杜仲胶接枝甲基丙烯酸丁酯的合成与表征

Synthesis and Characterization of Butyl Methacrylate Grafted on Eucommia Ulmoides Gum

采用溶液聚合工艺,以过氧化苯甲酰(BPO)为引发剂,成功制备了杜仲胶(EUG)和甲基丙烯酸丁酯的接枝共聚产物(EUG-g-BMA)。利用凝胶渗透色谱、核磁共振和红外光谱(IR)研究了接枝反应条件,如单体浓度、反应温度、引发剂浓度等对接枝共聚反应和接枝效率的影响。用差示扫描量热分析(DSC)研究了接枝率对产物熔融-结晶行为的影响。结果表明,当m(BPO)∶m(BMA)=0.05时,BMA浓度对接枝率和单体转化率影响明显,过高的反应温度导致交联产物的生成。IR谱图中1667 cm^(-1)处碳碳双键吸收峰的消失说明接枝反应发生在碳碳双键上。接枝改性导致杜仲胶分子链的结晶能力减弱。随着接枝率增加,产物的熔融温度和结晶温度向低温方向移动,结晶度降低;当接枝率达到17.6%时,DSC曲线上既不呈现熔融峰,也没有结晶峰,说明此时EUG-g-BMA已经完全失去结晶能力。

Graft copolymerization of butyl methacrylate （BMA） onto Eucommia ulmoides gum （EUG） was carried out through solution process in the presence of benzoyl peroxide as initiator. Gel permeation chromatography（GPC）, hydrogen nuclear magnetic resonance spectroscopy （IH-NMR） and infrared spectrometer （IR） were applied to study the influence of reaction conditions, such as monomer concentration, reaction temperature, initiator concentration on the graft copolymerization and grafting efficiency. Differential scanning calorimetry （DSC） was applied to investigate the effect of grafting efficiency on the melting-crystallization behavior of the grafted product. The results show that at suitable initiator concentration, BMA concentration shows a significant effect on the grafting efficiency and monomer conversion. High reaction temperature leads to formation of the cross-linking products. The disappearance of the absorption peak at 1667 cm-1, which corresponds to the carbon-carbon double bond, suggest that it is the carbon- carbon double bond taken part in the grafting reaction. Graft modification weakens the crystallization ability of EUG molecular chains. With the grafting efficiency increasing, the melting temperature and crystallization temperature of the grafted product move toward lower temperature direction, with decreased crystallinity; when the grafting efficiency reaches to 17.6 %, neither melting peaks nor crystallization peaks presented in DSC curves, indicate that EUG-g-BMA loses crystallization ability completely.