Crack-Bridging Property Evaluation of Synthetic Polymerized Rubber Gel (SPRG) through Yield Stress Parameter Identification

Yield stress parameter derivation was conducted by stress-strain curve analysis on four types of grout injection leakage repair materials (GILRM); acrylic, epoxy, urethane and SPRG grouts. Comparative stress-strain curve analysis results showed that while the yield stress point was clearly distinguishable, the strain ratio of SPRG reached up to 664% (13 mm) before material cohesive failure. A secondary experimental result comprised of three different common component ratios of SPRG was conducted to derive and propose an averaged yield stress curve graph, and the results of the yield stress point (180% strain ratio) were set as the basis for repeated stress-strain curve analysis of SPRGs of up to 15 mm displacement conditions. Results showed that SPRG yield stress point remained constant despite repeated cohesive failure, and the modulus of toughness was calculated to be on average 53.1, 180.7, and 271.4 N/mm2, respectively, for the SPRG types. The experimental results of this study demonstrated that it is possible to determine the property limits of conventional GILRM (acrylic, epoxy and urethane grout injection materials) based on yield stress. The study concludes with a proposal on potential application of GILRM toughness by finite element analysis method whereby strain of the material can be derived by hydrostatic pressure. Comparative analysis showed that the toughness of SPRG materials tested in this study are all able to withstand hydrostatic pressure range common to underground structures (0.2 N/mm2). It is expected that the evaluation method and model proposed in this study will be beneficial in assessing other GILRM materials based on their toughness values.

Study on Microstructure and Properties of the UV Curing Acrylic Epoxy/SiO2 Nanocomposite Coating

This study is aimed at exploring the effects of SiO2 nanoparticles on the crosslinking and mechanical and thermal properties of UV curing acrylic epoxy coating. The curing polymerization process and thermal and mechanical properties of UV-curable acrylate epoxy system have been evaluated with or without the presence of SiO2 nanoparticles. To fabricate the UV curing acrylic epoxy/SiO2 nanocomposite coating, nano-SiO2 particles (0.5–5 wt.% by weight of resin) were added in the photo-curable system using sonication for 3 h. Various techniques for characterization have been used, such as FESEM (field emission scanning electron microscope), FTIR (Fourier-transform infrared spectroscopy), TGA (thermogravimetry analysis), gel fraction, and swelling degree analyses. FESEM data indicated that at the content of 2.5 wt.%, nanosilica was homogeneously dispersed in the coating procedure. However, once added 5 wt.%, large aggregation portions were found inside the coating matrices. Surprisingly, nano-SiO2 could play dual roles, as both UV absorbers and nanoreinforcers, in this nanocomposite coating. Besides, data from FTIR, gel fraction, and swelling degree analyses confirmed the role of SiO2 nanoparticles as UV absorbers that reduced the conversion performance of acrylate double bonds, thus increased slightly the swelling degree of coating. In addition, incorporation of SiO2 nanoparticles (as nanofillers, at content of 2.5 wt.%) in the polymer matrix enhanced significantly the abrasion resistance and thermal stability of the coating, by 60% (from 98.3 to 158.4 lite/mil) and 9°C (from 348°C to 357°C), respectively.

Implications of Interfacial Energetics on the Tack/Debonding of Single and Hybrid Pressure Sensitive Adhesives

This paper present the implications of interfacial energetics on the tack/debonding of pressure-sensitive adhesives (PSA). The materials used include acrylic, pvc-abro, polyurethane and epoxy by single and hybrid combinations. Mild steel plate of 130mm x 130mm with 1.2mm thickness was used as a substrate. The contact angle was measured on surfaces of PSA and the substrate using OWK and Wu models. The force required to debond the PSA from the substrate (the tack) was measured with a universal testing machine. The results gave the maximum deflections as 4.9074 x10-4 N/mm2 and tack as 3.35769 x10-5 N/m for single PSA of Epoxy are higher than those for Acrylic, Pvc-Abro and Polyurethane PSAs materials. However, with Acrylic/Epoxy and Epoxy/ Pvc Abro hybrids, higher tack forces of 3 x10-5 mJ and 2.725 x 10-5mJ with corresponding higher values of 2.28225 x10-4N/mm2 and 1.61243 x10-4N/mm2 maximum deflections were obtained. These results showed that epoxy is better from tack force. The results clearly show that all the properties – surface free energy, work of adhesion, and tack are higher for hybrid PSA than for the single PSAs ranging from 1.5% to up to 80% difference. It was observed that as the angle of contact increased, the work of adhesion and cohesion increased. The results of this work can find application in dentistry in dentin/adhesive interface and hybridization of dental hard tissues with modified adhesive systems. Applications can also be found in carpentry, in polymer composites for automobile bodies and ceramics.

