Papers by Keyword: Thermoplastic Polymer

Abstract: In forming processes of thermoplastic composites, the combined forming behaviour of matrix material and fibre reinforcement determines the resulting geometry and structure. These specific characteristics of the components and their interaction vary during the processing steps, especially for the matrix material with change in temperature. During the forming step, the molten thermoplastic polymer exhibits viscoelastic behaviour. Therefore, the fibres encounter resistance if a forming load is applied. The resulting fibre alignment is dependent on the forming temperature, the forming speed, and the time between the release of load and cooling. An investigation into the specific matrix characteristics during the forming step is presented. In the experiments a representing fibre is drawn through a molten polymer specimen under variation of speed and temperature and the resistance force is measured. The experimental findings are compared to numerical results obtained with a computational fluid dynamics (CFD) package using a finite volume approach and its ability for the prediction of fibre movement in molten matrix during forming processes is evaluated. In addition, a better understanding of the impact of forming speed and temperature during forming processes due to the characteristics of the molten matrix is obtained.

Abstract: Carbon fiber reinforced polymers (CFRP), which are typical composite materials, and have been applied as light structural materials with high strength [1, 2]. The further strengthening has been always expected to develop high speed transports with small energy consumption. Although influences of electron beam (EB) irradiation with high energy on the fracture toughness of carbon cross of carbon fibers in thermo-hardened epoxy resin matrix (thermo-hardened CFRP) have been often reported [3], no one has succeeded the strengthening of CFRP irradiated by electron beam. On the other hand, the homogeneous low voltage electron beam irradiation (HLEBI) often induces not only the hardening, high wear resistance and sterilization for practical use of polymer, but also the mist resistance [4–6]. In addition, the irradiation has improved not only the bending fracture strain of carbon fiber [7, 8], but also the deformation resistivity, strength and fracture strain on static tensile test [9]. In our recent research, it has succeeded that the EB-irradiation also enhances the fracture stress and fracture strain of static bending test of thermo-hardened CFRP [10]. Furthermore, the improvement of impact value of thermo-hardened CFRP by EB-irradiation has been also reported to apply to high-speed transports [11]. However, the production rate of thermo-hardened CFRP has been serious problem in mass production.

Abstract: In recent years, advances in material testing equipment caused the determination of mechanical properties by means of three-point bending tests to lose ground in detriment to more accurate tensile tests. However, if components undergo bending deformation in service, the identification of the materials flexural behaviour is essential. The investigated material is a thermoplastic polymer, test specimens being cut in prismatic shapes from injected sheets, which present a variation in properties due to cooling conditions. This paper presents results of three-point bending tests with emphasis on the influence of strain rate and anisotropy on flexural strength and chord modulus. Results show an increase in flexural properties with strain rate and a considerable influence of anisotropy on mechanical properties.

Abstract: Contruction concrete that use of insulation wall in building construction faces some problems such as having high weight, very reflective sound, heat transfer (the effectiveness of heat conductivity) incompetence and mechanical properties (strength) constraints. The sounds which impinge the wall cannot be absorbed efficiently but instead gives high reflection. This causes some noise of high echo in a room. So a good acoustic insulation must be efficient in absorbing the sound. This project proposes lightweight concrete as a replacement for insulation wall. This lightweight concrete will be developed using thermoplastic polymer waste which is recycled plastic bottles, sand, water, and cement. This research used thermoplastic polymer waste which is PET (Polyethylene Terephthalate) material as the reinforcement material to replace small gravel in lightweight concrete. All its composition percentage of raw materials was divided into different samples composition. Its composition determines the performances of the samples in density, porosity and mechanical properties.

Abstract: Fused spinning method is the most commonly used method to manufacture man-made fiber and the most important physical property of as-spun fiber is tenacity, which is affected by process parameters including spinning nozzle temperature, cooling temperature, cooling wind speed and winding speed. First, we selected the appropriate orthogonal array for the experimental plan to conduct experiments. Coupled with signal-to-noise (SN) ratio and main effect analysis, we understood the impact of process parameters on quality and confirmed the reproducibility of the experiment, and furthermore obtained the optimal combination of process parameters.

