AbstractMechanical and solution properties, melting transitions, torsional stiffness temperatures,Tf, and selected modulus‐temperature curves are presented for copolymers of theN‐n‐alkylacrylamides with vinylidene chloride. Copolymers were prepared at 60°C across the range of compositions, using as comonomersN‐n‐butyl‐, octyl‐, dodecyl‐ and oleyl‐acrylamide, which have amorphous side‐chains, andN‐n‐octadecyl acrylamide andn‐octadecyl acrylate whose side‐chains are crystalline. The mechanical properties reflected the effect of the decline in backbone crystallinity and the simultaneous development of strong intermolecular interactions in the amorphous stage. Copolymers were stiff or showed brittle failure across the compositional range except when intermolecular forces were reduced (withn‐octadrcyl acrylate) and side‐chain crystallization eliminated (withN‐oleylacrylamide). These systems and then‐dodecylacrylamide copolymers had yield strengths less than brittle strengths and substantial elongations. Backbone crystallinity was eliminated at about 15 mole amide and side‐chain crystallinity vanished at less than 10 mole of the amide in theN‐n‐octadecylacrylamide series. No depression in side‐chain melting point occurred with dilution by segments of vinylidene chloride. Over‐all decline in the flex‐temperature was the normal monotonic function of composition except that values increased in magnitude at high vinylidene chloride contents, the effect presumably being caused by the presence of crystallinity. An empirical equation was developed which permitted the calculation ofTffor anyN‐n‐alkylacrylamide composition with a
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