Resistance to weathering of wood-polypropylene and wood-wollastonite-polypropylene composites made with and without carbon black

Abstract

Purpose

The purpose of this paper is to study natural and accelerated weathering of wood-polypropylene (WF-PP) and wood-wollastonite-polypropylene composites made with and without carbon black.

Design/methodology/approach

Natural weathering was conducted in Ruokolahti, Finland in the time of year when solar radiation was maximal. The accelerated weathering tests included exposure to a xenon-arc source with and without spray, and a cyclic test consisting of water immersion–freeze–thaw stages.

Findings

Both the type of weathering and the formulation of the composite determined the degree of change in their properties. Weathering, including xenon-arc exposure with spray resulted in much higher changes of colour of non-pigmented composites compared to natural weathering or xenon-arc weathering without spray. Both UV irradiation and moisture had an adverse effect on the Charpy impact strength of non-pigmented composites. Carbon black containing composites performed better than non-pigmented composites.

Research limitations/implications

This study is a part of an ongoing research on the development of wood-polymer composites (WPCs) suitable for outdoor applications in Finnish climatic conditions. Outdoor weathering limited to 1,000 h cannot be used for the prediction of the service life of composites and was used here solely for comparative purposes.

Originality/value

This paper will help to understand the effect of different weathering factors on the behaviour of WF-PP and wood-wollastonite-polypropylene composites made with and without carbon black (as UV stabiliser). The study demonstrated that while accelerated weathering tests provided useful information on the resistance of WF-PP composites to different weathering factors, they cannot be used alone to predict the behaviour of WPCs meant for outdoor application.

Citation

Butylina, S. and Kärki, T. (2014), "Resistance to weathering of wood-polypropylene and wood-wollastonite-polypropylene composites made with and without carbon black", Pigment & Resin Technology, Vol. 43 No. 4, pp. 185-193. https://doi.org/10.1108/PRT-03-2013-0019