Temperature effects on ageing properties and diffusivity of a HDPE GM in landfill

2021 ◽  
pp. 0734242X2110570
Author(s):  
Shengwei Wang ◽  
Tao Guo ◽  
Huan Tian ◽  
Zhigang Li ◽  
Kang Fei
Keyword(s):  
Diffusion Coefficient ◽  
Tensile Properties ◽  
Ageing Time ◽  
Melt Flow Index ◽  
Engineering Properties ◽  
Flow Index ◽  
Test Results ◽  
Oxidation Induction Time ◽  
Degradation Rates ◽  
And Migration

High-density polyethylene (HDPE) geomembranes (GMs) play a crucial role in preventing the leakage and migration of pollutants. GM service life and ageing properties are the main concerns for the choice of materials. However, it is not clear how the mechanical properties and anti-fouling performance of geomembranes change with ageing time. To solve this problem, a HDPE GM was selected for testing under exposed air condition. The tests included oxidation induction time (OIT), melt flow index (MFI), tensile properties and diffusivity under four temperature conditions for 1½ years. The test results showed that the GM has higher OIT degradation rates. Stage I – depletion of antioxidants occurred at only 10 years for the GM, which was approximately 1/4 that of the GM-GSE. The GM engineering properties index showed the same changes as those of the GM-GSE. However, MI rapidly decreased with the incubation time. The molecular weight degradation of the GM was approximately 57% and far greater than that of GM-GSE after 15 months, but the tensile properties of the two GMs showed little change. The diffusion coefficient Di of GM increases gradually with the increase of temperature in methane and trichloromethane. Under the same conditions, the diffusion coefficient Di of the GM in methane is significantly higher than that in trichloromethane, indicating that the GM has better barrier to trichloromethane.

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 Influence of Thickness on Water Absorption and Tensile Strength of BFRP Laminates in Water or Alkaline Solution and a Thickness-Dependent Accelerated Ageing Method for BFRP Laminates

2020 ◽  
Vol 10 (10) ◽  
pp. 3618
Author(s):  
Yanlei Wang ◽  
Wanxin Zhu ◽  
Xue Zhang ◽  
Gaochuang Cai ◽  
Baolin Wan
Keyword(s):  
Tensile Strength ◽  
Water Absorption ◽  
Tensile Properties ◽  
Alkaline Solution ◽  
Ageing Time ◽  
Accelerated Ageing ◽  
Specimen Thickness ◽  
Test Results ◽  
Strength Retention

This paper first presented an experimental study on water absorption and tensile properties of basalt fiber-reinforced polymer (BFRP) laminates with different specimen thicknesses (i.e., 1, 2, and 4 mm) subjected to 60 °C deionized water or alkaline solution for an ageing time up to 180 days. The degradation mechanism of BFRP laminates in solution immersion was also explored combined with micro-morphology analysis by scanning electronic microscopy (SEM). The test results indicated that the water absorption and tensile properties of BFRP laminates were dramatically influenced by specimen thickness. When the BFRP laminates with different thicknesses were immersed in the solution for the same ageing time, the water absorption of the specimens decreased firstly before reaching their peak water absorption and then increased in the later stage with the increase of specimen thickness, while the tensile strength retention sustaining increased as specimen thickness increased. The reason is that the thinner the specimen, the more severe the degradation. In this study, a new accelerated ageing method was proposed to predict the long-term water absorption and tensile strength of BFRP laminates. The accelerated factor of the proposed method was determined based on the specimen thickness. The proposed method was verified by test results with a good accuracy, indicating that the method could be used to predict long-term water absorption and tensile strength retention of BFRP laminates by considering specimen thickness in accelerating tests.

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).

Thermal and water ageing effect on mechanical, rheological and morphological properties of glass-fibre-reinforced poly(oxymethylene) composite

2018 ◽  
Vol 233 (2) ◽  
pp. 211-224 ◽  
Author(s):  
Emel Kuram
Keyword(s):  
Tensile Strength ◽  
Flexural Strength ◽  
Glass Fibre ◽  
Room Temperature ◽  
Ageing Time ◽  
Melt Flow Index ◽  
Morphological Properties ◽  
Flow Index ◽  
Melt Flow ◽  
Glass Fibre Reinforced

In this study, the ageing behaviour of glass-fibre-reinforced poly(oxymethylene) composite at different conditions was investigated. The ageing was performed in various controlled environments, namely in air at room temperature, in water at room temperature and in an oven at the temperature of 100 ℃. Tensile and flexural tests were conducted to determine the mechanical properties, melt flow index was measured to determine the rheological property and scanning electron microscopy was used to observe the morphological property of unaged and aged poly(oxymethylene) samples. A reduction in both tensile and flexural strength was observed with all ageing environment. The worst strength retention was obtained with water ageing. Water absorbed by glass-fibre-reinforced poly(oxymethylene) composite had a detrimental influence on the tensile and flexural strength. Tensile strength was affected by the ageing environments. The decrease in the tensile strength of air and thermally aged poly(oxymethylene) was slower than that of water aged poly(oxymethylene), and the tensile strength of aged samples decreased as the ageing time increased. The combined actions of heat, air and water (thermal + water + air ageing) did not further degrade glass-fibre-reinforced poly(oxymethylene) compared to only water ageing at the room temperature. All tensile stress–strain and flexural load–deflection curves showed the similar tendency and did not change with ageing environments and time. All aged samples showed higher melt flow index values than that of unaged sample and the changes in melt flow index could be an indicator of degradation.

