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91.
Ş. Temiz S. Akpinar M.D. Aydın E. Sancaktar 《Journal of Adhesion Science and Technology》2013,27(3):244-251
Single-lap joint (SLJ) geometry is the most widely used type of adhesive joint geometry. In this joint, peel stresses occur at the overlap ends due to load eccentricity and the presence of shear-free adhesive termination surfaces. These peel stresses, along with the transverse tensile stresses which occur along the overlap longitudinal axes, and adhesive shear stresses, ultimately cause joint failure. Obviously, reductions in these stresses should result in higher joint strength and increased load capacity. To this end, we exploited elastic spring-back capability of (steel) metal adherends by initially forming curved segments of varying arc lengths and radii at overlap ends. These adherends with curved-end sections were then bonded in single-lap configuration, simply by applying sufficient bonding pressure to elastically flatten the curved segments to result in typically flat overlap sections subsequent to adhesive cure and the removal of bonding pressure. Since the elastic adherend overlap ends tend to revert back to their initial curved form, they exert compressive residual stresses on the adhesive layer in the overlap end regions. We determined that the compressive residual stresses induced in this fashion considerably increased the load capacity of SLJs subjected to tension. 相似文献
92.
Two copolyimides, LARC-STPI and STPI-LARC-2, with flexible backbones were prepared and characterized as adhesives. The processability and adhesive properties were compared to those of a commercially available form of LARC-TPI.
Lap shear specimens were fabricated using adhesive tape prepared from each of the three polymers. Lap shear tests were performed at room temperature, 177°C, and 204°C before and after exposure to water-boil and to thermal aging at 204°C for up to 1000 hours.
The three adhesive systems possess exceptional lap shear strengths at room temperature and elevated temperatures both before and after thermal exposure. LARC-STPI, because of its high glass transition temperature provided high lap shear strengths up to 260°C. After water-boil, LARC-TPI exhibited the highest lap shear strengths at room temperature and 177°C, whereas the LARC-STPI retained a higher percentage of its original strength when tested at 204°C [68% versus 50% (STPI-LARC-2) and 40% (LARC-TPI)].
These flexible thermoplastic copolyimides show considerable potential as adhesives based on this study and because of the ease of preparation with low cost, commercially available materials. 相似文献
Lap shear specimens were fabricated using adhesive tape prepared from each of the three polymers. Lap shear tests were performed at room temperature, 177°C, and 204°C before and after exposure to water-boil and to thermal aging at 204°C for up to 1000 hours.
The three adhesive systems possess exceptional lap shear strengths at room temperature and elevated temperatures both before and after thermal exposure. LARC-STPI, because of its high glass transition temperature provided high lap shear strengths up to 260°C. After water-boil, LARC-TPI exhibited the highest lap shear strengths at room temperature and 177°C, whereas the LARC-STPI retained a higher percentage of its original strength when tested at 204°C [68% versus 50% (STPI-LARC-2) and 40% (LARC-TPI)].
These flexible thermoplastic copolyimides show considerable potential as adhesives based on this study and because of the ease of preparation with low cost, commercially available materials. 相似文献
93.
Numerical simulation study of the T‐peel behavior of coated fabric films used in inflatable structures 下载免费PDF全文
A simple and reliable finite element method was developed to analyze the T‐peel behavior of fabric coated with thin films. The material model was constructed simply by a tensile test of the coating and the coated fabric. In addition, the influence of the welding parameters on the mechanical properties of the welded zone was considered. Although some material characters were neglected, the material model was found to be convenient for engineering applications. The reliability was examined by a comparison of the numerical results with the experiments. A T‐peel test was conducted, and a camera configured with an optical microscope lens was used to observe the material flow from the thickness view. The load–displacement curve predicted by the simulation agreed well with the experimental results. Small voids were detected when the sample was near fracture. These places were consistent with the simulation results and showed where the maximum stress–strain was located. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41299. 相似文献
94.
