Combination of fumed silica with carbon black for simultaneously improving the thermal stability, flame retardancy and mechanical properties of polyethylene

Release and toxicity assessment of carbon nanomaterial reinforced polymers during the use and end-of-life phases: A comparative review

The research on carbon-based nanomaterial (C-NM) composites has increased in the last two decades. This family of functional materials shows outstanding mechanical, thermal and electrical properties, and are being used in a variety of applications. An important challenge remains before C-NM can be fully integrated in our production industries and our lives: to assess the release of debris during production, use, and misuse of composites and the effect they may have on the environment and on human health. During their lifecycle, composites materials can be subjected to a variety of stresses which may release particles from the macroscopic range to the nanoscale. In this review, the release of debris due to abrasion, weathering and combustion as well as their toxicity is evaluated for the three most used C-NM: Carbon Black, Carbon Nanotubes and Graphene-related materials. The goal is to stimulate a Safe-By-Design approach by guiding the selection of carbon nano-fillers for specific applications based of safety and performance.

Upcycling Waste Polyethylene into Carbon Nanomaterial Via A Carbon-Grown-On-Carbon Strategy

Upcycling waste plastics (e.g., polyethylene (PE)) into value-added carbon products is regarded as a promising approach to address the increasingly serious waste plastic pollution and simultaneously achieve carbon neutrality. However, developing new carbonization technology routes to promote the oxidation of PE at low temperature and construct the stable crosslinking network remains challenging. Here, we propose a facile carbon-grown-on-carbon strategy using carbon black (CB) to convert waste PE into core/shell carbon nanoparticles (CN) in high yields at low temperature. The yield of CN remarkably rises when the heating temperature decreases or the dosage of CB grows. The obtained CN displays turbostratic structure and closely aggregated granular morphology with a size of ca. 80 nm. It is found, prior to the oxidation and carbonization of PE, CB forms a 3D network architecture in the PE matrix. More importantly, CB not only catalyzes the partial oxidation of PE to form PE macromolecular radicals and introduce oxygen-containing groups at low temperature in the early stage, but also favors for the construction of a stable crosslinking network in the latter stage. This work offers a facile sustainable strategy for chemical upcycling of PE into value-added carbon products without post-treatments or usage of metallic catalysts. This article is protected by copyright. All rights reserved.

Preparation of LDHs Based on Bittern and Its Flame Retardant Properties in EVA/LDHs Composites

Bittern, as a byproduct of salt manufacture, is abundant in China. The researches and developments for seawater bittern have mainly focused on the reuse of magnesium, calcium, lithium, and boron. However, the utilization rate is less than 20%. The large amount of unused bittern has become a challenge that attracts much attention in academic and industry areas. In this paper, three kinds of layered double hydroxides (LDHs) were synthesized from bittern using a coprecipitation method and characterized by X-ray diffraction (XRD). The XRD results showed that the three kinds of LDHs(MgAl-LDHs, MgFe-LDHs and MgAlFe-LDHs) were successfully synthesized. Then, the flame retardant properties and thermal properties of the three LDHs in ethylene vinyl acetate (EVA)/LDHs composites had been tested by cone calorimeter test (CCT), limiting oxygen index (LOI), smoke density test (SDT), and thermogravimetry-Fourier transform infrared spectrometry (TG-IR). The CCT results showed that the heat release rate (HRR) of all three kinds of EVA/LDHs composites significantly decreased compared with that of pure EVA, and the EVA/MgAl-LDHs composites had the lowest PHRR value of 222.65 kW/m2. The LOI results showed that EVA/MgAl-LDHs composites had the highest LOI value of 29.8%. The SDT results indicated that MgAl-LDHs were beneficial to smoke suppression. TG-IR results showed that EVA/MgAl-LDHs composites had a better thermal stability.

In situ growth of 0D silica nanospheres on 2D molybdenum disulfide nanosheets: Towards reducing fire hazards of epoxy resin

This report described a facile process for the preparation of 2D/0D MoS₂-SiO₂ hybrids using a simple in situ growth method, with the purpose of promoting the dispersion of MoS₂ in polymer matrices and improving the properties of polymer materials. FTIR, XPS, TGA and TEM measurements were performed to characterize the structure and morphology of the synthesized hybrids which were then introduced into epoxy to reduce flammability. The hybrids dispersed well in the epoxy matrix. No obvious agglomerations were observed. In comparison with those of neat epoxy, the incorporation of a low loading of MoS₂-SiO₂ hybrids resulted in significant decrements in heat release rate, total heat release and volume of toxic effluents released during combustion, which indicated that the fire hazards of epoxy composites were strongly reduced. The good dispersion, labyrinth barrier effect and the catalytic effect of MoS₂-SiO₂ hybrids on char formation may contribute to the observed decrease in the flammability of epoxy resin.

Synthesis of a highly efficient phosphorus-containing flame retardant utilizing plant-derived diphenolic acids and its application in polylactic acid

A highly efficient phosphorous-containing flame retardant for PLA is synthesized from plant-derived diphenolic acids.

Synergistic effect of carbon fibers and carbon nanotubes on improving thermal stability and flame retardancy of polypropylene: a combination of a physical network and chemical crosslinking

CFs and CNTs showed a synergistic effect on significantly improving the thermal stability and flame retardancy of PP.

Simultaneously improving the thermal stability, flame retardancy and mechanical properties of polyethylene by the combination of graphene with carbon black

A novel combination of GNS with CB was demonstrated to improve thermal stability, flame retardancy and mechanical properties of LLDPE.