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The addition effects of hybrid copolymer between an urethane prepolymer and solid epoxy resin

Epoxy resin networks have been modified with hybrid copolymer consisting of an urethane prepolymer and a solid bisphenol A diglycidyl ether. Hybrid copolymer prepared from isocyanate-terminated urethane (NCOPUER) resulted in cured transparent epoxy networks with no discernible phase-separated morphology, as indicated by scanning electron microscopy. | Journal of Chemistry Vol. 45 6A P. 329 - 333 2007 THE ADDITION EFFECTS OF HYBRID COPOLYMER BETWEEN AN URETHANE PREPOLYMER AND SOLID EPOXY RESIN Received 15 October 2007 DO TRUONG THIEN DUONG ANH VU NGUyEN TIEN AN TRAN THI Y NHI Natural polymer laboratory - Institute of Chemistry - VAST summary Epoxy resin networks have been modified with hybrid copolymer consisting of an urethane prepolymer and a solid bisphenol A diglycidyl ether. Hybrid copolymer prepared from isocyanate-terminated urethane NCOPUER resulted in cured transparent epoxy networks with no discernible phase-separated morphology as indicated by scanning electron microscopy. The different morphological characteristics observed in this modified system were attributed to the different structure of the block copolymer. The visual homogeneity of the NCOPUER block copolymer-modified network can be attributed since the glass transition temperature of the epoxy matrix determined from differential scaning calorimetry analysis has not been substantially influenced by the presence of this block copolymer. The epoxy resin modified with the different block copolymer presented an improved toughness and chemical resistance. The best mechanical performance in terms of flexural and tensile properties was achieved with the block copolymer derived from isocyanate -terminated polyurethane whereas a more flexible material has been obtained with NCOPUER hybrid copolymer-modified network. Keywords Bisphenol A diglycidyl ether epoxy resin urethane impact modifier. I - INTRODUCTION Epoxy resin is one of the most important thermosetting polymers. This resin exhibits many desirable properties such as high thermal stability and excellent electric properties however epoxy resin is generally rather brittle. The brittleness of material is not only depending on the chemical structure ratio of aromatic aliphatic substance but also the crosslink. Polyurethane is another class of favored polymeric modifier for material applications .