Abstract
In recent years, wood fibres have often been applied as the reinforcement of thermoplastic materials, such as polypropylene, whereas their use in combination with thermosetting resin has been less widespread. This study concerns the production of PMMA-based composites by partly replacing alumina trihydrate (ATH) with wood waste fillers, namely rice husks and almond shells, which would otherwise be disposed by incineration. The amount of filler introduced was limited to 10% as regards rice husks and 10 or 15% almond shells, since indications provided by reactivity tests and viscosity measurements did not suggest the feasibility of total replacement of ATH. As a matter of fact, the introduction of these contents of wood waste filler in PMMA-based composite did not result in any significant deterioration of its mechanical properties (Charpy impact, Rockwell M hardness and flexural performance). Some reduction of these properties was only observed in the case of introduction of 15% almond shells. A further issue concerned the yellowing of the organic filler under exposure to UV light. On the other hand, a very limited amount of water was absorbed, never exceeding values around 0.6%, despite the significant porosity revealed by the filler’s microscopic evaluation. These results are particularly interesting in view of the application envisaged for these composites, i.e., wood replacement boards.
Highlights
In recent years, disposing of agro-waste in ways other than incineration or landfilling has often been considered
This study is aimed at evaluating the introduction of the above fillers, namely rice husk and almond shells, to compare their effectiveness in partly replacing alumina trihydrate (ATH) in poly(methyl methacrylate) matrix (PMMA)
The study of the polymerization curve is necessary to establish the right amount of organic filler that can be introduced in the formulation to replace ATH, avoiding modifications in the exothermic curve compared to that of Duralight®
Summary
In recent years, disposing of agro-waste in ways other than incineration or landfilling has often been considered. When agro-waste are wood-like materials, with a significant lignin content, they may be introduced in a material (most often in polymers) and modify, hopefully in a positive sense, its mechanical and structural performance. The combined presence of lignin and silica in the porous structure of rice hulls shows potential for example for the decontamination of environmental objects [3], while on the other hand providing significant interest in terms of offering an increased hardness and tear strength to a polymer matrix [4]. It is worth considering though that an increase of properties by the introduction of rice husk in materials is generally obtained through the extensive use of modifications, such as grafting [5] or application of foaming agents [6]. A work on poly(methyl methacrylate) with rice husk reported the application of a treatment with triphenylphosphine [7]
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