Effect of nanoclay addition on the foaming behavior of linear polypropylene‐based soft thermoplastic polyolefin foam blown in continuous extrusion

Abstract

The goal of this study is to fabricate a soft foam with high cell density and high foam expansion based on thermoplastic polyolefin (TPO), and to supply a potential candidate for soft thermoset foams. It was found that a linear polypropylene (PP)‐based TPO foam exhibited very poor cell morphology because of its weak melt strength. Nanoclay was introduced into the TPO to improve its foaming behavior. The extrusion foaming experiments demonstrated that the introduction of 0.5 wt% nanoclay significantly increased the cell morphology and expansion ratio of TPO/clay nanocomposite foams due to the enhanced cell nucleation and the possible cell coalescence suppression at low temperatures. At a high nanoclay content of 2.0 wt%, the cell density and foam expansion of foams increased continuously compared with the 0.5 wt% nanoclay addition. Our study suggested that it was possible to produce soft TPO foams with a well‐defined cell structure and high foam expansion using a continuous method, but that a proper PEOc content control was needed to maximize foam expansion. POLYM. ENG. SCI., 2011. ©2011 Society of Plastics Engineers.

Synthesis, structure, and thermal stability of poly(methyl methacrylate)‐co‐ poly(3‐tri(methoxysilyil)propyl methacrylate)/ montmorillonite nanocomposites

“…Various polymers, thermoplastics as well as thermosets, and several kinds of nanoparticles, such as nanotubes and clays have been used to prepare NPC with outstanding high‐performance that would not be obtained for conventional composites [1, 2]. Polymer/montmorillonite (MMT) NPC, produced by the addition of very low amount of clay filling (1–5 wt%), exhibits remarkable improvement in mechanical properties, heat resistance, barrier properties, tuning of crystallinity, and fire retardance [3–5].…”

Die opening-induced microstructure growth in extrusion foaming of thermoplastic sheets

“…The blowing agent gas dissolves inside the polymer melt and subsequently makes the polymer chain move easily under pressure. Literature studies show a reduction in the viscosity of polymer melt upon the dissolution of the blowing agent gas [12,30,31]. Such voids reportedly can act as the weakest section in the foamed material and thereby deteriorate the mechanical properties of the eventual foamed product [32,33].…”

Effects of nanoclays on the thermal stability and flame retardancy of microcellular thermoplastic polyurethane nanocomposites

“…In past years, the major flame retardants used have been halogenated additives to produce polymer‐based fireproofing materials. Because halogenated additives can release toxic gases in a fire, they have been gradually replaced by inorganic fillers, such as aluminum hydroxides, graphene oxides, and nanoclay particles, to reinforce the flame resistance of polymers . The flame retardant mechanism for aluminum hydroxides relates to an endothermic decomposition process where they can release water at high temperatures to cool down the condensed phase and dilute the oxygen concentration in air .…”