Papers by Keyword: Epoxy Resin

Abstract: In this paper, carbon nanotubes (CNTs) dispersion behavior in epoxy resin under synergistic effect of continuous stretching flow and ultrasound oscillation was studied. A small continuous stretching machine which could provide continuous stretching flow for polymer was designed and manufactured for studying the synergistic effect of continuous stretching flow and ultrasound oscillation on dispersive property. Firstly, the influence of different initial phase angle of dual rotor and mixing time on dispersive property were studied by preparing specimens of CNTs/epoxy resin composite under continuous stretching machine. Then, the synergistic effect of continuous stretching flow and ultrasound oscillation on dispersive property was studied with various ultrasonic power and synergistic time. In this study, the morphology of blends was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that initial phase angle of dual rotor and mixing time had great effect on the dispersion of CNTs in epoxy resin. The degree of CNTs dispersion was best when the initial phase angle of dual rotor was 0°, and increasing mixing time could improve the degree of CNTs dispersion. Increasing ultrasonic power and synergistic time were helpful to disperse CNTs in epoxy resin. It demonstrated that the synergistic effect of continuous stretching flow and ultrasound oscillation had obviously effect on the dispersion of CNTs.

Abstract: The discovery of the variation of the photoluminescence (PL) intensity of quantum dots (QDs) with mechanical deformation has stimulated the interest of developing QDs-based structures for the measurement and monitoring of stress or strain. In this work, tensile bars with the coating of QDs-epoxy composite are subjected to cyclic loading and unloading tests, and the PL intensity of the coating of QDs-epoxy composite is measured as a function of mechanical strain. There are four types of responses in the PL intensity, depending on the loading condition. Transmission electron microcopy is used to examine the rearrangement of QDs in the coatings before and after the tensile tests for understanding the change in the PL response.

Abstract: Three bis-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-phosphonamidates were successfully synthesized and well characterized. The influence of these DOPO-phosphonamidates on fire performance of epoxy resin was comparatively investigated. UL-94 tests results of various EP formulations indicated that DOPO-phosphonamidates exhibited superior fire performance. The EP composite containing extremely low loading of PiP-DOPO (0.5 wt% P) may pass the UL-94 V-0 rating, while EDA-DOPO and DDM-DOPO made the EP pass the V-1 rating. Thermal degradation results of the DOPO-phosphonamidate indicated the higher thermal stability with the initial degradation temperature over 340 °C under nitrogen. Moreover, only a very small residue was observed at 800 °C for DOPO-phosphonamidates and all EP formulations under air and nitrogen, indicating the limited condensed phase interaction. DDM-DOPO with richer aromatic structures presented the highest thermal stability and left more char residues. Large amount of gas products during the combustion of PiP-DOPO rapidly released in a short time, promoting flame inhibition, which may explain its superior flame retardant efficacy among all the DOPO-phosphonamidates investigated in this study.

Abstract: Glass waste is currently produced almost in all developed countries. It is the silicate based waste material which after suitable treatment has found application in many industries and therefore some types of waste glass belong to progressive secondary raw materials. However, the use of this silicate waste material which differ on the basis of an initial use of the glass in its physical and mechanical properties has not been fully explored in the field of building industry – the production of building materials. The replacement of the common filler – quartz sand in the polymer concrete (PC) could be one of the effective possibilities of the utilization of different type of waste glass in the building industry. Mainly for this reason, this work deals with the experimental examining the possibility of using various types of waste glass in the polymer concrete based on epoxy resin.

Abstract: Waste printed circuit board (WPCB) from waste electrical and electronic equipment (e-waste) can be recycled a precious metal part while a non-metal part was burned or landfilled, which normally generated toxic substance of organic component to environment. The research work aimed to recycle epoxy resin by hot solvent chemical extraction. Polyethylene glycol 400 (PEG400) and ethylene glycol (EG), at 180°C, were mainly using as solvent and sodium hydroxide (NaOH) as a catalyst. Extraction method was reflux technique. The thermogravimetric analysis (TGA), Specific viscosity, and Fourier transform infrared spectroscopy (FT-IR) methods were investigated and discussed. The TGA result showed that the organic composition was 40.73%wt. The maximum of percent yield was 97.89% at non-metal WPCB/PEG, equal to 0.05 g/ml. Moreover, the extracted product presented a functional group close to virgin epoxy resin according to the peak of FT-IR data. The recycled epoxy resin could be formed well on specimen by virgin epoxy resin and hardener filled with 50% recycled extraction product.

