Adhesion Properties of Adhesive Prepared from Waste Polystyrene

Solid and soft forms of waste polystyrene have been treated with coumarone–indene resin and benzene to produce a new adhesive. The adhesive is prepared from various compositions of polystyrene (13–38 wt%), coumarone-indene resin (5–7%) and benzene (57–80%). Viscosity, peel strength and tensile shear strength of the adhesive is determined by a HAAKE Rotary Viscometer, Lloyd Adhesion Tester and Instron machine, respectively. Rolling ball technique was used to measure the tackiness of the adhesive. Results show that the adhesion property increases with increase in polystyrene composition and coating thickness. This observation is attributed to the increasing wettability of adhesive on the substrate.     

Water-Soluble Pressure-Sensitive Adhesives Containing Carboxymethyl Starch with Improved Adhesion to Paper

Water-soluble pressure-sensitive adhesives (PSA) based on acrylic acid and carboxymethyl starch (CMS) have been prepared. The tack and peel adhesion to various paper types (newsprint, hygienic, packing, fax and art paper) as well as dynamic shear adhesion at higher temperatures (70–240?°C) have been tested with the aim of applying such PSA in a form of double-sided splicing tapes for paper industry. For all paper types tested tack and peel adhesion values increased with CMS content (0.1–10 wt% in PSA). The highest tack and peel adhesion values (for the system containing 10 wt% CMS) were noted for fax paper ca. 19.5 N/2.5 cm and 18.3 N/2.5 cm, respectively and the lowest ones for art paper: 14.7 N/2.5 cm and 13.5 N/2.5 cm, respectively. Obtained PSA were completely soluble in water, and the time of water-solubility depended on CMS content, as well as pH value, however it did not exceed 5 min.     

Enhanced Interfacial Adhesion and Characterisation of Recycled Natural Fibre-Filled Biodegradable Green Composites

The structural, thermal, mechanical, and biodegradable properties of composite materials made from polylactide (PLA) and agricultural residues (arrowroot (Maranta arundinacea) fibre, AF) were evaluated. Melt blended glycidyl methacrylate-grafted polylactide (PLA-g-GMA) and coupling agent-treated arrowroot fibre (TAF) formed the PLA-g-GMA/TAF composite, which had better properties than the PLA/AF composite. The water resistance of the PLA-g-GMA/TAF composite was greater than that of the PLA/AF composite; the release of PLA in water from the PLA/AF and PLA-g-GMA/TAF composites indicated good biological activity. The PLA-g-GMA/TAF material had better mechanical properties than PLA/AF. This behaviour was attributed to better compatibility between the grafted polymer and TAF. The results indicated that the T_g of PLA was increased by the addition of fibre, which may have improved the heat resistance of PLA. Furthermore, the mass losses following burial in soil compost indicated that both materials were biodegradable, especially at high levels of AF or TAF substitution.     

Effect of Hybrid Tackifiers on Adhesion Properties of Epoxidized Natural Rubber-Based Pressure-Sensitive Adhesives

Viscosity, peel and shear strength of epoxidized natural rubber (ENR)-based pressure-sensitive adhesive was studied by using hybrid tackifiers consisting of a mixture of coumarone-indene resin and petro resin. The coumarone-indene resin concentration was fixed at 40 parts per hundred parts of rubber (phr). The concentration of petro resin, however, was varied from 20 to 80 phr. Toluene and polyethylene terephthalate (PET) film were used as the solvent and coating substrate respectively throughout the experiment. Viscosity of adhesive was determined by a HAAKE Rotary Viscometer whereas peel and shear strength was measured by a Lloyd Adhesion Tester. Results show that viscosity and shear strength decreases with increasing petro resin concentration. However, peel strength exhibits a maximum value at 40 phr petro resin, an observation which is attributed to maximum wettability and compatibility of adhesive on the substrate. ENR 25-based adhesive exhibits higher viscosity and peel strength but lower shear strength compared to the ENR 50 adhesive system.     

