Improvement of selected properties of Wood-Polymer Composites (WPC) - Silane modification of wood particles
··· lezzter Preis 30.07€ ··· 9783869555614 ··· 10361192872 ··· Wood Polymer Composites are a new group of hybrid materials, which combine the advantagesof synthetic polymers such as polyolefines and natural polymers such as wood whereas thesynthetic polymer is used as matrix material and the wood as reinforcement material or filler. Asmatrix material, principally every thermoplastic polymer with a processing temperature below200°C can be used due to the temperature sensivity of wood. Wood Polymer Composites areprocessed typically with processing technologies from the plastic industry such as extrusion andinjection molding.The present study was conducted to explore the possibility of wood particle modification withdifferent types of silanes. It was the aim to contribute the silanes as compatibilizers or couplingagent and therefore improve the mechanical properties and the resistance against water. Norwayspruce (Picea abies) as representative wood species was used in three different particle types. Thesize distribution for the wood particles ranges from 70-2500 µm. Four commercial availablesilanes with various functional groups (amino, di-amino, alkyl) were used as modification agents.The concentrations varied between 1.5%, 3.0%, 4.5% and 7.5%. As reference system commonlyused maleated acid anhydride based coupling agents were used. The pre-treated wood particleswere compounded via extrusion with polypropylene and samples were produced via injection andcompression molding. The following properties were tested tensile, bending, and impactstrength, water uptake (cold and boiling water test), descent rate, weathering tests and durabilitytest against basidiomycetes.SEM-EDX investigations proved the presence of silane either in the cell wall structure, or on thewood particle surface. Due to the structure and the functionality of the silanes it was expectedthat the silane treated wood particles are able to improve the mechanical properties. It was shownthat the silanes had no significant effect as compatibilizer or coupling agent.The mechanical properties strongly increase with the usage of coupling agent. Both couplingagents were based on maleic acid anhydride grafted on a polymer backbone, whereas Type Ireaches an optimum regarding the mechanical properties at 3%, the coupling agent Type II stillimproves the mechanical properties up to a ratio of 4.5% with no clear optimum. The silane pretreatmentinfluences the improvement not significantly, compare to the improvement caused bythe coupling agent.The used wood particles showed mechanical degradation during the compounding process. Thebiggest degradation was monitored for the wood particles of Lignocel® Type 9. Due to its finestructure it can be assumed that the Arbocel® C100 wood particles consist of only cell wallfragments of the wooden cell wall, which express a better resistance against mechanicaldestruction during the process.The Wood Polymer Composites showed a lower decay rate compared to solid wood. Themoisture content within the Wood Polymer Composite samples ranges at the low optimum levelfor fungi attack and were not significantly improved by an accelerated wetting before the test.The core remains relatively dry. The main protection seems to come from the encapsulation bythe polymer.The weathered Wood Polymer Composite samples showed a strong color change within arelatively short period of exposure. The color changed independently from the silane type or thesilane ratio. Also an increase of cracks and gaps on the sample surface was observed compared tothe unexposed sample and the pure polymer reference. Hersteller: Cuvillier Verlag Marke: Cuvillier Verlag EAN: 9783869555614 Kat: Hardcover/Naturwissenschaften, Medizin, Informatik, Technik/Biologie/Landwirtschaft, Gartenbau, Forstwirtschaft, Fischerei, Ernährung Lieferzeit: Sofort lieferbar Versandkosten: Ab 20¤ Versandkostenfrei in Deutschland Icon: https://www.inforius-bilder.de/bild/?I=usO8Urur2jJl%2B8yqyTuHflRQvo8DljcOdK7KyvndWTM%3D Bild:
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