Download or read book Characterization of PF PVAC Hybrid Adhesive wood Interaction and Its Effect on Wood Strand Composites Performance written by Yang Cao and published by . This book was released on 2010 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Profile Forming of Wood strand Composites Processes Forming Characteristics and Product Properties written by Yi Wang and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Profile-formed wood-strand composites showed much better shape conformance than profiled veneer-based composites. Slow closing rate and relatively high moisture content caused flat and peak-at-core vertical density profiles (VDP). Lower moisture content resulted in more uniform VDP.

Download or read book Bio based Wood Adhesives written by Zhongqi He and published by CRC Press. This book was released on 2017-05-25 with total page 558 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adhesive bonding plays an increasing role in the forest product industry and is a key factor for efficiently utilizing timber and other lignocellulosic resources. As synthetic wood adhesives are mostly derived from depleting petrochemical resources and have caused increasing environmental concern, natural product and byproduct-derived adhesives have attracted much attention in the last decades. Although adhesives made from plant and animal sources have been in existence since ancient times, increased knowledge of their chemistry and improved technical formulation of their preparation are still needed to promote their broader industrial applications. The primary goals of this book are to (1) synthesize the fundamental knowledge and latest research on bio-based adhesives from a remarkable range of natural products and byproducts, (2) identify need areas and provide directions of future bio-based adhesive research, and (3) help integrating research findings in practical adhesive application for maximal benefits. This book covers information on a variety of natural products and byproducts and the latest research on formulation, testing and improvement of the relevant adhesives in fifteen chapters written by an international group of accomplished contributors. This book will serve as a valuable reference source for university faculty, graduate students, research scientists, agricultural and wood engineers, international organization advocators and government agency regulators who work and deal with enhanced utilization of agricultural and forest products and byproducts.

