{"title":"Wood Adhesives Based on Natural Resources: A Critical Review: Part IV. Special Topics","authors":"M. Dunky","doi":"10.1002/9781119846703.CH18","DOIUrl":null,"url":null,"abstract":"Various naturally-based chemicals can be used directly as wood adhesives or are precursors for the synthesis of adhesive resins. Liquefaction and pyrolysis of wood yield various smaller chemicals derived from the different wood components, which then are used in the preparation of adhesives\n by replacing mainly phenol as raw material. The possible replacement of formaldehyde in aminoplastic and phenolic resins would solve the question of the subsequent formaldehyde emission. The multiple unsaturations of the triglycerides in vegetable oils enable polymerization for\n the direct synthesis of thermosets, as well as bases for polyfunctionalization and crosslinking. Natural polymers, such as poly(lactic acid)s (PLAs), natural rubber, or poly(hyhydroxyalkanoate)s (PHAs) are thermoplastics and can be used for various special applications in wood bonding,\n in case they can also be crosslinked. For other thermoplastic wood adhesives, such as PUR or PA, chemicals based on natural resources can at least replace a part or even all synthetic raw materials (monomers); these monomers derive from targeted decomposition of the wood material in biorefineries.\n Cellulose nanofibrils (CNFs) can be used as as sole adhesives or as components of adhesives. Hydrogen bonding has a key function in binder applications related to adhesion between cellulose nanoparticles and other materials. CNFs are able to establish strong bonding between wood particles/fibres\n through flexible and strong films by a simple drying process. Cashew nut shell liquid (CNSL) is a by-product of the cashew nut processing with cardanol (CD) as main component. CD-formaldehyde resins show improved flexibility compared to phenol-formaldehyde (PF) resins; CD can replace\n up to 40% of the phenol.","PeriodicalId":43792,"journal":{"name":"Reviews of Adhesion and Adhesives","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2021-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/9781119846703.CH18","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Reviews of Adhesion and Adhesives","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1002/9781119846703.CH18","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"Materials Science","Score":null,"Total":0}
引用次数: 2
Abstract
Various naturally-based chemicals can be used directly as wood adhesives or are precursors for the synthesis of adhesive resins. Liquefaction and pyrolysis of wood yield various smaller chemicals derived from the different wood components, which then are used in the preparation of adhesives
by replacing mainly phenol as raw material. The possible replacement of formaldehyde in aminoplastic and phenolic resins would solve the question of the subsequent formaldehyde emission. The multiple unsaturations of the triglycerides in vegetable oils enable polymerization for
the direct synthesis of thermosets, as well as bases for polyfunctionalization and crosslinking. Natural polymers, such as poly(lactic acid)s (PLAs), natural rubber, or poly(hyhydroxyalkanoate)s (PHAs) are thermoplastics and can be used for various special applications in wood bonding,
in case they can also be crosslinked. For other thermoplastic wood adhesives, such as PUR or PA, chemicals based on natural resources can at least replace a part or even all synthetic raw materials (monomers); these monomers derive from targeted decomposition of the wood material in biorefineries.
Cellulose nanofibrils (CNFs) can be used as as sole adhesives or as components of adhesives. Hydrogen bonding has a key function in binder applications related to adhesion between cellulose nanoparticles and other materials. CNFs are able to establish strong bonding between wood particles/fibres
through flexible and strong films by a simple drying process. Cashew nut shell liquid (CNSL) is a by-product of the cashew nut processing with cardanol (CD) as main component. CD-formaldehyde resins show improved flexibility compared to phenol-formaldehyde (PF) resins; CD can replace
up to 40% of the phenol.
期刊介绍:
With the explosion of research activity and reports, the need for concise and critical reviews of topics of contemporary research interest is manifest. Reviews of Adhesion and Adhesives (RAA) provides in-depth, incisive, illuminating and thought-provoking reviews written by subject matter experts covering all aspects of adhesion science and adhesive technology. Each review will be imbued with the author’s experience so that the reader will be able to assimilate the research in the area discussed easily and will be able to apply it in practice.The journal has relevance to a myriad of industries including textiles, printing, coatings, aerospace, medical, nanotechnology, biotechnology, building and construction, and microelectronics. The topics to be covered include, but not limited to, basic and theoretical aspects of adhesion; modeling of adhesion phenomena; mecha¬nisms of adhesion; surface and interfacial analysis and characterization; unraveling of events at interfaces; characterization of interphases; adhesion of thin films and coatings; adhesion aspects in reinforced composites; formation, characterization and durability of adhesive joints; surface preparation methods; polymer surface modification; biological adhesion; particle adhesion; adhesion of metallized plastics; adhesion of diamond-like films; adhesion pro¬moters; contact angle, wettability· and adhesion; superhydrophobicity and superhydrophilicity. With regard to adhesives, RAA will include, but not limited to, green adhesives; novel and high-performance adhesives; and medical adhesive applications.