Weathering of wood Treesearch - Forest Service - USDA Source: Handbook of wood chemistry and wood composites. Boca Raton : CRC Press, 2005: pages 139-185. Weathering is the general term used to define the slow degradation of materials exposed to the weather. The degradation mechanism depends on the type of material, but the cause is a combination of factors found in nature: moisture, sunlight, heat/cold, chemicals, abrasion by windblown materials, and biological agents. Tall mountains weather by the complex and
Laboratory and environmental decay of wood–plastic composite UV radiation had no impact on flexural properties of field-exposed boards; loss occurred mainly on the side opposite to the sun-exposed surface. The mechanism of the aging process on colonization of WPC by fungi was examined and is consistent with development of slow crack growth in the polyethylene matrix combined with wood decay by fungi. wood particle decay, moisture, and elevated temperature were the major factors causing composite degradation, indicated by
Effects of increased solar ultraviolet radiation on materials. - NCBI Synthetic polymers such as plastics, as well as naturally occurring polymer materials such as wood, are extensively used in building construction and other outdoor applications where they are routinely exposed to sunlight. The UV-B content in Assessment of the damage to materials, associated with ozone depletion, requires a knowledge of the wavelength dependence as well as the dose-response characteristics of the polymer degradation processes of interest. While the recent
Weathering Characteristics of Wood Plastic Composites Reinforced 23 Jul 2016 UV radiation degrades the WPCs surface, further causing it to become cracked and flaky. Synergism between UV radiation and water also contribute to mechanical property losses of WPCs. The surface is eroded through water spray during weathering, providing new surfaces for degradation . When wood-flour-filled high-density polyethylene (HDPE) composites were exposed to xenon-arc radiation either with or without water spray in an accelerated weathering
degradation of polypropylene in naturally and artificially - SciELO Keywords: Crystallinity, molecular weight distribution, polypropylene, weathering, wood plastic composites. INTRODUCTION. wood plastic composites (WPC) are a group of plastic matrix composites made from a combination of wood fiber (or .. UV-exposure of stabilized and non-stabilized HDPE films: physico-chemical characterization. Polymer Degradation and Stability 49:251-262. Hulme, A.; Williams, G.; Shipton, P; Philip, M. 2004.The vulnerability of polypropylene recyclate.
Durability of Wood-Plastic Composites - Forest Products Laboratory degradation upon exposure to UV light. While all com- ponents of wood are susceptible to photodegradation, lignin absorbs 80 to 95% of the total amount of UV light absorbed by wood and only constitutes 25 to 30% of wood. (Fengel and Wegener 1983). As lignin oxidizes, the lignin. (and wood) content at the surface decreases (Fabiyi, et al. 2008, 2009). As a result, the surface of degraded wood is typically hairy and cellulose-rich. The plastic matrix theoretically should not undergo
Biological Degradation of Wood-Plastic Composites - CiteSeerX microbial decay. However, some WPC manufacturers initially believed that these materials were resistant to biodegradation due to encapsulation ofthe wood particles by the plastic. It is well known that polyolefins are highly resistant to biodegradation, especially without prior moisture, UV-light and temperature affect WPC performance, but these are not considered in this review. . of the composites were more affected by cyclic exposure than either by 2 hours water boiling or fungal
What Can Harm a Deck - Deck Doctor Unprotected wood is also subject to a variety of other “damage”. Surface degradation caused by constant exposure to the sun's harmful, ultra-violet rays is a common occurrence on decks, docks, fences and other outdoor wood structures. After consistent sun exposure over 1-3 years, the result is usually surface “graying”. The gray color is indicative of wood fiber degradation on the surface, and this graying will grow darker as years of sun exposure take their toll. Like sun-burnt skin, the
Wood Decay, Degradation & Stain - LSU AgCenter and moisture. Weathering. The surface of wood can be degraded if the wood repeatedly becomes wet and dry, is exposed to high and low temperatures and is exposed to direct sunlight. This degradation causes roughening of the surface, checking, splitting and wood cell erosion. Erosion, caused by the loss of wood cells from the lumber sur- face, is a slow process (Figure 1). Figure 1. Severe weathering oc- curred on the surface of these treated southern yellow pine boards used to.
Degradation of polypropylene in naturally and artificially weathered 13 Jun 2014 Effects of accelerated and natural weathering on the molecular weight distribution (MWD) and crystallinity of polypropylene (PP) in wood plastic composites (WPC) were investigated. The composites were produced from pine fibers Also, the flexural modulus of elasticity (MOE) of 50% wood flour filled HDPE decreased by 35% during the first 1000 h of exposure time of a 2000 h xenon-arc weathering trial (Lundin 2001). Falk et al. (2000) reported that color change
Exterior Decay of Wood–Plastic Composite Boards - Forest Products Exterior Decay of wood–Plastic. composite Boards: Characterization and Magnetic Resonance Imaging. Rebecca Ibach. Grace sun. Marek Gnatowski. Jessie Glaeser. Mathew Leung. John Haight. Abstract. Magnetic resonance imaging (MRI) was used to evaluate free water content and distribution in (WPC) materials decayed during exterior exposure because moisture is an essential factor for the progression of the decay . wood degradation process by this known reaction:.
Wood Plastic Composites Prepared from Biodegradable Poly wood plastic biocomposites of biodegradable poly (butylene succinate) (PBS) and Padauk sawdust was successfully prepared by using a twin screw extruder and an injection molding machine. The effects of water absorption and sunlight exposure on some properties of the composites were investigated. Water absorption of PBS composites was found to follow the Fick's law of diffusion, while the diffusion coefficient increased with increasing wood content. Maximum water absorption
Weathering of Wood Chapter 7 - CiteSeerX Handbook of wood Chemistry and wood composites. 7.5.6 Chemical Weathering is the general term used to define the slow degradation of materials exposed to the weather. . wood exposed outdoors will undergo a rather rapid color change in addition to the UV-induced degradation of lignin. In addition, rain will leach the water-soluble chemicals from the wood surface. Very little. UV radiation can penetrate common window glass; therefore, wood does not undergo UV-catalyzed.