Comparative Study of Effect of Addition of Calcium Carbonate and Clay on the Performance Properties of Polyvinyl Acetate Wood Glue

Polyvinyl alcohol (PVA) stabilized Polyvinyl acetate (PVAc) dispersions-based wood adhesive has poor water and heat resistance. Recently, the addition of fillers in the wood adhesive is one of the most effective ways to enhance the performance of PVAc wood adhesive. Inorganic fillers have unique characteristics to improve the performance of adhesive, such as small size, high surface energy and surface hardness. Hence, the present work investigates the applicability of calcium carbonate and clay incorporated 3% in situ emulsion polymerization PVAc wood adhesive. Effect on physical, thermal and mechanical properties was studied by viscosity, pH, contact angle measurement, differential scanning calorimetry (DSC) and pencil hardness test of films. Emulsions with 3% calcium carbonate and 3% clay were prepared and the shear strength of the applied adhesive on wood was measured. The viscosity of the adhesives was reduced in the case of the addition of calcium carbonate and increased in the case of clay. The mechanical properties like tensile strength of adhesives with calcium carbonate and clay were measured by a universal tensile machine (UTM). Thermal stability was studied by differential scanning calorimetry (DSC). The tensile shear strength demonstrates that clay can improve bonding strength as compared to calcium carbonate of PVAc adhesive in wet conditions. The hardness of PVAc films was also changed positively by the addition of calcium carbonate and clay. Thermal stability of PVAc was significantly improved as calcium carbonate and clay were added to PVAc. Here, we did a comparative study of the effect of the addition of calcium carbonate and clay filler materials in situ polymerization of PVAc on their different properties.

Characterization and Application of Naturally Occurring Mineral Based Pigment in Surface Coating

New naturally occurring mineral based pigment of general formula Hg2S have been processed and characterized for its application in surface coating. Various analytical protocol like XRD, FT-IR, SEM and CIE 1976 colour coordinate system have been performed for complete analysis of pigment. Characterizations using XRD, and CIE 1976 colour coordinate assessment reveal the formation of pigments displaying colours ranging from brick-red to dark-brown. The typical designed pigment samples have been evaluated for their mass tone/hiding power, tinting strength and weather resistance by coating on an MS steel panel. Optical, Chemical, Mechanical and performance properties of coating have been evaluated for its application. The results demonstrated that the dark-brown pigment obtained in the present study was found to be an interesting alternative to the existing classical toxic inorganic red pigments for surface coating applications.

Polyvinyl Acetate and Vinyl Acetate-Ethylene Hybrid Adhesive: Synthesis, Characterization, and Properties

The goal is to develop a hybrid IPN network of polyvinyl acetate (PVAc) and ethylene-vinyl acetate (VAE). In this research work, the vinyl acetate (VAc)/ VAE hybrid emulsion and polyvinyl acetate emulsion (PVAc) were effectively synthesized. Emulsions with various characteristics have been developed by adjusting the weight ratios between the vinyl acetate monomer and the VAE component. The impacts on the mechanical, thermal, and physical properties of the films were investigated using tests for pencil hardness, tensile shear strength, pH, contact angle measurement, differential scanning calorimetry (DSC), and viscosity. When 5.0 weight percent VAE was added, the tensile shear strength in dry conditions decreased by 18.75% after a 24-hour bonding period, the heat resistance decreased by 26.29% (as per WATT 91) and the tensile shear strength decreased by approximately 36.52% in wet conditions (per EN 204). The pristine sample’s results were also confirmed by the contact angle test. The interpenetrating network (IPN) formation in hybrid PVAc emulsion as primary bonds does not directly attach to PVAc and VAE chains. The addition of VAE reduced the mechanical properties (at dry conditions) and heat resistance as per WATT 91. Contact angle analysis demonstrated that PVAc adhesives containing VAE had increased water resistance when compared to conventional PVA stabilised PVAc homopolymer-based adhesives. When compared to virgin PVAc Homo, the water resistance of the PVAc emulsion polymerization was enhanced by the addition of VAE.

