Compression Moulding of Polypropylene Foams and Their Properties

Abstract

Compression moulding was used to produce polypropylene foams using azodicarbonamide as a chemical blowing agent. The morphology of the foams is reported in terms of cell size, cell density, and skin thickness using 1.5, 2, 2.5 and 3% of blowing agent. The resulting foams were characterized mechanically in terms of tensile and flexural moduli and comparison with mechanical models was made to predict foam performance. In general, mechanical properties, cell density, skin thickness and foam density decreased, while cell size increased with increasing amount of blowing agent. It was also found that simple mechanical models based solely on foam density and skin thickness were not able to correctly predict all the experimental data. For better prediction, foam density profile must be used.

Nano‐crystalline cellulose, chemical blowing agent, and mold temperature effect on morphological, physical/mechanical properties of polypropylene

“…CFA content also has a direct effect on E S , as less material is available to sustain the applied stresses, E S decreased when compared to the solid matrix (unfoamed PP), especially when increasing CFA from 0% to 1% (from 872 to 662 MPa.cm 3 /g for samples at 5wt % NCC and 80°C mold temperature). However, increasing CFA content from 1% to 2% did not significantly reduced the tensile modulus of samples molded at 30°C (less than 3.5%), but decreased their density by around 5%, so these E S values showed a marginal increasing trend compared to 1% CFA samples (average of 2.5% for NCC content of 0 to 5wt %).…”

Asymmetric microcellular composites: Mechanical properties and modulus prediction

“…According to previous studies, the tensile moduli of microcellular plastics 43 and microcellular composites 36,37 are lower than their unfoamed counterparts because less material is available to sustain the applied stresses. 44 Here, the core density is reduced by 19% on average and the stresses are mainly supported by the skins which represent 33 to 66% of the part thickness. 38 Indeed, increasing FA content from 0 to 1% Young's modulus decreased by 15% on average whatever the filler content.…”

Properties of Recycled LDPE/Birch Fibre Composites

“…Several studies on composite materials based on natural fibre are available, especially on mechanical and morphological properties [6][7][8][9][10]. Unfortunately, very few of them focused on their recycling.…”