Study On The Extrusion Moulding Of Ultrahigh Molecular Weight Polyethylene Under Ultrasonic Irradiance

The utilization of wave energy, as an important branch of vibration utilization which isan up-to-date side line of science is a newly developed study. As an important part of thestudy of the utilization of wave energy in polymer process has received much attention inrecent years and has get a rapid development. It has been successsively providing challeng-ing subjects to the study of the utilization of wave energy. Various wave energies are used inpolymer process. Some of them are used to improve process techn-ology, increase output ofmachinery and decrease energy consumption. Some of them are used to make chemical rea-ction take more easily and improve the quality of products. And even some of them havegiven rise to new process technology.Power ultrasonic treatment is an effective way to improve polymer microcosmic struct-ure and mechanical properties of material. Therefore it is surgently to carry out a deepgoinginvestigation in the region, which includes developing the power ultrasonic generator using inthe polymer processing industry, and discussing the microcosmic structure of grain finingwith ultrasonic and the technological parameters, in order to make grain fining with ultrasonicapply the polymer processing industry as possible as early. The existing ultrasonic generatorwas firstly transformed to the power ultrasonic generator by choosing the appropriate ultra-sonic frequency, the shape of transducer, and the material and the size of amplitude transfor-mer horn. After adjusting, sound power was measured,and efficiency of transducer and soundintensity in melts were calculated.This article introduces the clothes-rack-die to process Ultrahigh Molecular Weight Poly-ethylene (UHMWPE) material after comparing several kinds of extrusion die. In process-ing, supercritical carbon dioxide fluid was incorporated to reduce the viscosity of UHMWPEmelt. Ultrasonic apparatus and pressure transducers are employed in the die, which separatelycontrols the dilation of the bubbles and tests the rheological behavior of the polymer melt.An ultrasonic wave-extrusion system and a wave reactor for polymer melt degradationwere developed for studying the effect of ultrasonic wave on rheological behavior, structuresand properties of UHMWPE. The power-chemical degradation processing and mechanism ofUHMWPE were researched under ultrasonic irradiation to improving the processability andmechanics performance.The experimental results show that the apparent viscosity and the apparent viscosityactivation energy were reduced obviously by the effect of energy field, high frequency shear-ing libration and effusive under the ultrasonic irradiance. The extrusion yield increased andthe process temperature was reduced by 30℃. The sharkskin effect of the extrusion surfacedisappeared. The processability was improved obviously.