Copolymer relationship between flexibility

The relationship between flexibility and copolymer composition was explored by measuring Tg and Tgp for a series of copolymers consisting of styrene or methyl methacrylate paired with several "softer" comonomers. An example of the kind of results obtained is illustrated in Figure 11 with the methyl methacrylate/ ethyl acrylate pair. Included in this plot is a ductility, or toughness, parameter, q, defined by Wu as,... 

Experimental and theoretical results are presented for four nonlinear electrooptic and dielectric effects, as they pertain to flexible polymers. They are the Kerr effect, electric field induced light scattering, dielectric saturation and electric field induced second harmonic generation. We show the relationship between the dipole moment, polarizability, hyperpolarizability, the conformation of the polymer and these electrooptic and dielectric effects. We find that these effects are very sensitive to the details of polymer structure such as the rotational isomeric states, tacticity, and in the case of a copolymer, the comonomer composition. 

In this study, star-shaped PGCL copolymers were prepared in order to investigate the relationships between their structure and their thermal and mechanical properties, in view of a possible application as flexible monofilament sutures. The concept of the preparation of star-shaped stmctures was extended to PGCL as shown in Figure 10. 

To summarize, EVM vulcanizates possess an excellent heat aging resistance but there is an inverse relationship between best cold flexibility and best oil resistance. The cold flexibility increases with decreasing vinyl acetate content and the oil resistance decreases. So it is up to the compounder to choose the appropriate copolymer in order to meet the requirements of the finished product. 

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