Study On Highly Reflective Composites And Highly Filled Plant Fiber Composites

Reflective materials play a very important role in life.It is widely used in road traffic safety,new energy materials and packaging.At present,commercial reflective materials generally use glass beads or pearl powder to change the optical structure of the surface of the object to achieve a reflective effect.In the experiment,we found that polylactic acid(PLA)and polystyrene(PS)blended,its surface will have a reflective phenomenon,and completely different from other reflective materials that need to add inorganic particles.Therefore,we want to explore the factors that influence the reflection of PLA and PS blends.In this thesis,PLA and PS were blended to obtain PLA/PS blends.The effect of microscopic distribution size and crystallinity on the reflectivity was studied.Glass beads microspheres were also used to simulate PS beads in PLA.Decentralized verification of our inferences,did the following part of the work:(1)As the volume of the blend changes with the volume content,the particle size of the polystyrene pellets dispersed in the PLA also changes.The change of the particle size affects the surface reflective properties of the sample.The reflectance of the sample increases with the enlargement of the polystyrene pellets.When the average particle size of the polystyrene pellets reaches 5 ?m and the size is uniform,the reflectance of the surface of the blend is the largest,and then with the particles.As the diameter continues to increase,the reflectance will drop significantly.(2)PLA and PS are blended and quenched to perform isothermal crystallization treatment.The reflectance of the amorphous sample is significantly lower than that of the crystallized sample.It is indicated that crystallinity is an important factor affecting the reflectivity of the blend.Then,as the crystallinity continues to increase,the reflectance of the sample does not increase,but decreases slightly.(3)The solid glass beads were used instead of the PS beads to be dispersed in PLA for testing.To verify the above-mentioned inference about the change in particle size affecting the reflective properties of the blend.It was found through experiments that PLA was blended with glass beads.When the volume content was constant,the reflectance changed with the change of the particle size of the glass beads.It is consistent with the experiment of blending samples with PLA and PS.The effect of the content of the pellets on the retroreflective properties was investigated by specifying a particle size of the glass beads mixed with the polylactic acid to change the volume content of the glass beads.When the glass bead volume content increases from 1% to 7% in the blend,the reflectance on the surface also increases.The reflective properties of the surface of the PLA and the glass microbead copolymer can be controlled by controlling the crystallinity of the PLA.In the case where the PLA is amorphous,the reflectance is significantly lower than that of the PLA crystal.In the early stage of isothermal crystallization,the reflectivity of the blend will increase as the crystallinity increases,and in the later stage,the crystallinity will increase and the reflectance will decrease slightly.In conclusion,the phenomenon of reflection caused by the copolymerization of PLA and PS was studied.It was found that the change in the particle size of the polystyrene pellets dispersed in the PLA and the change in the crystallinity of the PLA are important factors influencing the retroreflective properties.It was also verified by replacing the polystyrene with glass beads.It provides a new idea for the future preparation of reflective materials by blending two polymers.A highly filled plant fiber composite was also prepared and its properties were studied.It can be found through experiments that it has better mechanical properties than traditional wood-like materials.By characterizing the length of the plant fiber in the material,it was found that the dispersion reached the centimeter level,indicating the reason for its excellent mechanical properties.After 100 days of water soaking experiments,the water absorption rate was found to be no more than 3%,indicating that the material has excellent water resistance.In the flame retardant test,the flame retardant modified sample cannot be ignited for the first time and can be ignited the second time.Through the above research,it can be found that this highly-filled plant fiber composite material is a material that is very suitable for replacing wood,and has a very broad application space.Among the two materials studied in this thesis,the reflective material blended with polylactic acid and polystyrene can be used as a spray-free material to reduce the use of coatings and solvents.And the composite matrix is polylactic acid,which can be degraded after use.Plant fiber-filled composite fillers are derived from natural plants and are safe and reliable.Therefore,these two materials are environmentally friendly and in line with our current environmental protection tenet.