melt polycondensation
1.Starting from lower molecular weight poly(D,L-lactic acid)(PDLLA) produced by direct melt polycondensation of D,L-lactic acid(D,L-LA),poly(lactic acid) drug delivery material was synthesized through diisocyanate chain extension.
2.Respectively starting from D,L-lactic acid (D,L-LA) and L-lactic acid (L-LA), biodegradable material poly(D,L-lactic acid) (PDLLA) and poly(L-lactic acid) (PLLA) were directly synthesized via melt polycondensation. Their relative molecular weight, structure and properties were systematically characterized and compared by intrinsic viscosity, GPC, FTIR, 1H NMR, DSC and X-ray diffraction.
3.Bromo and phenyl substituted terephthaloyl dichloride and 2,2′ dimethylbiphenyl 4,4′ dicarbonyl dichloride were used as monomers, which react respectively with methyl. t butyl and phenyl hydroquinones by melt polycondensation, a kind of wholly aromatic polyesters were synthesized, which have rigid and rodlike structures. All of the polyesters are thermotropic liquid crystals.
4.To analyze the influence of melt transferring condition on direct spinning FDY full package ratio. Try to find out the best process condition of melt transferring. It is regarded that polycondensation load are controlled at 150～{200 t/d},melt flow is kept above 1.45 t/h,temperature of melt is 286 ℃,temperature of Dowtherm is controlled at 280～300 ℃,and transferring press is 21 MPa.