Download or read book Bondability of modified wood written by Alireza Bastani and published by Cuvillier Verlag. This book was released on 2016-06-30 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study investigates the bonding properties of modified wood by considering three different aspects: water related characteristics, mechanical performance and optical (fluorescence microscopy and X-ray micro-computed tomography) observation of adhesive penetration into modified wood structure. In recent years, the new wood modifications have become more commercially available in the market for both exterior and interior applications due to improved properties that modification can bring to the wood e.g. the improved biological durability, dimensional stability, hardness and weathering resistance of the wood as well as the environmentally friendly nature of the wood modification processes (Militz and Hill 2005). Besides these advantages, modification can affect some technological aspects of the wood such as its bonding performance. For example, it can alter the strength of adhesion as a result of changes in chemical, physical and structural characteristics of the wood. For example, the less polar and less porous modified wood surfaces can result in reduced adhesion due to formation of less free OH groups for bonding leading to poorer adhesive wetting of the wood surface and weaker chemical bonds between the two adherents (Hunt et al. 2007). As modified wood becomes a more demanded material for different applications, there is a need to study its bonding performance where the challenge is to bond different modified materials as their physical and chemical characteristics are substantially changed by modification. In this thesis, measurements of capillary water uptake, contact angle and surface energy were used to determine the water related properties and hydrophobic behavior of furfurylated (FA40 and FA70, which represent 65 and 75 % WPGs) and N-methylol melamine (NMM) (10, 20 and 30%) modified Scots pine and thermally treated Scots pine and beech (modified through an industrial scale vacuum press dewatering method at 195 and 210 °C). The capillary water uptake results indicated a considerable reduction of water uptake for all modifications in all directions both after short (24 h) and long contact times (168, 336 h). Contact angle measurement data revealed an increased hydrophobicity of modified wood. However, some exceptions were observed, mainly for thermally treated wood. Modifications provided radial and tangential surfaces with a non-polar character. Penetration of adhesives into the wood structure plays an important role in the production of glued wood-based panels and products by affecting the bond quality (Frihart 2005, Kamke and Lee 2007). The gross penetration of emulsion polymer isocyanate (EPI), polyurethane (PU) and polyvinyl acetate (PVAc) adhesives into modified wood, both with and without pressure, were determined by using fluorescence microscopy based on measurements of effective (EP) and maximum penetration (MP). Without application of pressure, the EP of EPI adhesive reduced after NMM modification and furfurylation (FA70) and also PU adhesive after NMM modification while the EP of PVAc adhesive increased into furfurylated and NMM modified (10 and 20%) wood. For thermally treated Scots pine, increasing the treatment temperature improved EP of all adhesives. Among used adhesives, PU penetrated much deeper into thermally treated wood for both treatment temperatures. Comparison of penetration of adhesive with and without pressure revealed that with the exception of EP of PU and EPI adhesives into NMM-modified wood and PVAc into thermally treated beech at 195°C, application of pressure led to rather different results as compared to the EP data when no pressure was applied. Visual observation and analysis of fluorescence microscopy photomicrographs provided more detailed information on modality of penetration. Due to the large and deep penetration of PU adhesive into thermally treated Scots pine observed in both studies (with and without pressure), the 3D pattern of penetration of this adhesive was obtained by X-ray micro- computed tomography indicating the pathways which were used by this adhesive for penetration. In another study, the bonding shear strength of the same modified wood materials glued with the same adhesives was also investigated. For all adhesives used, the shear strength significantly reduced after furfurylation and NMM modification of Scots pine samples, mainly due to the brittle nature of the wood after modification rather to the failure of the bondline. Bonding strength of both Scots pine and beech was also negatively affected by thermal modification and the bondline was found to be the weakest link in thermally modified wood. The EP of adhesives and the bondline thickness did not relate to the shear strength of all modified wood materials. It was indicated that the lower shear strength of modified wood could be attributed to other factors, such as the decreased chemical bonding or mechanical interlocking of adhesives, and the reduced strength of brittle modified wood substrate. The effect of two important bonding variables, wood moisture content and open assembly time on penetration of PU adhesive into thermally modified wood (195 and 210 °C) was also studied. The equilibrium moisture content (EMC) level of 8.6% was found to be the optimum for an effective penetration of PU adhesive in thermally modified Scots pine treated at 195°C. In most of the cases, penetration of PU adhesive did not change significantly by increasing the open assembly time, which suggested using a shorter open assembly time of 15 min than 30 min for bonding of thermally modified Scots pine with PU adhesive, in order to save time and reducing the production costs. For samples treated at both treatment temperatures and after shorter open assembly time, the highest MP values observed at moderate EMC levels of 8.6 and 8.2% and the lowest at the higher EMC levels of 13.2 and 12.5%. In another study, the effect of phenol formaldehyde (PF) treatment on bonding performance of beech glued with PVAc and phenol resorcinol formaldehyde (PRF) adhesives was also investigated. The results of both dry and wet conditions indicated higher shear strength for samples bonded with PRF than PVAc. With the exception of 25% PF treated wood bonded with PVAc, the PF modified wood can be glued with both adhesives satisfactorily under dry condition, while under wet condition only the 25% PF modified samples bonded with PRF provided acceptable bonding. For both adhesive systems, PF modification caused a reduction of adhesive penetration into wood structure, especially in the case of higher load treatment. The development of bonding strength of modified birch veneers glued with hot curing phenol formaldehyde (PF) adhesive was investigated in different pressing (20 s , 160s) and open assembly times (20s , 10 min). Generally, the bonding strength improved by extending the pressing time. In 20 s pressing, increasing assembly time did not change the bonding strength in most of the cases while at 160 s pressing, prolongation of assembly time developed a better bonding for controls, NMM modified and thermally treated veneers at 180°C. The combination of 10 min assembly time and 160 s pressing time provided the highest bonding strength for controls, NMM modified and thermally treated veneers at 180°C while furfurylated samples achieved the highest values in 20 s assembly and 160 s pressing times. In general, modification affected negatively the bonding performance of the veneers, especially for furfurylated and NMM modified samples. In General, the overall results obtained in this thesis showed that modified wood has lower bonding ability and performance than unmodified wood as result of the decreased water related properties, less penetration of adhesive into wood structure and decreased bonding strength after modification. However, the increased dimensional stability and low water uptake of modified wood might lead to better performance in long term.

Download or read book Adhesives for Wood and Lignocellulosic Materials written by R. N. Kumar and published by John Wiley & Sons. This book was released on 2019-07-16 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unique and ground-breaking book from two leading specialists on adhesion and adhesives for wood and lignocellulosic materials The book is a comprehensive treatment covering a wide range of subjects uniquely available in a single source for the first time. A material science approach has been adopted in dealing with wood adhesion and adhesives. The approach of the authors is to bring out hierarchical cellular and porous characteristics of wood with polymeric cell wall structure, along with the associated non-cell wall extractives, which greatly influence the interaction of wood substrate with polymeric adhesives in a very unique manner not existent in the case of other adherends. Environmental aspects, in particular formaldehyde emission from adhesive bonded wood products, has been included. A significant feature of the book is the inclusion of polymeric matrix materials for wood polymer composites.

