【摘要】 以异佛尔酮二异氰酸酯(IPD I)为扩链剂,以外消旋乳酸(D,L-LA)直接熔融聚合合成的低分子量聚外消旋乳酸(PDLLA)为预聚体,在四氢呋喃溶液中进行扩链得扩链产物Ⅰ。Ⅰ用粘均分子量(Mη),IR,1H NMR,DSC及X-射线衍射等表征。与2,4-甲苯二异氰酸酯(TD I)的扩链产物(Ⅱ)比较,Ⅰ成功地引入了NH和IPD I反应后的刚性片段,使M,ηTg,Tm,结晶度等相应提高。但由于IPD I反应活性不如TD I,故反应速率比用TD I时慢;Ⅰ分子中脂肪环的刚性不如苯环,TⅠg低于TⅡg。更多还原

【Abstract】 Starting from cheaper D,L-lactic acid(D,L-LA),lower molecular weight poly(D,L-lactic acid)(PDLLA) was directly synthesized via melt polycondensation.And then,using PDLLA as a prepolymer,isophorone diisocyanate(IPDI) as a chain extender,and tetrahydrofuran as a solvent,PDLLA-IPDI(Ⅰ) was synthesized through diisocyanate chain extension in solution state.Compared with chain extender 2,4-toluylene diisocyanate(TDI),IPDI had lower reaction activity,and the maxium viscosity-average molecular weight(Mη) of chain extension product dissolvable in chloroform under the similar chain extension conditions was slightly lower.Similar to the product PDLLA-TDI(Ⅱ),through direct melt polycondensation-diisocyanate chain extension by TDI in solution state,Ⅰ usually had higher glass transition temperature(Tg),melting temperature(Tm),and crystallinity than prepolymer(PDLLA).However,the alicyclic rigidity of the introduced IPDI segment was lower than the aromatic ring rigidity of the introduced TDI segment,T~~Ⅰ_g was correspondingly lower than T~~Ⅱ_g.更多还原