Corrosion Resistance of Waterborne Epoxy Resin Coating Cross-Linked by Modified Tetrabutyl Titanate

The development of waterborne coating is essentially important for environmental protection, and cross-linking agent is of great significance for ensuring corrosion resistance of the coating. In this work, tetrabutyl titanate was modified by ethylene glycol and tris(2-hydroxyethyl) amine and used for the solidification of waterborne acrylic-epoxy resin. Fourier-transform infrared spectroscopy (FTIR) analysis revealed that the agent reacted with OH groups first to cross-link the resin preliminarily, and then, when the amount of agent was further increased, the amino groups opened epoxide rings resulting in a secondary cross-link. Field emission scanning electron microscope (FESEM) observation and electrochemical impedance spectroscopy (EIS) test found that, when the cross-linking agent was used at 6%, the coating remains intact and kept an impedance of as high as 108Ωcm2 even after being immersed in NaCl solution for 30 days. Copper-accelerated acetic acid-salt spray (CASS) test confirmed that the coating containing 6% cross-linking agent provided the best protection for the carbon steel substrate.

Flexural Behaviour of Timber Glass Composite Beams using Various Adhesives

This paper mainly deals with providing a clear understanding of the bonding nature of various adhesives as a structural connection in timber glass composite beams and investigates the flexural behaviour of the same. This paper depicts the clear idea of the critical factors to be considered for the application of adhesives as a structural connection in timber glass composite beams. The timber glass composite beams will be a significant alternative for the conventional beams, which are currently used in the beams in temporary structures. Apart from being a significant replacement for the conventional beams, the glass web portion permits the light to pass through it. Thus, the artificial light energy required inside the structure will be reduced. This makes the composite beams to be energy efficient structural component in the temporary structures. In this research, the flexural behaviour of the composite beams made using various adhesives such as Acrylic, Epoxy and Silicone were studied. The result shows that epoxy adhesive connection behaves much better when compared with silicone and acrylic adhesives.

Preparation and artificial ageing tests in stone conservation of fluorosilicone vinyl acetate/acrylic/epoxy polymers

In this work, a series of fluorosilicone vinyl acetate/acrylic/epoxy (FVAE) polymers for protection of stone relics were prepared with different content of hexafluorobutyl methacrylate (HFBMA) by the seed emulsion polymerization process. Properties and structure of FVAE materials were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and transmission electron microscopy (TEM). Viscosity, particle size, surface tension, gel content, adhesion and surface hardness of polymer materials were also determined. Surface morphology of the stone sample was observed by scanning electron microscopy (SEM). Compared with a commercial copolymer, ethyl methacrylate/methyl acrylate (EM/MA, Paraloid B72), protection ability of the prepared FVAE polymer was investigated using artificial ageing tests such as the freeze-thaw aging test, acid aging test and the soluble salts aging test. It was found that the FVAE polymers prepared can effectively prevent corrosion caused by H

Investigation of the Thermal and Optical Properties of Photopolymerizable Resin Enforced by Nanopowder in the Green Production Process

This study is to explore the mixture of the different amounts of nanopowders with different photopolymerizable monomer, polyfunctional monomer and acrylic epoxy resin to prepare novelty nanocomposite materials in green production process. The preparation of nanopowder enforced photopolymerizable resin substrate adopted green production process without solvent that its chemical properties, such asreaction rate, the effect of irradiation dose and operation time, can be controlled in the green production process to solve the underlying issues in applications. The thermal decomposition temperature, thermal expansion, the temperature of glass transition point and transmittance of the material can be measured by various testing methods. The results showed that the thermal decomposition temperature Td had a maximum increase of 17.18 °C. While the powder dosage was 3wt.%. The α1 has a minimum value, which is 29.21% decrease than the original one, from TMA. These were concluded that a material with an appropriate amount of nanopowder can enhance the performanceof the photopolymerizable substrates to the preparation of novelty materials in green production process.