Papers by Keyword: Polyethylene

Abstract: Thermal properties, i.e. melting point and decomposition temperature of polymers, azodicarbonamide (ADC), and other additives mixture, are the most important information to determine the appropriate foaming process parameters. ADC has been widely used as a blowing agent for foam fabrication. Here, ADC will decompose and release gas which will be trapped in the melting polymer to make a foamed product. Originally, ADC has a decomposition temperature at around 220°C. In this study, the effect of Zinc Oxide (ZnO) addition on the thermal properties of intermediate product and Polyethylene/Ethylene Vinyl Acetate (PE/EVA) foam with ADC as the blowing agent was investigated. ZnO addition decreased the decomposition temperature of ADC. The thermal properties were characterized by Differential Scanning Calorimetry (DSC). The result showed that the decomposition temperature of ADC significantly decreased from the temperature of 220°C to 170°C with the increment of the ZnO.

Abstract: The performance of graphene/polymer nanocomposites depends on many factors but the major factor is a nanoparticles dispersion and distribution into the host matrix. The present work investigates the effect of the dispersion of graphene oxide upon the structure-property relations in metallocene linear low density polyethylene (PE), homo polypropylene (PP), and blends thereof. These nanocomposites were prepared by solvent processing, where DMF and o-xylene were used as solvents for Graphene Oxide (GO) powder and the polymers respectively, before the two components were combined to form a well-mixed initial state. Characterization of the structure and crystallization of the nanocomposites was carried out by small- and wide-angle X-ray scattering and diffraction (SAXS and WAXD). The chemical structures were characterized by Fourier transform infrared spectroscopy (FTIR) and by Raman spectroscopy, and the latter used to calculate the ID/IG value for a pure GO samples. The thermal properties of the resulting nanocomposites were investigated by DSC and TGA in order to obtain Melting temperature ( ), crystallization temperature ( ) and degree of crystallinity ( ) as well as a range of degradation temperatures. The effect of GO on the mechanical properties was studied via the ultimate tensile strength and elastic modulus.

Abstract: The influence of carbon black on the deformation-strength properties of high density polyethylene is considered. It was found that the deformation-strength properties of the polymer matrix change over the entire range of the filler content. The amount of carbon black that can be introduced into high-density polyethylene and obtained a composite material with the optimal combination of stiffness, strength and ductility is established. It was shown that the change in the deformation-strength properties of composites is due to the behavior and influence of carbon black particles on the structure of the polymer matrix.

Abstract: Polyethylene (PE) has an exclusive set of properties, such as good toughness and mechanical resistance as well as high flexibility, and ease conformation. However, when exposed to degrading agents, such as heat, humidity and radiation, macromolecular changes can be observed and consequently affect the PE. This work evaluated for the first time the thermomechanical and fracture behavior of low-density polyethylene (LDPE) subjected to degradation at different times of exposure to ultraviolet (UV) radiation. The changes induced in the chemical structure and the highlighted behavior were investigated through thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transformed infrared spectroscopy (FTIR), reticulation content, tensile test, and scanning electron microscopy (SEM). The results suggest that UV radiation modify the failure of the polymer by reducing its crystallinity and dramatically increasing its degree of crosslinking. These modifications impair the LDPE mechanical performance as well as its thermal stability.

Abstract: The dependence of strain on temperature in polyethylene under various static loads and exposure doses has been studied experimentally. After electron irradiation with doses of 10, 30, 50, 70, and 100 kGy, significant changes in the mechanical properties were observed, which are caused by the formation of nanodefects in the material’s structure. With increasing radiation dose, PE deformation at different temperatures decreases due to destruction in the structure of the polymer material. At the same time, the return deformation increases with increasing dose, indicating a change in the modulus of elasticity (E). The increase in E occurs due to the decrease in the distance between macromolecules in the irradiated structure of the sample. The obtained curves for both non-irradiated and irradiated material are described in an exponential model satisfactorily.

Abstract: At present, when connecting polyethylene pipes for gas pipelines, two basic methods of welding are used: hot tool butt welding and welding with couplings and embedded heater. Hot tool flare welding is mainly used in polymer water supply systems. This paper presents results of research on implementation of this welding method when connecting polyethylene pipes in gas supply systems. It is proposed to use pieces of polyethylene pipes of larger diameter as couplings. Preliminary prolonged tensile tests of obtained welded joints showed effectiveness of this technology when joining polyethylene pipes.

Abstract: There are given the results of the evaluation of the starting polymers properties and the properties of the resulting WPC. The industrial objects of WPC based on various polymers were chosen as the objects of the study. In order to analyze the structure of the WPC there was used a computer microtomography, one of the recent non-destructive methods for studying the bulk structure of composites using X-ray radiation. To assess the overall durability and behavior of the end products under actual operating conditions, tests were carried out in special artificial weather equipment (weatherometer).

Abstract: A directed synthesis of zinc borate was carried out in order to obtain a product with a specific chemical composition and specified characteristics, which was used as a flame retardant for the polymer. It was found that the introduction of the obtained zinc borate into high-density polyethylene leads to a significant increase in the fire resistance of the starting polymer. It is shown that the deformation-strength properties of high-density polyethylene do not deteriorate with the introduction of zinc borate, but remain at the level of the original polymer.

Abstract: In this paper, the effect of unmodified halloysite nanotubes (HNTs) content on the chemical structure and the thermal and mechanical properties of blends based on starch-grafted-polyethylene (SgP) and high density polyethylene (HDPE) (70/30 w/w) nanocomposites was investigated at various filler content ratios, i.e. 1.5, 3 and 5 wt.%. The study showed the occurrence of chemical interactions between the polymer matrix and HNTs through OH bonding. Further, the addition of HNTs to the polymer blend led to an increase in the crystallization temperature of the nanocomposite samples, in particular at higher filler contents i.e. 3 and 5 wt.%, while the melting temperature remained almost unchanged. Tensile and flexural properties of the nanocomposite samples were however improved compared to the virgin blend with respect to the HNTs content ratio.

Abstract: Surface properties are important aspect for correct function of construction (technical) parts. By improving mechanical properties of surface, an increase of abrasion resistance and wear resistance is reached. Longevity and economical aspect have an important role in final useful properties of product. Measurement of surface properties was done by ultra-nanoindentation technique (UNHT³), this is the best tool available right now, this technique is based on instrumented testing. Surface properties were modified by ionized radiation, that caused the creation of crosslinked structure in polyethylene. During radiation a three dimensional network is created, that improves final properties of product such as: hardness, elasticity modulus, thermal stability, etc. During ionized radiation there are two actions that take place at the same time, crosslinking and degradation. Goal of this paper is to consider how radiation intensity affects surface properties (indentation hardness, indentation modulus, deformation work, etc.) Another goal of this paper is to find out the optimal dose of radiation, that will cause more three dimensional crosslinking and less degradation as degradation causes decrease in mechanical properties.