Effects of Sodium Bisulfite on the Physicochemical and Adhesion Properties of Canola Protein Fractions

This study focused on investigating the potential of using canola protein fractions as bio-degradable wood adhesives. Native and sodium bisulfite (NaHSO₃)-modified canola protein fractions isolated successively at different pH values (7.0, 5.5, and 3.5) was used as adhesives. Wood specimens were assembled with adhesives at a pressure of 2?MPa at 150, 170, or 190?°C for 10?min. The adhesion performance of adhesives were evaluated by wet, soak, and dry shear strength. Their physicochemical properties: extractability, electrophoresis profiles, thermal, rheological and morphological properties were also characterized. Results showed that canola protein had the highest protein yield and purity at pH 5.5. Electrophoresis profile proved that NaHSO₃ cleaved the disulfide bonds in canola protein. This could induce extra charges (RS-SO₃ ^?) on the protein surface, leading to the reduced apparent viscosity. Thermal analysis implied that the thermal transition temperature of canola protein decreased with modification of NaHSO₃. Canola protein adhesives showed excellent dry and soak shear strength with 100?% wood cohesive failure in all curing temperatures. The wet adhesion strength of native and modified canola protein fraction adhesives at pH 5.5 and pH 3.5 (3.9?C4.1?MPa) was higher than the fractions at pH 7.0. NaHSO₃ had insignificant effects on the adhesion performance of canola protein adhesives but notably improved the handling and flow-ability properties of canola protein adhesives.     

Self-Bonding Boards From Plantain Fiber Bundles After Enzymatic Treatment: Adhesion Improvement of Lignocellulosic Products by Enzymatic Pre-Treatment

Self-bonding boards were manufactured with treated fibers at different concentrations of a laccase enzyme. This enzyme induced the generation of phenoxy radicals in the fiber lignin which can generate covalent bonds and cross-linked by radical–radical coupling. The effect of laccase concentration on the properties of obtained fiberboards was evaluated. The formation of free radicals and changes in the lignin macromolecule was measured using scavenging activity test, infrared spectroscopy, electron paramagnetic resonance and scanning electron microscopy. Thermal and mechanical properties of the resulting fiberboards were determined by differential scanning calorimetry, thermo gravimetric analysis and flexion tests. Increased thermal stability, modulus of elasticity and modulus of rupture and also, a reduction in thickness swelling and water absorption, were observed at higher concentrations of laccase. These results are ascribed to the effect of the free radicals that were generated during the enzymatic treatment.     

Material Properties and Influence of Molecular Weight and Testing Rate on Adhesion Properties of Epoxidized Natural Rubber-Based Adhesives

The effect of molecular weight and testing rate on peel and shear strength of epoxidized natural rubber (ENR-50)-based adhesive was investigated using petro resin as the tackifier. Toluene and polyethylene terephthalate were used as the solvent and substrate respectively. Peel and shear strength were determined by a Llyod Adhesion Tester operating at different rates of testing. Result shows that peel strength and shear strength increases up to an optimum molecular weight of 4.2 × 10⁴ g/mol of ENR-50. This observation is attributed to the combined effects of wettability and mechanical strength of rubber for peel strength. For shear strength, it is ascribed to the optimum cohesive and adhesive strength. Both peel strength and shear strength increases with increasing rate of testing, an observation which is associated to the viscoeslastic response of the adhesive. Thermal study, SEM and FTIR study confirms the miscibility of tackifier with ENR-50.     

Effect of Matrix–Particle Interfacial Adhesion on the Mechanical Properties of Poly(lactic acid)/Wood-Flour Micro-Composites

