scholarly journals The Influence of the Accelerated Aging Conditions on the Properties of Polyolefin Geogrids Used for Landfill Slope Reinforcement

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1874
Author(s):  
Agnieszka Kiersnowska ◽  
Wojciech Fabianowski ◽  
Eugeniusz Koda
Keyword(s):  
Mechanical Properties ◽  
Relative Elongation ◽  
Oxidative Degradation ◽  
Accelerated Aging ◽  
Melt Flow Index ◽  
Flow Index ◽  
Scanning Calorimetry ◽  
Oxidation Induction Time ◽  
Aging Test ◽  
Different Temperatures

Polyolefin geosynthetics are susceptible to oxidative degradation, which in turn leads to diminished mechanical properties in geotechnical constructions. When using these materials, it is extremely important to determine their durability over time in particularly aggressive conditions. In order to prolong the life of a geosynthetic material, antioxidants are added during the manufacturing process. The function of antioxidants is to prevent polymer oxidation reaction in time. As the antioxidant content is depleted, the polymer becomes less protected towards oxidative attacks. This article describes the aging process of uniaxial (high density polyethylene) HDPE geogrids under the influence of chemical and environmental factors. Evaluations of accelerated aging test of the uniaxial HDPE geogrids were incubated in simulated landfill conditions for a period of 12 months. Three temperatures (25 °C, 45 °C, and 75 °C) were selected for carrying out the aging experiments in aqueous solutions mimicking landfill conditions. The changes observed by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and melt flow index (MFI) correlate with the mechanical properties of the aged geogrid. No significant changes in the FTIR and MFI were observed over the 12 months of accelerated aging tests at none of the three different temperatures. The oxidation induction time (OIT) test showed no antioxidant remaining in the geogrid following eight months of aging test at 75 °C. No significant changes in the influence of accelerated aging tests on the average relative elongation at 25 °C and 45 °C of the tested material were observed. Accelerated aging tests at 75 °C showed that the mean elongation of 12.12% for the sample not subjected to accelerated aging tests (new sample) increased to 19.32% (after 12 months of incubation).

scholarly journals Halloysite Nanotubes and Silane-Treated Alumina Trihydrate Hybrid Flame Retardant System for High-Performance Cable Insulation

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2134
Author(s):  
Sandra Paszkiewicz ◽  
Izabela Irska ◽  
Iman Taraghi ◽  
Elżbieta Piesowicz ◽  
Jakub Sieminski ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Polymer Blend ◽  
Hybrid System ◽  
Reference Sample ◽  
Melt Flow Index ◽  
Halloysite Nanotubes ◽  
Flow Index ◽  
Scanning Calorimetry ◽  
Limiting Oxygen Index ◽  
Alumina Trihydrate

The effect of the presence of halloysite nanotubes (HNTs) and silane-treated alumina trihydrate (ATH-sil) nanofillers on the mechanical, thermal, and flame retardancy properties of ethylene-vinyl acetate (EVA) copolymer/low-density polyethylene (LDPE) blends was investigated. Different weight percentages of HNT and ATH-sil nanoparticles, as well as the hybrid system of those nanofillers, were melt mixed with the polymer blend (reference sample) using a twin-screw extruder. The morphology of the nanoparticles and polymer compositions was studied using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The mechanical properties, hardness, water absorption, and melt flow index (MFI) of the compositions were assessed. The tensile strength increases as a function of the amount of HNT nanofiller; however, the elongation at break decreases. In the case of the hybrid system of nanofillers, the compositions showed superior mechanical properties. The thermal properties of the reference sample and those of the corresponding sample with nanofiller blends were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Two peaks were observed in the melting and crystallization temperatures. This shows that the EVA/LDPE is an immiscible polymer blend. The thermal stability of the blends was improved by the presence of HNTs and ATH-sil nanoparticles. Thermal degradation temperatures were shifted to higher values by the presence of hybrid nanofillers. Finally, the flammability of the compositions was assessed. Flammability as reflected by the limiting oxygen index (OI) was increased by the presence of HNT and ATH-sil nanofiller and a hybrid system of the nanoparticles.

scholarly journals Mechanical, Thermal and Rheological Properties of Polyethylene-Based Composites Filled with Micrometric Aluminum Powder

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1242
Author(s):  
Olga Mysiukiewicz ◽  
Paulina Kosmela ◽  
Mateusz Barczewski ◽  
Aleksander Hejna
Keyword(s):  
Mechanical Properties ◽  
Melt Flow Index ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Flow Index ◽  
Scanning Calorimetry ◽  
Metal Composites ◽  
Pre Treatment ◽  
The Impact ◽  
Properties Of Composites