Thermal Stability and Crystallinity Study of Polystyrene/SiO2 Nano-Composites Synthesis via Microwave-Assisted In Situ Polymerization

Serials of polystyrene/SiO2 Nano composites (PS/SiO2) with different content of inorganic fillers were successfully prepared by the in situ bulk radical polymerization of styrene under microwave irradiation. The effect of the amount of Nano SiO2 on the properties of the PS/SiO2 Nanocomposites along with the average relative molecular masses (Mn, Mz and Mw) was investigated by thermal analysis and X-Ray Diffraction (XRD). Their structural model was proposed on the basis of the Optical Microscopy, FTIR (Fourier Transform Infrared) analysis, differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and X-Ray Diffraction (XRD). The dispersion of nanoparticles in Polystyrene is observed in the magnified image. The effect of microwave irradiation power on molecular weight of polystyrene was also studied. It was found that, the microwave assisted reaction needs less time as compare to conventional polymerization and found to be in between 10 to 15 min.

Development of Cardanol-Based Polyol via Click Chemistry and Crosslinking with Melamine Formaldehyde Resin for Coating Applications

The research work presented in this article deals with the synthesis of cardanol-based polyol and its curing with hexabutoxymethyl melamine(HBMM)for application in coatings.Cardanol-based polyol was prepared via thiol-ene click reaction using thioglycerol.Unsaturation present in the long chain of cardanol was successfully utilized to synthesize polyol via thiol-ene coupling.The reaction was carried out between cardanol and thioglycerol in the presence of Irgacure 184(photoinitiator)and 1,8-Diazabicyclo[5.4.0]undec-7-ene(catalyst)under UV light for 12 h at 80°C.After completion of the reaction,one mole of thioglycerol was successfully added across the double bond of a fatty chain of cardanol and confirmed by Fourier transform infrared spectroscopy(FTIR)and proton nuclear magnetic resonance spectroscopy and hydroxyl and iodine values were determined.Furthermore,the polyol thus prepared was cured with commercial HBMM in various proportions,such as 1:0.6,1:0.8 and 1:1,on an equivalent basis.The coatings were then characterized for mechanical,chemical,optical,thermal and anticorrosive properties.It was observed that coatings exhibited excellent performance properties as compared to that of its acrylic counterpart.

State of Research and Trends in the Development of Polyvinyl Acetate-Based Wood Adhesive

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.

Study of Cross-Linking between Boric Acid and Different Types of Polyvinyl Alcohol Adhesive

Polyvinyl alcohol (PVA) is water-soluble polymer manufactured by the saponification of polyvinyl acetate. The physical properties and its specific application depend on the degree of hydrolysis. To enhance the properties of different hydrolyzed PVA grades, it is generally chemically modified with various cross-linkers. Here, different degree hydrolyzed PVA grades with enhanced properties were achieved by cross-linking with boric acid. These samples were then characterized by Differential Scanning Calorimetry (DSC) and Gel permeation chromatography (GPC). For further analysis a film of samples were prepared by casting on glass plate. The effects of amount of boric acid and degree of hydrolysis of PVA on performance properties like tensile strength, pencil hardness and thermal properties like glass transition temperature were studied. The results showed that by cross-linking there was an increase in mechanical strength and thermal property.

Study on Various Compositions of Polyvinyl Alcohol and Starch Blends by Cross-Linking with Glyoxal

The aim of this study is to analyze the various compositions of polyvinyl alcohol (PVA) and starch blends. The blends have been cross-linked with glyoxal to enhance its properties. The hydroxyl groups of PVA and starch react with glyoxal via formation of acetal bonds;hence crosslinking could take place. The cross-linking of glyoxal is observed in various analytical methods such as DSC and FTIR. The cross-linked blends showed better thermal and mechanical properties. Viscosity, tensile shear strength, pencil hardness and ultimate stress were evaluated to estimate the changes due to cross-linking. It was observed that the cross-linking is directly proportional to starch, since the starch hydroxyl groups are easily accessible for reacting. The cross-linked blend showed better cohesion between its chains, thereby increasing glass transition temperature. It was reflected in the subsequent increase in tensile strength properties.