Download or read book Eco Friendly Adhesives for Wood and Natural Fiber Composites written by Mohammad Jawaid and published by Springer Nature. This book was released on 2021-01-21 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an overview of eco-friendly resins and their composite materials covering their synthesis, sources, structures and properties for different industrial applications to support the ongoing research and development in eco-friendly and renewable commercial products. It provides comparative discussions on the properties of eco-friendly resins with other polymer composites. It is a useful reference on bio-based eco-friendly polymer resins, wood-based composites, natural fibers and biomass materials for the polymer scientists, engineers and material scientists.

Download or read book Wood Fiber Polyvinyl Chloride Composites and Their Microcellular Foams written by and published by . This book was released on 1997 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Load Transfer in Wood based Composites written by Matthew John Schwarzkopf and published by . This book was released on 2014 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mechanical performance of composite materials is determined by the mechanical properties of their individual components and the effective load transfer between these components. Binders are commonly used to bond composite components together and to provide effective load transfer between them. In wood-based composites the binder-component load transfer occurs at the micro-scale (1-100 [micro]m), where complex morphologies are in play. The bonding of these materials is relatively well understood on the molecular level with respect to the chemical compatibility of the binder and components, but the load transfer and the relative contribution of surface adhesion forcesof wood tissue at the micron- and sub-micron scale remains a subject of limited understanding. Understanding of the load transfer at this scale requires experimental observation of the responses of complex bond morphologies to external loads. It should be noted however, that load transfer in bonds in terms of internal force distribution and stress cannot be measured directly. Instead, methodologies are needed that allow back calculating complex stress distributions in the bond interphase from experimental measurements of displacements and strains. Recently, a conceptual framework for an integrated method for multi-scale/multi-modal investigation of micro-mechanical interaction in bond interphases has been proposed where measurements of properties associated with the load transfer across composite bonds were integrated with predictive numerical modeling tools (Muszynski et al. 2013) (reproduced in Appendix C). This general framework and the modeling tools used are generic and can be applied to a variety of composite materials. The general goal of this dissertation was to develop the crucial non-generic components for this approach, which are the specialized, experimental measurement tools, methods and procedures that are paired with modeling tools. Consequently, measurement methodologies have been developed to assess the deformations and strain patterns across the particle-matrix bonds in WPCs and across adhesive bonds in layered composites. The measurements in these methodologies are valuable as input data and are spatially tied to coordinate systems making them easily compatible with three-dimensional numerical modeling tools. A measurement methodology has also been developed to investigate local surface free energies of wood tissue at a micron and sub-micron scale. These measurements are able to further inform and enrich the predictions made by numerical models with respect to the bonding morphology. Currently these methods are being used to further develop, refine and ultimately validate the numerical model used to quantify and analyze load transfer in wood composite bonds.

