scholarly journals The effect of using the two-step extrusion method on the oxidation induction time value of recycled high density polyethylene

2012 ◽  
Vol 44 (5) ◽  
pp. 421-426 ◽  
Author(s):  
Yan Li ◽  
Haiyan Xu ◽  
Chifei Wu
Keyword(s):  
Induction Time ◽  
High Density Polyethylene ◽  
High Density ◽  
Oxidation Induction Time ◽  
Time Value ◽  
Extrusion Method

scholarly journals Chemical Modifications of Continuous Aramid Fiber for Wood Flour/High-Density-Polyethylene Composites with Improved Interfacial Bonding

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 236
Author(s):  
Wanyu Liu ◽  
Yue Li ◽  
Shunmin Yi ◽  
Limin Wang ◽  
Haigang Wang ◽  
...  
Keyword(s):  
High Density Polyethylene ◽  
Wood Flour ◽  
Tensile Modulus ◽  
High Density ◽  
Aramid Fiber ◽  
Chemical Modifications ◽  
Plastic Composites ◽  
Vinyl Triethoxysilane ◽  
Extrusion Method ◽  
Polyethylene Composites

To expand the use of wood plastic composites in the structural and engineering constructions applications, continuous aramid fiber (CAF) with nondestructive modification was incorporated as reinforcement material into wood-flour and high-density-polyethylene composites (WPC) by extrusion method with a special die. CAF was treated with dopamine (DPA), vinyl triethoxysilane (VTES), and DPA/VTES, respectively. The effects of these modifications on compatibility between CAF and WPCs and the properties of the resulting composites were explored. The results showed that compared with the original CAF, the adhesion strength of DPA and VTES combined modified CAF and WPCs increased by 143%. Meanwhile, compared with pure WPCs, CAF after modification increased the tensile strength, tensile modulus, and impact strength of the resulting composites by 198, 92, and 283%, respectively.

Pressure Effects on the Lifetime of Gas High Density Polyethylene Pipes

2021 ◽  
Author(s):  
Yang Wang ◽  
Hui-qing Lan ◽  
Tao Meng ◽  
Bing Wang ◽  
Du du Guo ◽  
...  
Keyword(s):  
Natural Gas ◽  
Induction Time ◽  
High Density Polyethylene ◽  
Reaction Rate ◽  
Low Pressure ◽  
Gas Pressure ◽  
High Density ◽  
Pressure Effects ◽  
Polyethylene Pipes ◽  
Hdpe Pipes

Abstract The purpose of this study was to propose low gas pressure effects on lifetime of natural gas high density polyethylene (HDPE) pipes by thermal-oxidative aging (TOA). The new method to assess the lifetime of HDPE natural gas pipes is based on gas pressure testing. An approach to monitor oxidative induction time (OIT) has been used to predict lifetime. Natural gas HDPE pipes were used to evaluate the effects of low gas pres-sures on oxidative induction time. In order to emphasize the pressure effects, relatively low temperatures at 45, 55, 65 and 75 °C were utilized for the exposure. The low-pressure conditions were created using air at levels of 0, 0.1, 0.2, 0.3 and 0.4 MPa. The property of high density polyethylene pipes was effectively moni-tored using the low pressure oxidative induction time (OIT) test. The results show that the aging reaction rate of high density polyethylene pipes increased exponentially with temperature and gas pressure according to the Arrhenius equation. Analytical models were developed to predict the aging reaction rate and lifetime of natural gas HDPE pipes.

Effect of texturing on the longevity of high-density polyethylene (HDPE) geomembranes in municipal solid waste landfills

2020 ◽  
Vol 57 (1) ◽  
pp. 61-72 ◽  
Author(s):  
M.S. Morsy ◽  
R. Kerry Rowe
Keyword(s):  
Municipal Solid Waste ◽  
Crack Resistance ◽  
Solid Waste ◽  
Induction Time ◽  
High Density Polyethylene ◽  
High Density ◽  
Smooth Edge ◽  
Core Thickness ◽  
Municipal Solid Waste Landfills ◽  
Solid Waste Landfills

The effect of texturing (co-extrusion using blowing agent) on the longevity of a geomembrane (GMB) when immersed in synthetic municipal solid waste leachate is investigated over a ∼3 year period. Based on data at four temperatures (40, 55, 75, and 85 °C), the time to antioxidant depletion of the textured portion of a 1.5 mm core thickness high-density polyethylene (HDPE) GMB is 40% (standard oxidative induction time) and 9% (high-pressure oxidative induction time) faster compared to the 1.5 mm smooth edge of the GMB. However, despite this, stress crack resistance results show that texturing may have no significant effect on the time to nominal failure for this GMB. It is also shown that HDPE GMBs made from nominally the same resin but from different production lots have different rates of stress crack resistance degradation and hence time to nominal failure; this should be considered both in landfill design and landfill construction quality assurance.