Synthesis and Characterization of UV Oligomer based on Cardanol

In the present research,cardanol based di-acrylic UV oligomer was synthesized by thiol-ene coupling followed by ring opening reaction with glycidyl methacrylate.The intermediate as well as final diacrylate materials were analyzed by chemical as well as spectroscopic analysis.Further,ultraviolet(UV)radiation curable formulations were prepared by replacing commercial epoxy acrylate with synthesized UV oligomer in 10-50 wt%and applied on wood panels.The coated films were then evaluated for their optical,mechanical,chemical and thermal properties.Studies showed that up to 30 wt%amount of UVoligomer the coatings exhibited at par mechanical and chemical properties.The stain resistance of all the coatings was observed to be excellent.

Effect of Cenosphere Concentration on the Mechanical, Thermal, Rheological and Morphological Properties of Nylon 6

Cenospheres are widely used as filler in thermoset plastics and concrete mainly for density reduction of the material. But there is no work noted of using cenosphere as filler in thermoplastics. In this paper cenosphere concentration was varied from 0 to 10 phr of nylon 6 and the effect of the same on the mechanical, thermal, rheological and morphological properties of the composite were studied. Elongation was found to have increased by 83% and impact strength by 44% at 2.5 phr loading of cenosphere. Flexural strength increased upto 25% at 10 phr content of cenosphere.

Polymers and Polymeric Materials in COVID-19 Pandemic: A Review

The coronavirus disease 2019 (COVID-19) pandemic has been at its worst and the world is fighting to help global public health. In this aspect the role played by polymers and polymeric materials including plastics as the main material in medical devices, personal protective equipment for health care workers is huge. Advantages like mass production, lower cost and possibilities for sterilization and disinfection of the plastic materials make them an inevitable material in healthcare sector. Apart from plastics, anti-viral and anti-microbial coatings, polymeric nanocomposites and functional polymers have been introduced as a helping tool against COVID-19. This review focuses on the application of polymers, and polymeric materials in COVID-19 pandemic. Usage of plastics and its applications in healthcare and related sectors have been reviewed. The major challenges faced and future prospects on the usage of polymers have also been discussed.

Silane Terminated Prepolymers: An Alternative to Silicones and Polyurethanes

Silane terminated prepolymers for adhesives, sealants and coatings are of great industrial importance. They are very important because of their low toxicity over polyurethanes, silicones, and solvent-based products. Hence, many pieces of literature which deal with the synthesis, properties and applications of this Silane terminated polymers hybrid system exist. Silylated polyether (MS polymers) and Silylated Polyurethane Polymers (SPUR) are the bases for numerous sealants, adhesives and coatings used worldwide. A hybrid system mixed with organic-polyurethane proportion and inorganic-alkoxysilane proportion combines the benefits of conventional polyurethane and silicone-based products. This article reviews the chemistry of MS polymers and SPUR and their advantages and disadvantages in silyl terminated prepolymer-based adhesives, sealants and coatings as well as provides information on different end applications.

Application of Thermally Expandable Microspheres in Adhesives: Review

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.

Surface Modification of Cellulose with Silanes for Adhesive Application: Review

There has been an increasing interest in research on using bio-renewable polymers as a replacement to traditional synthetic polymers based on petroleum resources for adhesive applications. Cellulose, which is the most abundant biopolymer finds application as a reinforcing agent in conventional adhesives. However, natural polymer cellulose suffers from a few drawbacks like poor water resistance, low mechanical strength, and compatibility within the hydrophobic matrix. For emerging as sustainable alternatives for synthetic polymers, cellulose and its derivatives must have comparable physical, chemical, thermal, and mechanical properties to those of synthetic polymers. To achieve this, cellulose has been chemically modified as it has free hydroxyl groups which act as a site for modification. Among various techniques used crosslinking and silane modification have shown better properties. Various silanes have been identified and used for modifying both micro-cellulose and nano-cellulose, by the formation of covalent bonds. Silanes have the ability to react with the low number of free hydroxyl groups present in the cellulose surfaces, therefore promotes surface modification. Hence referring to the increase in the research works related to the silane modification of cellulose and its applicability focusing on wood adhesives, the main aim of this review paper is to summarize various works relating to this field.

