Crosslinked Engineering Plastics

J. GEHRING, With radiation crosslinking of engineering plastics into the next millenium , Rad. Phys. Chem., 57 (2000) 361-365... 

J. D. Minford, Adhesive joining aluminum to engineering plastics II. engineering grade styrene and crosslinked styrene, in Physicochemical Aspects of Polymer Surfaces (K. L. Mittal, ed.), Vol. 2, p. 1161, Plenum Press, New York (1983). 

High Performance Polymers and Engineering Plastics Table 8.4 DSC analysis results for some crosslinkable polytriazole resin. 

Unsubstituted and nonheat-reactive phenolic resins are used to a very limited extent due to their nonfilm-forming character. These resins are generally used as hardeners with epoxy resins to produce thermoset systems with high-quality engineering plastic properties. The base-catalyzed curing produces a crosslinked polyether structure, as shown in reaction (30), which is resistant to chemicals and heat and shows good barrier properties against moisture vapour. 

Based on castor oil derived elastomers and crosslinked polystyrene, a simultaneous mode of polymerization can be successfully employed to synthesize prototype engineering materials such as tough, impact resistant plastics and reinforced elastomers. 

The crosslinking reaction is an extremely important one from the commercial standpoint. Crosslinked plastics are increasingly used as engineering materials because of their excellent stability toward elevated temperatures and physical stress. They are dimensionally stable under a wide variety of conditions due to their rigid network structure. Such polymers will not flow when heated and are termed thermosetting polymers or simply thermosets. More than 10 billion pounds of thermosets are produced annually in the United States. Plastics that soften and flow when heated, that is, uncrosslinked plastics, are called thermoplastics. Most of the polymers produced by chain polymerization are thermoplastics. Elastomers are a category of polymers produced by chain polymerization that are crosslinked (Sec. 1-3), but the crosslinking reactions are different from those described here (Sec. 9-2). 

While IPNs can be and have been made extremely tough and impact resistant, many of the proposed applications involve such diverse fields and sound and vibration damping, biomedical materials, and non-linear optics. This is because the presence of crosslinks in both polymers reduces creep and flow, allowing relatively stable materials with a wide range of moduli to be prepared. Thus, those materials with leathery mechanical behavior, combinations of elastomers and plastics, are especially interesting to scientists, inventors, and engineers. 

Wind, J.D. et al.. The effects of crosslinking chemistry on COj plasticization of polyimide gas separation membranes. Industrial and Engineering Chemistry Research, 2002. 41(24) 6139-6148. 

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