2019 Volume 68 Issue 1 Pages 47-53
In this study, mechanical properties and molecular motion at low temperature of novel polyolefin materials with cyclohexane moiety in the chemical structure synthesized by Takeuchi et al., Poly-alilcyclohexane (PACH-3), Poly-pentenylcyclohexane (PPCH-5), Poly-heptenylcyclohexane (PHCH-7) and Poly-undecenylcyclohexane (PUCH-11), were investigated1),2). From DSC results, the melting temperature of the samples decreased with an increase of the alkyl-chain length though, the enthalpy of heat of fusion of them increased with the alkyl-chain length. From DMA result, the α relaxation peak can be observed clearly and the temperature decreased with the alkyl-chain length. The β relaxation peak can also be observed at around -50 °C, and the peak intensity decreased with the alkyl-chain length. Moreover, the γ relaxation can be observed clearly around -100 °C, and the strength of the δ relaxation of PPCH-5 was the largest among these samples. From three-point-bending test result from -150 °C to RT, PACH-3 with the shortest alkyl-chain length had the highest modulus at -150 °C, but its modulus decreased most gradually with temperature and its modulus became the highest at room temperature. On the other hand, from Anharmonic estimation result, Grüneisen constant of PACH-5 in -150~-100 °C was the smallest in these samples. This result was consistent with the strength of the γ relaxation, indicating that an association between its anharmonicity and the molecular relaxation exits and PPCH-5 can be expected to have better mechanical properties at low temperatures because it has suitable cooperation size for a molecular motion which consists of cycro-ring and a certain alkyl-chain length.
