Bondability Of Modified Wood
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Bondability Of Modified Wood
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Author : Alireza Bastani
language : en
Publisher: Cuvillier Verlag
Release Date : 2016-06-30
Bondability Of Modified Wood written by Alireza Bastani and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-06-30 with Science categories.
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.
Wood Modification
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Author : Callum A. S. Hill
language : en
Publisher: John Wiley & Sons
Release Date : 2007-02-06
Wood Modification written by Callum A. S. Hill and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-02-06 with Science categories.
This book is exclusively concerned with wood modification, although many of these processes are generic and can be applied to other lignocellulosic materials. There have been many rapid developments in wood modification over the past decade and, in particular, there has been considerable progress made in the commercialisation of technologies. Topics covered include: The use of timber in the 21st century Modifying the properties of wood Chemical modification of wood: Acetic Anhydride Modification and reaction with other chemicals Thermal modification of wood Surface modification Impregnation modification Commercialisation of wood modification Environmental consideration and future developments This is the first time that a book has covered all wood modification technologies in one text. Although the book covers the main research developments in wood modification, it also puts wood modification into context and additionally deals with aspects of commercialisation and environmental impact. This book is very timely, because wood modification is undergoing huge developments at the present time, driven in part by environmental concerns regarding the use of wood treated with certain preservatives. There has been considerable commercial interest shown in wood modification over the past decade, with products based upon thermal modification, and furfurylation now being actively being marketed. The next few years will see the commercialisation of acetylation and impregnation modification. This is a new industry, but one that has enormous potential. This book will prove useful to all those with an interest in wood modification including researchers, technologists and professionals working in wood science and timber engineering, wood preservation, and well as professionals in the paper and pulp industries, and those with an interest in the development of renewable materials.
Wood Modification Technologies
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Author : Dick Sandberg
language : en
Publisher: CRC Press
Release Date : 2021-07-15
Wood Modification Technologies written by Dick Sandberg and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-07-15 with Nature categories.
The market for durable products using modified wood has increased substantially during the last few years. This is partly because of the restriction on the use of toxic preservatives due to environmental concerns, and to lower maintenance cost and time. Furthermore, as sustainability becomes a greater concern, the environmental impact of construction and interior materials is factored in planning by considering the whole life cycle and embodied energy of the materials used. Wood is modified to improve its intrinsic properties, enhance the range of applications of timber, and to acquire the form and functionality desired by engineers without calling the environmental friendliness into question. Wood modification processes are at various stages of development, and the challenges faced in scaling up to industrial applications differ. The aim of this book is to put together the key elements of the changes of wood constituents and the related changes in wood properties of modified wood. Further, a selection of the principal technologies implemented in wood modification are presented. This work is intended for researchers, professionals of timber construction, as well as students studying the science of materials, civil engineering and architecture. This work is not exhaustive, but intends to deliver an outline of the scientific disciplines necessary to apprehend the technologies of wood modification and its behavior during treatment, as well as during its use.
Wood Modification Technologies
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Author : Dick Sandberg
language : en
Publisher: CRC Press
Release Date : 2021-07-14
Wood Modification Technologies written by Dick Sandberg and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-07-14 with Nature categories.
Describes how to Improvement of wood products Describes Sustainable development Covers Environmental industrial processing
Wood Adhesives
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Author : Antonio Pizzi
language : en
Publisher: CRC Press
Release Date : 2011-01-07
Wood Adhesives written by Antonio Pizzi and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011-01-07 with Technology & Engineering categories.
Wood adhesives are of tremendous industrial importance, as more than two-thirds of wood products in the world today are completely or partially bonded together using a variety of adhesives. Adhesive bonding offers many advantages over other joining methods for wood components, and there has been a great deal of R& D activity in devising new wood adhesives or improving the existing ones. The modern mantra in all industrial sectors is: "think green, go green," which has attracted much attention in the wood adhesive industry. Therefore, there is also a lot of research activity in synthesizing environmentally benign and human-friendly wood adhesives. This book is divided into four parts: Part 1: Fundamental Adhesion Aspects in Wood Bonding; Part 2: Synthetic Adhesives; Part 3: Environment-friendly adhesives; and Part 4: Wood Welding and General Paper. It addresses many different types of wood adhesives, as well as bonding (welding) of wood components without adhesives, a more recent development. The information contained in this book is valuable for individuals engaged in all aspects of wood adhesion and adhesives and, hopefully, will inspire new ideas in wood adhesives, a topic of vital industrial importance.
