Toughening of benzoxazine structural adhesives and surface films

In this paper, acrylic triblock copolymer (BMG) was used to toughen the benzoxazine/epoxy (BZ/EP) resin system and prepare a BZ/EP/DDS/BMG resin. BZ/EP/DDS/BMG resin curing characteristics, viscosity-temperature characteristics, heat resistance, toughness, morphology, and bonding performance were studied. The results show that the curing agent 4,4-diamino diphenyl sulfone (DDS) can lower the curing temperature of the BZ/EP/DDS system, making it suitable for co-curing of benzoxazine prepreg. The BMG did not affect the curing temperature of the BZ/EP resin. When 15 phr BMG was added, the viscosity of the BZ/EP/BMG resin at 139-189 degrees C was lower than 5.0 Pa center dot s, showing a minimum viscosity of 2.0 Pa center dot s. BMG significantly increased the toughness of the BZ/EP/DDS/BMG system while barely decreasing its heat resistance. The impact strength of the BZ/EP/BMG resin increased by 71% when 20% BMG was added. Furthermore, theBZ/EP/DDS/BMG resin demonstrated excellent bonding performance, with lap shear strength and peel strength at room temperature reaching 30.6 MPa, and 37.2 N/cm, respectively. Therefore, the prepared BZ/EP/DDS/BMG resin is suitable as a matrix for BZ structural adhesives and composite surface films.

Automated summary

This study used an acrylic triblock copolymer to toughen the benzoxazine/epoxy resin system and prepare a resin suitable for structural adhesives and composite surface films. It was found that the addition of BMG significantly increased the toughness and bonding performance of the resin system while maintaining its heat resistance.