Synthesis of Microcrystalline Cellulose—Polyvinyl Alcohol Stabilized Polyvinyl Acetate Emulsion

Polyvinyl alcohol (PVA) colloid stabilized Polyvinyl acetate (PVAc) based wood adhesive has poor performance in highly humid conditions. Currently, the addition of natural fillers in the wood adhesive is one of the most effective ways to enhance the performance of PVAc wood adhesive in highly moist conditions. Microcrystalline cellulose (MCC) are strong renewable, bio-based material and has great potential in a reinforcement of the polymeric matrix. Hence, the present work investigates the applicability of microcrystalline cellulose incorporated 3% and 5% in situ emulsion polymerization PVAc wood adhesives. Effect on physical, thermal and mechanical properties was studied by viscosity, pH, contact angle measurement, differential scanning calorimetry (DSC) and pencil hardness test of films. Emulsions with different proportions of MCC were prepared and the shear strength of the applied adhesive on wood was measured. The viscosity of the adhesives was increased by increasing the concentration of MCC. The mechanical properties like tensile strength of adhesives with MCC were measured by universal tensile machine (UTM). Thermal stability was studied by differential scanning calorimetry (DSC). The tensile shear strength demonstrates that MCC can improve bonding strength as compared to PVAc Homo based adhesive in the wet condition which was validated through a contact angle study. The hardness of PVAc films were also changed positively by the addition of MCC. Here, we studied the effect of the addition of different concentrations of MCC materials in situ polymerization of PVAc on their performance properties.

Indoor Formaldehyde Removal Techniques through Paints: Review

Due to its ability to cause illnesses and discomfort even at low concentrations, formaldehyde pollution of indoor air poses a significant risk to human health. Sources of formaldehyde in indoor environments include textiles, paints, wallpapers, glues, adhesives, varnishes, and lacquers;furniture and wooden products like particleboard, plywood, and medium-density fiberboard that contain formaldehyde-based resins;shoe products;cosmetics;electronic devices;and other consumer goods like paper products and insecticides. According to the World Health Organisation, indoor formaldehyde concentrations shouldn’t exceed 0.1 mg/m3. The methods include membrane separation, plasma, photocatalytic decomposition, physisorption, chemisorption, biological and botanical filtration, and catalytic oxidation. Materials based on metal oxides and supported noble metals work as oxidation catalysts. Consequently, a paint that passively eliminates aldehydes from buildings can be developed by adding absorbents and formaldehyde scavengers to the latex composition. It will be crucial to develop techniques for the careful detection and removal of formaldehyde in the future. Additionally, microbial decomposition is less expensive and produces fewer pollutants. The main goal of future research will be to develop a biological air quality control system that will boost the effectiveness of formaldehyde elimination. The various methods of removing formaldehyde through paints have been reviewed here, including the use of mixed metal oxides, formaldehyde-absorbing emulsions, nano titanium dioxide, catalytic oxidation, and aromatic formaldehyde abating materials that can improve indoor air quality.

