Functionalized Graphene and Carbon Materials as Additives for Melt‐Extruded Flame Retardant Polypropylene

Abstract

Functionalized graphene nanosheets TRGO and MLG 250, prepared from thermally reduced graphite oxide, represent attractive carbon additives for improving the performance of flame retardant polypropylene (PP‐FR). The influence of carbon nanofiller type and content on morphology, thermal, mechanical, and electrical properties as well as the fire behavior of melt‐extruded PP‐FR is investigated. In contrast to conventional nano‐ and micron‐sized carbon fillers such as expanded graphite (EG 40), nano‐scaled carbon black (CB), and multiwall carbon nanotubes (CNT), only TRGO and MLG 250 afford uniform dispersion combined with simultaneously improved stiffness (+80%), electrical conductivity (3 × 10−5 S · cm−1) and enhanced flame retardancy of PP‐FR, as expressed by lower peak heat release rate (−76%).

Thermoplastic Carbon/Polyamide 12 Composites Containing Functionalized Graphene, Expanded Graphite, and Carbon Nanofillers

“…a)n.d., not determined. The bulk conductivity of CB and CNT was not measurable owing to the inherent test specimen brittleness; values for CNT, CB, and pristine graphite are adapted from previous publications …”

“…The pure carbon compounds were characterized by bulk conductivity measurements using compression‐molded specimens (7.4 kbar, pressure detention period 2 min, specimen diameter 13 mm, specimen thickness 0.30–0.45 mm). The electrical filler resistivity was detected by a four‐point measurement (electrode distance 2.5 mm) and converted into specific electrical conductivities, taking into account a correction factor regarding the spherical sample geometry . The resistivity of carbon filler/PA 12 nanocomposites was detected using injection molded DMA test specimens (50 × 6 × 2 mm 3 ).…”

Graphene-based flame retardants: a review

“…Dittrich et al [30] and Hofmann et al [43] incorporated layered highly exfoliated thermally reduced graphene (TRGO), layered minor exfoliated-expanded graphite (EG40), spherical carbon black (CB) and multiwall carbon nanotubes (MWNT) into polypropylene (denoted as PP) at various concentrations between 0.5 and 7.5 %. They found that the effect of the fillers on the thermal stability, flow behaviour, burning behaviour and flame resistance of the polymer depends on the concentration and morphology of the fillers.…”

Effects of hydrotalcites and tris (1-chloro-2-propyl) phosphate on thermal stability, cellular structure and fire resistance of isocyanate-based polyimide foams

“…The data for ignition time (IT), peak of heat release rate (PHRR), total heat released (THR) and total smoke production (TSP) was taken at flameout. Flameout was defined as the extinguishment of the visible yellow flame [23]. The density of PIFs after the postcuring process was determined by drainage method.…”