The influence of interfacial matrix/particle adhesion on the mechanical properties of poly(lactic acid) (PLA) micro-composites was investigated. The tensile strength of PLA/wood-flour micro-composites is almost independent of wood-flour content, suggesting only weak adhesion exists between the PLA matrix and the wood-flour particles. The addition of wood-flour resulted in an increase of up to 95% in the tensile modulus, in comparison with pure PLA, which showed a more resilient matrix. The addition of a coupling agent, methylenediphenyl-diisocyanate (MDI) to the composition resulted in an increase in tensile strength and tensile modulus of the micro-composites, of 10 and 135%, respectively, indicating enhanced matrix–particle interfacial adhesion. SEM and electron probe microanalysis provided evidence of improved interfacial adhesion between PLA and wood-flour particles from the addition of MDI. In contrast, addition of PEAA resulted in a micro-composite displaying substantially reduced tensile strength, up to 35% and a slightly increased in impact strength, up to 15%, consistent with the introduction of the rubbery PEAA component into the polymeric matrix. No evidence for increased matrix–particle adhesion was found for the PLA/wood-flour micro-composites containing PEAA.     

The Use of Interfacial Blend to Increase the Adhesion Properties of Natural Rubber/Polyvinylalcohol Multilayer Using Electron Beam Irradiation

Multilayers of natural rubber (NR) and polyvinylalcohol (PVA) were processed by casting natural rubber latex (NRL) then PVA with varying layer thickness. Adhesion between NR and PVA was found to be very poor, as determined with the peel method. The films of interfacial blend were composed of NRL and PVA having different ratios as a layer between NR/PVA layer, possessing good adhesion and exhibited one mechanical phase in tensile-elongation at break tests. The result of adhesion was confirmed by thermogravimetric analysis and scanning electron microscopy study. Also, adhesion was too strong for delamination at the interface when the unit of three layers NR/blend/PVA was irradiated at 25 kGy. To probe the effect of the adhesion difference on mechanical behavior and deformation of NR/blend/PVA layers at dry and wet conditions, the peel strength was examined as a function of layer thickness and aging time. The results indicated that the interfacial blend, irradiation process and film thickness were the key parameters affecting adhesion of NR/PVA layer.     

Investigation of Synthesis of Copolymers from the Waste Products of Industrial Oil Refinement having Adhesion Properties and Strength to the Thermal Destruction

In this study, the waste products of industrial vegetable oil refinement were transformed into the glycidyl ester for preventing the effects of them to the environment, the ways for evaluating them in polymer chemistry were investigated, copolymers having high adhesion property and strength to the thermal destruction were synthesized and the area of their usage was determined. For this reason, the waste product of sunflower oil refination as a vegetable oil in the industry; soap stock (SS) was converted to the unsaturated glycidyl esters by the interaction with epichlorohidrine in the alkaline medium. After that the copolymerization of synthesized unsaturated glycidyl esters and the other waste product of oil refinement fatty acid (FA) with styrene in the radicalic initiator medium were investigated and copolymers that have high strength to the thermal destruction and adhesion property were synthesized. From the results of TGA and DTA analysis, it was determined that synthesized copolymers have low loss of weight at high temperature. The structures of copolymers were fixed by spectral and chemical analysis methods.     

Effect of Magnesium Oxide Loading on Adhesion Properties of ENR 25/NBR Blend Adhesives in the Presence of Petro Resin and Gum Rosin Tackifiers

The adhesion properties of magnesium oxide filled epoxidized natural rubber (ENR 25)/acrylonitrile-butadiene rubber (NBR) blend adhesives were studied using petro resin and gum rosin as tackifiers. Toluene was used as the solvent throughout the experiment. Five different loadings, i.e. 10, 20, 30, 40 and 50 phr magnesium oxide was used in the adhesive formulation. The SHEEN hand coater was used to coat the adhesive on polyethylene terephthalate at 30 and 120 µm coating thickness. The tack, peel strength and shear strength were determined by a Lloyd adhesion tester operating at 30 cm min^?1. Results shows that all the adhesion properties of the ENR 25/NBR adhesives show a maximum value at 10 phr filler loading. Loop tack and peel strength pass through a maximum, an observation which is associated to the optimum wettability of adhesive on the substrate. For the shear test, maximum shear strength occurs due to the optimum cohesive strength of the adhesive. Results also show that all petro resin based adhesives have higher adhesion properties than gum rosin based adhesive. In all cases, the adhesion properties of adhesives also increase with increasing coating thickness.