Effect of Molecular Weight and Annealing Treatment on Mechanical and Thermal Properties of Polycarbonate
The mechanical and thermal properties of polycarbonate with different molecular weight and injection molding annealing heat treatment time were studied,and the reasons for the influence of molecular weight and annealing on the properties were analyzed.The results show that the high molecular weight polycarbonate has better tensile fracture resistance and impact performance without annealing.Low molecular weight and annealing heat treatment can improve the tensile yield stress and bending properties.The photoelastic analysis of impact samples shows that high molecular weight unannealed polycarbonate has high residual stress,large degree of entanglement,plastic deformation after impact and high impact toughness.Through dynamic mechanical analysis(DMA)and differential scanning calorimetry(DSC),it is found that as the molecular weight increases,the glass transition temperature increases and the chain motion tends to be more elastic.
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