晶型转变对尼龙11分子链运动的影响

Crystal Transition Effect on Chain Movement in Nylon 11

为进一步认识分子链运动与晶型之间的关系,用熔融、冰水淬火和退火等方法制备了α和δ′两种晶型的尼龙11薄膜试样.42Hz～5MHz的介电松弛谱显示了两种不同晶型试样的分子运动特征.不同频率下的介电温度谱显示α型结晶中代表分子链段运动的主松弛较δ′型结晶出现在更高温度,说明退火引起的δ′向α晶型转变使分子链段运动受到了限制.研究结果还显示,α和δ′型结晶中分子链局域松弛运动的活化能基本相同,但α型的松弛时间较δ′型的大,松弛强度则较δ′型的小,表明晶型转变使尼龙11的分子链局域松弛运动也受到了一定程度的抑制.

Two crystal forms （ α and δ＇ form） of nylon 11 were prepared by melting, ice-water bath quenching and annealing. The characteristic of chain movement of two forms was investigated using dielectric relaxation spectroscopy in the frequency range from 42 Hz to 5 MHz. The dielectric temperature spectra at different frequencies show that the primary α-relaxation corresponding to the chain segment movement is located at higher temperature in α form, indicating the chain segment movement is restricted after δ＇→α crystal transition. The activation eneron of secondary β-relaxation remained almost unchanged for two forms, but the relaxation time was longer and the relaxation strength was weaker for α form, confirming that the local relaxation was also restricted to some extent after δ＇→α crystal transition.