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The aim of the study was to assess the usefulness of agricultural biomass residues as reinforcement in recycled polymer matrices. In this study, recycled polypropylene and high-density polyethylene composites (rPPPE) filled with three types of biomass residues, sweet clover straws (SCS), buckwheat straws (BS) and rapeseed straws (RS), are presented. The effects of the fiber type and the fibers content on the rheological behavior, mechanical properties (including tensile, flexural and impact strength), thermal stability and moisture absorbance were determined, in addition to morphological analysis. It was revealed that the addition of SCS, BS or RS increased the materials' stiffness and strength. The reinforcement effect increased as the loading of the fibers was increased, especially for BS composites in the flexural test. After the moisture absorbance test, it was found that the reinforcement effect slightly increased for the composites with 10% fibers but decreases with 40% fibers. The results highlight that the selected fibers are a feasible reinforcement for recycled polyolefin blend matrices. [ABSTRACT FROM AUTHOR]

In the current development of the plastics industry, the use of biodegradable and recycled plastics not only effectively reduces the volume of landfills and incineration but also significantly decreases environmental damage. However, the extensive application of biodegradable polylactic acid (PLA) is limited by its poor toughness and thermal properties. The study introduced recycled linear low-density polyethylene (R-LLDPE) and ethylene-octene copolymer (POE) to modify PLA, primarily based on their excellent toughness and thermal resistance. Furthermore, being a recycled material, R-LLDPE is economically advantageous and conforms to the ecological requirements of resource recycling. Therefore study introduced glycidyl methacrylate (GMA) and styrene (St) to synthesize the graft copolymer (R-LLDPE/POE)-g-(GMA-co-St) (RPGS). The RPGS serves as a modifier for PLA resin. The effects of different GMA amounts in RPGS on the properties and microstructure of PLA/RPGS blends were examined. The results illustrate that GMA was successfully grafted onto the molecular chains of R-LLDPE/POE (RP), with St acting as a "bridge" to enhance further the grafting efficiency of GMA on RP macromolecular chains. After introducing RPGS into the PLA matrix, the epoxy groups of GMA reacted with the terminal hydroxyl groups of PLA, significantly decreasing the particle size of the dispersed phase and closely integrating with the PLA matrix, hence greatly improving the compatibility between PLA and RP. With the increase of GMA amount, the optical, thermal, and hydrophobic properties of the blends were increased, while the flexibility first increased and then decreased. When the GMA amounts were 5 wt% in RPGS, the G d and G e of GMA reached optimal values of 2.55 % and 51 %, the blend exhibited the optimum overall properties: haze decreased to 28.3 %, light transmittance increased to 92.5 %, thermal decomposition temperature increased to 368.12 °C, and the Vicat softening temperature increased to 78.2 °C. While maintaining the tensile strength at 54.3 MPa, the notched impact strength and elongation at break increased to 10,182.4 J/m 2 and 231.7 %, respectively, with the matrix exhibiting significant shear yielding. The research presents an eco-friendly and efficient method for producing high-performance PLA-based materials, effectively addressing the shortcomings of PLA in toughness and thermal resistance. The modified materials had excellent mechanical and thermal capabilities while offering financial and environmental benefits. The development of this material is anticipated to enhance the industrial utilization of biodegradable and recycled plastics, offering essential support for attaining sustainable manufacturing and a circular economy., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2024. Published by Elsevier B.V.)

High-performance antennas operating at ultra-high frequency (UHF) are typically designed and fabricated using specialized radio frequency (RF) materials with low loss and consistent properties. This paper proposes and investigates the use of recycled polyolefin (high-density polyethylene and polypropylene) which is not specifically manufactured for RF applications and thus with unknown RF properties, as dielectric substrate for high-performance UHF patch antennas. As a demonstrative application, a polarization-reconfigurable patch antenna with dual feeds is designed and fabricated using adhesive copper foil on recycled polyolefin substrate. Depending on the feed's magnitude and phase, different types of linear and circular polarizations can be achieved. The point of resonance for both ports is centered at 915 MHz with 10 dB return loss and bandwidth of 28 MHz. Port isolation is as low as −17 dB with peak linear and circular gain of 7.0 dBi, and 7 dBiC, respectively, observed in all polarizations. The resulting antenna not only performs well, but is also lightweight, low moisture absorbent, mechanically sturdy, inexpensive and ecologically friendly arising from its use of recycled materials. [ABSTRACT FROM AUTHOR]

