| Straw-plastic composites are popular with people because of wood sense and wood texture.Due to its acid and alkali corrosion resistance,thermal stability,mothproof,low maintenance costs and other advantages,it is widely used in automotive interiors,furniture and other fields.However,the addition of fibers leads to the deterioration of the mechanical properties of composites and the mildewy color which limits the application range of materials.With improvement of people’s living standard,it is still required to have certain antibacterial effect when used in public places such as shopping malls,hospitals and parks.In this paper,PP and natural wheat straw were used as main raw materials to prepare straw/PP composite materials.Polypropylene grafted maleic anhydride(PP-g-MAH),ethylene-octene elastomer(POE)and organic antibacterial agent zinc pyrithione(ZPT)were added into composite materials.The effects of each component on the mechanical properties,rheological properties,crystallization properties,antibacterial and anti-mildew properties of the composites were studiedCAE technology were used to analyze and simulate the process of injection molding and predictting the cooling effect of the cooling pipeline and the warping deformation of the product.Orthogonal experiments were carried out with melt temperature,mold temperature and cooling time as horizontal factors and warping as optimization factors to optimize the mold structure,molding process parameters and improving product quality.(1)With the increase of straw content,the bending strength of the composites increased first and then decreased,reaching the highest when the straw content was 10wt%,and the bending strength reached the maximum of 32.36 MPa and then decreased 28.29 MPa.When straw content was 40 wt%,tensile strength decreased from 21.54 MPa to 17.11 MPa.Impact strength decreased from 12.06 kJ/m~2 to 3.80kJ/m~2.(2)The mechanical properties of the composites were significantly improved by adding the compatibilizer PP-g-MAH.When the addition amount was 6 wt%,the bending strength reached 41.23 MPa and,tensile strength reached 25.70 MPa and impact strength reached 5.31 kJ/m~2.(3)Adding POE can significantly improve the impact strength of the composite materials.The impact strength reached 7.27 kJ/m~2 when the addition amount is 8%.(4)The tensile,bending and impact properties of the straw/PP composite decreased slightly when the content of zinc pyridine thioketone increased.When the dosage of antibacterial agent was 2%,bending strength,tensile strength and impact strength decreased by 1.24%,4.49%and 2.41%.(5)When the zinc content of Pyridin was 0.5%,the antibacterial rates of E.Coli and S.aureus were 95.10%and 92.48%,which were higher than the National Standard.When the amount of antibacterial agent was 2%,the antibacterial rate was99.02%and 99.25%,which was more than 99%.After 100 days of storage,the antibacterial rate decreased to 96.50%and 95.30%.When the zinc content of Pyridin was 2%,the mould resistance rating reached 0 Grade.(6)The simulation results showed that the cooling effect of baffle type is better than through cooling channel.The highest temperature of the former product is 6.68℃ lower than latter,the average temperature of the former product is 6.45 ℃ lower than latter,and the time to reach ejecting temperature decreased by 17.2 s.(7)The simulation analysis of orthogonal experiment showed that the melt temperature is the most important factor to influence the warpage,the cooling time and mold temperature are the second.The best process parameters are melt temperature 180℃,mold temperature 45℃,and cooling time 220s. |
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