene block copolymers, acrylics, polycarbonates, cellulosics, thermoplastic elastomers (TPE), and ethylene-propylene thermoplastic vulcanizates. Coextruded structures of up to seven layers include barriers of EVAL, Saran, or nylon, with polyolefins, and/or styreneics for functional properties and decorative aesthetics at reasonable costs.239-241... 

Examples of vulcanizable elastomers include natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), ethylene-propylene-diene monomer-rubber (EPDM), butyl rubber (HR), polychloroprene or neoprene (CR), epichlorohydrin rubber (ECO), polyacrylate rubber (ACM), millable polyurethane rubber, silicone rubber, and flu-oroelastomers. Examples of thermoplastic elastomers include thermoplastic polyurethane elastomers, styrenic thermoplastic elastomers, polyolefin-based thermoplastic elastomers, thermoplastic polyether-ester (copolyester) elastomers, and thermoplastic elastomers based on polyamides. 

The worldwide annual production of thermoplastic elastomers of all types is estimated at about 2,500,000 metric tons in 2005 [47] with a value of almost 12 billion. Production is expected to rise to about 4,200,000 metric tons in 2014 [48]. This is equivalent to an annual growth rate of about 5.3%. In 2009, North America consumed about 25% of this amount. Western Europe about 20%, and China about 33%. Japan and other Asia/Pacific countries accounted for most of the rest. The styrenic block copolymers represented about 45% of the total market and polypropylene/EPDM or EPR combinations (including thermoplastic vulcanizates) about another 30%. The thermoplastic polyurethanes and the thermoplastic polyesters together made up another 20% [48]. Major end uses are transportation, footwear, industrial goods, wire insulation, medical (growing very rapidly), adhesives, coatings, and so on. 

The use of thermoplastic olefins or TPOs is growing at a faster rate than the styrenic block copolymers (SBC) just discussed, or the thermoplastic vulcanizates (TPVs), which are discussed in the next section. The TPO growth rate is currently about 10% annually worldwide. Unlike the SBCs, certain TPOs can sometimes be used at higher service temperatures. Unlike the TPVs (which are derived through dynamic vulcanization), the TPOs are usually used uncured or are only very slightly vulcanized, if at all. This means that the TPOs are usually less costly than the TPVs. The TPOs have been very successful in the automotive industry in replacing the soft polyvinyl chloride compounds used in car interiors. TPOs are commonly available in softness ranges from 60 Shore A to 60 Shore D. A major use for TPOs is in the manufacture of automotive fascias, where appearance is very important. 

OBCs are advantaged in their eapability to retain oil when compared to Polyolefin Elastomers of similar density and Ml, and can therefore deliver lower hardness compounds ( 20 Shore A). This is hypothesized to be due to the OBC block structure wherein the blocks of amorphous segments may allow for more swelling and oil incorporation. Oil-filled OBCs also show decreased compression set at both room temperature and elevated temperature, which is again attributed to their imique block structure. These combined benefits expand Ae application range of OBC compounds to include markets currently served by high performance thermoplastic elastomers, such as styrenics block copolymers (SBCs), thermoplastic urethanes (TPUs) and thermoplastic vulcanizates (TPVs). 

Anandhan, S., De, P.P., Bhowmick, A.K., Bandyopadhyay, S., and De, S.K., Thermoplastic elastomeric blend of nitrile rubber and poly(styrene-co-acrylonitrile). n. Replacement of nitrile rubber by its vulcanizate powder, J. Appl. Polym. Set, 90, 2348, 2003. 

Thermoplastic elastomers (TPEs), which combine the elastic response like rubber vulcanizates with the processability of thermoplastics, are becoming one of the industrially important polymeric materials [60-62]. The morphology control by processing conditions is a key issue to improve mechanical properties of TPEs. Therefore, the effects of processing conditions on morphology and microscopic mechanical properties ofpoly(styrene-fe-ethylene-co-butylene-fc-styrene) (SEES) triblock copolymer, one of the most widely used TPEs, is investigated by nanomechanical mapping [45]. 

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