Ageing of exposed geomembranes at locations with different climatological conditions

2015 ◽  
Vol 52 (3) ◽  
pp. 326-343 ◽  
Author(s):  
R. Kerry Rowe ◽  
A.M.R. Ewais
Keyword(s):  
High Pressure ◽  
Crack Resistance ◽  
Induction Time ◽  
High Density Polyethylene ◽  
High Density ◽  
Cold Climate ◽  
Field Conditions ◽  
Research Site ◽  
Hot Climate ◽  
Exposure Conditions

The degradation of high-density polyethylene (HDPE) geomembranes exposed to the elements depends, inter alia, on the climatological conditions. This study investigates the degradation in the properties of HDPE geomembranes installed at two mine facilities after almost 16 years of exposure in a warm–hot climate and at a research site after 6 years of exposure in a mild–cold climate. Samples were exhumed at the field sites from different locations and the properties of the geomembrane were measured in the laboratory. The depletion of antioxidants detected by the standard oxidative induction time (Std-OIT) test for the geomembrane installed at the research site was faster on the slope than on the base; however, there was negligible difference in the depletion of antioxidants–stabilizers detected by the high-pressure oxidative induction time (HP-OIT) test between the slope and base. Under the field conditions described, the antioxidant depletion time for the exposed geomembrane installed at the research site (mild–cold climate) was inferred to be 20 to 54 years. The exposed HDPE geomembranes installed at the mine facilities (warm–hot climate) have reached the time of nominal failure based on their stress crack resistance. However, they have not ruptured under the exposure conditions even though the stress crack resistance has dropped to as low as 70 h at some locations.

Long-term performance of high-density polyethylene (HDPE) geomembrane seams in municipal solid waste (MSW) leachate

2017 ◽  
Vol 54 (12) ◽  
pp. 1623-1636 ◽  
Author(s):  
R. Kerry Rowe ◽  
Mohamad Shoaib
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Induction Time ◽  
High Density Polyethylene ◽  
High Density ◽  
Depletion Rate ◽  
The Times ◽  
Long Term Performance ◽  
Term Performance

The effect of a synthetic municipal solid waste leachate on the long-term performance of dual-wedge welds in a 1.5 mm thick high-density polyethylene geomembrane (GMB) is reported based on 4 years of testing at 40, 65, 75, and 85 °C. The effect of leachate on the GMB well away from the weld, in the heat-affected zone (HAZ) beside the weld, and in the welded zone are investigated. The slowest antioxidant depletion rate was in the weld itself and the fastest rate for the HAZ adjacent to the weld. The shear break and peel break properties started to decrease after the standard oxidative induction time had depleted to residual, but before the high-pressure oxidative induction time had reached residual. Failures occured at the HAZ adjacent to weld in both the shear and peel tests. No failure of the seam itself was observed. The times to nominal failure of the GMB in the critical HAZ are predicted. The rate of degradation in the weld and sheet are compared.

scholarly journals On the Use of Phenolic Compounds Present in Citrus Fruits and Grapes as Natural Antioxidants for Thermo-Compressed Bio-Based High-Density Polyethylene Films

Antioxidants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 14
Author(s):  
Sandra Rojas-Lema ◽  
Sergio Torres-Giner ◽  
Luis Quiles-Carrillo ◽  
Jaume Gomez-Caturla ◽  
Daniel Garcia-Garcia ◽  
...  
Keyword(s):  
Phenolic Compounds ◽  
High Density Polyethylene ◽  
Food Packaging ◽  
Mechanical Performance ◽  
Natural Antioxidants ◽  
High Density ◽  
Hydroxyl Groups ◽  
Citrus Fruits ◽  
Oxidation Induction Time ◽  
Active Food Packaging

This study originally explores the use of naringin (NAR), gallic acid (GA), caffeic acid (CA), and quercetin (QUER) as natural antioxidants for bio-based high-density polyethylene (bio-HDPE). These phenolic compounds are present in various citrus fruits and grapes and can remain in their leaves, peels, pulp, and seeds as by-products or wastes after juice processing. Each natural additive was first melt-mixed at 0.8 parts per hundred resin (phr) of bio-HDPE by extrusion and the resultant pellets were shaped into films by thermo-compression. Although all the phenolic compounds colored the bio-HDPE films, their contact transparency was still preserved. The chemical analyses confirmed the successful inclusion of the phenolic compounds in bio-HDPE, though their interaction with the green polyolefin matrix was low. The mechanical performance of the bio-HDPE films was nearly unaffected by the natural compounds, presenting in all cases a ductile behavior. Interestingly, the phenolic compounds successfully increased the thermo-oxidative stability of bio-HDPE, yielding GA and QUER the highest performance. In particular, using these phenolic compounds, the onset oxidation temperature (OOT) value was improved by 43 and 41.5 °C, respectively. Similarly, the oxidation induction time (OIT) value, determined in isothermal conditions at 210 °C, increased from 4.5 min to approximately 109 and 138 min. Furthermore, the onset degradation temperature in air of bio-HDPE, measured for the 5% of mass loss (T5%), was improved by up to 21 °C after the addition of NAR. Moreover, the GA- and CA-containing bio-HDPE films showed a high antioxidant activity in alcoholic solution due to their favored release capacity, which opens up novel opportunities in active food packaging. The improved antioxidant performance of these phenolic compounds was ascribed to the multiple presence of hydroxyl groups and aromatic heterocyclic rings that provide these molecules with the features to permit the delocalization and the scavenging of free radicals. Therefore, the here-tested phenolic compounds, in particular QUER, can represent a sustainable and cost-effective alternative of synthetic antioxidants in polymer and biopolymer formulations, for which safety and environmental issues have been raised over time.