Wood Composites
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Author : Martin P Ansell
language : en
Publisher: Woodhead Publishing
Release Date : 2015-07-24
Wood Composites written by Martin P Ansell and has been published by Woodhead Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-07-24 with Technology & Engineering categories.
Recent progress in enhancing and refining the performance and properties of wood composites by chemical and thermal modification and the application of smart multi-functional coatings have made them a particular area of interest for researchers. Wood Composites comprehensively reviews the whole field of wood composites, with particular focus on their materials, applications and engineering and scientific advances, including solutions inspired biomimetrically by the structure of wood and wood composites. Part One covers the materials used for wood composites and examines wood microstructure, and wood processing and adhesives for wood composites. Part Two explores the many applications of wood composites, for example plywood, fibreboard, chipboard, glulam, cross-laminated timber, I-beams and wood-polymer composites. The final part investigates advances in wood composites and looks at the preservation and modification of wood composites, environmental impacts and legislative obligations, nano-coatings and plasma treatment, biomimetic composite materials, the integration of wood composites with other materials and carbonized and mineralized wood composites. Comprehensively reviews the entire field of wood composites in a single volume Examines recent progress in enhancing and refining the performance and properties of wood composites by chemical and thermal modification and the application of smart multi-functional coatings Explores the range of wood composites, including both new and traditional products
Reaction Of Epoxides With Wood
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Author : Roger M. Rowell
language : en
Publisher:
Release Date : 1984
Reaction Of Epoxides With Wood written by Roger M. Rowell and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1984 with Epoxy compounds categories.
Recent Research On Wood And Wood Based Materials
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Author : Nobuo Shiraishi
language : en
Publisher: Elsevier
Release Date : 2013-10-22
Recent Research On Wood And Wood Based Materials written by Nobuo Shiraishi and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-10-22 with Technology & Engineering categories.
Current Japanese Materials Research, Volume 11: Recent Research on Wood and Wood-Based Materials is a collection of papers that details the advancement of the field of wood science and technology in Japan. The coverage of the book includes various technological processes applied to wood, including steam-injection, chemically modification, and plasticization. The text also presents studies that cover the fundamental aspects of wood technology, such as structure and chemical composition of wood as a natural composite material; wood-preserving techniques to prevent biodeterioration; and wood as a livable interior material. The book will be of great use to researchers and professionals from various disciplines, including botany, engineering, and agriculture.
Progress In Adhesion And Adhesives Volume 4
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Author : K. L. Mittal
language : en
Publisher: John Wiley & Sons
Release Date : 2019-07-11
Progress In Adhesion And Adhesives Volume 4 written by K. L. Mittal and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-07-11 with Technology & Engineering categories.
A solid collection of interdisciplinary review articles on the latest developments in adhesion science and adhesives technology With the ever-increasing amount of research being published, it is a Herculean task to be fully conversant with the latest research developments in any field, and the arena of adhesion and adhesives is no exception. Thus, topical review articles provide an alternate and very efficient way to stay abreast of the state-of-the-art in many subjects representing the field of adhesion science and adhesives. Based on the success of the preceding volumes in this series "Progress in Adhesion and Adhesives"), the present volume comprises 9 review articles published in Volume 6 (2018) of Reviews of Adhesion and Adhesives. The subject of these reviews fall into the following general areas: 1. Adhesion to wood and wood bonds 2. Adhesive joints 3. Adhesion in microelectronic packaging 4. Surface modification 5. Contact angle, wettability and surface free energy. The topics covered include: Adhesion phenomena in microelectronic packaging; adhesives for wood and lignocellulosic materials; adhesion to wood and lignocellulosic materials; adhesively bonded lap joints having bi-adhesive and modulus-graded bondlines; adhesion between compounded elastomers; applications of contact angle measurements in pharmaceuticals and foods; oxygen or ammonia plasma treatment of polyolefin surfaces; surface free energy determination of powders and particles; wood bonds; and dispersion adhesion forces between macroscopic objects.
Research Paper Fpl
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Author :
language : en
Publisher:
Release Date : 1983
Research Paper Fpl written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1983 with Forest products categories.