Abstract: In the latest years, several studies were realized concerning about the application of biocidal compound in polymers or ceramics, due to the risk offered to human life by the action of pathogenic microorganisms. Many of these materials, considered special, are directed to medical area and to the food industry, for the production of food packaging. Essential oils (EOs) are aromatic liquids obtained from plant material that have bactericidal activities. One example of essential oil is Eugenol, major component of clove oil. Eugenol is the essential oil compound that better reduce the bacterial activities. This work aimed to study the processing conditions used to incorporate an antimicrobial additive in polypropylene in order to find the processing conditions in which the sample obtained have the best bactericidal properties. To evaluate the effect of the processing conditions in the bactericidal action of the compound it was used an statistical experimental factorial planning. The samples obtained underwent microbiological and physical tests to prove its antibactericidal efficiency. The preview results obtained showed significance to some of the studied variables.

Abstract: In an electrospraying process, the polymer solution interacts with the electric field. Charged polymeric solutions causing polymer liquids to move, break into drops or spray into fine droplets. Electrospraying has the ability to generate very small & uniform droplets of polymeric solution. It is envisaged that electrospraying is a promising technology to coat a polymer on surface at submicron range. The polymer aggregation is important while coating. The process parameters including applied voltage, nozzle-collector distance, solution flow rate, and solution concentration play an important role in polymer droplets aggregation on surface. This research paper investigates the effect of applied voltage on aggregation of polymer droplets.

Abstract: Electrospraying is inexpensive and an effective way to produce submicron range coating. Spray Angle and Jet Length are important characteristics that affect coating quality while polymer solution subjected to electrospraying. It was of interest to determine the effect of the process parameters on Jet Length. In this paper, an attempt was made to apply the electrospraying concept for coating textile surfaces. Series of experiments were carried out employing different settings of process parameters such as voltage, nozzle-collector distance and polymer concentration. Thermoplastic polyurethane dissolved in tetrahydrofluran was used as a solution. The results provide some insight into the effect of electrospraying process parameters on Jet Length

Abstract: This study focused on investigating the Nd:YAG laser perforation process of several common plastic films including biaxially-oriented polypropylene (BOPP), biaxially-oriented polyethylene terephthalate (BOPET) and low density polyethylene (LDPE) films. Films were perforated under various pulse energies of 50, 150 and 250 mJ and with pulse duration of ~10 ns and pulse repetition of 1 Hz. It was found that, BOPP, BOPET and LDPE films could be perforated using our developed Nd:YAG laser perforating system. Perforation width or diameters of all films increased with increasing pulse energies. Observed perforations were different among the three film types. For instance, at the pulse energy of 150 mJ, average microperforation diameters of BOPP, BOPET, and LDPE were 51.9, 57.5, and 31.0 microns, respectively. Overall results clearly demonstrated that a Nd:YAG laser perforation process used in this study was effective in developing breathable packaging films with tailored oxygen permeation property. Commercial BOPP films containing 200-1,400 micro-perforations/m2 (average perforation diameter of  50 µm) showed a significant improvement in oxygen transmission rates (OTR) of 25-700% over that of the regular BOPP. Very high OTR films of 16,000 cc/m2.day could be effectively produced for the micro-perforated BOPP, where OTR values of close to 20,000 cc/m2.day was obtainable in the case of BOPET films.

Abstract: This paper proposes an alternative ultrasonic welding technique capable of welding plastic parts with different shapes and sizes. In this method, a thin plastic sheet of less than 0.5 mm in thickness is fixed to the ultrasonic vibration body called the horn, and two plastic workpieces to be welded are pressed upon the sheet from both sides at a constant normal pressure. Once the horn starts to ultrasonically vibrate, frictional heat is momentarily generated between the sheet and the plastic workpieces, increasing the frictional temperature to a high level. When the temperature increases to over the melting point of all the materials, the materials melt and eventually are welded after the ultrasonic vibration stops. In the current work, an experimental apparatus was designed and constructed. A series of experiments was subsequently carried out on the apparatus to investigate how the surface roughness of the workpieces, the welding time, and the normal welding pressure affect the actual welding area and the tensile strength of the welded workpieces. The experimental results showed that a bigger welding area and a higher tensile strength can be obtained under the appropriate welding conditions, providing validation of the new welding method.