Investigations related to polymer/metal composites are often limited to the analysis of the electrical and thermal conductivity of the materials. The presented study aims to analyze the impact of aluminum (Al) filler content (from 1 to 20 wt%) on the rarely investigated properties of composites based on the high-density polyethylene (HDPE) matrix. The crystalline structure, rheological (melt flow index and oscillatory rheometry), thermal (differential scanning calorimetry), as well as static (tensile tests, hardness, rebound resilience) and dynamic (dynamical mechanical analysis) mechanical properties of composites were investigated. The incorporation of 1 and 2 wt% of aluminum filler resulted in small enhancements of mechanical properties, while loadings of 5 and 10 wt% provided materials with a similar performance to neat HDPE. Such results were supported by the lack of disturbances in the rheological behavior of composites. The presented results indicate that a significant content of aluminum filler may be introduced into the HDPE matrix without additional pre-treatment and does not cause the deterioration of composites’ performance, which should be considered beneficial when engineering PE/metal composites.

scholarly journals A Study of the Mechanical Behavior and Crystal Structure of UHMWPE/HDPE Blend Fibers Prepared by Melt Spinning

2018 ◽  
Vol 13 (3) ◽  
pp. 155892501801300
Author(s):  
Fei Wang ◽  
Lichao Liu ◽  
Ping Xue ◽  
Mingyin Jia ◽  
Hua Sun
Keyword(s):  
Crystal Structure ◽  
Mechanical Properties ◽  
Tensile Strength ◽  
Mechanical Behavior ◽  
Melt Spinning ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Melt Flow Index ◽  
Flow Index ◽  
Scanning Calorimetry ◽  
Spinning Process

Ultrahigh molecular weight polyethylene (UHMWPE) and high-density polyethylene (HDPE) blend fibers with the highest tensile strength of 1.13 GPa were prepared by a melt spinning process. The crystal structure and mechanical behavior of the as-spun filaments and fibers were studied by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), sound velocity orientation test and tensile strength test. The results suggested that the degree of molecular chain orientation, crystallinity and mechanical properties of the blend fibers were improved by blending with the low melt flow index (MFI) HDPE. The crystal grains of low MFI HDPE blend fibers that were formed by more highly oriented molecular chains could be stretched more effectively in the drawing direction, and the improved mechanical properties were due to the more regular and compact crystal structure.

scholarly journals Application of Physical Methods for the Detection of a Thermally Degraded Recycled Material in Plastic Parts Made of Polypropylene Copolymer

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 552
Author(s):  
Luboš Běhálek ◽  
Jozef Dobránsky ◽  
Martin Pollák ◽  
Martin Borůvka ◽  
Pavel Brdlík
Keyword(s):  
Mechanical Properties ◽  
Volume Flow Rate ◽  
Melt Flow Index ◽  
Bending Test ◽  
Flow Index ◽  
Melt Flow ◽  
Scanning Calorimetry ◽  
Physical Methods ◽  
Plastic Parts ◽  
Recycled Material

The paper deals with the possibility of applying physical methods to detect a thermally degraded recycled material in plastic parts made of polypropylene. Standard methods of evaluating the mechanical properties of the material under static tensile and bending stress, as well as under dynamic impact stress using the Charpy method, were used for the experimental measurements. The rheological properties of materials were monitored using a method involving measuring the melt flow index, while their thermal properties and oxidative stability were monitored using differential scanning calorimetry. Based on the methods used, it can be clearly stated that the most suitable technique for detecting thermally degraded recycled material in polypropylene is the method involving establishing the melt flow index. The bending test seems to be the most suitable method for detecting recycled material by measuring the material’s mechanical properties. Similarly to the melt volume flow rate (MVR) method, it was possible to unambiguously detect the presence of even a small amount of recycled material in the whole from measuring the material’s bending properties. It is clear from the results that in the short term, there may be no change in the useful properties of the parts, but in the long term the presence of degraded recycled material will have adverse consequences on their lifespan.

scholarly journals Effect of short basalt fibers on durability, mechanical properties, and thermal properties of polylactic acid composites

2019 ◽  
Vol 10 (1-3) ◽  
pp. 45-59
Author(s):  
Lu Han ◽  
Fangwu Ma ◽  
Shixian Chen ◽  
Yongfeng Pu
Keyword(s):  
Mechanical Properties ◽  
Polylactic Acid ◽  
Basalt Fiber ◽  
Tensile Modulus ◽  
Accelerated Aging ◽  
Mechanical Analysis ◽  
Basalt Fibers ◽  
Scanning Calorimetry ◽  
Accelerated Aging Test ◽  
Aging Test

