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Accelerated Weathering

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Cevdet Kaynak – 1st expert on this subject based on the ideXlab platform

  • Effects of Accelerated Weathering in Polylactide Biocomposites Reinforced with Microcrystalline Cellulose
    International Polymer Processing, 2016
    Co-Authors: Cevdet Kaynak, B. Dogu

    Abstract:

    Abstract The aim of this study was to reveal effects of Accelerated Weathering in neat polylactide (PLA) and its biocomposite reinforced with microcrystalline cellulose (MCC); compounded by twin-screw extrusion melt mixing and specimen shaping by injection molding. Weathering conditions were applied via consecutive steps of UV irradiation and humidity in accordance with ISO 4892–3 standards for 200 h. Various characterization techniques and mechanical tests indicated that photolysis, photo-oxidation and hydrolysis were the main degradation mechanisms leading to significant decrease in the molecular weight of PLA via main chain scission. Consequently, except elastic modulus other mechanical properties; strength, ductility and fracture toughness of PLA and PLA/MCC decreased substantially. However, after comparing the mechanical properties of the neat PLA and PLA/MCC biocomposite specimens having 200 h of Accelerated Weathering, it was concluded that; for the outdoor applications use of PLA/MCC biocomposite …

  • mechanical and thermal properties of polylactide talc microcomposites before and after Accelerated Weathering polylactide talc microcomposites before and after Accelerated Weathering
    Polymers for Advanced Technologies, 2016
    Co-Authors: Cevdet Kaynak, Ali Riza Erdogan

    Abstract:

    The purpose of the first part of this study was to investigate effects of micron-sized talc content on the properties of polylactide (PLA). PLA/talc microcomposites were compounded by melt-mixing method via twin-screw extruder, while specimens for testing and analyses were shaped by injection molding. It was observed that, because of the effective stiffening, strengthening, toughening mechanisms of talc, and also their nucleation agent effects for higher crystallinity, many mechanical and thermal properties were improved. In the second part of the study, effects of Accelerated Weathering on the behavior of PLA microcomposites with 5 wt% talc were investigated by applying ultra violet irradiation and humidity steps according to Cycle-C of International Organization for Standardization 4892-3 standards for durations of 100, 200, and 300 hr. Various analyses revealed that, because of the degradation mechanisms of photolysis and hydrolysis during each Weathering periods, molecular weight of PLA reduced drastically, that is, mechanical properties almost vanished. Copyright © 2015 John Wiley & Sons, Ltd.

  • Accelerated Weathering performance of polylactide and its montmorillonite nanocomposite
    Applied Clay Science, 2016
    Co-Authors: Cevdet Kaynak, Burcu Sari

    Abstract:

    Abstract The goal of this study was to compare Accelerated Weathering performance of neat polylactide (PLA) and its 1 mass% organically modified montmorillonite (Mt) nanocomposite; compounded and shaped by twin-screw extrusion melt mixing and injection molding, respectively. Accelerated Weathering test system applied consecutive steps of UV irradiation and humidity in accordance with ISO 4892-3 standards for 200 h. Chain scission reactions such as photolysis, photooxidation and hydrolysis resulted in significant decrease in the molecular weight of PLA; consequently reductions in the mechanical properties of modulus, strength, ductility and toughness of the specimens occurred. However, after comparing mechanical properties of PLA and Mt–PLA before and after 200 h Accelerated Weathering, use of PLA with only 1 mass% Mt was extremely beneficial not only for “indoor applications” but also for “outdoor applications”. This was due to the effective nanoscale reinforcing and barrier actions of intercalated/exfoliated Mt layers. For example, flexural strength was 6% beneficial before Weathering, but after Weathering the benefit was 88%.

Timo Karki – 2nd expert on this subject based on the ideXlab platform

  • Accelerated Weathering of fire retarded wood polypropylene composites
    Composites Part A-applied Science and Manufacturing, 2016
    Co-Authors: Irina Turku, Timo Karki

    Abstract:

    Abstract In this study, the influence of fire retardants, namely aluminum trihydrate, zinc borate, melamine, graphite, titanium dioxide on the durability of polypropylene-based co-extruded wood–plastic composites is studied. The composites underwent Accelerated Weathering under a xenon-arc lamp source during 1000 h. FTIR analysis of the composite surface revealed a degradation process which was accompanied by chemical changes, including vinyl-like and carbonyl groups accumulation; fire retardants did not influence the photo-oxidation mechanism of the composite. Fire retardant-loaded samples had smaller color change compared to the unfilled one. The tensile properties of all composites declined after the Weathering. Significant changes in the surface morphology of the weathered composites were observed with a scan electron microscope.

  • Accelerated Weathering of fire-retarded wood–polypropylene composites
    Composites Part A-applied Science and Manufacturing, 2016
    Co-Authors: Irina Turku, Timo Karki

    Abstract:

    Abstract In this study, the influence of fire retardants, namely aluminum trihydrate, zinc borate, melamine, graphite, titanium dioxide on the durability of polypropylene-based co-extruded wood–plastic composites is studied. The composites underwent Accelerated Weathering under a xenon-arc lamp source during 1000 h. FTIR analysis of the composite surface revealed a degradation process which was accompanied by chemical changes, including vinyl-like and carbonyl groups accumulation; fire retardants did not influence the photo-oxidation mechanism of the composite. Fire retardant-loaded samples had smaller color change compared to the unfilled one. The tensile properties of all composites declined after the Weathering. Significant changes in the surface morphology of the weathered composites were observed with a scan electron microscope.

