Preparation of poly(1,4-cyclohexylenedimethylene phthalate)s and their useas modifiers for aromatic diamine-cured epoxy resin

Poly(1,4-cyclohexylenedimethylene phthalate) s, prepared by the reaction of phthalic anhydride and 1, 4-cyclohexane dimethanol (35/65 or 73/27 mol% ci s/trans or trans alone), have been used to improve the toughness of bisphen ol-A diglycidyl ether epoxy resin cured with 4,4'-diaminodiphenyl sulfone. The aromatic polyesters include poly(cis/trans-1,4-cyclohexylenedimethylene phthalate) (PCP) based on a commercial cyclohexane dimethanol, poly(trans- 1,4-cyclohexylenedimethylene phthalate) (trans-PCP) and poly(cis/trans-1,4- cyclohexylenedimethylene phthalate) (cis-rich PCP) prepared from a cis-rich diol. The polyesters used were soluble in the epoxy resin without solvents and were effective as modifiers for toughening the cured epoxy resin. For example, the inclusion of 20wt% of PCP (MW 6300 g mol(-1)) led to an 80% in crease in the fracture toughness (K-IC) of the cured resin with no loss of mechanical and thermal properties. The toughening mechanism is discussed in terms of morphological and dynamic viscoelastic behaviours of the modified epoxy resin system. (C) 2000 Society of Chemical Industry.