Modified poly (vinyl acetate) copolymers with epoxidized linseed oil (ELO) as co‐monomer have been prepared. The polymerization was performed in aqueous medium without any additional protective colloid in the presence of sodium persulfate as catalyst. The effect of vinyl acetate (VAc)/ELO feed ratio, reaction temperature, reaction time, and catalyst amount has been studied. FTIR spectroscopy showed that the reaction between ELO and VAc resulted in slight decrease and shift in ELO characteristic bands of oxirane groups; and new bands were detected in the copolymer spectra attributed to PVAc and ELO functional groups. Moreover, new signals attributable to the copolymer were observed in the 1H NMR spectra (δ 4.07 and 1.62 ppm) and in the 13C NMR spectra (δ 15.29 and 31.0 ppm). Analysis by differential scanning calorimetry (DSC) showed a single Tg for the copolymerization product of VAc and ELO and two Tg for the PVAc/ELO blend, indicating the chemical reaction between VAc and ELO. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42089. 相似文献
95.
Flexible /PET/batio3/ layer–layer composite film with enhanced dielectric properties fabricated by highly loaded /batio3/ coating with acrylic resin as binder 下载免费PDF全文
Flexible layer–layer poly(ethylene phthalate) (PET)/BaTiO3 composite films with enhanced dielectric permittivity were fabricated by spin coating method, consisting of PET substrate film layer and modified BaTiO3/acrylic resin hybrid coating layer. The thickness of coating layer was less than 3 μm (about 2% of PET film thickness), and therefore, the PET/barium titanate (BT) composite films remained flexible even at high volume fraction of BaTiO3 fillers. The volume contents of BaTiO3 were varied from 0 to 80%, and the solid contents of BaTiO3/acrylic resin were in the range of 51.8–72.9%. Scanning electron microscopy showed strong interaction of finely dispersed BaTiO3 particles with acrylic resin. Morphological profile also displayed uniform coating layer of modified BaTiO3/acrylic resin and its strong adhesion with PET film. The dielectric constant of the PET/BaTiO3 composite films increased by about 26% at 60 vol % BaTiO3 loading when compared with the pristine PET film, whereas the dielectric loss decreased slightly. In addition, PET‐grafted poly(hydroxylethyl methacrylate) brushes were used as substrate to introduce covalent bonding with the coating layer. Further enhancement of dielectric constant and reduction of dielectric loss were realized when compared with the composite films with bare PET substrate. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42508. 相似文献
96.
对比了乳胶浆与溶剂胶浆的优缺点,并肯定了乳胶浆在胶鞋制造中的实用价值.给出了各种助剂分类、功能及配方示例.还讨论了这一领域的最近发展. 相似文献
97.
98.
Jae‐Ho Kim Ho‐Gyum Kim Jeoung‐Cheol Lim Kwang‐Soo Cho Kyung‐Eun Min 《应用聚合物科学杂志》2012,124(4):3312-3319
The thermal stability and adhesion properties, such as lap‐shear strength of hot‐melt adhesives were obtained from amorphous poly(α‐olefins) and thermoplastic rubber [styrene–ethylene–butylene copolymer (SEBS)] blends. The addition of SEBS increased the toughness and viscosity and decreased the lap‐shear strength of the hot‐melt adhesive. Terpene tackifier resin offered enhanced lap‐shear strength; this was more effective when combined tackifier resin was added on the hot‐melt adhesive. Only a small amount of wax and antioxidant affected the thermal stability and lap‐shear strength of the hot‐melt adhesive. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
99.
E. A. S. Marques R. D. S. G. Campilho Lucas F. M. da Silva 《Journal of Adhesion Science and Technology》2016,30(7):691-707
The use of adhesives for high-performance structural applications has significantly increased in the last decades. However, the use of adhesive joints in adverse environmental conditions is still limited due to the reduced capability of adhesives to withstand large thermal gradients. Dual adhesive joints, which contain two adhesives with remarkably different mechanical behaviours, are a technique suitable for being used in extreme temperatures. The object of this study is a ceramic–metal joint, representative of the thermal protection systems of some aerospace vehicles. In this paper, several joint-mixed joint geometries are presented, studied with recourse to finite element analysis. In a first phase, the three-dimensional finite element models and the material properties are validated against experimental data. In a second phase, the model geometry is modified, with the aim of understanding the effect of several changes in the joints’ mechanical behaviour and comparing the merits of each geometry. The models’ presented good agreement was found between experimental and numerical data and the alternative geometries allowed the introduction of additional flexibility on the joint but at the cost of lower failure load. 相似文献
100.
着重介绍了扬声器用胶过程控制的有关问题,其中说明了使用胶粘剂的种类和部位,讨论了扬声器用胶在实际过程中,如何进行过程控制的问题。 相似文献