The influence of injection molding parameters and blowing agent addition on selected properties, surface state, and structure of HDPE parts

Abstract

The investigation of the influence of injection molding parameters (injection velocity, mold temperature and injection temperature, and additionally, as a result of these three parameters change, injection time, hold time, and cooling time) and blowing agent percentage on selected properties of HDPE molded parts such as weight, density, mechanical properties (tensile strength and elongation at maximum force), surface state (gloss and color), and structure was the aim of this work. The examination showed, that the mold temperature has the main influence on properties and surface state of molded parts from solid and foam HDPE. The weight, density, mechanical properties and gloss of molded parts increased with the increase in mold temperature. The mold temperature also influences significantly the number and size of pores in molded parts. The addition of blowing agent in a quantity of 2% is sufficient to obtain parts with favorable mechanical properties and good surface quality. POLYM. ENG. SCI., 53:780-791, 2013. FIG. 8. The change of the tensile strength of molded parts from HDPE: without blowing agent in function of the injection velocity v w and the mold temperature T f (T w ¼ 2308C) (a); the mold temperature T f and the injection temperature T w (v w ¼ 45 mm/s) (b), with 2% addition of blowing agent in function of the injection velocity v w and the mold temperature T f (T w ¼ 2308C) (c); the mold temperature T f and the injection temperature T w (v w ¼ 45 mm/s) (d), with 4% addition of blowing agent in function of the injection velocity v w and the mold temperature T f (T w ¼ 2308C) (e); the mold temperature T f and the injection temperature T w (v w ¼ 45 mm/s) (f).

Polymer foaming with chemical blowing agents: Experiment and modeling

“…In all the cases, the percentages represent the weight concentration respect to PE matrix. In the following, CBA refers to the compound and not to the reactive elements only [16][17][18][19][20].…”

The influence of the type of polypropylene and the length of the flow path on the structure and properties of injection molded parts with the weld lines

“…Porous moldings are produced by the injection method using physical blowing agents (CO 2 , nitrogen), water, or chemical blowing agents . Injection molding using chemical blowing agents is becoming more and more popular, due to the possibility of conducting the process using conventional injection molding machines, only with changed injection parameters . For this reason, the study of the influence of the foaming process on the structure and properties of injection moldings with the weld line areas was taken into consideration.…”

Technological characterization of PE/EVA blends for foam injection molding

“…The main result is that the part thickness has the most influence on the expansion ratio and cell morphology. Bociaga and Palutkiewicz [17] investigated the influence of injection molding parameters and blowing agent content on selected properties of HDPE molded parts. The results show that the mold temperature is the main influencing factor on the properties and surface state of foamed parts.…”