The use of virgin and recycled plastic macro fibers as reinforcing elements in construction materials has recently gained increasing attention from researchers. Specifically, recycled fibers have become more attractive owing to their large-scale availability, negligible cost, and low environmental footprint. In this work, we investigate the benefits related to the use of fully-recycled synthetic fibers as dispersed reinforcement in Fiber Reinforced Cement Composites (FRCCs). In light of the reference performance of FRCCs including virgin polypropylene (PP) fibers only, the mechanical response of composites reinforced with polyolefin filaments treated with a sol-gel silica coating and polyethylene terephthalate (PET)/polyethylene (PE) cylindrical draw-wire fibers is here assessed through three-point bending tests. Remarkably, recycled polyolefins lead to a notable enhancement in terms of peak strength and post-crack energy dissipation capability. This improvement is ascribed to both the flattened shape of fibers and the surface coating, which turns out to be very effective at strengthening the fiber-to-matrix bond. On the other hand, PET/PE fibrous reinforcement generally leads to a lower toughness, if compared to the virgin fibers. However, no reduction in terms of peak stress is evidenced. Balancing the significance of mechanical performance and environmental sustainability in the framework of a circular economy approach, both fully-recycled fibers at hand can be regarded as promising candidates for innovative structural applications.

This work investigated the effects of date palm leaf fiber (DPLF) content on the thermal and tensile properties; and morphology of compatibilized polyolefin ternary blend. Recycled polyolefin ternary blend consisting of low density polyethylene (RLDPE), high density polyethylene (RHDPE) and polypropylene (RPP) were fabricated at different parts per hundred resin (phr) of DPLF. Maleic anhydride grafted polyethylene (MAPE) was used as compatibilizer to enhance the adhesion between filler and polymer matrix. The composites were prepared using melt extrusion and tests samples were produced via injection molding process. Thermal conductivity results showed that as much as 11 % reduction in thermal conductivity was achieved with the incorporation of 30 phr DPLF. Highest tensile strength was observed with the incorporation of 10 phr DPLF. The elongation at break was reduced with the addition of DPLF due to impediment of chain mobility by the fillers. Initial degradation temperature increased with the addition of DPLF. Hence, it is concluded that DPLF can be used to develop green and thermally insulating composites. It is hoped that the present results will stimulate further studies on the thermally insulative materials based on natural fibers reinforced polymer composites for applications in the building industries. [ABSTRACT FROM AUTHOR]

Abstract: Products manufactured from recycled polyolefin blends were subjected to accelerate weathering conditions and subsequent tests. Field-aged products were also tested. Samples were analysed for changes in mechanical, rheological and chemical properties. Data obtained in this study, by means of tensile, impact, and melt flow tests, GPC, gloss and colour analyses showed that the effect of UV exposure, whether in the field or artificial environments, was not significant as far as the mechanical properties of the materials were concerned. There was some change in the surface characteristics but such surface effects would not compromise the mechanical integrity of the product when recycled. During reprocessing of the materials, it is likely that stabilizer is redistributed at the surface of any new moulding, thus renewing the surface characteristics. Hence damaged or end-of-life products need not be discounted from recycling. [Copyright &y& Elsevier]

The use of virgin and recycled plastic macro fibers as reinforcing elements in construction materials has recently gained increasing attention from researchers. Specifically, recycled fibers have become more attractive owing to their large-scale availability, negligible cost, and low environmental footprint. In this work, we investigate the benefits related to the use of fully-recycled synthetic fibers as dispersed reinforcement in Fiber Reinforced Cement Composites (FRCCs). In light of the reference performance of FRCCs including virgin polypropylene (PP) fibers only, the mechanical response of composites reinforced with polyolefin filaments treated with a sol-gel silica coating and polyethylene terephthalate (PET)/polyethylene (PE) cylindrical draw-wire fibers is here assessed through three-point bending tests. Remarkably, recycled polyolefins lead to a notable enhancement in terms of peak strength and post-crack energy dissipation capability. This improvement is ascribed to both the flattened shape of fibers and the surface coating, which turns out to be very effective at strengthening the fiber-to-matrix bond. On the other hand, PET/PE fibrous reinforcement generally leads to a lower toughness, if compared to the virgin fibers. However, no reduction in terms of peak stress is evidenced. Balancing the significance of mechanical performance and environmental sustainability in the framework of a circular economy approach, both fully-recycled fibers at hand can be regarded as promising candidates for innovative structural applications. [ABSTRACT FROM AUTHOR]