The Ultimate Bond

Being introduced in India in 1956 as an easy –to-use white glue for carpenters in replacement of Saresh (fat-based adhesives), the ULTIBOND company started its journey and never looked back. As The ULTIBOND Company was well known to recognize the need of their product and convert it into a marvelous opportunity, the company started manufacturing AI glue products for students as well as for professional and educational institutes. In order to shift end-users from natural glues and other synthetic adhesives available at the time, AI glue embarked on a bold marketing game plan. Instead of selling through stores, AI glue approached carpenters directly. This direct marketing initiative was one of the most successful strategies employed by the company and helped the brand gain a strong foothold in the white glue market. By 1965, the brand was big enough to develop its own manufacturing plant in Maharashtra. Primarily the company decided to enter into the retail market with a packaging of 33 grams collapsible tube in early 1970’s, later came up with many other unique packaging styles to cater the need and requirements of different segments of its customer base.

Pengaruh Variasi Bio Based Adhesive terhadap Kekuatan Peeling dan Shearing Kayu Pinus pada Adhesive Joint

The methods of joining engineering materials using adhesives is mostly implemented by using synthetic adhesives from non-renewable sources. Even though it has good joining performance, its poisonous nature and difficult to decompose naturally makes the adhesive needs to seek alternatives that are more environmentally friendly. Another reason is to support FAO campaigns for the use of environmentally friendly and biodegradable materials. One that has the potential to replace synthetic one is adhesives from natural sources such as gum rubber, jackfruit, and breadfruit. Because each natural sap has a different composition, the adhesive strength will also be different. Therefore it is necessary to examine the adhesive strength of each of these natural gums. In this research, natural adhesives (gums) and synthetic adhesives were used to joint pine wood as a test specimen. After joining, peeling and shearing tests on the specimens were carried out so that the mechanical strength of the joints for each adhesive variation was recognized. Fracture analysis was then performed to analyze the mechanism of joint failure for each adhesive variation. From this research, the highest peeling strength was obtained from rubber tree sap of 0.15 MPa, while the highest shearing strength was also obtained for rubber sap of 0.68 MPa.

Eco-friendly natural rubber latex and modified starch-based adhesive for wood-based panels application- A review

The use of formaldehyde-based synthetic adhesives for the development of wood-based panels has increased rapidly in the industry. Synthetic adhesives are regarded as a threat to human health and a pollutant because they emit formaldehyde's carcinogenic gas. The breakthrough has prompted to seek for a long-term solution to the formaldehyde threat with natural resources. There has been a significant rise in bio-based adhesive technology and development in the wood-based panel industry. The current review article is intended to present the potentials and the drawbacks of the development of bio-adhesives from sustainable resources such as natural rubber latex (NRL) and starch. This review also discussed the chemical modification and crosslinkers of starch to improve water resistance and adhesion properties. Moreover, this article discusses the compatibility of modified rice starch and NRL for their conclusive applications as wood-based panels adhesive. The findings suggested that bio-based adhesives could replace more synthetic-based adhesives with comparable performance in the near future.

Fillers in Wood Adhesives

The introduction of a second component to polymers has been presented; this component is often used to modify the characteristics of the products and to acquire new polymer materials with improved properties. Composite materials have a pivotal role in industries that are now considered the most progressive worldwide. At present, synthetic adhesives based on formaldehyde such as phenol-formaldehyde (PF), urea formaldehyde (UF), and melamine formaldehyde (MF) are predominantly used for wood composite production, and these adhesives are commonly used in the wood panel industry. These adhesives have some advantages and disadvantages. The use of PF adhesives is as important as UF adhesives in the wood panel industry. However, their application is still limited because of its brittleness, brown color, high curing temperature, long curing time, and toxicity due to liberation of phenol and formaldehyde. A variety of methods have been used to improve the performance of UF and PF adhesives as well as to expand their use. These methods are widely used in the industry; they include the simple addition of fillers. Moreover, the addition of fillers could reduce shrinkage and alleviate the stress on the glue line, which improves the hardness and durability.