Download or read book Microscopic Characterization of Adhesive wood Interactions 1 78 7 written by Lidija L. Murmanis and published by . This book was released on 1979 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Interactions and Interfacial Properties of Wood polyurethane Composites written by Xuerong Wang and published by . This book was released on 1991 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Enhancement of Interfacial Properties Through Surface Modification in Poly lactic Acid Wood flour Composites written by Eustathios Petinakis and published by . This book was released on 2015 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to develop filled polymer composites and blends from sustainable resources, the primary objective that needs to be considered is the nature of the interface between the natural filler and the polymer matrix. A fundamental understanding of filler-filler interactions and the filler-matrix interface is critical to the design and manufacture of biopolymer composite materials and the interfacial properties of such materials. The improvements achieved can lead to increase market share of such materials in more demanding applications. The early part of this thesis focuses on the efficacy of lignocellulosic fillers like wood-flour as a low-cost filler in Poly(lactic) acid (PLA) wood-flour biocomposites. A primary emphasis is on evaluating the effect of wood-flour on the mechanical, impact and thermal performance of the resulting biocomposites. The early part of this thesis also investigates the role that surface modification can play in improving interfacial interactions between PLA and wood-flour.The hydrophilic nature of lignocellulosic fillers introduces challenges in developing biopolymer composites with superior mechanical and thermal performance. Hence, a critical part of materials design for developing biopolymer composites is to deploy surface modification strategies to overcome the hydrophilic nature of lignocellulosic fibres. The implementation of surface modification through a variety of wet and dry techniques and a combination of both, do not always lead to improvements in interfacial adhesion. This lack of effect is primarily attributed to the heterogeneous structure and variation in the chemical composition of lignocellulosic fibres, which can vary from species to species for different varieties of biomass sources. In order to address the technical challenges, this thesis focuses more closely on the role of surface modification. Initially, surface modification of the filler or polymer matrix is investigated and compared. In the middle chapters, the role of pre-treatment through chemical (alkaline) or physical processes (plasma) is conducted in conjunction with chemical treatment in order to evaluate the influence on the practical adhesion at a macro level. And finally, the influence of pre-treatment and chemical modification is assessed on a micro level for their effect on the PLA composites themselves.The interfacial properties of PLA/wood-flour composites were evaluated using two strategies: the first approach evaluated chemical modification of wood-flour using methylene diphenyl isocyanate (MDI), whilst the second strategy focused on the physical modification of PLA using polyethylene acrylic acid (PEAA) as an impact modifier. MDI was found to improve the interfacial adhesion between PLA and wood-flour and this was confirmed by Electron Probe Microanalysis (EPMA). The analysis indicated that MDI was present at the interface between PLA and wood-flour but also distributed to some degree within the PLA matrix. In comparison, PEAA was found to lower the tensile strength of the biocomposites but increased the impact performance. The enhancement in impact performance was due to the formation of a separate phase observed within the PLA matrix, which comprised spherical domains. The presence of these domains impeded crack propagation, resulting in higher impact strength.The heterogeneous nature of lignocellulosic materials and their varying chemical composition, contribute to their reduced surface functionality. In an effort to promote increased surface functionality, a pre-treatment process was used in conjunction with chemical modification. A macro-scale method was developed to evaluate the effectiveness of silane modification performed in conjunction with alkaline pre-treatment on the surface chemical and physical characteristics of a model wood substrate. Three silanes with different chemical end groups were used to modify the surface of wood. PLA film was bonded to the model wood surface using a melt press and the level of practical adhesion was assessed by peel adhesion testing. Surface characterisation studies proved that alkaline pre-treatment and subsequent chemical modification with an amino silane produced the highest peel fracture energy following peel adhesion.The macro scale, peel adhesion method for evaluating the effectiveness of different surface modification techniques was used to assess the suitability of plasma techniques for modifying the surfaces of a model wood substrate. Surface treatment using plasma based techniques has the potential to be a more benign approach to activate the surfaces of lignocellulosic substrates. Low-pressure plasma treatment was conducted on pinewood veneers using a custom built 13.5 MHz Inductively Coupled Plasma Chamber. A dual plasma pre-treatment process that involved a combination of continuous wave and pulse mode was found to be more conducive to optimising surface active groups. The results of XPS analyses showed that plasma treatment based on a dual process was more effect than a single process plasma treatment due to the higher levels of oxygen relative to carbon (O/C) and O functional groups. The main peaks that proved the benefits of the dual plasma process was the higher atomic ratio of oxygen, which was attributed to a higher incidence of surface hydroxyl groups. Plasma treatment alone of the wood veneer produced a more homogeneous surface morphology, compared to unmodified wood veneer. The appearance of nano-like nodules were more even in height and furthermore, evenly distributed across the wood veneer surface. AFM was successfully used to define the surface morphology that was created following plasma treatment and chemical grafting using an amino silane and two polyethyleneimines with different molecular weight. AFM also showed that grafting with the amino silane did not alter the surface morphology. AFM phase imaging showed variations in PEI grafting onto plasma modified wood veneer. Peel adhesion studies showed that plasma pre-treatment combined with chemical modification (ex-situ) lead to significant enhancements in the fracture energies of wood-PLA laminates that were superior to those following low-pressure plasma treatment alone. The findings of the macro scale studies were used to prepare PLA based composites and evaluate the effect on the mechanical and thermal performance. PLA biocomposites were produced from wood-flour subjected to pre-treatment using alkaline treatment or low-pressure plasma and then chemically modified (ex-situ) using an amino silane and two polyethyleneimines. A micro extruder was used to compound PLA wood-flour formulations and mini injection moulder was used to prepare sample test bars. The results of mechanical testing showed that pre-treatment using a low-pressure plasma dual process (CW+P) combined with chemical modification (ex-situ) produced composites with enhancements in the flexural and impact properties of the resulting composites. Low-pressure plasma treatment of wood-flour alone did not enhance the mechanical and impact performance, compared to untreated wood-flour and wood-flour subjected to alkaline treatment. DMA testing also showed the benefits of using low-pressure plasma treatment combined with chemical treatment, due to enhanced interfacial properties of the resulting biocomposites. Low-pressure plasma treatment of lignocellulosic fibre/fillers is a useful approach and an alternative to more conventional chemical pre-treatment processes including alkaline treatment.