  • Accelerated Weathering of wood–polypropylene composite containing carbon fillers
    Journal of Composite Materials, 2015
    Co-Authors: Irina Turku, Timo Karki

    Abstract:

    The effect of freeze-thaw Weathering on the tensile properties, and Accelerated Weathering with xenon-arc light on the color stability and the tensile properties of co-extruded wood–polypropylene composite loaded with different carbon fillers, such as carbon black, graphite, expandable graphite, carbon nanotubes, and carbon fibers is studied. The results showed that carbon fillers prevented the composites from the fading during xenon-arc light Weathering. Almost all types of composites showed the reduced tensile properties after the Weathering so that during xenon-light treatment, the tensile strength decline for 10–22% and modulus for 9–25%; during freeze-thaw cycling reduction was 3–21% for the strength and 4–20% for the modulus. Scanning electron microscopy analysis revealed deterioration of the polymer surface layer in all xenon-light weathered composites.

Teng-chun Yang – 3rd expert on this subject based on the ideXlab platform

  • effect of titanium dioxide particles on the surface morphology and the mechanical properties of pvc composites during quv Accelerated Weathering
    Polymer Composites, 2016
    Co-Authors: Teng-chun Yang, Minoru Isshiki, Takafumi Noguchi, Jyh-horng Wu

    Abstract:

    In this study, QUV Accelerated Weathering of polyvinyl chloride (PVC) composites with different amounts of titanium dioxide (TiO2) particle was conducted to investigate the effect of TiO2 particle on the surface morphology and the mechanical properties. The results indicate that the surface morphology of PVC without TiO2 particle did not exhibit changes up to 960 h, but exhibited a rough and brittle surface after 1920 h of QUV Accelerated Weathering. In addition, the tan δ intensity, the elongation at break, and the mean failure energy (MFE) decreased significantly with increasing exposure time due to embrittlement. In contrast, for TiO2 particle-loaded PVCs, no significant influence on the tan δ intensity and the mechanical properties after Accelerated Weathering were observed, despite the appreciable degradation that occurred in the surface layer. The weatherability, as determined by the mechanical performance, was improved with increasing loading of TiO2 particle in the PVC composites. Although the TiO2 particle in the PVC matrix acts as a photocatalyst to enhance the surface degradation, it is also an effective radiation screener that inhibits embrittlement and retards the decrease in mechanical properties caused by the Accelerated Weathering process. POLYM. COMPOS., 37:3391–3397, 2016. © 2015 Society of Plastics Engineers

  • effect of titanium dioxide on chemical and molecular changes in pvc sidings during quv Accelerated Weathering
    Polymer Degradation and Stability, 2014
    Co-Authors: Teng-chun Yang, Minoru Isshiki, Takafumi Noguchi, Jyh-horng Wu

    Abstract:

    Titanium dioxide (TiO2) is the most essential additive in polyvinyl chloride (PVC) matrixes used for outdoor applications. In this study, we primarily investigate the effect of TiO2 on the chemical and molecular changes in PVC sidings during QUV Accelerated Weathering. The results of this study show that carbonyl and polyene groups were generated on the surface of all of the specimens after 480 h of Accelerated Weathering but that loading TiO2 into PVC successfully inhibited the increase in the number of these oxidative groups over the entire exposure period compared to PVC without TiO2. In addition, a significant decrease in the number average molecular weight (Mn) and the formation of an insoluble gel were observed for PVC without TiO2 after Accelerated Weathering. However, the time required for the Mn to decline increased with the amount of TiO2 that was loaded into the PVC matrix, and no insoluble gel was observed during Weathering. Furthermore, the crystallinity of PVC without TiO2 increased noticeably after 1920 h of Accelerated Weathering, whereas no significant change was observed in the crystallinity of PVC with TiO2. These results demonstrate that simultaneous chain scission and crosslinking reactions occurred in PVC without TiO2, whereas only chain scission occurred in PVC containing TiO2. In addition, the chain scission of PVC without TiO2 was initiated earlier than for PVC with TiO2, producing shorter and more mobile chains that underwent secondary crystallization. Accordingly, TiO2 acted as a UV absorber and a radiation screener such that the probability of chain scission was reduced for TiO2-loaded PVC sidings.

  • Methodology of Accelerated Weathering test through physicochemical analysis for polymeric materials in building construction
    Materials Research Innovations, 2014
    Co-Authors: Teng-chun Yang, Jyh-horng Wu, T. Noguchi, Minoru Isshiki

    Abstract:

    Physicochemical analysis in the microscopic sense is a critical assessment of monitoring the polymeric materials under a Weathering test, and it links the Accelerated laboratory test with the outdoor performance results for a long-term durability. Here, by taking an experimented example for vinyl siding after an outdoor Weathering test in Okinawa, Japan for 17 years and a QUV Accelerated Weathering test for 2880 hours, it was observed that there were entirely different results on the functional groups and the surface image with the atom concentration measured by the attenuated total reflectance Fourier transform infrared and scanning electron microscopy with energy dispersive spectroscopy, respectively. Furthermore, the optimal conditions of a specified Accelerated Weathering test based on a replication of the natural Weathering characteristics are deliberated, thus correcting the deterioration factors configuration in consideration for the physicochemical degradation of a specific material. The aim of this study places an emphasis on the crucial points for improving the Accelerated Weathering test through a physicochemical analysis.