Effects of Calcium Carbonate on Melt Flow and Mechanical Properties of Rice Husk/HDPE and Kenaf/HDPE Hybrid Composites

2013 ◽  
Vol 795 ◽  
pp. 286-289 ◽  
Author(s):  
Abd Aziz Noor Zuhaira ◽  
Mohamed Rahmah
Keyword(s):  
Mechanical Properties ◽  
Calcium Carbonate ◽  
Impact Strength ◽  
Rice Husk ◽  
Hybrid Composite ◽  
Hybrid Composites ◽  
Melt Flow Index ◽  
Flow Index ◽  
Test Results ◽  
Melt Flow

In this research, calcium carbonate (CaCO3) was compounded with rice husk/high density polyethylene (HDPE) and kenaf/HDPE composite at different filler loadings to produce hybrid composites. Melt flow index (MFI) and mechanical properties of hybrid composite was investigated. From the test results, the addition of CaCO3 filler had decreased melt flow index (MFI) on both composites. In terms of mechanical properties, tensile strength, elongation at break and impact strength decreased, whereas Youngs Modulus increased with the increase of CaCO3 in both kenaf/HDPE and rice husk/HDPE composites. Impact strength of unfilled rice husk/HDPE composite was lower than unfilled kenaf/HDPE composite, however impact strength of CaCO3/rice husk/HDPE hybrid composite were found to have slightly higher than CaCO3/kenaf/HDPE hybrid composite with addition of 10% and 20% of CaCO3.

Tensile Properties and Melt Flow Index of Polypropylene/Ethylene Propylene Diene Monomer Nanocomposites

2015 ◽  
Vol 1107 ◽  
pp. 125-130 ◽  
Author(s):  
Muhammad Safwan Hamzah ◽  
M. Mariatti ◽  
M. Kamarol
Keyword(s):  
Tensile Strength ◽  
Tensile Properties ◽  
Melt Flow Index ◽  
Filler Loading ◽  
Flow Index ◽  
Ethylene Propylene Diene Monomer ◽  
Melt Flow ◽  
Elongation At Break ◽  
Ethylene Propylene ◽  
Internal Mixer

In this article, we report three nanofillers filled polymer composite systems. Nanofillers composed of alumina, titania and organoclay were embedded separately in 50% polypropylene (PP) and 50% ethylene propylene diene monomer (EPDM) blends. The nanocomposites were prepared using an internal mixer and were molded using a compression mold to form test samples. Effect of filler loading (2, 4, 6, and 8 vol.%) on the tensile properties and melt flow index (MFI) were determined. The mechanical properties of alumina are the highest compared to titania and organoclay. Alumina and organoclay shows an ascending trend in tensile strength with the increase of nanofiller loading. In contrast, the increment of titania filler loading reduces the tensile strength of the nanocomposites. The Young's modulus of the nanocomposites increases with the addition of filler loading. Elongation at break of the nanocomposites shows a descending trend with the addition of filler loading. The addition of 8 vol. % titania and organoclay slightly changes the MFI of the PP/EPDM nanocomposites whereas the addition of 8 vol. % alumina drastically decreased the MFI values. Further addition of nanofillers up to 8 vol. % decreases the MFI values of the PP/EPDM nanocomposites.

scholarly journals Effect of the Prodegradant-Additive Plastics Incorporated on the Polyethylene Recycling

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Miguel Aldas ◽  
Andrea Paladines ◽  
Vladimir Valle ◽  
Miguel Pazmiño ◽  
Francisco Quiroz
Keyword(s):  
Melt Flow Index ◽  
Melt Processing ◽  
Flow Index ◽  
Heating Process ◽  
Test Results ◽  
Low Concentrations ◽  
Matrix Properties ◽  
The Matrix ◽  
Degraded Material ◽  
Mixer Chamber

The effect of degraded plastic with prodegradants on the polyethylene properties was studied. First, the mixture of low-density polyethylene (LDPE) with 5 wt.% prodegradant (oxo-degradable) additive was prepared by melt processing using a mixer chamber. Then, the degradation of the mixtures was evaluated by exposing the oxo-degradable LDPE in a Xenon arc chamber for 300 hours. The degraded material was characterized by infrared spectroscopy (FTIR) assessing the carbonyl index and the hydroperoxide band. Then, different percentages of degraded material (1, 5, 10, 20, and 50 wt.%) were incorporated into the neat LDPE. Mechanical and rheological tests were carried out to evaluate the recycling process of these blends. Also, the feasibility of the blends reprocessing was determined by analysing the melt flow index for each heating process and shear stress applied. It was evidenced that the increment of the content of the degraded material in the neat LDPE decreased the mechanical strength and the processability of blends due to the imminent thermal degradation. All the test results showed that the incorporation of degraded material causes a considerable reduction in the matrix properties during the reprocessing. Nevertheless, at low concentrations, the properties of the oxo-degradable LDPE–LDPE blends were found to be similar to the neat LDPE.