Download or read book Development and Characterization of Whey Protein based Environmentally Safe Wood Adhesives written by Wenbo Wang and published by . This book was released on 2013 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of ammonia/sulfite mole ratio, amount of the formaldehyde scavenger combination and PFO levels on bonding performances and formaldehyde emission were evaluated. Plywood evaluations indicated that the most preferable whey protein-based adhesive modified by 30% PFO with ammonia/sulfite mole ratio of 4:3 and 19% stoichiometric excesses of the combination had a dry bond strength of 1.98 MPa, a wet-state strength of 1.73 MPa comparable to those of phenol-formaldehyde (PF) resins and very low formaldehyde emission (0.0067 mg/L) which was much lower than that of PF resins. Findings from this study demonstrated that whey protein-based adhesives may be considered as an environmentally safe alternative to petroleum-based wood adhesives on the market with proper formulations according to the requirements of target wood composite products.

Download or read book The Glossary of Prosthodontic Terms written by and published by . This book was released on 1994 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Anatomy of Bamboo Culms written by Walter Liese and published by BRILL. This book was released on 1998 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Given its unrivalled position in terms of diversity, distribution and uses, coupled with the vital role it plays in the rural economies of several countries around the world, bamboo has emerged in recent years as potentially the most important non-wood forest resource to replace wood in construction and other uses. Concomitantly, the interest being shown in this invaluable natural resource since the 1980s has resulted in the accumulation of a considerable body of information through research on various aspects of bamboos, including the anatomy of the bamboo culm. There is, however, no comprehensive publication available on the anatomy of bamboo culm, with the available literature being fragmented, scattered and inadequate. This landmark monograph by renowned wood biologist, forestry expert and bamboo specialist, Professor Walter Liese, whose innovative work on the study of anatomical structure using advanced microscopy and other techniques has won him wide international acclaim, fulfils the need for a comprehensive overview of current knowledge on this subject. It is the first attempt to synthesize information from studies on this subject, many of which have been contributed by Professor Liese, spread over the past four decades. By identifying gaps in the current anatomical knowledge base of bamboo culm, it is expected to stimulate further research and to act as a prime mover for knowledge generation in the key areas of bamboo anatomy, growth and taxonomy.

Download or read book Green Biocomposites written by Mohammad Jawaid and published by Springer. This book was released on 2017-02-11 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the concept, design and application of green biocomposites, with a specific focus on the current demand for green biocomposites for automotive and aerospace components. It discusses the mathematical background, innovative approaches to physical modelling, analysis and design techniques. Including numerous illustrations, tables, case studies and exercises, the text summarises current research in the field. It is a valuable reference resource for researchers, students and scientists working in the field of materials science.

Download or read book Advanced Wood Adhesives Technology written by A. Pizzi and published by CRC Press. This book was released on 1994-08-10 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work discusses the latest innovations in the manufacture of wood adhesives, and shows how to test their composition. Methods of varying parameters to obtain particular effects are explained, and background summaries of each class of adhesives are provided.

Download or read book Materials Chemistry written by Bradley D. Fahlman and published by Springer. This book was released on 2018-08-28 with total page 817 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 3rd edition of this successful textbook continues to build on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field — in a concise format. The 3rd edition offers significant updates throughout, with expanded sections on sustainability, energy storage, metal-organic frameworks, solid electrolytes, solvothermal/microwave syntheses, integrated circuits, and nanotoxicity. Most appropriate for Junior/Senior undergraduate students, as well as first-year graduate students in chemistry, physics, or engineering fields, Materials Chemistry may also serve as a valuable reference to industrial researchers. Each chapter concludes with a section that describes important materials applications, and an updated list of thought-provoking questions.