Preparation of borate-modified expandable graphite and its flame retardancy on acrylonitrile-butadiene-styrene resin

Abstract

A borate-modified expandable graphite (written as MEG) was prepared through one step intercalating reaction of natural graphite, using KMnO 4 as oxidant, H 2 SO 4 and sodium tetraborate as intercalator and assistant intercalator, respectively. The dilatability, structure, element contents, thermal stability, and flame retardancy on acrylonitrile-butadiene-styrene (ABS) were investigated. Compared with the normal expandable graphite (written as EG, which was prepared with only H 2 SO 4 as intercalator), the results show that MEG exhibits higher expandable property, thermal stability and flame retardancy on ABS. The EDS, FT-IR, and XRD results reveal that borate has been inserted into graphite layers. With the addition of MEG or EG at a 30 wt%, LOI of 70ABS/30MEG composite improved to 27.9%, 2.2% higher than that of 70ABS/30EG. Moreover, the synergistic effect between MEG and traditional intumescent flame retardant (IFR, consists of ammonium polyphosphate (APP), pentaerythritol (PER), and melamine (MEL) with a mass ratio of 7.5:4.5:3.0) improves the LOI of 70ABS/15MEG/15IFR composite to 32.6%, and the UL-94 level reaches V-0. This synergistic efficiency is attributed to the formation of continuous and compact residual char. Addition of MEG together with IFR changes the ABS pyrolysis behavior, and there is not only physical synergy, but also chemical reaction. POLYM. COMPOS., 37:2673-2683, 2016.

Effect of different size‐modified expandable graphite and ammonium polyphosphate on the flame retardancy, thermal stability, physical, and mechanical properties of rigid polyurethane foam

“…In addition, CO 2 , H 2 O, and SO 2 gases released in the redox reaction between graphite and H 2 SO 4 /HSO 4 − can dilute the concentration of flammable gas in the flame . Because of its excellent performance, EG is widely used as a flame retardant additive for polymer materials such as ethylene vinyl acetate (EVA) , polyolefin , acrylonitrile‐butadiene‐styrene (ABS) , epoxy resin , and silicone rubber . However, the used EG is commodity, and it is prepared by using H 2 SO 4 as an intercalating agent, which makes the GIC usually contain high levels of sulfate and release more SO 2 gas during combustion.…”

Structure and thermal property of intumescent char produced by flame‐retardant high‐impact polystyrene/expandable graphite/microencapsulated red phosphorus composite

“…As a commercially available inorganic intumescent flame retardant (IFR), expandable graphite (EG) can expand in the perpendicular direction and generate a vermicular structured layer when exposed to heat source. [5][6][7] In contrast with the traditional chemical IFR consisting of ammonium polyphosphate/pentaerythritol/melamine (APP/PER/MEL), EG has a series of advantages, such as low cost, low toxicity, and good water and corrosion resistance. However, the worm-like intumescent char generated by EG upon burning or heating is usually fragile and fluffy and easily destroyed by heat convection and flame pressure during combustion process.…”

Effect of graphene nanoplatelets structure on the properties of acrylonitrile–butadiene–styrene composites

“…Due to its outstanding mechanical and transport properties [10][11][12], in recent year graphene has attracted the attention of several researchers as a nanofiller for multifunctional composites. In fact, graphene-based nanocomposites are massively investigated [11,[13][14][15][16][17][18][19][20][21][22][23]. In particular, some studies on ABS with graphite/graphene as novel fillers were also reported.…”