Study On The Preparation And Properties Of High Impact High Surface Hardness Polymer Blends

PVC is one of the world’s largest output of plastic varieties, it has good comprehensive performance:high strength, good rigidity, flame retardancy, corrosion resistance, electrical insulation, low price and so on, but it has the disadvantages of poor processability, low impact strength, bad cold tolerance. PVC/ABS blends could improve the properties of PVC. This paper systematically studied the properties of PVC/ABS blends in different ratios. Appropriate toughening agent and surface hardness modifier were blended into PVC/ABS blends by melt blending to prepare the polymer blends with high impact strength and high surface hardness.The polymer blends were prepared with PVC(SG-5) which was suitable for hard materials and two kinds of ABS (PA747, PA757) in different ratios. The mechanical properties, heat resistance, hardness were measured by electronic universal testing machine, impact strength meter, thermal gravimetric analyzer and Barcol hardness meter. The compatibility and structure of fracture surface were respectively characterized by dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The results showed that PVC/ABS blends was partially compatible, and the compatibility was dependent on the blending ratio as well as other properties. The impact strength (45.03kJ/m2) is superior to other systems when the ratio of PVC/ABS is40/60, while the pure ABS is only32kJ/m2.In order to improve the impact performance, the third component (MBS, NBR serves as toughening agent) was added to PVC/ABS747(40/60) blends. It was found that the impact strength increased obviously when the MBS or NBR was added to PVC/ABS747system in a certain proportion. When the amount of MBS or NBR was both12phr(the total amount of PVC and ABS is100phr), the impact strength was respectively51.46kJ/m2and64.16kJ/m2, while the growth rates were15.56%and44.08%; the decline rates of tensile strength were14.4%and7.99%, flexural strength were20.11%and10.2%. The initial decomposition temperature of NBR system was lower than blank sample while the PVC/ABS/MBS was almost unaffected. So we preferred to MBS as toughening agent of PVC/ABS system. The solubility parameter of PMMA is similar to PVC and ABS, it has high surface hardness, good weather resistance and rigidity. The impact strength decreased and surface hardness of blends increased significantly when choosed PMMA as surface hardness modifier, the Barcol hardness increased from18.43to27.67. In addition, PMMA can make up the decrease of the flexural and tensile strength, caused by the addition of MBS.