Enhanced flame retardancy, smoke suppression, and acid resistance of polypropylene/magnesium hydroxide composite by expandable graphite and microencapsulated red phosphorus

Abstract

Low flame retardant efficiency and poor acid resistance of filled polymer composites are two main drawbacks of magnesium hydroxide (MH) as a flame retardant (FR). To solve these problems, expandable graphite (EG) and microencapsulated red phosphorus (MRP) were introduced into polypropylene/ magnesium hydroxide (PP/MH) composite by melt compounding. The obtained PP/MH/EG/MRP quadruple composite was studied regarding its fire behavior as well as acid resistance. Obvious flame retardant synergism among MH, EG, and MRP is found in PP, which diminishes the loading of FR from 63.0 to 37.5 wt% to obtain V-0 rating in UL-94 test and low smoke release.Compact intumescent char with high thermo-oxidative stability was generated on composite surface, which plays a vital role in flame retardancy. The removal of MH by acid erosion on PP/MH/EG/MRP composite surface does not affect production of intumescent char and fire behavior of this composite.

Concurrently improving fire safety and processability of ethylene vinyl acetate copolymer by expandable graphite and polyphosphoric acid

“…It is noteworthy that the average effective heat of combustion values of all the four EVA materials are all but identical despite the fact that they display vast distinction in fire retardance. This hints that the salient betterment of EVA/EG7.5/PPA2.5 composite in flame retardancy occurs in condensed phase rather than in gas phase 27,33 . Thus, the change of EVA composite in condensed phase plays a prominent role during combustion.…”

“…This hints that the salient betterment of EVA/EG7.5/PPA2.5 composite in flame retardancy occurs in condensed phase rather than in gas phase. 27,33 Thus, the change of EVA composite in condensed phase plays a prominent role during combustion. Figure 3 presents the effect of FR content on flammability of two distinct EVA composites.…”

“…For instance, the polypropylene/EG composite with 50 wt% EG still has no rating in UL-94 VBT. 27 Strong flame retardant synergism between EG and phosphorus-containing substances (such as ammonium polyphosphate, red phosphorus, phosphorus polyol, phytic acid, and so on) has been reported in many polymers due to gluing effect to expanded char, which can raise FRE of EG substantially. [23][24][25][26]28 In this work, EG and polyphosphoric acid (PPA) were introduced into EVA melt and the fire behavior, thermal endurance, water resistivity, processability and mechanical property of EVA/EG/PPA composite were investigated in detail.…”

“…Nonetheless, the FRE of EG is rather low by itself. For instance, the polypropylene/EG composite with 50 wt% EG still has no rating in UL‐94 VBT 27 . Strong flame retardant synergism between EG and phosphorus‐containing substances (such as ammonium polyphosphate, red phosphorus, phosphorus polyol, phytic acid, and so on) has been reported in many polymers due to gluing effect to expanded char, which can raise FRE of EG substantially 23–26,28 …”

Heat transfer prediction during curing of thick part of unsaturated polyester resin containing nanoparticles of graphene oxide and modified graphene oxide

“…2,3 Particles are used in polymers to improve their physical-mechanical properties, [4][5][6] thermal properties, [7][8][9] electrical conductivity, 10 and flame retardancy. [11][12][13] Therefore, the use of particles to improve the properties of unsaturated polyester resins (UPR) has always been the focus of researchers, because of their various industrial applications. Investigation of the effect of particles on the properties of UPR has often been conducted in parts with low thicknesses.…”