Papers by Keyword: Artificial Weathering

Abstract: The aim of this study was to characterize and evaluate the performance of two wood species, pine (Pinus sylvestris L.) and spruce (Picea abies Karst.) used for wooden furniture in outdoor coated with a water based ecological paint and subjected to artificial weathering. Another task of this research was to investigate the potential of the application of paint using dipping method in alternative to traditional brush or spraying coating application methods, since, if wood samples are grouped in stacks, the processing time can be reduced, compared to samples painted singularly. From the analysis of the dipping parameters, such as time and paint concentrations, more practical and specific knowledge was obtained regarding this painting method.From the characterization of the painted samples and from the measurements of color changes during artificial weathering it was observed that coated wood surfaces have similar optical properties also in case of different dipping times, although the type of wood could affect the performance of final product during artificial weathering test as in case of spruce wood samples, specifically those prepared with the shortest dipping time: for these samples a lower resistance to weathering and higher color changes were observed.

Abstract: The aim of this research is to investigate and to evaluate the changes that occur on the surface of wood specimens, coated with three different coatings and exposed to artificial weathering. The three used coatings contain linseed oil and different types of pigments. Specimens of pine wood (Pinus sylvestris L.) were painted with one or two layers of coatings to evaluate the discoloration and changes in lightness. For all the tested coatings, discoloration and loss of lightness were observed for all specimens regardless of the applied coatings. Different rates of color changes were observed for the tested coatings. The presence of pigments in the coatings formulation delays the discoloration of wood; as also the composition of pigments plays a significant role in the process.

Abstract: Construction sector has consumed an important percentage of natural resources and generated much of the waste discharged into the environment in the last decades. This is the reason why the social consciousness has strongly grown towards sustainable development. Concepts such as recycle, reuse, reduce and energy saving are gaining importance in obtaining products under a clearly defined objective of a sustainable development. The revaluation of agroforestry waste has established itself as a solution to the problems associated with these wastes and, increasingly, is being incorporated into the manufacture of new materials. The Wood Plastic Composites (WPC’s) are an important group within these new sustainable building materials. WPC’s are obtained from recycled plastics and natural fibres waste. This kind of materials reduces the consumption of resources and the amount of waste. These materials have emerged to replace natural wood in some exterior applications, where the durability of natural wood is most damaged. Natural wood, in addition to the loss of color that suffers in exterior, has other disadvantages such as anisotropy and hygroscopicity. WPC's do not have these drawbacks. In this way, the WPC’s try to imitate the appearance of natural wood, with a good durability outdoors. Because of this, there are numerous companies that develop WPC products with different plastics and natural waste, with the aim of obtaining the best appearance and durability. In this paper, the color degradation of various WPC materials when exposed to ultraviolet (UV) radiation is evaluated. An artificial aging chamber with a fluorescent UV lamp and a colorimeter have been used to quantify the color parameters. Thus, conclusions are drawn on which plastics and residues achieve a minor alteration of color, an aspect highly appreciated in outdoor applications.

Abstract: The properties of plastic parts that used for outdoor applications are changed under weathering conditions. Weathering involves considering the effects of solar radiation, temperature, humidity, pollutants. By adding some additives such as carbon black, TiO2, Hals and Tinuvin, the weathering effect could be decreased. In this study, LDPE films by adding different percentages (0.1, 0.5 and 1%) of carbon black (C.B.) with 0.2 mm thickness were produced by extrusion process. Samples were cut according to ASTM D882 and to accelerate the tests, samples located in accelerated artificial weathering device up to 1400 hour. The device was set at 40°C and humidity of 50%. Required samples for tensile strength test bring out of device at selected period and tensile strength was done by 350 mm/min strain rate. The results show that samples containing carbon black have tensile stress and elongationmore than the clear films. Carbon black absorbs UV light and heat that causing to delay in broken links and destroying the molecular. The optimum percent for tensile stress was 0.5 and for elongation was 1% C.B.

Abstract: The effects of natural and artificial weathering on mechanical properties of Chlorinated Polyvinyl Chloride (CPVC) pipe material are investigated. Tensile specimens, prepared from locally manufactured CPVC commercial pipes (4-in Schedule 80) were exposed for periods ranging from 2 weeks to 18 months in the harsh weather conditions of Dhahran, Saudi Arabia. The accelerated artificial weathering was carried out in the Q- Sun Xe-3-HS Xenon Test Chambers for periods ranging from 100 to 3000 hours. Standard tensile tests were performed before and after exposure. The tensile test results show that natural and accelerated artificial weathering had limited effects on the tensile and fracture strengths and modulus of elasticity of the material. However, the deterioration of the fracture strain is noticeable for exposure periods as short as 15 days of natural exposure and 100 hours of artificial UV exposure. Visual analysis of exposed specimens revealed that both types of exposures resulted in the discoloration of the specimens.

Abstract: Ultraviolet aging of B.mori silk fabric was studied under natural and artificial weathering conditions. Exposed samples were removed periodically and characterized by several analytical techniques. During both types of weathering, the results showed that yellowness index presented a rising trend with the extension of aging time; breaking strength of B.mori silk fabric decreased approximately 93.62%, 43.30% under natural aging 150 days and artificial accelerated aging 80 h, respectively; the peak intensity of amide I, and amide II, etc. significantly declined, even disappeared. At the same time, the conformation transition of B.mori silk was from random coil to β–pleated sheet following the prolonging of ultraviolet aging time. What’s more, the content of amino acid obviously declined especially histidine, tyrosine, and lysine etc. In addition, the results evidenced that during natural and artificial weathering, various performances of B.mori silk fabric changed similarly. So artificial weathering can be used to substitute for natural weathering for its weathering evaluation, which is helpful to understand the aging behavior and take measures to avoid aging and elongate its service life.