scholarly journals On the Use of Gallic Acid as a Potential Natural Antioxidant and Ultraviolet Light Stabilizer in Cast-Extruded Bio-Based High-Density Polyethylene Films

Polymers ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 31 ◽  
Author(s):  
Luis Quiles-Carrillo ◽  
Sergi Montava-Jordà ◽  
Teodomiro Boronat ◽  
Chris Sammon ◽  
Rafael Balart ◽  
...  
Keyword(s):  
Gallic Acid ◽  
High Density Polyethylene ◽  
Food Packaging ◽  
Uv Light ◽  
High Density ◽  
Natural Antioxidant ◽  
Oxidation Induction Time ◽  
Sustainable Food ◽  
Light Stability ◽  
Twin Screw

This study originally explores the use of gallic acid (GA) as a natural additive in bio-based high-density polyethylene (bio-HDPE) formulations. Thus, bio-HDPE was first melt-compounded with two different loadings of GA, namely 0.3 and 0.8 parts per hundred resin (phr) of biopolymer, by twin-screw extrusion and thereafter shaped into films using a cast-roll machine. The resultant bio-HDPE films containing GA were characterized in terms of their mechanical, morphological, and thermal performance as well as ultraviolet (UV) light stability to evaluate their potential application in food packaging. The incorporation of 0.3 and 0.8 phr of GA reduced the mechanical ductility and crystallinity of bio-HDPE, but it positively contributed to delaying the onset oxidation temperature (OOT) by 36.5 °C and nearly 44 °C, respectively. Moreover, the oxidation induction time (OIT) of bio-HDPE, measured at 210 °C, was delayed for up to approximately 56 and 240 min, respectively. Furthermore, the UV light stability of the bio-HDPE films was remarkably improved, remaining stable for an exposure time of 10 h even at the lowest GA content. The addition of the natural antioxidant slightly induced a yellow color in the bio-HDPE films and it also reduced their transparency, although a high contact transparency level was maintained. This property can be desirable in some packaging materials for light protection, especially UV radiation, which causes lipid oxidation in food products. Therefore, GA can successfully improve the thermal resistance and UV light stability of green polyolefins and will potentially promote the use of natural additives for sustainable food packaging applications.

Antioxidant depletion in high-density polyethylene (HDPE) geomembrane with hindered amine light stabilizers (HALS) in low-pH heap leach environment

2016 ◽  
Vol 53 (10) ◽  
pp. 1612-1627 ◽  
Author(s):  
R. Kerry Rowe ◽  
Fady B. Abdelaal
Keyword(s):  
High Pressure ◽  
Induction Time ◽  
High Density Polyethylene ◽  
Incubation Temperature ◽  
Low Ph ◽  
High Density ◽  
Residual Value ◽  
Heap Leach ◽  
Residual Values ◽  
Hindered Amine Light Stabilizers

Antioxidant depletion from a high-density polyethylene (HDPE) geomembrane with hindered amine light stabilizers (HALS) immersed in seven different low pH solutions is examined over a 3 year period. The examined solutions had the range of pH (0.5, 1.25, and 2.0) likely to encompass the pH of the leach solutions found in copper, nickel, and uranium heap leach pads. The metal concentration for these solutions is adopted from copper raffinate solutions. Additional solutions are investigated to examine the effects of field practices such as using surfactants in the leach solutions and pre-curing of the ores used to improve the metallurgical response of the ore. For the antioxidants detected by standard oxidative induction time (Std-OIT), there was a depletion to residual value of about 20% of the initial Std-OIT that varied depending on the incubation temperature and pH of the solution whereas decreasing the pH from 2 to 0.5 did not significantly affect the depletion rates of Std-OIT. The antioxidants detected by high-pressure oxidative induction time (HP-OIT) exhibited the fastest depletion in pH = 1.25 with the highest residual values followed by pH 2.0 and the slowest HP-OIT depletion was in pH = 0.5, but with the lowest residual values. Arrhenius modelling is used to predict the length of the antioxidant depletion stage for each solution based on both Std-OIT and HP-OIT.

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