Papers by Keyword: Epoxy Adhesive

Abstract: In this new world, polymer nanocomposites have developed to be one of the latest evolutionary steps in the polymer technology, besides showing a great deal to become the most versatile industrial advanced materials. In comparison with conventional composites, nanocomposites demonstrate significantly higher levels of mechanical performance with less content of particles. Thus, this study was carried out to investigate the effect of nano& micron size of clay particles to mechanical properties of epoxy adhesive. Three types of mechanical test were performed; tensile, impact and shear test. The result shows that the tensile strength was increase by using micron clay while shear and impact strength was increase by using nanoclay. The dispersion of clay in the epoxy adhesive is very important because it will affect the mechanical properties of epoxy adhesive itself. The function of clay to enhance the properties of epoxy adhesive is more effective when the clay is well dispersed. FESEM shows that the nanoclay was well dispersed in the epoxy adhesive while micron sized clay was partially intercalated.

Abstract: Epoxy adhesive used in electronic packaging could normally be cured by ultraviolet light, heat at high temperature or dual cured by both processes. Differential scanning calorimetry (DSC) has been used to identify and analyze the occurred reaction during the curing process. The structural modification of epoxy during curing could be examined by measuring its thermal properties, and the change in molecular structure of epoxy could be observed by a relative small area of DSC peak. This provided the heat amount required for complete cure. It is found that the DSC peak area after heat cure at 90 °C increased linearly as a function of heating time while that at 120 °C decreased exponentially. For UV cure, it indicated that the curing mechanism was strongly depend on the energy from UV light. For dual cure at 90 °C, the heat curing time could be reduced from single curing process of 50 minutes to 6 minutes, while the heating time for dual cure at 120 °C could be reduced from 4 minutes to 2 minutes.

Abstract: Epoxy adhesive has been widely used in microelectronic production process and the technique to determine the degree of tiny dot adhesive cure is essential to evaluate the products. In this work, micro Raman spectra were demonstrated to examine the adhesive curing at small diameter of about hundred micrometers. There are two Raman peaks that can be observed then modification during the curing process while it is bond to observe the change in the infrared absorption due to the background absorption. These two Raman peaks located at 1260 and 790 cm^-1 due to C-C breathing and C-O-C epoxide ring vibrating, respectively. It is found that the relative peak heights decrease as a function of UV exposure time. The vibration of Raman peak for heat cure were investigated for comparison the bond vibration of epoxy was also study by DFT in term of vibration rotation analysis for both close and open epoxy ring models which used to describe the vibration before and after curing processes. The open epoxide ring model shows the reducing of epoxide peak. Relative Raman peak heights are proposed to be used for determining the degree of adhesive cure. With imaging ability of micro Raman system, the mapping of curing sample can be illustrated by setting the color map with the proposed relative Raman peak height.

Abstract: The use of waste materials is one of the options for sustainable construction. In this paper the coconut shell waste is considered as coarse aggregate (after the same has been crushed) for preparing light weight concrete. The natural material like bamboo which is having considerable tensile strength is considered for reinforcement along with coconut shell concrete. Since the bamboo may absorb moisture from the concrete, to find its effect, the bamboo is treated with water repellent substance like epoxy adhesive is considered. Four types of short columns are tested. Type A Conventional concrete with steel reinforcement, Type B Coconut Shell concrete with steel reinforcement, Type C Coconut Shell concrete with treated bamboo reinforcement, Type D Coconut Shell concrete with untreated bamboo reinforcement. The conclusions drawn from the study are the load carrying capacity of Type B column is 89% of Type A column. For Type D column the ultimate load is 90% of Type C column. For Type C column the ultimate load is 70% of Type A column. For Type D column the ultimate load is 63 % of Type A column. For Type A column the stiffness is higher than the stiffness of Type B, Type C and Type D column. The energy absorption capacity of Type A, Type B columns are higher than that Type C and Type D columns. The epoxy treatment of bamboo has improved the ultimate load capacity by 1.1 times of the Type D column.