Setal Field Transects, Evolutionary Transitions and Gecko–Anole Convergence Provide Insights Into the Fundamentals of Form and Function of the Digital Adhesive System of Lizards

Recent years have witnessed a multitude of studies focusing on gekkotan adhesion. Intense interest in this phenomenon was triggered by the discovery of the manner and magnitude of the forces generated by the hair-like filaments (setae) on the toe pads and inspired the development of the next generation of smart, reversible synthetic adhesives. Most studies pursuing these goals have concentrated on the generalized form and properties of gekkotan setae outlined in those key early studies, resulting in the fabrication of synthetic filaments of uniform dimensions. Although there are over 1,800 species of extant geckos, and hundreds of species of anoles (a separate lizard lineage that has convergently evolved adhesive toe pads), most investigations have used relatively few species as the source of basic information, the Tokay gecko (Gekko gecko) being the most prominent among these. Such exemplar taxa generally exhibit structurally intricate setae and morphologically complex configurations of the adhesive apparatus. Setal structure taken to be characteristic of these taxa is generally reported by singular statements of maximal length, diameter, density and branching pattern. Contemporaneous work focusing on the configuration of setae at locations across the toe pads and upon the evolutionary origin of adhesively competent digits in anoles and specific lineages of geckos, however, has revealed extensive variation of setal structure within individuals, information about how setae may have arisen from non-adhesive filamentous precursors, and how newly adhesively competent digits have been integrated into pre-existing patterns of locomotor mechanics and kinematics. Such observations provide insights into what is minimally necessary for adhesively competent digits to function and reveal the simplest configuration of components that make this possible. We contend that information gleaned from such studies will assist those seeking to employ the principles of fibrillar-based adhesion, as exemplified by lizards, for bio-inspired applications.

PRE-TREATMENT AND INVESTIGATION OF WHEAT STRAW AND HEMP SHIVES FOR BINDER-LESS FIBREBOARD PRODUCTION

Wood-based panels (WBP) comprise a considerable part in the output of the European wood industry, GDP, and export. Over 30% of fibreboards and about 50% of other boards used in constructions and carpentry are produced in Europe. Industrially produced WBP contain synthetic adhesives determining mechanical properties and being made from oil are often toxic present health risks. Synthetic adhesives may comprise up to 15 % of the total WBP mass and up to 60 % of the total production costs. Production costs of WBP are important under the circumstances of rising oil prices. Moreover, synthetic bonding agents rather often is a source of emissions of formaldehyde and another problems with advancement of WBP solutions being offered by synthetic adhesives without formaldehyde (polymeric methylene diphenyl di-isocyanate – PMDI), or by natural adhesives from renewables (e.g., tannins or soy flour), or by pre-treatments activating bonding agents contained in the source material. The availability of raw materials for WBP is still another problem under the circumstances of the rate of population growth exceeding the rate of the regeneration of wood resources. Expanding the diversity of raw materials for production of WBP by utilization of agricultural residues containing components like wood is one of the possible solutions. The present study is aimed at development of technology of binder-less fibreboards made of steam-exploded agricultural residues, such as wheat straw (Triticum aestivum L.) and industrial hemp (Cannabis sativa L.) shives. Some aspects of the study, like differences in chemical composition, thermal properties of raw and pretreated materials potentially affecting binder-less fibreboard bonding, presented.

Utilization of Partially Liquefied Bark for Production of Particleboards

Bark as a sawmilling residue can be used for producing value-added chemicals and materials. This study investigated the use of partially liquefied bark (PLB) for producing particleboard with or without synthetic adhesives. Maritime pine (Pinus pinaster Ait.) bark was partially liquefied in the presence of ethylene glycol and sulfuric acid. Four types of particleboard panels were prepared with a PLB content of 4.7%, 9.1%, 20%, and 33.3%, respectively. Another five types of particleboard panels were manufactured by using similar amounts of PLB and 10 wt.% of melamine–urea–formaldehyde (MUF) adhesives. Characterization of bark and solid residues of PLB was performed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and automated vapor sorption (AVS). Mechanical and physical properties of the particleboard were tested according to the European standards EN 310 for determining modulus of elasticity and bending strength, EN 317 for determining thickness swelling after immersion in water, and EN 319 for determining internal bond strength. The results showed that the increase in PLB content improved the mechanical strength for the non-MUF boards, and the MUF-bonded boards with up to 20% of PLB met the requirements for interior uses in dry conditions according to EN 312. The non-MUF boards containing 33.3% of PLB and the MUF-bonded boards showed comparable thickness swelling and water absorption levels compared to the reference board.

