Effect of Plasticzer on the Characterisics Behavior Polyvinyl Alcohol (PVA)

• Main Authors: Jhe-Yi Wu, 吳哲儀
• Other Authors: Yao-Chi Shu
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/62329933574185277434

碩士 === 萬能科技大學 === 工程科技研究所 === 97 === Polyvinyl alcohol-glycerol (PVA-G) and polyvinyl alcohol-D-sorbitol (PVA-D) polyblends were obtain by blending polyvinyl alcohol with different molecular weights (PVA17 and PVA24) and plasticizers (glycerol and D-sorbitol) in various blended ratios through melting process. Furthermore, the various plasticizers and contents effects on the characteristics of polyvinyl alcohol were investigated. Thermalgravimetric analysis (TGA) indicated that polyblends with various plasticizers presented different thermal degradation behaviors. PVA-G polyblends revealed three stages of degradation; the first stage at about 200~230 ℃ resulted from glycerol degradation and polyvinyl alcohol decomposition led to the second stage at about 225~410 ℃ and third stage at about 400~535 ℃. PVA-D polyblends manifested two stages of degradation; the overlapping degradations of D-sorbitol and polyvinyl alcohol brought about the first stage(220~400℃) and the second stage (400~560℃) associated with polyvinyl alcohol degradation. The thermal degradation analysis of polyvinyl alcohol with different molecular weights demonstrated that PVA17 had closed characteric degradation temperatures to PVA24, exhibiting the similar degradation behaviors. Thermalgravimetric analysis-fourier transform infrared spectroscopy (TG-IR) was used to examine the gasous products of degradation and established the degradation mechanisms of polyvinyl alcohol. Two degradation kinetics methods, Ozawa and Horowitz-Metzger, were employed to analyse the activation energies of polyblends. The activation energies calculated from both methods were varied but showed the same tendency. PVA-D polyblends revealed thermal stability at relative low temperature and PVA-G polyblends presented thermal stability at relative high temperature. Differential scanning calorimeter (DSC) analyses of polyblends showed melting temperatures (Tm1 and Tm2) of the initial and melt-quenching scans in the heating curves, and crystallization temperature (Tc) in the cooling curves, and the calculated crystalline parameters-crystalline rate parameters (Kmax), crystalline size distributions (D) and plasticization parameters (P). The crystalline behaviors and plasticizers effects of PVA-G and PVA-D polyblends were set up herein.