Abstract Synthetic wood adhesives, consisting of urea-formaldehyde resins (UF), phenol-formaldehyde resins (PF), melamine-formaldehyde resins (MF), and polyurethane resins, are widely used. For UF and MF, most investigations are concerned with reducing free formaldehyde content; for PF, most studies focused on finding new alternative chemicals to replace phenol. These adhesives come under the Carcinogenic, Mutagenic, and Reprotoxic chemicals (CMR) category. Due to global energy issues and dependency on petroleum sources, the focus has shifted to look for alternative and renewable raw material sources for wood adhesives. Conventionally available wood adhesives are polyvinyl alcohol (PVA) stabilized, with drawbacks like poor water resistance, poor heat resistance, low-temperature workability, and it’s based on petroleum resources. Polyvinyl acetate (PVAc) is non-resistant to moisture polymer, and if such adhesive joints are exploited in a moist environment, its strength substantially decreases. Sufficiently moisture-resistant adhesive joints are obtained by modifying PVAc dispersion with special compounds like reactive comonomer, Silanes, and modified PVA. To improve the workability at low temperature, Vinyl acetate (VAc) is copolymerized with specific comonomers like butyl acetate without affecting the performance properties. Here, we aim to present an overview of the research trend of PVAc-based adhesives in the wood industry. The review summarizes the current state of research PVAc-based adhesives.

Abstract Bio-degradable cassava starch-based adhesives were produced from chemically gelatinized starch formulations. The varying combinations of process parameters applied include: concentration of gelatinization modifier, mass % borax/starch, and temperature of reaction mixture. The physico-chemical parameters for characterizing the adhesive samples were viscosity, density, pH and bonding strength. The effects of the variation of process parameters on the quality of the adhesives were assessed using response surface (central composite) designs with 2 factors, to relate the highest adhesive quality with the optimal combination of process factors. The adhesives produced using HCl as the gelatinization modifier were of a higher quality than those produced using NaOH with one of the most important quality assessment para meters which is the bond strength being 22.31 kPa at 0.01 M and 20% mass borax/starch and 11.60 kPa at 0.01 M and 8% mass borax/starch for HCl and NaOH respectively. The experimental results demonstrated that the optimal temperature for the production of the adhesive was 85˚C.

Abstract A cup shape is a dynamic morphology of cells and organelles. With the aim of elucidating the formation of the biotic cup-shaped morphology, this study investigated cup-shaped vesicles consisting of an amphiphilic diblock copolymer from the aspect of synthetic polymer chemistry. Cup-shaped vesicles were obtained by the polymerization-induced self-assembly of poly(methacrylic acid)-block-poly(n-butyl methacrylate-random-methacrylic acid), PMAA-bP(BMA-r-MAA), in an aqueous methanol solution using the photo nitroxide-mediated controlled/living radical polymerization technique. Field emission scanning electron microscopic observations demonstrated that the cupshaped vesicles were suddenly formed during the late stage of the polymerization due to the extension of the hydrophobic P(BMA-r-MAA) block chain. During the early stage, the polymerization produced spherical vesicles rather than a cup shape. As the hydrophobic block chain was extended by the polymerization progress, the spherical vesicles reduced the size and were accompanied by the generation of small particles that were attached to the vesicles. The vesicles continued to reduce the size due to further extension of the hydrophobic chain; however, they suddenly grew into cup-shaped vesicles. This growth was accounted for by a change in the critical packing shape of the copolymer due to the hydrophobic chain extension. These findings are helpful for a better understanding of the biotic cup-shaped vesicle formation.

Abstract Today, packaging plays a crucial role in maintaining the quality of products during uses by providing safeguarding against physical, chemical and environmental challenges. While polymer-based packaging material has been very extensively used, there has been a recent move to paper-based packaging products because of their economic and environmentally-friendly nature. Currently, Paper and paper-based board materials have been used as packaging material for food products, and e-commerce business. Adhesives in packaging industries are critical to the structure of most paper and paper board packaging, whether applied during the process of conversion and on the packaging line. From a production point of view, adhesive choice can significantly affect process line efficiency and production performance. Adhesive types used in paper industries are water-based adhesives both synthetic and bio-polymer based (starch, cellulose, protein and itaconic acid), Solvent-based adhesives (polyurethane and acrylic-based) and 100% solids adhesives like heat sealing adhesive and hot melts. More recently, water-based heat-expandable adhesive having thermally insulative and cushion-like properties has been provided for use in protective packages and wrap. Here, we aim to present an overview of the research trend of adhesives in the paper packaging industry. The overview summarizes the different adhesives for paper packaging industries.

Abstract Adhesives are used to bond various substrates such as metals, polymers, ceramics, rubber, wood and wood-based products. The use of adhesive as bonding agent rather than mechanical fasteners like nails results in the potential for reduced cost and weight of assemblies. However, adhesives are unprotected to a wide range of conditions, such as thermo-mechanical cycling in the environment, creep and fatigue imposed by structural joint configurations, and residual stress due to mismatch of thermal expansion between adhesives and objects. Thus, there will be a need for development of new chemistries and processes for easy repair and reprocessing of bonded structures are becoming of current great interest for the industries. In some cases, to improve the protection of various items/objects during handling and transportation, currently used protective products such as padded wraps, envelopes, packages and containers need to be modified. One technology which can solve the problem is the adhesives modified with thermally expandable particles (TEPs) which can be dismounted by heating the joint in a few seconds.The expandable composition is providing the necessary protective insulation and cushioning required in packages and containers. This paper reviews the application of unexpanded microspheres in the adhesive segment.