天然杜仲胶的环氧化改性

Epoxidized modification of natural eucommiaulmoides gum

采用溶液法对杜仲胶(EUG)进行环氧化改性,制得环氧化EUG(EEUG),考察了不同反应温度、原料配比等反应条件对环氧度和环氧化反应的影响,并用红外光谱法、核磁共振氢谱法和差示扫描量热法等研究了环氧化反应程度和环氧度对环氧化产物熔融-结晶行为的影响。结果表明,随着反应温度的提高和甲酸用量的增加,EEUG的环氧度逐渐增大;反应温度提高至50℃,双键/甲酸/双氧水(摩尔比)为1.0/0.8/1.0时,所得产物的环氧度较高且无明显的副反应出现。环氧化反应没有改变EUG分子链的结构,EEUG分子链仍然是反式-1,4-结构,没有出现顺式-1,4-结构。随着环氧度的增大,EUG的结晶能力减弱,当环氧度为24.8%时完全失去结晶能力,由室温下的硬质树脂转变为弹性体。

Epoxidized eucommiaulmoides gum（ EEUG） was prepared by eucommiaulmoides gum（ EUG） epoxidation modification in solution. The effects of reaction conditions,such as reaction temperature and fomic acid amount,on epoxy degree and epoxidation reaction were investigated. The effects of the degree of epoxidation reaction and epoxy degree on melting crystallization behavior of EEUG were also characterized by infrared spectroscopy,nuclear magnetic resonance and differential scanning calorimeter. The results showed that the epoxy degree of EEUG gradually increased with the reaction temperature rising and formic acid increment. At the conditions of reaction temperature 50 ℃,double bond / formic acid / hydrogen peroxide（ mole ratio） 1. 0 /0. 8 /1. 0,the epoxy degree of EEUG was relative high and side reaction was rarely observed. Epoxidation reaction did not change the molecular chain configuration of EUG and the double bonds of EEUG was also trans-1,4-unit other than cis-1,4-unit. With the epoxy degree increment,the crystallization ability of EUG decreased and even disappeared when the epoxy degree was up to24. 8%. In that case,EUG transformed from hard resin to elastomeric material at room temperature.