Relationship between structure, properties and UV/Heat protection behavior of two different types of polyethylene manufactured in Qatar

Accelerated (artificial) weathering and thermal ageing tests were performed to investigate the effectiveness of different UV/HALS formulations in reducing the UV/heat degradation effect for two different low-density polyethylene grades with different structures because of production through two different production methods (autoclave and tubular reactors). Combinations of two commercial-grade HALS (Chimassorb 944 and Sabostab 119) and two UV absorbers (Chimasorb 81 and Tinuvin 1577) were introduced to both the LDPE grades at different loadings. The morphologies, as well as thermal and mechanical properties, of the investigated samples were determined through tensile and impact testing, gel permeation chromatography (GPC), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). All the results from the different characterization techniques showed a significant degradation for the unstabilized neat samples of both LDPEs, while little or no degradation was observed for the stabilized ones, confirming the effectiveness of the selected UV/HALS systems in improving the weathering resistance of the two LDPE grades and enhancing their useful lifetime. The GPC results showed that the LDPE-A contained significantly more long-chain branching (LCB) than the LDPE-T, implying that the LDPE-A was much more compact than the LDPE-T. Young’s modulus values for LDPE-T were much higher than those of LDPE-A, indicating a higher crystallinity of the LDPE-T samples. For the heat exposed samples, more brittle behaviour was observed for the LDPE-T samples. There was very little difference in the maximum tensile stress values of LDPE-A and LDPE-T, except for LDPE-T/UV3 where the σ value increased by about 9% after 12 months. LDPE-T was found to be thermally more stable than LDPE-A, even after long UV exposure times. For stabilized formulations, LDPE-A/UV8 seems to be the best formulation in terms of thermal stability whereas LDPE-T/UV8 was the least promising formulation. Generally, the UV/heat stabilized LDPE-A samples were thermally more stable than LDPE-T The carbonyl indices were similar for the two polymers, which means that the differences in polymer structure had little influence on the formation of carbonyl groups during the oxidative degradation proces

Enhancing the UV/heat stability of LLDPE irrigation pipes via different stabilizer formulations

Herein different stabilizer formulations of linear low-density polyethylene (LLDPE) against UV- and heat-initiated degradation are described. The project aims at outdoor applications, such as irrigation piping and profiles, in the Middle East desert regions, where long-term weathering stability due to high temperatures and solar radiation is important. Two UV/heat formulations, without and with carbon black (CB) as pigment, were incorporated into LLDPE by melt compounding. Neat LLDPE and the stabilized compounds were exposed to accelerated UV and heat aging. Morphological analysis through scanning electron microscopy of the UV-exposed neat LLDPE showed more severe surface cracking compared to the CB-containing LLDPE, while all stabilized compounds did not show any surface degradation. Crack formation was less visible for the thermally aged samples. A significant decrease in molecular weight (MW) was observed for the neat UV-exposed LLDPE, while both unpigmented stabilized compounds showed little change in MW. Mechanical properties, thermal analysis, and carbonyl index results supported the morphological results, which confirmed that CB alone was slightly more effective in protecting the LLDPE against UV initiated degradation, but performed worse against thermal initiated degradation. UV1 and UV2 compounds were efficient against both UV- and heat-initiated degradation, with UV1 performing better for unpigmented compounds, and UV2 for the pigmented ones.This publication was made possible by the NPRP award (NPRP 9-161-1-030) from the Qatar National Research Fund (a member of The Qatar Foundation). We are also grateful to BASF and Sabo for supplying the additives at no cost. We further express our gratitude to Dr. Robert Brüll from Fraunhofer LBF, Darmstadt, Germany for doing the GPC analyses on our samples. The statements made herein are solely the responsibility of the author(s).Scopu

Activated Algerian kaolins as low-coast potential adsorbents for the removal of Derma Blue R67 acid dye

