Chain extension and modification of polypropylene carbonate using diphenylmethane diisocyanate

In the present work, with the application of diphenylmethane diisocyanate (MDI) as the chain extender, poly(propylene carbonate) (PPC) was modified by chain extension. The changes in the chemical, thermal and mechanical properties of PPC after modification were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, thermogravimetry and elemental analysis. The experimental results indicate that during melt blending of MDI and PPC the terminal hydroxyl group in PPC can react with the isocyanate group in MDI, leading to chain extension of PPC. Via modification, the physical properties and thermal stability of PPC can be enhanced considerably. With the addition of 1.5% MDI, the glass transition temperature increased from 14.1 °C to 28.2 °C and the thermal decomposition temperature T_?5% increased from 162.7 °C to 246.8 °C. Moreover, the tensile strength of the modified PPC was improved from 3.1 MPa to 20.3 MPa. © 2015 Society of Chemical Industry