聚乙烯醇缩丁醛改性酚醛树脂的耐热与增韧性能

Heat Resistance and Toughening Properties of Polyvinyl Butyral Modified Phenolic Resin

选用聚乙烯醇缩丁醛(PVB)对酚醛树脂进行增韧改性,制备了PVB含量不同的改性酚醛树脂,并基于半凝胶状态制备了改性树脂浇铸体。采用扫描电镜观察酚醛树脂浇铸体拉伸断裂截面,发现该方法所制备的浇铸体内部无气泡存在;通过红外光谱对改性前后的酚醛树脂进行结构表征,证实了PVB与酚醛树脂发生了接枝反应;通过差示扫描量热分析和凝胶时间测试确定了改性酚醛树脂的固化工艺;采用热重分析对改性前后酚醛树脂进行热稳定性分析及对比,发现PVB改性酚醛树脂的热稳定性下降;对改性前后酚醛树脂浇铸体进行拉伸、弯曲性能测试,结果表明,PVB的添加量为14%时,增韧效果尤为显著,其拉伸强度为44.46 MPa,断裂伸长率为1.19%,弯曲强度为93.06 MPa,分别较酚醛树脂增加了48.82%,36.50%,135.25%。

Polyvinyl butyral(PVB)was used to modify phenolic resins,and modified phenolic resins with different PVB contents were prepared.Besides,the modified resin castings were prepared under the semi-gelatinous condition.SEM was used to observe the stretched fracture sections of phenolic resin castings and the results confirm that there are no bubbles in the phenolic resin castings prepared under the semi-gelatinous condition.The structures of phenolic resins before and after modification were characterized by FT-IR and the results confirm that the graft reaction between PVB and phenolic resin is sure to happen.The curing process of modified phenolic resins were analyzed by differential scanning calorimetry(DSC)and gel time determination.The thermal stability of phenolic resins before and after modification was analyzed and compared by thermogravimetric analyzer and the results confirm that the addition of PVB can weaken the thermal stability of modified phenolic resins.The tensile and bending properties of phenolic resin castings before and after modification were tested by universal testing machine and the results confirm that the addition of PVB can enhance and toughen the modified phenolic resins to some extent.Additionally,when the dosage is 14%,the enhancement effect is particularly significant.The tensile strength is 44.46 MPa,the elongation at break is 1.19%,and the bending strength is 93.06 MPa,which are increased by 48.82%,36.50%and 135.25%,respectively,compared with phenolic resin.