The Impact of Mould Temperature and Blowing Agent Content on Structure and Properties of Injection Moulded Parts

Abstract

The investigation of the influence of mould temperature and blowing agent percentage on structure, and selected properties (weight, mechanical properties, surface state - gloss and colour) of moulded parts from HDPE was the aim of this work. The structure of moulded parts in cross-section perpendicular and parallel to the direction of polymer flow, and quantitative assessment of porous structure using microscopic image analysis were carried out. It was shown that the content of blowing agent in polymer influences not only the amount of pores in the part core, but also the thickness of solid skin. Lower mould temperature favors the formation of a fine porous structure. The formation of the porous structure influenced slightly the weight and mechanical properties of moulded parts. With the increase in blowing agent content, the gloss of parts decreased and also caused the change in their colour. Parts with higher amount of blowing agent were brighter.

The influence of blowing agent addition, talc filler content, and injection velocity on selected properties, surface state, and structure of polypropylene injection molded parts

“…The properties of porous molded parts and their structure depend on many parameters of the injection molding process, such as mold temperature, injection temperature, injection pressure, melting temperature, hold pressure, hold time, backpressure, suck-back, and so on as well as on the shape and dimensions of the mold cavity and length of the runners. 1 -17…”

Foamability and Special Applications of Microcellular Thermoplastic Polymers: A Review on Recent Advances and Future Direction

“…[ 275 ] An increase in blowing agent content has also been reported to result in decrease in gloss of parts produced by foam injection molding. [ 276 ]…”

The Effect of Blowing Agents on the Effectiveness of Poly(vinyl Chloride) Extrusion

“…Cells produced thereby are filled with air or various gases, e.g. CO 2 or N 2, and later replaced with air due to diffusion [8,14,18].…”

“…Also, investigation of the extrusion process with regard to decomposition, number of cells, mechanical properties and structure of cellular extruded products made of HDPE/PP, PVC were conducted [9,12,18]. The studies about investigate the effectiveness of manufacturing cellular products are also significant [2,14]. Despite the numerous publications on extrusion including cellular extrusion, there is, in fact, lack of information on the effectiveness of extrusion performed using different blowing agents, the same starting parameters and a constant geometry extruder.…”