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

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.