Research Of Fabrication And Modification Of Poly(Lactic Acid)/Bamboo Particles/Ultrafine Bamboo-char Composites

Brittleness and high cost of poly(lactic acid)(PLA)have severely limited its extensive application.In order to meet the needs of sustainable development,as well as maintain the biodegradability of PLA,bamboo particles(BP)and ultrafine bamboo-char(UFBC)derived from bamboo processing waste were used in blending modification of PLA.Polyethylene glycol(PEG)was further introduced to plasticize the composites.The effects of BP and UFBC loadings on mechanical properties,moisture resistance,melt fluidity and surface hydrophilcity of PLA/BP composites were studied.Thermal properties and interfacial bonding among components were also characterized to confirm the suitable proportion.The mechanism of interface combination and UFBC mechanisms of action in PLA/BP/UFBC composites were explored.The morphology of fractured surface and Fourier transform infrared spectroscopy(FTIR)were used to reveal the interaction mechanism among components.The plasticization effects and mechanism of different PEG loadings on PLA/BP/UFBC composites were analyzed.The main research contents and conclusions were as follows:(1)The effects of different BP additions on properties of PLA/BP composites were study.The addition of BP reduced mechanical strength and toughness of PLA.When 30%BP were added,composites exhibited better tensile,flexural and impact properties.Compared with pure PLA,the tensile and flexural modulus of composites increased with increasing BP content.The addition of BP reduced the glass transition temperature,cold crystallization temperature and melting temperature of PLA,the crystallinity of composites increased.Moisture resistance of pure PLA and PLA/BP composites remained at a good level.The flowability of PLA/BP composites got worse with increasing BP addition.Paticularly,when BP addition were over 30%,composites had difficulty in processing.The addition of BP improved surface hydrophilcity of composites.(2)UFBC particles were introduced into PLA/BP composites to prepare ternary composites.The effects of UFBC loadings on properties of PLA/BP composites were studied.The addition of UFBC reduced tensile and flexural properties of PLA/BP composites.The addition of 3%UFBC increased impact strength of composites by 10%.The mechanical properties began to decline significantly once over 3%UFBC was added.Moisture resistance of composites was not obviously affected by UFBC with the moisture absorption fluctuated in a narrow range.Flowability of PLA/BP composites increased with increasing UFBC loading.When addition of UFBC reached 3%,the melt flow index increased significantly,and truned slowly thereafter.The addition of UFBC obviously increased water contact angles of composites surface,and the surface hydrophilcity of composites was reduced.(3)PEG plasticizer was used in plasticization of PLA/BP/UFBC composites.The plasticizing effects of different PEG loadings on PLA/BP/UFBC composites were studied.The addition of PEG reduced tensile properties and impact resistance of composites.The addtion of 6%PEG significantly increased tensile modulus of composites.Flexural strength and modulus of composites reduced with increasing PEG content.Flexural strain at break of composites increased with incresing addition of PEG.When PEG addition increased from 8%to 10%,the flexural toughness of composites improved obviously.Better tensile,flexural and impact strength of composites were obtained at 6%PEG content,as well as obviously improved flexural toughness.When PEG addition was 6%～10%,drastic difference of composites crystallizing behavior occurred,and the plasticizing effect was significant.