Photooxidative degradation of graphene‐reinforced high‐density polyethylene nanocomposites

Shehzad, Farrukh; Ahmad, Muhammad Shakil; Al‐Harthi, Mamdouh A.

doi:10.1002/app.47030

Cited by 10 publications

(7 citation statements)

References 46 publications

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“…The transformations of molecular structure and functional groups changed the absorption and reflection of the material to the spectrum, which led to the discoloration and cracking of the coating [19]. The variation on microscopic morphology and molecular weight of HDPE samples were studied and compared by differential scanning calorimetry (DSC) and crystallization fractionation [20]. The results indicate that molecular chain breakage and molecular weight reduction appeared in samples with exposure time.…”

Section: Introductionmentioning

confidence: 99%

Differential Distribution Analysis and Region and Grade Regulation on Auto-Parts Weathering External Factors with Non-Uniform Thermal Environment

2020

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It is difficult to comprehensively master and precisely regulate the external factors distribution of automobile weathering in non-uniform thermal environment as well as the consequent disequilibrium weathering problem, while exploring weather-resistant materials in uniform thermal environment. Thus, a numerical calculation method for the weathering external factors is proposed, on the basis of annual experimental study on the outdoor weathering inconsistencies of auto-parts. The time–space distribution characteristics and day–night variation rules of the external factors are studied, and the disequilibrium weathering mechanism among parts is revealed from the perspective of non-uniform distribution of external factors. The laws of automotive physical parameters, orientations and locations, as well as their influences on external factors distribution are analyzed in detail, and hereby the targeted schemes to effectively reduce the local external factor intensity and the thermal gradient between parts are investigated. The method can be used to rapidly predict weathering external factors distribution of vehicle exposed to outdoor in any direction during day and night, so as to provide auto-parts with differentiated test schemes in accelerated tests and IP/DP box tests, and it also contributes to present some pertinence guidance for the accurate regulation of automobile disequilibrium weathering on regions at different levels.

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Section: Introductionmentioning

confidence: 99%

Differential Distribution Analysis and Region and Grade Regulation on Auto-Parts Weathering External Factors with Non-Uniform Thermal Environment

2020

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“…Figure 3A presents HDPE's FTIR absorption spectra at different UV exposure times. It can be seen from Figure 3A that UV exposure causes the appearance of new absorption peaks at 1715 and 1740 cm −1 , corresponding to internal ketones and ester groups, respectively 32,33 . Moreover, the shape and intensity of these peaks vary as a function of UV exposure time.…”

Section: Resultsmentioning

confidence: 97%

Photo‐stabilization mechanisms of High‐Density Polyethylene (HDPE) by a commercial few‐layer graphene

Karimi,

Helal,

Gutierrez

et al. 2023

Polymer Engineering & Sci

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This work studied few‐layer graphene (FLG) dominant action mechanisms as a photo‐stabilizer. High‐density polyethylene (HDPE) containing 0–0.5 wt% FLG were exposed to UVA radiation in a QUV chamber, according to ASTM G154 for different exposure times, ranging from 0 to 672 h. The chemical, rheological, and mechanical properties were tracked using attenuated total reflection‐Fourier transform infrared (ATR‐FTIR), rheological measurements, and tensile tests. The experimental results showed that the addition of only 0.25 wt% FLG fully stabilized 1‐ to 3‐mm thick HDPE for an exposure time of 672 h. Electron paramagnetic resonance (EPR) test was performed on the UV‐exposed mixture of hydrogen peroxide (H2O2) and the FLG aqueous suspensions (0, 0.2, 1, and 5 mg/mL), to study the FLG performance and mechanisms as a photo‐stabilizer. The results showed that FLG effectively decreased the characteristic EPR signal intensity due to both UV absorption/reflection and free radical scavenging. Fifty‐seven percent of the reduction was found to be due to UV absorption/reflection and 43% due to free radical scavenging. It is demonstrated that UV absorption/reflection and free radical scavenging are the dominant ones among the three FLG photo‐stabilizing mechanisms (UV absorption/reflection, free radical scavenging, and physical barrier to oxygen).Highlights FLG showed potential as a photo‐stabilizer for HDPE. Addition of 0.25 wt% FLG fully stabilized HDPE for 672 h of UVA exposure. FLG demonstrated UV absorption/reflection and free radical scavenging effects.

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“…High density polyethylene (HDPE) is one of the most frequently used thermoplastic materials in various fields such as pipelines and food packaging. Typically, PEs are not inherently prone to degradation in nature, but the existence of chromophores impurities including carbonyl and hydroperoxide functional groups, catalyst residues, and double bonds in their structure can substantially increase the degradation vulnerability 1,2 …”

Section: Introductionmentioning

confidence: 99%

Theoretical and experimental assessment of UV resistance of high‐density polyethylene: Screening and optimization of hindered amine light stabilizers

Davand

Rahimpour

Hassanajili

et al. 2021

J of Applied Polymer Sci

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Hindered amine light stabilizers (HALS) are widely used chemical stabilizers for preventing polymer degradation. In this study, the effects of type of HALS and its content in high‐density polyethylene (HDPE) over the stabilization process are investigated employing density functional theory (DFT) and experimental approach. The electrophilicity index of four types of commercial HALS are compared by DFT to select the most effective one. Besides, the HDPE sample containing a phenolic antioxidant and different contents of the selected HALS are experimentally exposed to UV irradiation. The effect of HALS content on the changes in chain microstructure and molecular weight of HDPE are evaluated using gel permeation chromatography and frequency sweep rheometry. In the absence of HALS, HDPE suffers degradation and the phenolic antioxidant causes chain scission. However, by adding HALS, the chain branching and crosslinking mechanisms are predominant. The results of FTIR, DSC, and tensile analyses follow similar trends, revealing that the best stabilization performance corresponds to adding 600 ppm HALS to HDPE.

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Photooxidative degradation of graphene‐reinforced high‐density polyethylene nanocomposites

Cited by 10 publications

References 46 publications

Differential Distribution Analysis and Region and Grade Regulation on Auto-Parts Weathering External Factors with Non-Uniform Thermal Environment

Differential Distribution Analysis and Region and Grade Regulation on Auto-Parts Weathering External Factors with Non-Uniform Thermal Environment

Photo‐stabilization mechanisms of High‐Density Polyethylene (HDPE) by a commercial few‐layer graphene

Theoretical and experimental assessment of UV resistance of high‐density polyethylene: Screening and optimization of hindered amine light stabilizers

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