Study On The Effect Of Environmental Protection Additives On The Properties Of PLA-based Composites

Polylactic acid(PLA)is an environmentally friendly plastic made from cereal starch as raw material,and it is the most promising polymer material.PLA has many applications,packaging can be used in fresh vegetables,green electronic product packaging and environmental protection tableware,etc.However,the cost of preparing PLA is high,in order to reduce the preparation cost of PLA,improve its performance,in this paper,the effects of wood fiber types,rice husk fiber content and rice husk fiber particle size on the thermal properties,mechanical properties and water absorption properties of the composites were studied.To determine the optimal performance of the wood filler parameters;The properties of bamboo wool modified rice husk fiber/PLA wood-plastic composites with different additions and particle sizes were studied;The effects of inorganic mineral filler talc and montmorillonite on the properties of PLA composites were discussed.The effects of the addition amount and particle size on the flame retardancy,mechanical,thermal and water absorption properties of the composites were discussed.The main conclusions are as follows:(1)Comparing the properties of PLA composite materials with wheat straw powder,rice straw powder and rice husk powder,Rice husk fibre/PLA the highest hardness value,35.4 HRC,The flexural strength and impact strength of wheat straw fiber/PLA composites were 28MPa and 2.1KJ/m2 respectively,The water absorption rates of rice husk fiber/PLA,rice straw/straw and wheat straw/PLA composites were 9%,10%and 12%,respectively.The initial thermal decomposition temperature of rice husk fiber/PLA composites and the remaining mass was the highest,297.2? and 13.80%respectively.Compared with different content of rice husk fibre(30 wt%and 40 wt%,50 wt%)preparation of composite filling PLA performance it is concluded that:With the increase of rice fiber content,the mechanical properties of the composites increased first and then decreased,When the content of rice husk fiber is 40wt%,the composite mechanical properties are the best,The hardness,flexural strength and impact strength were increased by 22%,48%and 24%respectively when the content of rice husk fibre was 50wt%,The water absorption of 24h was increased with the increase of rice fiber content,and the water absorption rate of 40wt%composites was the smallest and the interface effect was the best.The performance of the hybrid rice composites with different particle sizes(60 mesh,80 mesh and 100 mesh)shows:When the grain size of rice husk fiber is 60 mesh,the composite mechanical properties are the best,The hardness,flexural strength and impact strength were 59.8HRC,38MPa and 3.8KJ/m2 respectively,which were 50%and 21%higher than those of 80 mesh rice husk fiber/PL A composites respectively.When the number of rice husk fiber was 60 mesh,the water absorption rate of rice husk fiber/PLA composites was the lowest at 24 hours,which was 6.8%lower than that of rice husk fiber/PLA composites with diameter of 100 mesh.The interface effect was also the most it is good.(2)The effects of different bamboo charcoal additions(2,4,6,8phr)on the performance of rice husk fiber/PLA wood-plastic composites were compared and analyzed.When the amount of bamboo charcoal is 4 phr,the hardness,impact strength and bending strength of the prepared composite BC-4 are 78HRC,4.2KJ/m2 and 42MPa respectively.The thermal stability of BC-4 is better than BC-2,the interface is the best,the number of-OH is the least,and the water absorption is the best.Comparative analysis of different particle size(100,200,300 and 400 mesh),bamboo charcoal effect on the properties of rice husk fibre/PLA composite material is:When the diameter of bamboo charcoal is 400 mesh,the hardness,impact strength and flexural strength of the composite BC-400 are 83.8HRC,4.4KJ/m2 and 48MPa respectively.The initial decomposition temperature of BC-400 is higher,the residual mass of combustion is more,the thermal stability is better,and the interface is better.The water absorption is the lowest.(3)Different levels(2,4,6,8 PHR)talcum powder filler rice husk fibre/PLA composite materials research results show that:When the talc content is 2 phr,the composite mechanical properties are the best,and the hardness,flexural strength and impact strength are 72.6HRC,41MPa,3.7KJ/m2 respectively.The higher the thermal stability of the composites,the better the decomposition temperature,the decomposition temperature and the residual mass increase with the talc powder content.Talc powder content of 8phr,the composite material 24h minimum water absorption.The research of(2,4,6,8 phr)montmorillonite filled rice husk fiber/PLA composites showed that:When the content of montmorillonite is 8 phr,the hardness,flexural strength and impact strength of the composites are the highest,which is 76%,87%and 72%higher than that of montmorillonite is 2phr.With the increase of montmorillonite content,the initial decomposition temperature,the decomposition temperature and the residual mass of the composites increased.The 24h water absorption of the composites decreased with the increase of montmorillonite content.(4)The effects of different shellings(3,6,9 and 12 phr)shell powder on the performance of rice husk fiber/PLA composites were compared and analyzed:When the amount of shell powder was 12 phr,the SP-12 had a maximum oxygen limit of 24.7%.SP-12 hardness,bending strength of the largest,respectively,48.2HRC,40MPa,sp-6 impact strength of the largest,3.12 KJ/m2.The thermal stability of SP-12 is the best,the combustion mass is 28.75%,and the number of-OH is less,and the water absorption is the smallest.The effects of shell powder on the performance of rice husk fiber/PLA composites with different particle sizes(200,400 and 600 mesh)were compared.When the shell powder particle size is 600 mesh,the SP-600 has a maximum oxygen limit of 25%.The hardness,impact strength and flexural strength of SP-600 were 62.4HRC,3.3KJ/m2 and 43.0MPa respectively,and the SP-200 with the worst mechanical performance increased by 56%,7.5%,32%and 4.57%respectively.The thermal stability of SP-600 is better,and its functional groups are affected by the size of shell powder.The interface is the best,and the water absorption is the smallest.