Explain why copolymers of ethylene and propylene can be elastomers when the pure polyethylene and pure polypropylene are not elastomeric. Discuss whether you would expect a blend (instead of a copolymer) of polyethylene and polypropylene to be elastomeric
What will be an ideal response?
The homopolymers of ethylene and propylene are nonelastomeric because they both have high crystallinity. Even low molecular weight polyethylene has considerable crystalline content. However, when the materials are copolymerized, the ability of the polymers to pack together tightly is significantly reduced when compared with the homopolymers.
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