Tensile Properties and Degradability of Polyvinyl Alcohol and Starch Succinate Blend

2015 ◽  
Vol 1113 ◽  
pp. 122-126
Author(s):  
Mohd Muizz Fahimi bin Mohamed ◽  
Rahmah Mohamed
Keyword(s):  
Polyvinyl Alcohol ◽  
Tensile Properties ◽  
Sun Exposure ◽  
Melt Flow Index ◽  
Visual Observation ◽  
Flow Index ◽  
Screw Extruder ◽  
Soil Burial ◽  
Twin Screw ◽  
Flow Modifier

The purpose of this study was to determine the tensile properties of biodegradable Polyvinyl Alcohol (PVA) impregnated with commercial grade starch succinate (SS). PVA is a hydrophilic and hygroscopic polymer, and inclusion of SS reduces PVA's hygroscopicity and hydrophilicity. The compounding of PVA with SS was prepared by using a twin screw extruder with fixed flow modifier. The ratios of SS were varied between 5% to 20%. Melt flow index, tensile properties, soil burial and sun exposure degradability were investigated in this study. Tensile strength was observed to increase proportionate to the amount of SS incorporated while the blends were found to have greater flexibility as their elongation increases as their modulus dropped. SS was found to have greater flexibility chain which imparted greater elongation during stretching test. Higher content of SS was found to impart better degradation rate as derived from visual observation of the samples exposed to sunlight and soil burial.

scholarly journals Enhancement of mechanical, thermal and water uptake performance of TPU/jute fiber green composites via chemical treatments on fiber surface

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 133-143 ◽  
Author(s):  
Tuffaha Fathe Salem ◽  
Seha Tirkes ◽  
Alinda Oyku Akar ◽  
Umit Tayfun
Keyword(s):  
Water Absorption ◽  
Water Uptake ◽  
Mechanical Test ◽  
Fiber Surface ◽  
Melt Flow Index ◽  
Jute Fiber ◽  
Morphological Properties ◽  
Flow Index ◽  
Melt Flow ◽  
Treatment Type

AbstractChopped jute fiber (JF) surfaces were modified using alkaline, silane and eco-grade epoxy resin. Surface characteristics of jute fibers were confirmed by FTIR and EDX analyses. JF filled polyurethane elastomer (TPU) composites were prepared via extrusion process. The effect of surface modifications of JF on mechanical, thermo-mechanical, melt-flow, water uptake and morphological properties of TPU-based eco-composites were investigated by tensile and hardness tests, dynamic mechanical analysis (DMA), melt flow index (MFI) test, water absorption measurements and scanning electron microscopy (SEM) techniques, respectively. Mechanical test results showed that silane and epoxy treated JF additions led to increase in tensile strength, modulus and hardness of TPU. Glass transition temperature (Tg) of TPU rose up to higher values after JF inclusions regardless of treatment type. Si-JF filled TPU exhibited the lowest water absorption among composites. Surface treated JFs displayed homogeneous dispersion into TPU and their surface were covered by TPU according to SEM micro-photographs.

scholarly journals Green TPUs from Prepolymer Mixtures Designed by Controlling the Chemical Structure of Flexible Segments

2021 ◽  
Vol 22 (14) ◽  
pp. 7438
Author(s):  
Paulina Kasprzyk ◽  
Ewa Głowińska ◽  
Paulina Parcheta-Szwindowska ◽  
Kamila Rohde ◽  
Janusz Datta
Keyword(s):  
Chemical Structure ◽  
Melt Flow Index ◽  
Molar Ratio ◽  
Flow Index ◽  
Step Method ◽  
Elongation At Break ◽  
Molecular Weights ◽  
Trimethylene Glycol ◽  
Hard Segments ◽  
A Chain

This study concerns green thermoplastic polyurethanes (TPU) obtained by controlling the chemical structure of flexible segments. Two types of bio-based polyether polyols—poly(trimethylene glycol)s—with average molecular weights ca. 1000 and 2700 Da were used (PO3G1000 and PO3G2700, respectively). TPUs were prepared via a two-step method. Hard segments consisted of 4,4′-diphenylmethane diisocyanates and the bio-based 1,4-butanodiol (used as a chain extender and used to control the [NCO]/[OH] molar ratio). The impacts of the structure of flexible segments, the amount of each type of prepolymer, and the [NCO]/[OH] molar ratio on the chemical structure and selected properties of the TPUs were verified. By regulating the number of flexible segments of a given type, different selected properties of TPU materials were obtained. Thermal analysis confirmed the high thermal stability of the prepared materials and revealed that TPUs based on a higher amount of prepolymer synthesized from PO3G2700 have a tendency for cold crystallization. An increase in the amount of PO3G1000 at the flexible segments caused an increase in the tensile strength and decrease in the elongation at break. Melt flow index results demonstrated that the increase in the amount of prepolymer based on PO3G1000 resulted in TPUs favorable in terms of machining.

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