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The sensitivity of the flow stress of polymers to strain-rate is one of the major concerns in mechanics of materials since polymers and polymer matrix composites are widely used in many engineering applications. In this paper, we present tests on Nylon 6 and Nylon 66 on wide range of strain-rates (0.001-5000s⁻¹). Specifically, we used INSTRON machine for low strain-rates. The high strain-rate measurements were inferred from the Hopkinson bar tests. Only the compressive behaviour was investigated. To eliminate any interference with temperature and humidity effects, test samples were conditioned at 20°C and 50% of hygrometry. Moreover, the effects of the specimen geometry were considered. The current study results are also compared to values found in literature.

In this research, a series of amorphous nylons 6 were prepared by introducing adipic acid and different structure amines into the copolymerization with caprolactam. The effects including thermal properties, crystallinity, dynamic mechanical properties, optical properties, and water absorption of different copolymerization structure and copolymerization ratio on the properties of nylon 6 were investigated. The results show the melting point and thermal cracking temperature Td 5 of nylon 6 are, respectively, between 179${}^{\circ }$C and 217${}^{\circ }$C and 278${}^{\circ }$C to 336${}^{\circ }$C. Nylon 6 structure introducing a methyl side chain is more effective than a meta-benzene ring, a meta-cycloalkyl, and bicycloalkyl groups, so CAMM and CAI have the lowest crystallinity.