Effect Of Ultrasonic Irradiation On The Properties Of Polyolefin Materials

Polyolefin materials are the most commonly used plastics in demand.When producing polyolefin materials,they often increase the production cost of the enterprise due to their higher melt viscosity.Furthermore,people are increasingly demanding the quality and requirements of polyolefin materials.To improve,scholars from various countries have done a lot of research work on polyolefins,and the application of ultrasound-assisted molding in polyolefin materials has also emerged.However,due to the relatively complicated influence of ultrasound-assisted molding on polymer properties and the technology is not mature enough,the application There are some difficulties in the actual production of the enterprise.Therefore,it is very important to study the influence of ultrasonic irradiation on the performance of polyolefin materials,and to provide a reference for the application of ultrasonic assisted molding in actual production.In this paper,two common polyolefin materials,high-density polyethylene(HDPE)and polypropylene(PP),are used as the research objects.The two polyolefin materials are designed with different ultrasonic irradiation parameter schemes.Polyolefin material samples,and then the molecular weight and crosslinking degree of the two samples were tested,and the thermal stability changes were analyzed by the simultaneous thermal analyzer(TGA)and differential scanning calorimeter(DSC).X-ray diffractometer(XRD)and DSC crystallization curves were used to analyze the effect of crystallinity,and the rheological properties were analyzed by rotary rheometer.Based on the above experimental results,the inherent laws of the performance effects of polyolefin materials with different ultrasonic parameters are obtained.The study found that:(1)Ultrasound irradiation will break the molecular chain of polyolefin material,reduce the molecular weight,and at the same time,the degree of cross-linking between molecules increases,but the decrease in polyolefin molecular weight has a limit value,which tends to the limit The decrease began to become slow.(2)Ultrasonic irradiation will cause the melting temperature of polyolefin material to fall first and then rise.When the melting temperature reaches the maximum,it is higher than the melting temperature of the unirradiated sample,which on the one hand confirms the ultrasonic irradiation can improve the thermal stability of polyolefin materials;on the other hand,the 5%weightlessness temperature of HDPE increases the most after 15 minutes of irradiation with 400W of ultrasonic power,and its 5%weightlessness temperature is higher than that of HDPE 5%The 5%weightlessness temperature of PP increased the most after irradiated with 300W ultrasonic power for 10 minutes,and its 5%weightlessness temperature increased by nearly 6.3%compared to the unirradiated PP 5%weightlessness temperature.(3)Ultrasonic irradiation also has an effect on the crystallinity of polyolefin materials.In the case of small ultrasonic power and ultrasonic irradiation time,the crystallinity has increased.As the power continues to increase and the time increases,due to crosslinking,the degree of increase becomes the main factor,and the crystallinity begins to decrease.Ultrasonic irradiation has the effect of grain refinement,and the greater the ultrasonic power,the longer the irradiation time,the smaller the grain size.However,ultrasonic irradiation has no effect on the crystal structure of polyolefin materials.(4)Ultrasonic irradiation treatment of polyolefin materials can effectively reduce the viscosity of the system,improve rheological properties,facilitate processing and improve production efficiency.When HDPE is irradiated with 400W of ultrasonic power for 10 minutes,the shear viscosity reaches the minimum,and then the shear viscosity rebounds.The ultrasonic parameters at this time are most conducive to processing;ultrasonic irradiation treatment of PP can effectively reduce the oscillation of 1Hz?10Hz,the complex viscosity at frequency improves the rheological properties.The parameter is that the complex viscosity is minimized when irradiated at 300W ultrasonic power for 10 minutes,which is conducive to processing.Ultrasonic irradiation will increase the storage modulus of PP and increase it.The ability of PP to resist deformation.