Photoaging and stabilization of rigid PVC/wood‐fiber composites

Abstract

Ultraviolet (UV) weathering performance of unpigmented and rutile titanium dioxide pigmented rigid polyvinyl chloride (PVC)/wood-fiber composites has been studied. The composite samples were manufactured by dry-blending PVC, wood fibers, and other processing additives in a high-intensity mixer. The dry-blended compounds were extruded and compression molded into panel samples. The manufactured samples were artificially weathered using laboratory accelerated UV tests. Composite samples were exposed to 340-nm fluorescent UV lamps and assessed every 200 h, for a total of 1200 h of accelerated weathering. Each assessment consisted of a visual examination of surface roughness or erosion, a contact angle measurement, a FTIR collection, and a color measurement. The experimental results indicated that wood fibers are effective sensitizers and that their incorporation into a rigid PVC matrix has a deleterious effect on the ability of the matrix to resist degradation caused ultraviolet irradiation. The light stability of these composites could be improved quite efficiently with the addition of rutile titanium dioxide photoactive pigment during formulation.

Photodegradation profiles of PVC compound and wood/PVC composites under UV weathering

“…Studies on the factors affecting on the properties of WPC under weathering conditions have focused on various aspects, such as weathering conditions (e.g. moisture, temperature, and biological decay) [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], wood content, processing method, weathering condition, and type and content of UV absorbers and pigments [3][4][5][6][7][8][9][10][11][12][13][14]. The presence of wood has been found to accelerate the photodegradation of WPC.…”

“…Works by Stark and Matuana [3,4] showed that wood particles accelerated the oxidation reaction at the surface of wood/high density polyethylene (WPE) composite, to a greater extent than that of neat high density polyethylene (HDPE). In the case of wood/polyvinyl chloride (WPVC) composites, the presence of wood strongly accelerated the photodegradation of PVC [5][6][7] and interfered with the function of a UV absorber [7]. The chromophore groups or carbonyl groups in lignin as a component of wood accelerated the photodegradation of polymer matrix with enhancing absorption of UV light on the WPC surface.…”

Fotodegradação de compósitos de poliestireno/argila montmorilonita: efeito do tipo de argila e presença de sal

“…Estudos de fotodegradação de compósitos poliméricos mostram que alguns componentes retardam, mas também podem acelerar o processo degradativo do outro componente. Um exemplo é o efeito fotodeteriorativo ao se inserir fibra ou pó de madeira em uma matriz de PVC rígido [7,8] . Contudo, esse mesmo tipo de aditivo impediu a formação de reticulações em estágios iniciais de fotodegradação quando inserido em matriz de PEAD, neste caso através de um impedimento físico [9] .…”

Influence of accelerated ageing on the physico-mechanical properties of alkali-treated industrial hemp fibre reinforced poly(lactic acid) (PLA) composites

“…Durability of natural fibre composites upon exposure to UV-light is of particular concern as UV-light can cause the changes in the surface chemistry of the composites commonly known as photodegradation [5,6]. The degradation ranges from mere surface discoloration affecting the aesthetic appeal in indoor applications to extensive loss of mechanical properties [7,8].…”