The thermo-oxidative durability of polyethylene reinforced with wood-based fibres

Lilian Forsgren,Ezgi Ceren Boz Noyan,Alberto Vega,Nazdaneh Yarahmadi,Antal Boldizar

doi:10.1016/j.polymdegradstab.2020.109374

Lilian Forsgren, Ezgi Ceren Boz Noyan + Show 3 more

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https://doi.org/10.1016/j.polymdegradstab.2020.109374

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Abstract

Aiming at better understanding the ageing behaviour of cellulose composites, the accelerated thermo-oxidative ageing of polyethylene reinforced with two types of wood-based cellulose fibres was studied. Materials were prepared by extrusion mixing of either un-stabilized or stabilized polyethylene reinforced with 5 and 20 vol % cellulose content. The materials were extruded into strips and then aged at 90°C in circulating air. The effect of accelerated ageing up to 31 days was assessed by oxidation induction time and mechanical properties in tension. The results indicated that the added cellulose fibres did not increase the degradation of the composites during this ageing. Reinforcement with 20 % cellulose fibre having a 28 % lignin content together with 0.005 % Irganox 1010 antioxidant resulted in a remarkable improvement in the resistance against accelerated thermo-oxidation, compared to the pure polyethylene with added antioxidant. The findings of increased lifetime of LDPE by addition of wood-based reinforcement is of great interest, since the durability aspect is crucial to understand and predict before usage in commercial applications and especially as structural composites.

Highlights

Substantial research efforts have been devoted to the reinforcement of thermoplastics with cellulosic fibres, such as with woodbased fibres
18.5 ± 0.8 14.1 ± 2.0 0.35 0.23 modulus for samples stabilized with AO, which may indicate that the degradation was not prominent, as indicated by the oxidation induction time (OIT) and Fourier transform infrared spectroscopy (FTIR) results
The results obtained here shows no differences in mechanical loss factor between composites containing 20 % thermomechanical pulp (TMP) or cellulose tissue (CT) and the unfilled low-density polyethylene (LDPE)

Summary

Introduction

Substantial research efforts have been devoted to the reinforcement of thermoplastics with cellulosic fibres, such as with woodbased fibres. A rather broad span of potential or intended applications can be found in the literature for such composite materials, ranging from relatively short-term packaging applications to longer term applications in automotive and building [3,4,5]. Substantial volumes of cellulose composites (mainly wood powder composites) are used for outdoor building applications, such as roofing and decking [6,7], and for automotive interior parts [6,7,8,9]. Polyethylene and polypropylenes are greatly in favour as matrices, mainly due to their relatively low melting ranges and their low cost [5,6,10]. It can be noted that the low melting temperature and the flow properties of low-density polyethylene (LDPE) are very interesting for such composites [11]

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