Abstract: In the present investigation, the forming behaviour of adhesive bonded sheets with the pre-generated infinite defects in the adhesive layer is studied. The infinite defects are generated with different orientations like longitudinal, transverse and at an angle of 45°. The base sheet materials used are deep drawing quality steel and SS 316L sheets, and two part epoxy adhesive is used for bonding the base sheet materials. The formability is quantified by monitoring the load-extension behaviour, and limit strain, evaluated through tensile tests and in-plane plane strain (IPPS) formability tests. It is observed that there is a significant decrease in formability because of the presence of infinite defects in the adhesive layer. While comparing the formability of adhesive bonded blanks with respect to different orientations, transversely oriented defect shows more reduction than 45° and longitudinal cases. There is not much difference between the transversely oriented and 45° oriented infinite defects in tensile tests, whereas in the IPPS formability test results, there is no considerable difference between 45° and longitudinally oriented defect.

Abstract: A method for modifying the properties of adhesives is by the addition of metallic wire strand in fibre form to improve the thermal conductivity for use in electrical applications. Clearly any advantage gained as far as thermal conductivity is concerned should not be counteracted by deficiencies in mechanical properties. In this work, the influence of copper wire reinforcements on the tensile behaviour of adhesive bonded steel sheets will be presented. The adhesive used is a two-part epoxy resin with a mix ratio of 1:1 parts by weight of resin to hardener. Wire strands used are copper wires having a diameter of 0.3 mm. The base materials are made of Stainless Steel. The stress-strain behaviour, and limit strain are evaluated through tensile tests and in-plane plane-strain (IPPS) formability tests. It is found that the ductility and limit strain of adhesive bonded sheets with wire reinforcement are better than that of the case without reinforcement. The ductility and limit strain of wire reinforced adhesive bonded sheets increases till three wires in the case of tensile tests, and four wires in the case of IPPS formability tests, after which it decreases.

Abstract: The paper deals with the evaluation of epoxy adhesive modification by silane coupling agent used for gluing process of spruce wood. Moreover, the usage of primer containing the silane coupling agent was performed to find out, whether better compatibility between spruce wood and epoxy adhesive at the interface bondline can ensure sufficient resistance to delamination process. As the main criterion, tensile shear strength properties of glued specimens in different thermal and moisture exposures were carried out.

Abstract: This paper presents a systematic investigation of the influence of sandblasting pretreatment parameters on the surface roughness and mechanical characteristics of adhesive-bonded joints. The preliminary surface treatment in a bonding process has two important aims: first of all, it eliminates contaminants (dust, grease, humidity and corrosion products) which can modify the wettability of the substrate, then it increases surface roughness and, consequently, the contact area between substrate and adhesive, creating a mechanical interlocking that maximizes adhesion. To enhance the strength and avoid the de-adhesive failure of the joint, it is therefore advisable to increase the contact substrate-adhesive by a mechanical treatment of sanding, grinding or preferably sandblasting, usually considered one of the most effective methods to control the desired level of surface roughness and joint strength. This process, apparently easy to manage, is controlled by a great number of operating parameters, which all contribute to creating a good result. With the aim of evaluating the influence that some of these parameters have on the mechanical characteristics of adhesive-bonded joints, an experimental campaign was carried out. In particular, a steel substrate, an epoxy adhesive and various types of sand, different in nature and granulometry were used. The variable parameters for the execution of blasting are sand, impact angle and pressure. The assessments departed from an investigation into their effect on surface roughness and thereafter the mechanical properties of the bonded joints were analyzed.

Abstract: The behavior of two types of modifications to glued joints utilizing epoxy resin-based adhesive was examined in a manner specified by the EN 302 standard using adherent beech wood specimens. The investigation was focused on the improvement of glued joint strength and adhesive properties. The first type of modification involved reinforcement of the epoxy-based adhesive with scattered polypropylene fibers with the aim of enhancing the tensile shear strength of the assembly. The other type of glued joint modification was the electrical discharge plasma treatment of the adherend surface. This technique for treating the surfaces of materials enables the greater spreading of liquids due to the increase in surface wettability it provides. Relevant characteristics of the test specimen – tensile shear strength and wood failure - were tested in order to analyze the behavior of the thus-modified epoxy-based adhesive-glued joints.

Abstract: The rheological mechanical properties of two kinds of self-designed epoxy adhesive curing systems were studied in this paper through the dynamic and static thermodynamics instrument named EPLEXOR 500N made by GABO® company in Germany. Short-term creep tests were carried out under three different temperature conditions of 20°C, 30°C and 40°C and the rheological model is developed to describe the materials creep law. In addition, the test results from the two different epoxy adhesive are also compared and analyzed.