桐油制备C_(21)聚酰胺环氧固化剂的性能及固化反应动力学研究

以桐油的甲醇酯交换产物桐酸甲酯和丙烯酸为原料,通过Diels-Alder加成反应合成了C21二元酸单甲酯(TMAA),桐酸甲酯和丙烯酸的加成温度为180℃,反应时间3 h,比通用C21二元酸的合成反应温度低70℃。然后用C21二元酸单甲酯和不同多元胺酰胺化制备了3种不同胺值的C21二酸聚酰胺环氧固化剂。机械性能测试显示,C21二元酸聚酰胺和双酚A环氧树脂(DGEBA)的环氧固化物和C36二聚酸聚酰胺650C的DGEBA固化物相比,具有更高的机械强度和模量。胺值为496 mg/g的C21二元酸聚酰胺与DGEBA的固化产物拉伸强度达58.63 MPa,断裂伸长率为3.27%,弹性模量达2 635.84 MPa,弯曲强度达99.9 MPa。差示扫描热分析法(DSC)测得C21二元酸聚酰胺的DGEBA固化物的玻璃化温度分别为108、109和116℃,比C36二聚酸聚酰胺的DGEBA固化物的玻璃化温度高出50℃左右。n级反应机理求取的3种固化剂与DGEBA的固化反应活化能分别为62.179、56.551和59.761 kJ/mol,比C36二聚酸聚酰胺与DGEBA的固化反应活化能高出约10 kJ/mol。固化反应动力学得出固化剂与DGEBA的凝胶温度、固化温度和后固化温度分别为40、90和150℃左右。

Properties and Kinetics of curing of C_(21) Polyamides as Epoxy Curing Agents Derived from Tung Oil

Methyl ester of C21 diacid(TMAA) was synthesized from acrylic acid and methyl ester of tung oil fatty acids through Diels-Alder reaction.The reaction temperature was 180 ℃.The reaction time was 3 h.Three kinds of novel C21 diacid polyamide curing agents with various amine values were synthesized from tung oil.Compared with the cured product of polyamide prepared from C36 dimer acid,the cured product of polyamides made from TMAA and bisphenol A epoxy resin(DGEBA) had higher mechanical strength and modulus.The tensile strength,tensile strain,elasticity modulus and bending strength of cured product made from DGEBA and C21-based polyamide of which the amine value is 496 mg/g were 58.63 MPa,3.27%,2 635.84 MPa and 99.9 MPa,respectively.Differential scanning calorimetry(DSC) indicated that the glass transition temperature of three C21-based polyamide samples cured by DGEBA were 108,109 and 116 ℃,respectively,which were 50 ℃ higher than that of the cured product made from C36-based polyamide 650C.The activation energy of three samples in curing reactions were calculated by n order model were 62.179,56.551 and 59.761 kJ/mol,respectively,which were 10 kJ/mol higher than that of C36 polyamide.The kinetics of curing shows that the gel point,setting point and post cure temperature of them are about 40,90 and 150 ℃,respectively.