聚合条件对合成聚1-丁烯热塑性弹性体的影响

Effects of polymerization conditions on synthesis of poly-1-butene thermoplastic elastomer

以1-丁烯(B t)为原料,负载钛(简称Ti)-三异丁基铝(简称Al)为催化体系,用本体聚合法合成了聚1-丁烯(PBt)热塑性弹性体(TPE)。考察了聚合条件对PBt TPE的影响,并用差示扫描量热法对聚合物进行了分析。结果表明,随着氢气压力的升高,单体转化率、催化效率呈下降趋势;随着Al/Ti(摩尔比)的增加,转化率和催化效率先升高后降低;随着Ti/Bt(摩尔比)的增加,转化率和催化效率逐渐升高;随着聚合温度的升高,转化率和催化效率先升高后降低;在氢气压力为0.2 MPa、Al/Ti为300、Ti/Bt为2×10-5、反应温度为30℃的聚合条件下,合成出转化率为80.0%的PBt TPE。随着氢气压力的升高,聚合物的特性黏数([η])和全同立构质量分数都呈下降趋势,氢气压力能较好地调节聚合物的相对分子质量;随着Al/Ti的增加,[η]逐渐下降,全同立构质量分数变化不明显;随着Ti/Bt的增加,[η]先升高后降低,最后趋于平稳,而全同立构质量分数略有降低后趋于平稳;随着聚合温度的升高,[η]和全同立构质量分数都呈下降趋势。反应温度为40℃时,PBt TPE的结晶度最高,为20.3%。

By mass polymerization, poly-l-butene （PBt） thermoplastic elastomer （TPE） was synthesized with 1-butene（Bt） in the presence of a catalytic system consisting of supported titanium （ simplified as Ti） and triisobutyl-aluminum （ simplified as Al）. The polymerization conditions were examined, and the PBt TPE was characterized by differential scanning calorimetry. The results demonstrated that conversion and catalytic efficiency decreased with the increase of hydrogen pressure, and varied in a way of going up and then declining with the increase of Al/Ti（ mole ratio）. Both conversion and catalytic efficiency rose gradually with the increase of Ti/Bt （mole ratio）; Conversion and catalytic efficiency increased first and then decreased with the increase of polymerization temperature. The conversion reached 80.0% under the conditions of hydrogen pressure 0.2 MPa, Ti/Bt （mole ratio） 2 × 10^-5, Al/Ti（mole ratio）300 and 30℃. Limiting viscosity number（ [ η] ） and mass fraction of isotacticity decreased with the increase of hydrogen pressure, so that relative molecular mass of polymerization could be adjusted by hydrogen pressure. With the increase of Al/Ti （ mole ratio ） , [ η] increased first, then de- creased and then smoothly, whereas the mass fraction of isotacticity changed scarcely. With the increase of Ti/Bt（ mole ratio） , [ η] varied in a way of going up first and then declining, and the mass fraction of isotacticity decreased slightly and then went to changelessness. With the increase of polymerization temperature, [ η] and the mass fraction of iso- tacticity declined continuously. PBt TPE had maximum crystallinity （20.3 % ） at 40℃.