Modification and compatibility of epoxy resin with hydroxyl-terminated or amine-terminated polyurethanes.: An article from: Polymer Engineering and Science

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From the author: Phenolic hydroxyl-terminated (HTPU) and aromatic amine-terminated (ATPU) PU modifiers were prepared by reacting two different macroglycols (PTMG, polytetramethylene glycol, [M.sub.n] = 2000, and PBA, polybutylene adipate, [M.sub.n] = 2000) with 4,4[prime]-diphenylmethane diisocyanate (MDI), then further coupling with two different coupling agents, bisphenol A or 4,4[prime]-diaminodiphenyl sulfone (DDS). These four types of PU prepolymers were used to modify the epoxy resin with 4,4[prime]-diaminodiphenyl sulfone as a curing agent. From the experimental results, it was shown that the values of fracture energy, [G.sub.IC], for PU-modified epoxy were dependent on the macroglycols and the coupling agents. Scanning electron microscopy (SEM) revealed that the ether type (PTMG) of PU-modified epoxy showed the presence of an aggregated separated phase, which varied between 0.5 [[micro]meter] and 4 [[micro]meter] in the ATPU (PTMG) and between 1 [[micro]meter] and 1.5 [[micro]meter] in HTPU (PTMG) modified system. On the contrary, the ester type (PBA) PU-modified epoxy resin showed a homogeneous morphology and consequently a much smaller effect on toughening for its good compatibility with the epoxy network. In addition, it was found that the hydroxyl-terminated bisphenol A as a coupling agent improved fracture toughness more than the amine-terminated DDS because of effective molecular weight buildup by a chain extension reaction. The glass transition temperature ([T.sub.g]) of modified epoxy resin as measured by dynamic mechanical analysis (DMA) was lower in PTMG-based PU than in a PBA-based PU series with the same weight of modifier.

Citation Details
Title: Modification and compatibility of epoxy resin with hydroxyl-terminated or amine-terminated polyurethanes.
Author: Huei-Hsiung Wang
Publication:Polymer Engineering and Science (Refereed)
Date: September 1, 1995
Publisher: Society of Plastics Engineers, Inc.
Volume: v35 Issue: n18 Page: p1468(8)

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