Showing 8 results for Thermoplastic
Volume 4, Issue 2 (10-2020)
Abstract
Abstract
Research subject: The need to increase agricultural production in proportion to population growth and water crisis management requires initiatives that can increase the quantity and quality of crops by using soil moisture storage methods while preserving the environment. In this study, the effect of different wt. % of Thermoplastic starch (TPS) with maleic anhydride (MA) as compatibilizer and nanoclay (15A) on gel content and mechanical properties of Polylactic acid (PLA) and blends of Linear low-density polyethylene/ Low-density polyethylene (LLDPE / LDPE) was evaluated.
Research approach: Here, 0, 10, 20 and 30 wt. % TPS were added to the blends of LLDPE/LDPE (20/80) and also PLA. Independent parameters in the experimental design were wt. % of TPS, basic polymer type that was PLA or TPS and aging test. For dependent parameters were considered gel content, tensile strength, elongation at break and elastic modulus. Experiments were designed in General Full Factorial Design and performed in three replications.
Main results: Gel content in LLDPE/LDPE blends increased with the addition of TPS and decreased for PLA blends. The gel content change range for experimental samples before and after the aging test was between 10 to 21 and 2 to 5 percent, respectively. Tensile strength and elongation at break were reduced by adding TPS in both series of compounds before aging test. But this reducing rate was less in the 20 wt. % of TPS. The values of tensile strength and elongation at break were: 12 to 19 MPa and 50 to 350 percent, respectively. These values changed after the aging test between 7 and 11 MPa and from zero to 5 percent, respectively.
Keywords: biodegradability, low density polyethylene, poly lactic acid, thermoplastic starch.
Volume 14, Issue 2 (8-2014)
Abstract
In this research, microcellular thermoplastic polyurethane foams are investigated as an absorbing material in the X-band (8.2-12.4GHz) frequency range by means of numerical analysis and experiment. In the frame of this work, we aim at establishing relationships between the foams morphology including cell size and air volume fraction and their radar absorbing properties.
We therefore first describe numerical method and modelling. Then numerical analysis of microcellular foams in various cell sizes and air volume fractions are explained. Then design basis and preparation of nanocomposite foams of various morphologies using supercritical carbon dioxide (scCO2) as physical foaming agent are presented. After measuring the S-Parameters of the samples by VNA, numerical and experimental results are compared and finally we establish structure/properties relationships that are essential for further optimizations of the materials for the radar absorbing applications.
Vahid Zal, Hassan Moslemi Naeini, Ahmad Reza Bahramian, Hadi Abdollahi, Amir Hossein Behravesh,
Volume 15, Issue 11 (1-2016)
Abstract
In this paper, the effect of processing temperature on the elastic and viscoelastic properties including storage modulus, loss modulus and damping value of PVC/plain weave fiberglass composites laminates was investigated. For this, composite samples with [0/90]10 lay ups were produced in three different temperatures including 160 ᵒC, 200 ᵒC and 230 ᵒC using film stacking procedure. Firstly, the flexural strength and modulus of the samples were measured using three points bending test according to ASTM D790-07 standard. Then, viscoelastic properties of the samples were measured in the temperature range of 25 ᵒC up to 220 ᵒC using Dynamic Mechanical Thermal Analysis (DMTA) and the effect of temperature on the viscoelastic properties was studied. Also, the effect of fiber/ matrix impregnation quality on the thermal and dynamic properties of the samples was evaluated using optical microscope images. It was concluded that the temperature of 230 ᵒC is proper to achieve high quality impregnation, according to both DMTA and three points bending test. Also, it was seen that increase of processing temperature up to 230 ᵒC increases the storage modulus; however, processing temperature doesn’t affect the glass transition temperature of the samples.
Mojtaba Nadernejad, Majid Elyasi, Morteza Hosseinzadeh,
Volume 16, Issue 1 (3-2016)
Abstract
Values of tensile strength and hardness of different welding joint area has great importance. In this study a combination of welding processes include Friction Stir Welding (FSW) and ultrasonic welding has been used in butt joint for ABS type plastic sheets. Thus ultrasonic vibrations is put on FSW rotary tool, then some parameters effects such as tool rotary speed, travel speed and tool shoulder diameter on tensile strength and hardness of welded samples have been studied. With attention to parameters number and related levels to each one for doing experiments with Taguchi method L18 array has been selected. Parameters effect has been studied separately. Results showed that ultrasonic vibration putting improves tensile strength and hardness of welded joint. After ultrasonic vibration, tool rotary speed, tool shoulder diameter and travel speed were the most effective parameters on tensile strength and hardness of joint in order. Results from optimization with analysis method showed that ultrasonic vibration put rotary speed of 1200 RPM, travel speed of 60 mm/min and tool shoulder diameter of 22 mm causes the most hardness and tensile strength of joint simultaneously.
