| 摘要 |
Branched polyester compositions having high melt viscosities, especially under conditions of low shear, are prepared in a two-step method. The first step is the reaction of a linear polyester, polycarbonate or polyester-polycarbonate containing free carboxylic acid groups with a polyfunctional epoxyalkyl compound such as triglycidyl isocyanurate to form a reactive concentrate. The second step is the reaction of said reactive concentrate with a polyester, such as poly(ethylene terephthalate) or poly(butylene terephthalate), containing a measurable proportion of carboxylic acid end groups. By this two-step method, it is possible to use less epoxy compound for a given melt viscosity level than is the case when the epoxy compound is directly blended with the polyester.
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