Preparation And Properties Of PVA With High Decomposition Temperature

Poly(vinyl alcohol),as a water-soluble polymer material,which has excellent transparency,biocompatibility and gas barrier properties.It is widely used in the fields of medicine,food and other packaging materials.However,due to the presence of a large number of hydroxyl groups in the PVA molecule,it is easy to form hydrogen bonds between the molecule and the molecule,which makes the melting point of the PVA close to the decomposition temperature(230-250?),so it is difficult to process the PVA thermoplastically.In this paper,PVA was blended with a small amount of ionic liquid methacryloxyethyl trimethylammonium chloride(DMC)to prepare PVA complex with high decomposition temperature and its mechanism was studied.1.After adding trace DMC(less than 2% wt),the thermal stability of PVA was significantly enhanced,and the decomposition temperature increased from 258? to 311? while the melting temperature remained basically unchanged.The thermal degradation kinetics of PVA and PVA/DMC composites were studied by differential method,Kissinger equation method and Flynn equation method.The results showed that DMC inhibited the first step of thermal degradation of PVA,and improved its decomposition temperature and decomposition activation energy.Gas pyrolysis and thermogravimetric infrared analysis show that the thermal degradation of PVA will be inhibited in the low temperature region of the first stage.This is mainly because DMC can inhibit the zipper-like degradation of PVA by capturing alkyl radicals and hydroxyl radicals generated by the molecular chain of PVA through electron transfer or radical addition.2.According to the mechanical analysis,the tensile strength of pure PVA is 17.3 MPa and the elongation at break is 106.8%.With the increase of DMC content,the tensile strength of the blend decreases and the elongation at break increases.When DMC content was 1.0 wt%,the excellent mechanical properties of 15.1 MPa and 104.3% elongation at break were maintained.3.The transparency analysis shows that the addition of DMC has no effect on the transparency of PVA.When the content of DMC is 1.0 wt%,the transmittance of PVA is still 87%.