Study On Polyethylene(PE) Composites Modified By Alpha-hemihydrate Phosphogypsum Whisker

Polymer materials have gained rapid development in recent years because of their superior overall performance and relatively simple molding process.As one of the five synthetic resin polyethylene is also widely used.However,polyethylene also has some disadvantages such as poor heat resistance,brittle and poor impact resistance.It is an important way to improve the performance by adding inorganic filler.The α-hemihydrate gypsum whiskers obtained in the preparation of phosphoric acid are filled in polyethylene,which not only retains the main properties of the polyethylene material,but also improves the properties of the material by the enhancement of whisker and toughening while reducing the cost of materials at the same time.In this paper,α-hemihydrate gypsum whiskers were prepared by acid hydrolysis of phosphate rock.The effects of phosphoric acid concentration,sulfuric acid concentration and stirring rate on whisker aspect ratio were investigated.We studied the effects of the modification process and the amount of different modifier on the results of whisker modification using five kinds of conventional modifier and optimized the appropriate process and ratio of treatment.The effects of different filling and different aspect ratio of α-hemihydrate gypsum whiskers on the properties of polyethylene composites were studied,when the treated α-hemihydrate gypsum whisker was filled into polyethylene materials.The results were as follows:（1）When the phosphoric acid mass concentration was not less than 29%,the main component of the phosphogypsum was α-CaSO₄·0.5H₂O.（2）The maximum of aspect ratio of obtained α-hemihydrate phosphate gypsum whisker was 45 under the conditions which the concentration of phosphoric acid was 33%,the concentration of sulfuric acid was 39.2% and the stirring rate was 400 r / min at 90℃.The minimum aspect ratio of α-hemihydrate phosphate gypsum whisker obtained under the conditions which the concentration of phosphoric acid was 37%,the concentration of sulfuric acid was 58.8% and the stirring rate was 200 r / min was 8.（3）The best modification process conditions was that the modified temperature was 60℃,modification time was 60 min,ethanol dosage was 5 times of α-hemihydrate gypsum whisker.The modification effect of α-hemihydrate gypsum whiskers was the best under the best modification process conditions when the modifier was stearic acid and the dosage was 5%.（4）When the mass content of α-hemihydrate gypsum whisker was 5%,the mechanical properties of polyethylene composites are the best,which the crystallinity was the highest,the tensile strength was 25.0MPa and the flexural strength was 44.0Mpa.The reason was that the whiskers were evenly distributed in the matrix and had a certain induction effect on crystallization behavior of polyethylene,which resulting enhanced crystallization degree of polyethylene material.（5）When the mass content of the filler was 5%,the mechanical properties of the polyethylene composites with 45 of the aspect ratioare was better than that with 15 of the aspect ratio,which the tensile strength was improved by 4.28%,the bending strength was increased by 3.41% and the impact strength was increased by 3.98%.