Microwave‐Assisted Confining Flame‐Retardant Polypropylene in Carbon Nanotube Conductive Networks for Improved Electromagnetic Interference Shielding and Flame Retardation

Abstract

Electrical conductive polymer composites (CPCs) with segregated structure can achieve better electrical conductivity with low content of conductive filler. Nevertheless, the undesirable properties of these CPCs, such as ease of burning, high smoke generation, weak interfacial adhesion, and poor mechanical performance, have restricted their practical applications. Herein, a promising microwave‐assisted strategy is developed for the fabrication of a flame‐retardant and electrically conductive polypropylene/ammonium polyphosphate/carbon nanotube (PP/APP/CNT) composite. Highly conductive networks can be set via the microwave‐selective heating, which results in an electromagnetic shielding effectiveness (EMI SE) of 32.1 dB of the composite with 7 wt% content of CNTs. Furthermore, the conductive segregated CNT network also serves as an excellent char‐forming agent to enhance the nonflammability and overcome the melt dripping issue of the pure PP matrix. As a result, the segregated conductive PP composites with 7 wt% CNTs and 15 wt% APP exhibit melt dripping and prompt self‐extinguishment, achieving the V‐0 rating level in the UL‐94 test. In brief, the well‐defined microwave‐assisted process provides a promising approach to fabricate various CPCs with simultaneously improved EMI shielding and flame‐retarding properties.

Enhanced Electromagnetic Shielding and Thermal Conductive Properties of Polyolefin Composites with a Ti3C2Tx MXene/Graphene Framework Connected by a Hydrogen-Bonded Interface

“…In order to compare our results with previously reported polyolefin composites based on the same criteria, the value of SSE/t per 1 wt % of filler (SSE: specific SE) was calculated by eq : where SE is the measured SE T , t is the sample thickness (1.85 mm for M- o -GWF/PE), ρ is the density (0.94 g cm –3 for M- o -GWF/PE), and w is the filler content (2.98 wt % for M- o -GWF/PE). As a result, Figure i and Table S3 show the superiority of our M- o -GWF/PE composites, which have a high SSE/t per 1 wt % of filler of 11 742 dB cm 2 g –1 , compared to other polyolefin (PE and PP) composites filled with graphene, carbon nanotubes, and their hybrids. ,,− Accordingly, we conclude that the excellent EMI SE of M- o -GWF/PE composites can be attributed to two main reasons. First, by premodifying MXene nanosheets on the surface of seamless GWFs, followed by the “folding–hot pressing” process, we constructed a multilayered MXene conductive-enhanced continuous graphene network inside PE composites, as illustrated in Figure j.…”

Phosphorus–Oxygen-Codoped Graphitic Carbon Nitride for Enhanced Hydrogen Evolution and Photocatalytic Degradation under Visible Light Irradiation

“…30,34 Thus, it is desirable to seek a new precursor to ameliorate pristine CN. Ammonium polyphosphate (APP), 35 a low-cost 36 and environmental friendly 37 inorganic salt, is commonly used as a commercial intumescent flame retardant for metal batteries, 38 vinyl ester matrix composites, 39 flame-retarding resin, 40 hydrogels, 41 water-based hybrid coatings, 42 etc. Its excellent flame-retarding property is conferred by the endothermic process of APP decomposition and the generation of ammonia and water, which dilute the combustible gases during combustion.…”

“…Ammonium polyphosphate (APP), a low-cost and environmental friendly inorganic salt, is commonly used as a commercial intumescent flame retardant for metal batteries, vinyl ester matrix composites, flame-retarding resin, hydrogels, water-based hybrid coatings, etc . Its excellent flame-retarding property is conferred by the endothermic process of APP decomposition and the generation of ammonia and water, which dilute the combustible gases during combustion. − Therefore, in a pyrolysis process, APP could work as the evaporable source. , With a high phosphorus content, APP is also a good precursor to fabricate phosphorus-doped materials …”

Hollow Nanospheres of Red Phosphorus for Fireproof Flexible Sensors Fabricated via 3D Printing

“…The addition of flame retardants (FRs) into CPC can help hinder the burning tendency and create the possibility for continuous good running, but the choice of proper counterparts is intractable. A considerably high loading and toxicity of flame retardants would restrict the construction of conductive networks and deteriorate the processing features of the composites . Several halogen FRs with high efficiency have already been banned in electrical and electronic equipment by RoHS directive issued by the European Union, whereas the substitutes perform worse and are not suitable for improving the highly strict flame retardancy of strain sensors .…”

“…A considerably high loading and toxicity of flame retardants would restrict the construction of conductive networks and deteriorate the processing features of the composites. 2 Several halogen FRs with high efficiency have already been banned in electrical and electronic equipment by RoHS directive issued by the European Union, whereas the substitutes perform worse and are not suitable for improving the highly strict flame retardancy of strain sensors. 3 Guo et al prepared an electronic sensor based on epoxidized natural rubber exploiting phytic acid (PA) as a green curing agent to improve the flame retardancy.…”