A Novel System Design for Continuous Processing of Plastic/Wood-Fiber Composite Foams with Improved Cell Morphology

摘要

It is believed that the moisture that is inherently present in non-dried wood-fibers adversely affects the cell morphology of plastic/wood-fiber composite foams processed in extrusion. Based on this hypothesis, achieving a continuous extrusion-based production of fine-celled plastic/wood-fiber composite foams with a desirable qulity would be strongly conditioned by the efficiency of the system designed for uninterrupted wood-fiber moisture elimination.This paper presents an innovative approach in addressing system in a chemical blowing agent (CBA) based production of plastic/wood-fiber composite foams. It comprises a moisture-evaporation tandem extrusion system equipped with a vent at the interconnection of the two extrusion system equipped with a vent at the interconnection of the two extruders to serve for purging the moisture in the atmosphere. In order to check the performance of the newly developed system, an experimental study has been carried out for comparing the cell morphology and the volume expansion ratios of the foams obtained by processing identically formulated foamable plastic/wood-fiber composite mixtures using simulltaneously the cascade devolatilizing tandem extrusion system and a corresponding single extruder with no vent. The experimental results revealed that the foams produced by using the cascade devolatilizing tandem system exhibited significantly improved cell morphology and surface quality.