Impact of Bio-Based (Tannins) and Nano-Scale (CNC) Additives on Bonding Properties of Synthetic Adhesives (PVAc and MUF) Using Chestnut Wood from Young Coppice Stands

Sustainability and ecotoxicity issues call for innovations regarding eco-friendly adhesives in the production of biocomposite wood materials, and solutions involving nano-scale and bio-based compounds represent a valid and promising target. One possible approach is to increase the performance of adhesives such as polyvinyl acetate (PVAc) or melamine-urea-formaldehyde (MUF) by means of nanoparticles in order to obtain a material with better mechanical and environmental resistance. When applying cellulose-based nanoparticles or tannin, the concept of a circular economy is successfully implemented into the forest/wood value chain, and chances are created to develop new value chains using byproducts of forestry operations. In this study, assortments coming from young sweet chestnut (Castanea sativa Mill.) coppice stands were utilized for the preparation of single lap joint assemblies using different commercial adhesives (PVAc, MUF) and cellulose nanocrystals (CNC) and tannin as additives. The results showed that addition of CNC and tannin to PVAc glue increased tensile shear strength in lap joint tests presenting a promising base for future tests regarding the addition of CNC and tannin in MUF or PVAc adhesive formulations. Unfortunately, the tested bio-based additives did not reveal the same encouraging results when tested in the wet state.

Design of Tree-Frog-Inspired Adhesives

Synopsis The adhesive toe pads of tree frogs have inspired the design of various so-called ‘smooth’ synthetic adhesives for wet environments. However, these adhesives do not reach the attachment performance of their biological models in terms of contact formation, maintenance of attachment, and detachment. In tree frogs, attachment is facilitated by an interconnected ensemble of superficial and internal morphological components, which together form a functional unit. To help bridging the gap between biological and bioinspired adhesives, in this review, we (1) provide an overview of the functional components of tree frog toe pads, (2) investigate which of these components (and attachment mechanisms implemented therein) have already been transferred into synthetic adhesives, and (3) highlight functional analogies between existing synthetic adhesives and tree frogs regarding the fundamental mechanisms of attachment. We found that most existing tree-frog-inspired adhesives mimic the micropatterned surface of the ventral epidermis of frog pads. Geometrical and material properties differ between these synthetic adhesives and their biological model, which indicates similarity in appearance rather than function. Important internal functional components such as fiber-reinforcement and muscle fibers for attachment control have not been considered in the design of tree-frog-inspired adhesives. Experimental work on tree-frog-inspired adhesives suggests that the micropatterning of adhesives with low-aspect-ratio pillars enables crack arresting and the drainage of interstitial liquids, which both facilitate the generation of van der Waals forces. Our analysis of experimental work on tree-frog-inspired adhesives indicates that interstitial liquids such as the mucus secreted by tree frogs play a role in detachment. Based on these findings, we provide suggestions for the future design of biomimetic adhesives. Specifically, we propose to implement internal fiber-reinforcements inspired by the fibrous structures in frog pads to create mechanically reinforced soft adhesives for high-load applications. Contractile components may stimulate the design of actuated synthetic adhesives with fine-tunable control of attachment strength. An integrative approach is needed for the design of tree-frog-inspired adhesives that are functionally analogous with their biological paradigm.

Soybean Meal-Based Wood Adhesive Enhanced by Phenol Hydroxymethylated Tannin Oligomer for Exterior Use

Bio-based adhesives have low water resistance and they are less durable than synthetic adhesives, which limits their exterior applications. In this study, a bio adhesive was developed from soybean meal and larch tannin that was designed for exterior use. Phenol hydroxymethylated tannin oligomer (PHTO) was synthesized and then mixed with soybean meal flour in order to obtain a soybean meal-based adhesive (SPA). The results showed that the moisture absorption rate, residual rate, and solid content of SPA with 10 wt % PHTO (mass ratio with respect to the entire adhesive) were improved by 22.8%, 11.6%, and 6.8%, respectively, as compared with that of pure SPA. The wet shear strength of plywood with SPA with 10 wt % PHTO (boiling in 100 °C water for 3 h) was 1.04 MPa when compared with 0 MPa of pure SPA. This met the bond strength requirement of exterior-use plywood (GB/T 9846.3-2004). This improved adhesive performance was mainly due to the formation of a crosslinked structure between the PHTO and the protein and also PHTO self-crosslinking. The formaldehyde emission of the resulting plywood was the same as that of solid wood. The PHTO-modified SPA can potentially extend the applications of SPAs from interior to exterior plywood.