Study On The Chinese Medicine Residues (CMR) Reinforced Polylactide (PLA) Biocomposites

A new kind of completely biodegradable composite which prepared by Chinese Medicine Residues(CMR)and Polylactide(PLA)was studied in this article.By adding modifiers to improve the processability and mechanical properties of CMR/PLA composites,the hydrothermal aging and Soilburial tests were carried out at the same time.The main conclusions of this paper are generalized as follows:1.After analyzing the main components of the Chinese Medicine Residues are: 42.28% cellulose,27.25% hemicellulose,12.47% lignin,ash and the others 2.26%.CMR were rich in cellulose,hence it could be used to reinforce composites.By melt blending method,the Chinese Medicine Residues(CMR)and Polylactide(PLA)were mixed together.The extrusion and injection molding processes were used to prepare all the specimens of CMR/PLA composites.Compared with wood fiber/PLA composites,the mechanical property of CMR/PLA composites are no different than wood fiber/PLA composites and tensile strength of CMR/PLA composites even better.The CMR/PLA composites which preperad by CMR(40 mesh)had the best comprehensive mechanical properties.The rheological,thermogravimetric and the dynamic mechanical properties of CMR/PLA composites also were studied.The processability and interfacial compatibility between CMR and PLA still need to be improved.2.The various properties.of CMR/PLA composite was improved by using plasticizer DOP,maleic anhydride(MAH)and ACR.The best melt index(MI)is 29.7g/10 min,but the mechanical properties of composite gradually decreased with the increasing of DOP at the same time.A decline of 17.8% in flexural strength for adding 7% DOP.The mechanical strength of CMR/PLA composite exhibited increase first and decrease then when using MAH.The tensile and flexural strength was 43.04 MPa and 70.2MPa respectively when the addition of MAH was 1% and 1.5%.After adding ACR the elongation at break point rose to about 4.8 times of pure PLA,but tensile and flexural strength were decreasd markedly.the waterproof of composites and interfacial compatibility between CMR and PLA was improved after adding MAH.The thermostability of composites was also improved by using 4%ACR,meanwhile a better fluidity and processing performance were provide.3.Hydrothermal ageing was implemented through immersing samples in distilled water at 60?,90? and room temperature in different ageing cycles.The properties of the CMR/PLA composites were characterized by mechanical property testing,thermogravimetric analysis,FTIR and Scanning Electron Microscope.The result showed that the temperature has a significant effect on the hydrothermal ageing behavior of the composites.After 60 ? hydrothermal ageing of 8 days,the bending strength and the tensile strength has reduced to 7.04 and 4.32 MPa respectively,while the bending strength and the tensile strength became to 1.32 and 2.48 MPa after 90 ? hydrothermal ageing of 15 hours and then the mechanical properties completely lost after 20 hours.4.Chinese Medicine Residues enhanced the biodegradation capability of CMR/PLA composites.The degradation percentage of CMR/PLA composites with 40% CMR in soil after 120 days was about 16.0%.While the bending strength and the tensile strength became to 6.89 MPa and 26.78 MPa after degradation.This study also found that temperature and monthly precipitation were also the important factors affecting the natural degradation.The thermal-decomposition temperature increased slowly during degradation.Compared with PLA,after 120 days degradation the surface colour of composites faded gradually and there were large quantities of mildew spots and cracks on its surface.This study showing that the microbial degradation of composites were promoted by adding CMR.