The effect of basalt fiber (BF) content on the properties of BF-reinforced polylactic acid (PLA) composites was investigated. Composites with 10, 20, 30, 40, 50, and 60 wt% BF were fabricated. The results revealed that (1) the mechanical properties improved with increasing BF content. The maximum tensile strength and modulus of the composites (i.e. 140 and 5050 MPa, respectively) occurred at a BF content of 50%. The maximum flexural strength, that is, 159.5 MPa was two times larger than that of the pure PLA and was obtained at a BF content of 40%. However, the mechanical properties deteriorated at BF contents >50%. (2) BF can stop storage modulus loss and are effective in improving the crystallinity, as revealed by dynamic mechanical analysis and differential scanning calorimetry measurements. The crystallinity improved from 34.6% to 54.6% with BF addition. (3) After the accelerated aging test, pure PLA was too weak for testing. However, high values of the tensile modulus (i.e. 60% that of the nonaged samples) were maintained by the BF-reinforced PLA. This resulted possibly from the high crystallinity of the PLA composites. Therefore, suitable amounts of BF as reinforcements can yield improvements in the performance of PLA composites.

scholarly journals Laboratory Study of the Ultraviolet Radiation Effect on an HDPE Geomembrane

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 390
Author(s):  
Fernando Luiz Lavoie ◽  
Marcelo Kobelnik ◽  
Clever Aparecido Valentin ◽  
Érica Fernanda da Silva Tirelli ◽  
Maria de Lurdes Lopes ◽  
...  
Keyword(s):  
Ultraviolet Radiation ◽  
Morphological Changes ◽  
Field Performance ◽  
Melt Flow Index ◽  
Flow Index ◽  
Test Results ◽  
Upward Trend ◽  
Scanning Calorimetry ◽  
Ultraviolet Exposure ◽  
Brittle Behavior

High-density polyethylene (HDPE) geomembranes are polymeric geosynthetic materials usually applied as a liner in environmental facilities due to their good mechanical properties, good welding conditions, and excellent chemical resistance. A geomembrane’s field performance is affected by different conditions and exposures, including ultraviolet radiation, thermal and oxidative exposure, and chemical contact. This article presents an experimental study with a 1.0 mm-thick HDPE virgin geomembrane exposed by the Xenon arc weatherometer for 2160 h and the ultraviolet fluorescent weatherometer for 8760 h to understand the geomembrane’s behavior under ultraviolet exposure. The evaluation was performed using the melt flow index (MFI) test, oxidative-induction time (OIT) tests, tensile test, differential scanning calorimetry (DSC) analysis, and Fourier transform infrared spectroscopy (FTIR) analysis. The sample exposed in the Xenon arc equipment showed a tendency to increase the MFI values during the exposure time. This upward trend may indicate morphological changes in the polymer. The tensile behavior analysis showed a tendency of the sample to lose ductility, without showing brittle behavior. The samples’ OIT test results under both device exposures showed faster antioxidant depletion for the standard OIT test than the high-pressure OIT test. The DSC and FTIR analyses did not demonstrate the polymer’s changes.

scholarly journals Post-Processing Time Dependence of Shrinkage and Mechanical Properties of Injection-Molded Polypropylene

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 22
Author(s):  
Artur Kościuszko ◽  
Dawid Marciniak ◽  
Dariusz Sykutera
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Injection Molding ◽  
Accelerated Aging ◽  
Mold Temperature ◽  
Degree Of Crystallinity ◽  
Injection Mold ◽  
Secondary Crystallization ◽  
Scanning Calorimetry ◽  
Injection Molded

Dimensions of the injection-molded semi-crystalline materials (polymeric products) decrease with the time that elapses from their formation. The post-molding shrinkage is an effect of secondary crystallization; the increase in the degree of polymer crystallinity leads to an increase in stiffness and decrease in impact strength of the polymer material. The aim of this study was to assess the changes in the values of post-molding shrinkage of polypropylene produced by injection molding at two different temperatures of the mold (20 °C and 80 °C), and conditioned for 504 h at 23 °C. Subsequently, the samples were annealed for 24 h at 140 °C in order to conduct their accelerated aging. The results of shrinkage tests were related to the changes of mechanical properties that accompany the secondary crystallization. The degree of crystallinity of the conditioned samples was determined by means of density measurements and differential scanning calorimetry. It was found that the changes in the length of the moldings that took place after removal from the injection mold were accompanied by an increase of 20% in the modulus of elasticity, regardless of the conditions under which the samples were made. The differences in the shrinkage and mechanical properties of the samples resulting from mold temperature, as determined by tensile test, were removed by annealing. However, the samples made at two different injection mold temperature values still significantly differed in impact strength, the values of which were clearly higher for the annealed samples compared to the results determined for the samples immediately after the injection molding.