Abstract: The current tendency in electronics is the reduction of size while continuously increasing the power consumption due to new functionalities and applications. Both aspects generate a heat increment. Consequently, dissipating the heat to the environment is necessary in order to avoid component overheating. [1,2]. The most efficient way to achieve it is to allow the heat to flow from the hot component to a heat sink. In order to improve the efficiency of this process, thermal resistance between both components must be reduced which is usually done by using a thermal interface material (TIM) between both surfaces [3-5]. This material should fill the gaps created due to the microscopic roughness of both surfaces and it must have good thermal conductivity [6]. These air filled gaps result in a very high contact resistance between joined parts, as the air thermal conductivity is very low [7].

Abstract: The development of optical fibre temperature indicator using epoxy glue as a detection membrane is presented. This study, investigates the effects of epoxy glue from the reaction of epoxy resin, bisphenol A (BPA) (80-05-7) and adhesive epichlorohydrine (ECH) (106-89-8) as a temperature indicator membrane. In this work the response of epoxy glue to excitation source 395 nm is tested and analyzed under cryogenic conditions. A fiber optic temperature sensor for detecting ambient temperature ranging from 15 °C to 80 °C has been examined. The epoxy glue fluoresce when excited with UV-blue light source. The intensity of the fluorescence of the material decreases when the epoxy glue is exposed to an environment of higher temperature. These decrease level of fluorescence signal has been used to indicate temperature. In this paper, the basic principle of operation, development process and emission response characteristics of this sensor are discussed.

Abstract: In this paper issues of stress analysis of composite materials are presented. The components of composite materials and principles of composition has been discussed. Particular attention was paid to the epoxy resins and the fabrics made from carbon fibers. The article also includes basic information about strain measurements performed on with a resistance strain gauge method. For the purpose of the laboratory tests a series of carbon - epoxy composite samples were made. The main aim of the studies was to compare the results of two different research methods – laboratory and simulation method. During laboratory strain tests described in the paper, a composite samples were loaded with a specified load. Tenmex's delta type strain gauge rosettes were used to measure strain. They were arranged in specific locations on the surface of the samples. Data acquisition procedure were carried out using HBM measurement station. Numerical studies were carried out in a computing environment, Siemens NX 9.0. The results of simulation and laboratory tests were compared and presented in the form of graphs. They allow you to validate the method of laboratory measurements. The results of both research types have shown the percentage difference between them for individual loads applied to each composite.

Abstract: In this paper the results of storage modulus (E’), loss modulus (E’’) and damping parameter tan (δ)=E''/E' of epoxy resins Epidian 57 and L285 with curing agents Z1 and LH285, respectively are presented. In addition to this the stress-strain and thermal expansion characteristics of Epidian 53, 57 and L285 were obtained experimentally in order to compare Dynamic Mechanical Analysis (DMA) results. Temperature range of DMA investigations using Netzsch (Germany) DMA 242C analyzer was from-120 °C to +110 °C at the heating rate of 1 K/min with frequency of {0.1, 1, 10} Hz, respectively. Netzsch DIL 402C dilatometer was used to study the thermal expansion of the tested samples within temperature range from 30 °C to 80 °C at 1 K/min of heating and cooling rates, respectively and Huang TA computer servo control material testing machine HT-2402 was applied to determine the stress-strain characteristics. Measurements of sample elongation ΔL and physical α* were performed twice in heating and cooling cycles. The glass transition temperature T_g determined from maximum of tan (δ) curve at f = 1Hz was equal to 76.7 °C for E57 and 87.2 °C for L285. It has been observed durable deformed shape of L285 sample with deflection in the middle about 5 mm just after finishing the DMA first run of heating which significantly affected DMA results during the second run of heating

Abstract: The paper deals with the possibilities of enhancing the durability of wood bonds using the epoxy resin. These types of resin very often failed while exposing the water uptake when wood adherend swells and the bonds failed in bonding interface layer. Using the nanocellulose fibers in epoxy resin leads to higher fracture toughness while the interphase could better accommodate the large dimensional changes of the wood. That was the reason, why the different amount of nanocellulose fibers in epoxy resin were applied and the durability test of single-lap wood joints were performed. The higher percentage of cohesive failure in wood adherend and higher shear strengths after exposing the hygrothermal exposures were achieved.