生物可降解聚酯熔体的流变性质

Rheological Properties of Biodegradable Polyesters

采用毛细管流变仪,研究了PGA和PGLA910两种生物可降解聚酯熔体的流变性质。实验结果表明,两种聚合熔体均具有较低的剪切粘度,其非牛顿指数分别为:n_(PGA)=0.80-0.94,n_(PGLA910)=0.87-0.95;粘流活化能分别为:E_(PGA)=5.74-7.31kcal/mol,E_(PGLA910)=2.64-4.31kcal/mol。还采用“末端校正法”测定了两种聚合物熔体的剪切模量(G)和弹性可复形变(Sr),结果表明,PGLA熔体的弹性比PGA熔体大。

PolygIycolide (PGA) and polyglactin910(PGLA910) can be made into absorbablsurgical sutures by melt spinning, The cone--and--plate viscometer has been reportedfor the measurements of rheological properties of PGA at low shear rate (r<ls^(-1)). Inthis literature the capillary viscometer is used, fitted with dies of L/R=10, 20, 40 and60. The effects of shear rate, temperature and molecular weight on shear viscosity ofPGA and PGLA910 melts are investigated at higher shear rate(r=10~2--10~4). Thc shearelastic modulus and recoverable deformation of both melts are determined by themethod of Bagley corrections. The recoverable deformation can be regarded as the cri-terions of melt fracture. The stabilityin melt spinning becomes worse with the increasin shear rate. Melt fracture will occur if Sr>5--8. For PGLA910 melt the shear rate inmelt spinning should be controlled under 4000s^(-1)(at 210t℃).