Factor Affecting Gel Time/Process-Ability of Urea Formaldehyde Resin Based Wood Adhesives

Urea-formaldehyde (UF) resin presents the most utilized adhesive system in the manufacture of plywood, particleboard and fiberboard. At the temperatures above 100°C in the presence of hardener, this resin undergoes cross-linking reaction and the formation of three dimensional cross linked structures takes place and bonding of wood particles in a hot press [1]. UF powder resins show high reactivity and good performance in the production and by their low price;however they lack in water resistance of the hardened resin [2]. Urea-formaldehyde (UF) resins are the most important type of adhesive resins for the production of wood based panels but process-ability and curing behavior of urea formaldehyde resin depended on various factors related to resin properties, types of wood and their properties, amount & type of catalyst, types and amount of polymers addition and environmental conditions [3]. This factor decides the process-ability of UF resin based composite during manufacturing of plywood, particle board and fiberboard. In this review paper, various factors affecting gel time and process-ability of UF resin based wood composite are reviewed.

Silane Modification of Starch-Based Wood Adhesive: Review

Currently there has been a growing interest in substituting traditional synthetic polymers with biobased renewable polymers for adhesive applications. However, biobased renewable polymers such as starch suffer from few draw-backs like poor water resistance and mechanical strength. To become important potential alternatives of synthetic polymers, starch must have comparable physical, chemical, thermal and mechanical properties to that of synthetic polymers. To achieve this, starch has been modified by a series of crosslinkers like boric acid, citric acid, glyoxal, gluteraldehyde, etc. and silane modification. Silane modification by chloropropyl trimethoxysilane, γ-Methacryloxypropyl trimethoxy silane and vinyl trimethoxy silane is a suitable method to improve the performance in terms of mechanical and thermally. Silane forms covalent bonds with starch during starch modification resulted in enhanced shear strength and storage stability. A new research on biodegradable, renewable, environmentally friendly silane modification of starch-based wood adhesive that was prepared by reacting with various silanes. This paper, we reviewed silane as a modifying agent for starch-based wood adhesive.

Biosynthesis of Zinc Oxide Nanoparticles Using Ixora Coccinea Leaf Extract—A Green Approach

Green synthesis of metal oxide nanoparticles using plant extract is a promising alternative to traditional method of chemical synthesis. In this paper, we report the synthesis of nanostructured zinc oxide particles by biological method. Highly stable and spherical zinc oxide nanoparticles are produced by using zinc acetate and Ixora coccinea leaf extract. Formation of zinc oxide nanoparticles has been confirmed by UV-Vis absorption spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Dynamic light scattering analysis (DLS), zetapotential study and Scanning Electron Microscope with the Energy Dispersive X-ray studies (EDX). Dynamic light scattering analysis shows average particle size of 145.1 nm whereas high zeta potential value confirms the stability of formed zinc oxide nanoparticles. The Scanning Electron Microscope reveals spherical morphology of nanoparticles and Energy Dispersive X-ray analysis confirms the formation of highly pure zinc oxide nanoparticles. The zinc oxide nanoparticles from Ixora coccinea leaves are expected to have applications in biomedical, cosmetic industries, biotechnology, sensors, medical, catalysis, optical device, coatings, drug delivery and water remediation, and also may be applied for electronic and magneto-electric devices. This new eco-friendly approach of synthesis is a novel, cheap, and convenient technique suitable for large scale commercial production.

Recycling and Disposal Methods for Polyurethane Wastes: A Review

Polyurethanes (PU) are a general class of polymers prepared by the polyaddition of isocyanates and hydroxyl group containing compounds. PU foams are formed via the reaction of poly-isocyanate and multi-functional hydroxyl compounds resulting in urethane linkages. The foams are formed in wide range of densities and maybe flexible, semi-flexible or rigid in structure. To control the foam structure, blowing agents are employed. These agents are introduced during foam formation through volatilization of low-boiling liquids or through the formation of gas due to chemical reaction. Additionally, surfactants, catalysts, etc. are used during the manufacturing of foams. PU, including PU foams, is one of the most important groups of materials today and hence, their recycling has been of great interest. Many methods of recycling PU are available and many more are being studied further. However, no method has seen large scale commercialization or is brought into regular practice. The objective of this review is to bring to light the various technologies available and their current status of development as well as newer upcoming methods that may be available in the future.