摘要
讨论了大分子溶致凝聚过程中体系熵变的特点和影响。在分子链无规凝聚形成无定形聚合物时,正是熵增的贡献使体系自由能下降,无规凝聚过程得以进行。在有规凝聚形成结晶聚合物时,熵变对结晶过程产生复杂影响。由于熵变和内能变化相互竞争,使溶致结晶时最优生成的晶体结构为松散折叠链片晶;而从熔体结晶时则得到晶相和非晶相(无定形相)两相并存的复杂结构。区分了两类不同性质的熵变:阶跃性熵变导致熵致相变发生;渐变性熵变使体系力学性质变化或发生力学状态转变。
In this work the features and influences of entropy in the lytropic condensation of macromolecules were discussed. In an irregular condensation, in that the amorphous polymers were generated, just the entropy increase causes a decrease of Helmholtz＇s free energy, and so that the condensation process can go on. In a regular condensation, in that the crystalline polymers were generated, the change of entropy induces very complex effects for polymer crystallization. Due to the competition between entropy and internal energy, a folded chain lamellae with loose structure was prior generated in the lytropic crystal process ~ and a two phases structure with crystal and amorphous region was generated in the crystal process from polymer melts. Two different changers ways of entropy were distinguished~ a jump change of entropy can induce a thermodynamic phase transition-entropy induced phase transition, but a gradual change of entropy can change only the mechanical property or initiate a mechanical state transition of polymers.
出处
《高分子通报》
CAS
CSCD
北大核心
2013年第2期1-5,共5页
Polymer Bulletin
基金
国家自然科学基金资助项目(50973050)
关键词
大分子
溶致凝聚过程
熵变
熵致相变
Macromolecules
Lytropic condensation
Change of entropy, Entropy induced phase transition
