Editing Polystyrene (section)

==== Styrene-butadiene rubber ====
{{main article|Styrene-butadiene}}

Styrene-butadiene rubber (SBR) is produced like PS-I by graft copolymerization, but with a lower styrene content. Styrene-butadiene rubber thus consists of a rubber matrix with a polystyrene phase dispersed therein.<ref name="Pfropfcopolymere">{{cite web|title=PS-Pfropfcopolymere auf chemgapedia.de|url=http://www.chemgapedia.de/vsengine/vlu/vsc/de/ch/9/mac/werkstoff_polystyren/sorten/sorten.vlu/Page/vsc/de/ch/9/mac/werkstoff_polystyren/sorten/copolymere/sb/pfropfcopolymere.vscml.html}}</ref> Unlike PS-I and SBC, it is not a [[thermoplastic]], but an [[elastomer]]. Within the rubber phase, the polystyrene phase is assembled into domains. This causes physical cross-linking on a microscopic level. When the material is heated above the glass transition point, the domains disintegrate, the cross-linking is temporarily suspended and the material can be processed like a thermoplastic.<ref>{{cite web|title=styrenic block copolymers – IISRP|url=https://iisrp.com/wp-content/uploads/08SBC16Aug2012.pdf}}</ref>