Characterization of microwave-treated oil palm empty fruit bunch/glass fibre/polypropylene composites

2015 ◽  
Vol 30 (7) ◽  
pp. 986-1002 ◽  
Author(s):  
MR Islam ◽  
A Gupta ◽  
M Rivai ◽  
MDH Beg
Keyword(s):  
Glass Fibre ◽  
Oil Palm ◽  
Melt Flow Index ◽  
Flow Index ◽  
Mechanical And Thermal Properties ◽  
Empty Fruit Bunch ◽  
Scanning Calorimetry ◽  
Fixed Temperature ◽  
Polypropylene Composites ◽  
Degradation Temperature

Composites were prepared from recycled polypropylene (RPP), oil palm empty fruit bunch (EFB) and/or glass fibre (GF) using extrusion and injection moulding techniques. Two types of maleic anhydride-grafted polypropylene such as Polybond 3200 and Fusabond P 613 were used to improve the interfacial adhesion between fibres and matrix. The EFB: GF ratio was fixed as 70:30 and fibre loading was considered as 40 wt%. Microwave was used to treat the EFB fibre, which was soaked in a fixed mass concentration (12.5%) of alkali solution at different temperatures (70, 80 and 90°C) for a fixed period of time (60 min) and for different times (60, 90 and 120 min) at a fixed temperature (90°C). A magnetron controller was developed to control the time and temperature accurately for the treatment of fibre. Various characterization techniques such as density, melt flow index, tensile, Izod impact, flexural, field-emission scanning electron microscopy and water uptake testing were performed for the composites. Besides, thermogravimetric analysis and differential scanning calorimetry were also used to evaluate the thermal and crystalline properties of the composites, respectively. Result analyses revealed that microwave-treated fibre-based composites showed improved mechanical and thermal properties. EFB fibres treated at 90°C for 90 min were found to be suitable for better reinforcement into the composite in terms of mechanical, thermal and crystalline properties. Moreover, onset degradation temperature and water absorption properties were also found to be changed apparently due to treatment.

Cable and Wire Application: Adoption of Nanomagnesium Hydroxide Blended with LDPE/EVA for Mechanical and Physical Properties

2013 ◽  
Vol 701 ◽  
pp. 202-206
Author(s):  
Ahmad Aroziki Abdul Aziz ◽  
Sakinah Mohd Alauddin ◽  
Ruzitah Mohd Salleh ◽  
Mohammed Iqbal Shueb
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Melt Flow Index ◽  
Low Density Polyethylene ◽  
Flow Index ◽  
Low Density ◽  
Elongation At Break ◽  
Mechanical And Physical Properties ◽  
Poly Ethylene ◽  
Loading Amount

Effect of nanoMagnesium Hydroxide (MH) nloading amount to the mechanical and physical properties of Low Density Polyethylene (LDPE)/ Poly (ethylene-co vinyl acetate)(EVA) nanocomposite has been described and investigated in this paper. The tensile strength results show that increased amount of nanofiller will decrease and deteriorate the mechanical properties. The elongation at break decreased continuously with increasing loading of nanofiller. Generally, mechanical properties become poorer as loading amount increase. Melt Flow Index values for physical properties also provide same trend as mechanical properties results. Increase filler amount reduced MFI values whereby increased resistance to the flow.

scholarly journals Effect of Hard Plastic Waste on the Quality of Recycled Polypropylene Blends

Recycling ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 58
Author(s):  
Patrizio Tratzi ◽  
Chiara Giuliani ◽  
Marco Torre ◽  
Laura Tomassetti ◽  
Roberto Petrucci ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Polymeric Materials ◽  
Melt Flow Index ◽  
Plastic Waste ◽  
Flow Index ◽  
Yield Strain ◽  
Melt Index ◽  
Polypropylene Blends ◽  
Post Industrial ◽  
Plastic Containers

The recycling of plastic waste is undergoing fast growth due to environmental, health and economic issues, and several blends of post-consumer and post-industrial polymeric materials have been characterized in recent years. However, most of these researches have focused on plastic containers and packaging, neglecting hard plastic waste. This study provides the first experimental characterization of different blends of hard plastic waste and virgin polypropylene in terms of melt index, differential scan calorimetry (DSC), thermogravimetric analysis (TGA), mechanical properties (tensile, impact and Shore hardness) and Vicat softening test. Compared to blends based on packaging plastic waste, significant differences were observed in terms of melt flow index (about 10 points higher for hard plastic waste). Mechanical properties, in particular yield strain, were instead quite similar (between 5 and 9%), despite a higher standard deviation being observed, up to 10%, probably due to incomplete homogenization. Results demonstrate that these worse performances could be mainly attributed to the presence of different additives, as well as to the presence of impurities or traces of other polymers, other than incomplete homogenization. On the other hand, acceptable results were obtained for selected blends; the optimal blending ratio was identified as 78% post-consumer waste and 22% post-industrial waste, meeting the requirement for injection molding and thermoforming.

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