The Effect of Recycling on Wood-Fiber Thermoplastic Composites.

Luísa Rosenstock Völtz,Shiyu Geng,Kristiina Oksman,Irangeli Di Guiseppe

doi:10.3390/polym12081750

Luísa Rosenstock Völtz, Shiyu Geng + Show 2 more

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https://doi.org/10.3390/polym12081750

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Journal: Polymers	Publication Date: Aug 5, 2020
Citations: 17	License type: CC BY 4.0

Affiliation: Luleå University of Technology

Abstract

The aim of this study was to investigate the effect of recycling on polypropylene (PP) and wood-fiber thermoplastic composites (WPCs) using a co-rotating twin-screw extruder. After nine extrusion passes microscopy studies confirmed that the fiber length decreased with the increased number of recycling passes but the increased processing time also resulted in excellent dispersion and interfacial adhesion of the wood fibers in the PP matrix. Thermal, rheological, and mechanical properties were studied. The repeated extrusion passes had minimal effect on thermal behavior and the viscosity decreased with an increased number of passes, indicating slight degradation. The recycling processes had an effect on the tensile strength of WPCs while the effect was minor on the PP. However, even after the nine recycling passes the strength of WPC was considerably better (37 MPa) compared to PP (28 MPa). The good degree of property retention after recycling makes this recycling strategy a viable alternative to discarding the materials. Thus, it has been demonstrated that, by following the most commonly used extrusion process, WPCs can be recycled several times and this methodology can be industrially adapted for the manufacturing of recycled products.

Highlights

Environmental regulations are placing pressure on manufacturers to consider the environmental impact of their products
The fibers extracted from the samples before recycling (WPC-0) presented longer fibers, around 2 to 3 mm
The fiber shortening started to be more noticeable after the third recycling step (WPC-3)

Summary

Introduction

Environmental regulations are placing pressure on manufacturers to consider the environmental impact of their products. By replacing conventional materials with renewable and biodegradable materials such as natural fibers, or reusing materials by reprocessing them several times [1,2], environmental impact can be avoided. From a material point of view, the recycling and reuse of materials present an excellent opportunity for producing new products with comparable properties. From the environmental point of view, the natural fibers are renewable, abundant, and biodegradable [4]. Due to the increase in consumer ecological awareness, the WPCs have gained more attention as an alternative to traditional polymeric materials [6,7]. Recycled plastics have been used for the production of WPCs since the 1990s with an expressed increase in the last few years [8]

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