Papers by Keyword: Plastic

Abstract: In this paper, the lightweight concrete made from polystyrene and ethylene vinyl acetate (EVA) waste was studied. EVA waste from footwear industry and waste polystyrene were used as an aggregate in the lightweight concrete. Each of the plastic wastes was used alone (as a sole aggregate) or in combination with the other in a ratio of 1:3, 1:1 and 3:1. The water-cement ratio of 0.50 and the dose of cement – 175 kg·m^-3 were used for all mixtures. Test results showed that the bulk density and the thermal conductivity of lightweight concrete tended to increase with increasing EVA waste content. The maximum compressive strength of lightweight concrete was reached with the waste materials in a ratio of 1:1. Based on the results, the application of EVA waste as lightweight filler showed a good possibility for use in the lightweight concrete.

Abstract: Rotational molding is a manufacturing method which supposes the rotation of the mold, during the solidification of the liquid phase material, so that finally a part having a hollow could be obtained. The method could be applied in manufacturing of metallic and nonmetallic parts. Usually, the equipment for rotational molding ensures slow speed rotating of the mold around two axes placed perpendicularly each other and this fact led to relatively complex equipment for achieving rotational molding. The capacity of the liquid material to entirely cover the internal walls of the mold depends essentially on the liquid material viscosity, on the rotation speed and on the movements applied to the mold. Simplified equipment including a single rotation movement could be materialized. In order to test such a solution, a preliminary experiment was designed and materialized, by using a device adapted on universal lathe. Thus, the objective of the research presented in the paper was to study if it is possible to achieve plastic parts made by rotational molding using a single rotation movement. A polyurethane resin obtained from two liquid components was used in order to obtain the liquid material that could be introduced in the mold. The research results proved the possibility to use simplified equipment for achieving a rotational molding process, at least in certain cases and with some technological limits.

Abstract: Low-pressure steam turbine parts are generally exposed to lowest steam parameters only and it could seem that they should not be susceptible to permanent deformation. However, this assumption is incorrect and permanent changes in geometry become visible in low-pressure turbine casings when they are disassembled after the first time in operation. The driving mechanism of the plastic deformation of the low-pressure casings is mainly the non-uniform temperature field. This paper deals with results obtained from a numerical FEM simulation of a steam turbine low pressure part, which includes elastic-plastic behavior of the material, and results measured under the real conditions.

Abstract: One attempt to utilize low grade iron ores involved the oxygen reduction by carbon monoxide. Carbon monoxide commonly produced from the carboneous materials such as coal but using coal as a reductant may harm the environments. On the other hand, plastic wastes or polyethilene have large potential as reductants for iron ores because their major elements are hydrogen and carbon. If these wastes could be effectively used in the iron-making process, the total CO₂ emissions caused by coal would decrease because a significant amount of plastic wastes is still simply incinerated without effective heat. Furthermore, the problems of polyethylene as a waste to the environments also can be eliminated. The aim of this research is to obtain sponge iron which has metallization more than 80 percent by using a mixture of coal and polyethilene as a reducing agent. The research variables are the compositions of reductant (3,5; 7,4; 10; 15 percent), temperature (900, 1100, and 1200°C), and times of the reduction (30, 60, 120, and 240 minutes). The result of the experiment shows that the most higher metalization is 80.22 percent reached by the temperature reduction 1200°C and time of reduction is 240 minutes. The experiment also shown that the used of 15 % HDPE giving maximum metalization for 86.79 percent. Although for 15 % LLDPE poliethilene giving maximum metalization for 81.31 percent.

Abstract: This article contains information about creating special unit for scanning 3D objects. The main part of the unit is ultrasonic transducer, which is sends the sound wave to the object and receive back wave for calculating distance. After that, microcontroller send to PC data, and computer program create model for printing from the plastic etc.

Abstract: The article deals with the basic technological aspects of injection moulding, pointing to the importance of correct product geometry design. Large differences in the wall thickness of the mould result in uneven cooling, material shrinkage, and the formation of internal stress. This ultimately may give rise to deformations, such as those in form sink marks, and may affect the required quality of the mould. The article describes the application of a specific example of one of the ways of correction of the mould wall thickness used in technological practice of the injection moulding technology. This is a case of employing the method of the so-called relief pins. After the introduction of the proposed modification of the form, the mould quality has improved, thereby increasing the production efficiency in the process of shape optimization of manufacturing the product called Installation Box Series S-BOX 106 made of polyamide PA 66. In addressing the issue, simulation of cooling plastic and injection pressure in Cadmold 3D-f software was employed.

Abstract: The world’s demand for construction aggregates has been increasing over the last years, mainly due to the rapid economic growth of countries such as Brazil, China and India. Naturally, this growth stimulates the development of construction and demolition activities, thereby generating increasing amounts of waste. This paper presents a state-of-the-art review of the experimental research on the effect of incorporating aggregates of different types and shapes, sourced from construction and demolition waste. This review also covers studies on the incorporation of waste materials coming from industrial activities, emphasising those performed in the Instituto Superior Técnico, of the University of Lisbon, Portugal.

Abstract: Plastic materials are widely used in automobile manufacturing, and they have different mechanical characteristics at high and low temperature, which has a major influence on automobile safety. This paper mainly studies the relationship between elastic modulus and yield strength of plastic materials at high and low temperature, in order to predict the elastic modulus by the yield strength. On this basis, the values of the parameter of the constitutive model will be predicted to obtain the constitutive equation. The method meeting the precision is validated by the experiments. The method decreases experimental working, and provides technical support for product development as well.

Abstract: The purpose of this study is to analyse, by simulation, the injection of ABS plastic parts and track results on piece deformations after the latter was removed from the mould. Injection Process. Analysis was performed using the Autodesk Moldflow professional package. The results of the theoretical analysis by numerical methods are used for optimal design of the die to reduce and eliminate the strains and defect parts.

Abstract: The plastic has become one of the most widely used material. Current also has the extremely widespread application in the field of product design. Types and characteristics, this paper analyzes the commonly used plastic and plastic application in product design are discussed in detailed research.