Branching theories and thermodynamics used to help designing precursor architectures and binder systems
Tóm tắt
Cross-linking hydroxy-functional stars and copolymer precursors with a triisocyanate and associated structural changes were studied theoretically and experimentally. The model of network formation was based on the statistical generation of structures from units which were in different reaction states. The differences in gel point conversion and cross-link density were interpreted in terms of precursor functionality and functionality distribution, and differences in the reactivity of functional groups. Hydroxy-functional copolymer systems containing precursors of the same number-average functionality gel at lower conversions than stars which are monodispersed mainly due to functionality distribution. The structure of copolymers characteristic of several internal cross-links contributes more to the concentration of elastically-active network chains than stars with a single cross-link. Cyclization accompanies intermolecular cross-linking; its intensity is higher for copolymer systems compared with stars.
Tài liệu tham khảo
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