Rohollah Rostamian, Mohammad Golzar,
Volume 17, Issue 3 (5-2017)
Abstract
In the pultrusion process, continuous fibers reinforcement in roving forms are drawn through a pultrusion die. Therefore, the fibers reinforcement in the final product are generally oriented in the longitudinal axis. In this research, for manufacturing of composite rods, on the basis of previous studies and researches, the E-glass fiber-polyethylene prepregs were produced firstly. Then due to the Design of Experiments (DOE), the pultruded rods with unidirectional and helically-wound layers were produced by using the prepregs. In this study, mechanism of the pull-winding process is created as a secondary process during the main process to improve the mechanical and physical properties in the other directions. One of the most important issues in the thermoplastics pultrusions is the fibers impregnation quality with the polymer base. The fiber volume fractions of the productions are found by the burn tests. The density of the specimens is found by the liquid displacement method. The microscopic images were taken from cross-section of the pultruded rods to investigate the fiber impregnation and the void distribution. Due to the surveys conducted, the fiber volume fractions in the pultruded rods was increased, using the pull-winding technique, and also the void content of these rods was decreased.
Mohamad Hossein Mohammadipour, Mohammad Golzar,
Volume 17, Issue 6 (8-2017)
Abstract
This paper presents a numerical model for predicting pressure, impregnation and pulling force in pultrusion die which circular cross section witch two reinforcement fibrous tows pass through it. Pulling force and degree of impregnation are the most important parameters associated with pultrusion process that determine production cost and quality of pultruded profile respectively. Main idea in this approach is obtaining characteristic equations in purely polymer region and purely fibrous region and establishing relations between them by using conservation law. The superiority of this approach compared to other methods is ability to considering both straight and conical part of the die, calculating pulling force, ability of investigating influence of a variety of parameters such as those associated with die geometry, material rheology and process parameters. In this paper the influence of fibers position and fibers radius on pulling force, impregnation and pressure inside die is investigated. Due to the ability of simultaneous calculation of force and impregnation, this model can be used to establish an optimum condition between cost and quality of produced profiles.
Sattar Maleki, Atieh Andakhshideh, Mehdi Malaeen,
Volume 18, Issue 7 (11-2018)
Abstract
Dual laminate pipes made of thermoset polymer composite structure and thermoplastic liner are the only alternative in pipelines conveying high temperature corrosive fluids. Investigating the bonding between thermoset composite and thermoplastic liner is very important in these pipelines. Calculating the strain energy release rate of first mode of failure is very important criteria in bonding strength and failure of doulas pips. ASTM-D5528 is the standard for experimental test procedure of strain energy release rate of symmetric double cantilever beam. In this study, using the classical laminates theory, the general equation for determination the laminates thicknesses in unlike double cantilever beam is presented, for the first time. To study the validity of the equation, in unlike double cantilever beam samples consists of laminates with different thicknesses are manufactured for the experimental tests. Upper, lower and bonding regions consist of composite made of unidirectional fiberglass/Vinylester resin, PVCU and epoxy or Vinylester primers, respectively. The samples of this study are manufactured base on the practical case studies of chemical fluid pipelines with chlor-alkali process like Arvand Petrochemical units. The main aim of this work is to help manufacturers of these unites equipment to have practical guideline. To qualify the efficiency of the proposed equation, finite element simulation base on the virtual crack closure technique is presented. Good agreement is achieved in comparing the numerical and experimental results that shows the efficiency and accuracy of the proposed equation.
M.e. Imanian, F. Reza Biglari ,
Volume 20, Issue 3 (2-2020)
Abstract
In this study, a selective laser sintering 3D printer has been designed and built. 3D laser printing is one of the flexible additive manufacturing methods, which can use different powdered materials. Recently, additive manufacturing technologies have been introduced into the pharmacy, and in August 2015, they received FDA approval as the three-dimensional drug products. By using additive manufacturing in the pharmacy, controlled release, dosage tailored to the characteristics of individuals, the desired morphology of the drugs can be achieved and we move toward the personalization of the medicine. One of the important issues is to determine the properties of tablets before printing. In this paper, the effect of important variables of selective laser sintering on tablet breaking force is investigated with the aid of central composite design and modeling. Using the proposed modeling, the value of each variable can be determined so that the tablets are printed with the required breaking force. The cylindrical tablets with a diameter of 1.2 cm and a height of 3.6 mm were printed for use in the experiments. To fabricate tablets, the thermoplastic polymer, Kollicoat IR (75% polyvinyl alcohol and 25% polyethylene glycol copolymer), was used and 5% paracetamol (acetaminophen) was added. Also, some edible black color was added to increase the absorption of laser light. Laser feed rate, the percentage of the tablet infill density and percentage of the added color are the studied variables. According to the results obtained in the considered range, by increasing laser feed rate, tablet breaking force decreases, but tablet braking force increases by increasing infill density and amount of added color.