International audienceThere are significant amounts of unused dyes remaining in wastewater from dyeing industry. The release of these effluents causes abnormal coloration of surface waters and there is a risk of toxicity. This research involved the efficient adsorption of anionic dyes (Bleu Derma R67) by local natural and treated clay; Djebel Debagh (DD3) and Tamazert (KT2) a low-cost materials abundant in highly weathered soils from Algerian East. Adsorption experiments were accomplished using acid dye adsorbed on activated kaolins (DD3 and KT2) by acid treatment. These two clays were first treated by acid in order to enhance their retention capacities, and then characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), surface area measurements (BET method), surface charge (PZNPC), and electrophoretic mobility (Zetaphoremeter). Preferred format: Poster Session number and name: B2 : Environment and geological process "The role of clays and modified clays in remediating environmental pollutants"

Synthesis of nanocrystalline NiAl by mechanically activated self-propagating high-temperature synthesis and mechanically activated annealing process

The mechanically activated self-propagating high-temperature synthesis (MASHS) technique and the mechanically activated annealing process (M2AP) were used to produce NiAl intermetallic compound. Rietveld analysis of X-ray diffraction data was used to characterize the mechanically activated powders, MASHS and M2AP end-products. Two-phase (B2+L12) nickel aluminide intermetallic compounds were synthesized by the mechanically activated volume combustion synthesis (MASHS). A single phase B2 NiAl was formed when mechanically activated annealing process (M2AP) was performed. Starting from a mixture of elemental pure powders, both M2AP and MASHS milling processes lead to nanostructured powders. Structural analysis deduced from the Rietveld refinement of X-ray diffraction patterns of NiAl compounds synthesized by SHS after a milling of 6 h show the formation of β-NiAl phase with a cell parameter a = (0.2885 ± 1.2618 × 10−4) nm. The average crystallite size is D = (44.6421 ± 2.4263) nm and the microstrains values are close to those of metallic alloys τ = (0.2142 ± 1.6186 × 10−2)%. Finally, scanning electron microscopy (SEM) was carried out to characterize the microstructure of end-products

A novel alternative to free oil remediation and recovery: Foamy absorbents designed from low molecular paraffinic waste

This study focuses on preparing porous, hydrophobic, and oleophilic hydrocarbon-based foams applicable for removing free oils from water surfaces. Paraffinic waste material generated during industrial production of low-density polyethylene (Qatar Petrochemical Company) was used for the preparation of foamy, elastic structures through crosslinking of short aliphatic chains by dicumyl peroxide and foaming by 1,1′-azobiscarbamide. The porosity of the foam determined by computer microtomography was 58.9%, and the bulk density was 0.42 g.cm−3. The sorption ability of the foam was tested using diesel oil, motor oil, and heavy crude oil. The absorption capacity of foam was characterized as the ratio between the mass of oil absorbed by the foam and the mass of a neat foam (Sw) and as the ratio between the volume of oil absorbed by the foam and the volume of a neat foam (Sv). The absorption capacities of the new foam reported in this study (referred to here as Qwax foam) are 6.6 ± 0.3 g/g, or 3.3 ± 0.2 cm3/cm3 for diesel oil, 3.9 ± 0.4 g/g or 1.9 ± 0.3 cm3/cm3 for motor oil, and 3.4 ± 0.2 g/g or 1.4 ± 0.4 cm3/cm3 for crude oil. To compare the sorption ability of Qwax foam with some standard foams, the absorption capacities of highly porous commercial polyurethane (PU) and melamine (MA) foams were investigated under the same conditions. These foams showed much higher sorption capacity considering the Sw parameter as a reference; however, there was a lower sorption capacity compared to parameter Sv. In the last paragraph, the suitability and the relevancy of parameters Sw and Sv for a comparison of the absorption capacity of foams were theoretically analyzed. © 2022 Elsevier B.V.RP/CPS/2020/003; Qatar National Research Fund, QNRF: NPRP12S-0311-190299; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠM