Molybdenum disulfide (MoS 2 ) with two-dimensional (2D) lamellar structure was functionalized with melamine-cyanuric acid (MCA) hybrids via a facile way. A core-shell composite particle (MoMA) was obtained. Acting as one kind of synergistic flame retardant, it was mixed with traditional intumescent flame retardant (IFR) to prepare the flame retardant poly(lactic acid) composites by melt blending. UL-94 V-0 rating and LOI value of 29.8% for PLA composites were achieved while the total amount of flame retardants was 12 wt%, with the optimal weight ratio of IFR to MoMA 3:1. The inclusion of MoMA can enhance the amount of char residue and suppress the pyrolysis rate. The thermal degradation kinetic studies indicated that more pyrolysis conversion energy was needed. Finally, the investigation of char residue further confirmed that the addition of MoMA can improve the continuity and thermal stability of intumescent char layer and promote its graphitization degree. The condensed phase mechanism was mainly responsible for the improved flame retardant performance. This work suggests a novel strategy for improving flame retardant performance of PLA by combination of MoMA with IFR. The mechanical properties were studied as well.
In this research, water-swellable rubbers (WSRs) were prepared by the blending of acrylonitrile butadiene rubber (NBR) with epoxidized acrylonitrile butadiene rubber (ENBR), precipitated silica, vulcanizing agents, and polyacrylic acid sodium (PAAS) as superabsorbent polymers (SAPs). ENBR was prepared with a molybdenum trioxide catalyst and a tert-butyl hydroperoxide oxidant through a free-radical reaction under specific conditions and was used as a compatibilizer to improve the interfacial adhesion of the NBR matrix and hydrophilic components of the WSRs. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to analyze the structure and properties of ENBR. The dispersion of silica and SAPs in the rubber matrix was investigated by transmission electron microscopy. The presence of ENBR enhanced the water-absorption properties of the WSRs. The NBR-ENBR composites exhibited a higher mechanical performance after water absorption than that without ENBR. Both the swelling ratio and the absorption rate increased with the ENBR content. When the weight ratio of NBR-ENBR was 25/75, an equilibrium swelling ratio of 172% (13% higher than that of the sample without ENBR) was obtained. Scanning electron microscopy analysis revealed that the addition of ENBR improved the compatibility between the SAPs and the NBR matrix.
The utilization of waste fibers represents an important environmental benefit and great economic savings for the community. In this study short nylon fibers waste was modified with Glycidyl 3-Pentadecenyl Phenyl Ether (GPPE) in the presence of Triethylamine/Ammonium persulfate by a simple two-step procedure. The reinforcing effects of modified fibers (MNSF-2) on the vulcanization characteristics, mechanical properties, dynamic mechanical properties, and the wear resistant property of Styrene Butadiene Rubber (SBR) tread compounds were investigated. The addition of the MNSF-2 resulted in slightly lower minimum torque (ML) and maximum torque (MH), as well as longer cure time (t90) and scorch time (t10) of tread compounds. The deterioration of tensile strength and elongation at break of the tread compound containing short nylon fibers waste (NSF) was apparent. Conversely, the modified fibers showed reinforcing effect on tread compounds. The tensile strength values of compounds increased with MNSF-2 content, passed through a maximum value, and then reduced slightly. The modulus and the tear strength of compounds increased significantly with fiber loadings. The highest tear strength value was observed in 8phr MNSF-2 reinforced SBR compounds, 31.9% higher than that of the gum compound. Meanwhile elongation at break of MNSF-2 compound maintained a relative high value than that of NSF/SBR compound. The addition of NSF exaggerated wear volume of compounds. However, the wear resistance of MNSF-2 compounds was superior to that of NSF compounds and comparable with that of the gum compound. The DMA results reveal that E′ and tanδ values decreased at elevated temperature. Meanwhile enhanced storage modulus in MNSF-2/SBR tread compound can be observed. It is worth highlighting that MNSF-2/SBR compounds show higher tanδ at 0°C, indicating improved wet traction of tread compounds, while tanδ at 60°C maintains almost the same value as that of the gum sample. The results of this study are encouraging, demonstrating that the use of short nylon fibers waste in composites offers promising potential for the green tire application.
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