modification polymer properties (7 Ergebnisse)

Taschenbuch. Zustand: Neu. Neuware -The study investigated the influences of wood modification on the properties of Polyvinyl chloride (PVC) based Wood Polymer Composites (WPC). Various ethanolamines, L-arginine, pre-hydrolyzed and monomeric aminosilane, melamine and acetic anhydride treatment were used to improve the adhesion between wood and polymer as well as water absorption behavior and resistance to basidiomycetes. Amine based treatments were chosen to change the nature of wood from acidic to basic in order to increase the compatibility with the acidic polymer. Treated and untreated wood flour, PVC and additives were dry blended in a mixer. The dry blend was compounded to granulate by counter-rotating twin screw extrusion and compression moulded into panels using a hydraulic press. Elemental analysis (nitrogen content) via gas chromatography showed expected fixation of aminosilane and melamine treatment. The nitrogen fixation of ethanolamine and L-arginine treated material were obviously reduced, whereas the amount and reactivity of the aminogroups influenced the fixation behavior. With increasing content of amino-groups and reactivity, the fixation was improved. Fourier transform infrared (FTIR) analyses revealed interactions between monoethanolamine and cell wall components. The amine based treatments changed the nature of wood from acidic to basic. An improvement of the interphase was detected via mechanical property testing. Tensile strength, elongation at break and unnotched impact strength of the composite were obviously increased by Larginine, ethanolamine and aminosilane treatments. It has to be considered that amine based treatments (monoethanolamine in this study) led to reduced thermal stability of the composite. Thermogravimetric analysis showed a decrease of onset temperature with increasing monoethanolamine content. Water repellence of the composite was improved by melamine, pre-hydrolyzed aminosilane and acetic acid treatment. Treated and untreated composites revealed high resistance against basidiomycetes. Due to the low initial moisture content and low weight loss of untreated and treated composites, no effect of the various modifications was distinguished. 88 pp. Englisch.

Taschenbuch. Zustand: Neu. Neuware -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 the synthetic polymer is used as matrix material and the wood as reinforcement material or filler. As matrix material, principally every thermoplastic polymer with a processing temperature below 200°C can be used due to the temperature sensivity of wood. Wood Polymer Composites are processed typically with processing technologies from the plastic industry such as extrusion and injection molding. The present study was conducted to explore the possibility of wood particle modification with different types of silanes. It was the aim to contribute the silanes as compatibilizers or coupling agent and therefore improve the mechanical properties and the resistance against water. Norway spruce (Picea abies) as representative wood species was used in three different particle types. The size distribution for the wood particles ranges from 70-2500 µm. Four commercial available silanes 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 commonly used maleated acid anhydride based coupling agents were used. The pre-treated wood particles were compounded via extrusion with polypropylene and samples were produced via injection and compression molding. The following properties were tested; tensile, bending, and impact strength, water uptake (cold and boiling water test), descent rate, weathering tests and durability test against basidiomycetes. 196 pp. Englisch.

Taschenbuch. Zustand: Neu. Neuware -Polymer nanocomposites (PNC) are of great interest owing to the many potential property enhancements possible via introducing different types of nanofillers in polymer matrices. In recent decades, increasing attention has being paid to PNCs due to their light weight, low cost, and ease of processability compared to metal alternatives and due to their novel capability to tune properties. Depending on the end-use application, certain PNC properties are targeted and the their formulation and processing can be manipulated to achieve the desired properties. In this work, different PNC properties have been improved by employing different strategies;(1) Modification of nanofillers: Chemical treatment of nanoclay, multiwall carbon nanotube (MWCNT) and graphene nanoribbon (GNR);(2) Synthesis of novel nanofillers: GNR was synthesized from parent MWCNT to benefit from higher surface area and interaction of the novel nanofillers with the polymer chains;(3) Implementation of hybrid fillers: nanoclay as the secondary filler was utilized to further enhance the desired properties of PNC consisting of MWCNT;(4) Amendment of PNC production methods: Optimized PNC production conditions.Books on Demand GmbH, Überseering 33, 22297 Hamburg 228 pp. Englisch.

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