Polyglycerol‐modified polyvinyl alcohol with improved stability during thermoplastic processing

Abstract

AbstractPolyvinyl alcohol (PVA), which can be synthesized via a non‐petroleum route, is a multi‐hydroxyl polymer with good comprehensive properties and environmental friendliness. However, poor thermal processability impedes its development. Herein, polyglycerol (PGL) was firstly adopted to substitute parts of glycerin as one of the plasticizers to prepare modified PVA with greater thermal stability. FTIR spectra revealed the strong hydrogen‐bonding interaction between PGL and PVA which would be destroyed during heating, indicating that PGL was suitable for plasticizing PVA. The introduction of PGL weakened the volatilization of plasticizer as T5% of modified PVA was remarkably improved from 174.7°C to 245.8°C with the addition of 20 wt% PGL. The effects of PGL content on the crystallization behaviors, melting characteristics, dynamic rheological behaviors, and mechanical properties of PVA were investigated. It revealed that the substitution of PGL for glycerin did not influence the final crystalline structure and crystallinity of PVA, but shortened the crystallization time, improved the tensile strength and decreased the melt index owing to the entanglement between PVA and PGL molecules. Dynamic oscillatory rheological measurement showed that the lowest complex viscosity was obtained when 10 wt% PGL was incorporated, which is beneficial for practical processing and film forming. Under proper processing conditions, the production and application of this hot‐blown PVA film were realized at an experimental scale. This work sheds light on the exploitation of new plasticizers with high plasticizing efficiency and thermal stability during processing of PVA.