Study On Preparation And Performance Of Polyethylene Glycol/Nanocellulose/Polylactic Acid Composite

As one of the most widely used biodegradable materials,polylactic acid(PLA)has the advantages of excellent reproducibility and degradability,which can replace refractory petroleum-based materials in production and life.Due to the defects of PLA itself in terms of crystalline performance and thermal stability,it has seriously affected the application of PLA.In this paper,nano-cellulose(CNC)was selected as the nucleating agent and polyethylene glycol(PEG)as the compatibilizer to the PLA to improve its defects.Then,PLA/CNC-PEG composites were prepared by different processes of solution blending and melt blending.The effects of CNC and different molecular weight PEG on PLA performance were studiedIn this paper,four molecular weights of PEG(include PEG400,PEG1000,PEG4000 and PEG20000)are mixed with CNC and added to PLA by solution blending.The experimental results show that the addition of CNC and PEG can significantly improve the crystallization performance of PLA;Compared with PLA,the crystallinity of PLA/CNC-PEG400 composite material is increased by 49.2%,and the crystallization activation energy is reduced by 144.5KJ/mol;comparing the crystallization performance of PLA/CNC-PEG composite materials made of different PEG molecular weights,PLA/CNC-PEG400 composite film has the best crystallization performance;Based on the experimental results,the theory of CNC and PEG enhancing the crystallization performance of PLA was established.Next,4 kinds of molecular weight PEG(include PEG400,PEG600,PEG1000 and PEG1500)are mixed with CNC to obtain modified CNC-PEG,and CNC-PEG and polylactic acid are melt blended to prepare PLA/CNC-PEG composite board.Studies have shown that the addition of CNC-PEG can significantly improve the crystallinity of PLA,in which the crystallinity of PLA/CNC-PEG400 increases to 32.1%;with the addition of PEG the molecular weight increases the crystallinity of PLA/CNC-PEG composites from 32.1%Dropped to 13.3%,and the number of crystals also decreased,but the size of the crystals formed increased.According to the experimental results,the theory of CNC-PEG enhancing PLA crystallization performance under temperature field and shear field is established.Finally,the film prepared by the solution blending method and the sheet prepared by the melt blending method were subjected to thermogravimetric analysis and mechanical property testing to study the effect of PEG molecular weight on the thermal stability and mechanical properties of PLA/CNC-PEG composite products.Experiments have found that the toughness of the PLA composite film prepared by solution blending increases first and then decreases with the increase of the molecular weight of PEG,and the thermal stability will increase with the increase of the molecular weight of PEG;PLA composite sheet prepared by melt blending,Toughness and thermal stability both decrease with the increase of the molecular weight of PEG.