Synthesis and thermal degradation property study of N-vinylpyrrolidone and acrylamide copolymer

Abstract

A series of acrylamide (AM) copolymers with various N-vinylpyrrolidone (NVP) contents were prepared by free radical solution polymerization. The chemical structures of polyacrylamide (PAM) and its copolymers were analyzed by Fourier transform infrared spectrometer (FTIR) and H NMR. Systematic investigations had been carried out to reveal the role of NVP in copolymer thermal degradation using a variety of techniques, such as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermogravimetric analysis coupled Fourier transform infrared spectroscopy (TGA-FTIR). The DSC measurement showed an increase of 18 °C in the glass transition temperature (T_g) for the copolymer, meaning better thermal stability at 10% NVP content. TGA-FTIR analysis revealed that in the copolymer, low temperature pyrolysis products, such as ammonia and amides, were slowed down until NVP cleaved at about 400 °C. Furthermore, nitriles, which were derived from imide or isolated amide breakdown, were only detected in the copolymer over 350 °C, verifying that the amide or imide groups in the copolymer were also protected by NVP from another point of view. These results also revealed that NVP formed hydrogen bonds with amide groups and promoted the remote side group or inter-molecule crosslinking under heating.