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Block copolymers of polycarbonates with several hydroxy‐terminated elastomers to yield thermoplastic elastomers for higher service temperature
Author(s) -
Memon Nazir A.,
Williams H. Leverne
Publication year - 1973
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1973.070170505
Subject(s) - thermoplastic elastomer , materials science , copolymer , elastomer , composite material , polybutadiene , glass transition , morphology (biology) , monomer , thermoplastic , ultimate tensile strength , polymer , polymer chemistry , biology , genetics
The synthesis of block copolymers and the study of their morphology were undertaken to find improved thermoplastic rubbers for service at elevated temperatures. The basis was the extraordinary properties possessed by ABA‐type block copolymers in which the terminal blocks are polystyrene and the central block is either polyisoprene or polybutadiene. In these systems it has been well established that the unusual properties are a result of domain formation in which the hard and the soft blocks aggregate separately into distinct phases. The hard segment is thought to act both as a crosslink and as a filler. Block copolymers were synthesized with different soft and hard segments. The effects of these segments and of their properties on the morphology and the stress‐strain properties of the block copolymers were measured and evaluated. Electron microscopy and birefringence were used to determine the morphology. It was found that the glass transition temperatures of the segments, the bulk of the monomer unit in the glassy segment, and the morphology determined the strength of the material. Some of the materials prepared have tensile strengths of 0.1 kg/cm 2 or more at temperatures in excess of 180°C and therefore appear promising as elastomers for service at elevated temperatures.