Conformational motion and disorder in aliphatic nylons The case of nylon 6.6
Conformational motion and disorder in aliphatic nylons The case of nylon 6.6
复制标题
脂肪族尼龙的构象运动和紊乱以尼龙6.6为例
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
B. Wunderlich
中科院分区：
文献类型：
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作者：
A. Xenopoulos;B. Wunderlich
在热分析的基础上，提出了脂肪族尼龙的晶体在玻璃化转变以上表现出构象无序。无序在约室温下逐渐开始，并且通过热容量增加到高于熔体的值来证明。尼龙6.6的特殊情况下，通过热分析和X-射线衍射研究。构象紊乱的发生可以清楚地与预熔融分开。它示出的Brill转变，所定义的合并的两个主峰在X射线衍射图中，逐渐发生，是热历史依赖。这种转变不是一级的，它只是一种附带的热效应，与晶体中的堆积变化有关。在溶液结晶（sc）的样品中，这种变化与一个明显的吸热峰有关，而在熔融结晶（mc）的样品中，它与一个宽的吸热峰有关。
On the basis of thermal analysis it is suggested that the crystals of aliphatic nylons exhibit conformational disorder above the glass transition. The disorder begins gradually at about room temperature and is evidenced by an increase of the heat capacity to values higher than that of the melt. The specific case of nylon 6.6 is investigated by thermal analysis and x-ray diffraction. The onset of conformational disorder can be clearly separated from premelting. It is shown that the Brill transition, as defined by the merging of the two main peaks in the x-ray diffraction pattern, occurs gradually and is thermal-history-dependent. The transition is not a first-order one, it is only an incidental thermal effect, associated with a packing change in the crystal. In solution-crystallized (sc) samples this change is related to a distinct endothermic peak, while in melt-crystallized (mc) samples it is related to a broad endotherm.