An investigation into synergistic effects of rare earth oxides on intumescent flame retardancy of polypropylene/poly (octylene‐co‐ethylene) blends

Abstract

Synergistic effects of two kinds of rare earth oxides (REOs), neodymium oxide (Nd2O3) or lanthanum oxide (La2O3) on the intumescent flame retardancy of thermoplastic polyolefin (TPO) made by polypropylene/poly (octylene‐co‐ethylene) blends were investigated systemically by various methods. The limiting oxygen index (LOI) of flame retardant TPO (FRTPO) filled by 30 wt% intumescent flame retardants (IFR) composed of ammonium polyphosphate (APP) and pentaerythritol (PER) has been increased from 30 to 32.5 and 33.5 when 0.5 wt% of IFR was substituted by La2O3 and Nd2O3, respectively. Cone calorimetry tests also reveal the existence of synergistic effects. Thermalgravimetric analyses (TGA) demonstrate that the presence of REOs promotes the esterification and carbonization process in low‐temperature range while enhances the thermal stability of IFR and FRTPO in high‐temperature range. X‐ray diffraction (XRD) reveals that the interaction of Nd2O3 with IFR results in the formation of neodymium phosphate (NdP5O14) with high‐thermal stability. Thermal scanning rheological tests show that the presence of REOs increases complex viscosity of FRTPO in the temperature range of 190∼300°C so as to suppress melt dripping but decreases the complex viscosity and increases the loss factors tan δ in temperature range of 300∼400°C to make the carbonaceous strucuture more flexible and viscous to resist stress, expand better and keep intact. Copyright © 2009 John Wiley & Sons, Ltd.

Intumescence: Tradition versus novelty. A comprehensive review

“…PPR has proved to exhibit more effective carbonization and a higher degree of graphitic network than that of free β-CD. A c c e p t e d M a n u s c r i p t 22 As far as starch is concerned, Wu and coworkers [93] prepared biodegradable PVA/glycerolplasticized thermoplastic starch (TPS) and then blended it with microencapsulated APP (MCAPP).…”

Influence of zinc borate on the flame retardancy and thermal stability of intumescent flame retardant polypropylene composites

“…To solve these problems, researchers have made great efforts to develop oligomeric or polymeric IFRs with relatively higher molecular weight and synergistic agent have been sued to enhance the flame retardancy of IFR [11][12][13][14]. The previous studies showed that some silicon-containing compounds, boron-containing compound, transitional metal oxides, 4A zeotile, metal compounds could serve as synergistic agents to increase the strength and stability of char layer to enhance the flame retardant performance of the composites [15][16][17][18][19][20][21][22][23].…”

“…The most researches about synergistic effect focused on the traditional IFR systems containing ammonium polyphosphate (APP)/ pentaerythritol (PER) or other char forming agent containing hydroxyl group [15][16][17][18][19][20][21][22][23]. However, the presentation of hydroxyl group in the IFR would deteriorate compatibility between the flame retardants and the matrix and increase the moisture sensitivity of the composites.…”

Synergistic effects of rare earth oxides on intumescent flame retardancy of Nylon 1010/ethylene-vinyl-acetate rubber thermoplastic elastomers

“…In this case, rare earth based-compounds may be a promising synergist for IFR to promote the formation of carbonaceous materials. Ren et al [19] investigated the synergistic effects of neodymium oxide (Nd 2 O 3 ) and lanthanum oxide (La 2 O 3 ) on the intumescent flame retardancy of polypropylene/poly (octyleneco-ethylene) blends filled by 30 wt% IFR composed of APP and PER. They found that the limiting oxygen index (LOI) of the blends has been increased from 30 to 32.5 and 33.5 when 0.5 wt% of IFR was substituted by La 2 O 3 and Nd 2 O 3 , respectively.…”