Search

Currently, the mechanical performance reduction caused by excessive phosphorus content in the halogen-free flame-retardant EP has been an obstacle to its extensive application. This study presents the effective synthesis of a novel flame-retardant BDD with great efficiency, achieving an optimum phosphorus level of merely 0.25 wt %. The structure of BDD was verified by FTIR, 1H NMR, 31P NMR and XPS spectra. To investigate the flame-retardant properties of BDD, several EPs with various phosphorus levels were synthesized. The addition of phosphorus to the EP significantly increases its LOI value from 25.8% to 33.4% at a phosphorus level of 0.25 wt%. Additionally, the resin achieves a V-0 grade in the UL 94 test. The P-HRR and THR of the modified resin measured by the cone calorimeter are also significantly reduced. At the same time, the addition of a modest quantity of BDD has a minimal impact on the mechanical properties of epoxy resin. This study shows that the removal of hydroxyl groups significantly enhances the fire resistance of phosphate-based flame retardants, thereby providing a novel approach to synthesizing efficient flame retardants. [ABSTRACT FROM AUTHOR]

The synergistic flame retardant system consisted of intumescent flame retardant (IFR) and organic modified attapulgite (OATP) synergist was used to improve the mechanical properties and flame retardancy of continuous glass fibre reinforced polyethylene composites (GFPE). The IFR was composed of ammonium polyphosphate (APP) as acid source and poly(1,3-diaminopropane-1,3,5-triazine-o-bicyclic pentaerythritol phosphate) (PDTBP) as carbon source. The mechanical properties (tensile strength) of GFPE/IFR/OATP were improved by 35%–43% after adding OATP synergist with rod-like fiber structure due to its strengthening and toughening effect on the resin matrix, and the flame retardancy increased first and then decreased with the increase of OATP synergist loading. When 4 wt% OATP synergist was added into GFPE/IFR, the LOI value increased from 29.5% to 31.3% and the flame spread rate significantly reduced. The synergistic flame retardant system of IFR/OATP could form a stable and dense char layer on the surface of glass fibre and weaken the wicking actions of glass fibre. The synergistic flame retardant system of 26 wt% IFR/4 wt% OATP could endow GFPE with best comprehensive performance. [ABSTRACT FROM AUTHOR]

A novel intumescent flame retardant (IFR) system composed of ammonium polyphosphate and poly (1,3-diaminopropane-1,3,5-triazine-o-bicyclic pentaerythritol phosphate) (APP/PDTBP) was mixed with polyethylene to prepare the continuous glass fibre reinforced polyethylene (CGF/PE) unidirectional prepregs by melt impregnation process, and then the CGF/PE/IFR composite laminate were consolidated by hot compression moulding method. The flame retardancy, thermal stability and mechanical properties of CGF/PE/IFR composite laminates were investigated by limiting oxygen index, vertical burning test, cone calorimetric test, thermogravimetric analysis, tensile and flexural strength tests, mode I interlaminar fracture toughness test, and scanning electron microscopy (SEM). The flame retardancy of CGF/PE composite laminates increased with the increase of IFR system loading, which attributes to the formation of intumescent char layer from flame retardants and the weakening of wicking actions of glass fibres. The mechanical properties increased and then decreased with addition of flame retardants, except for the flexural strength with continuous increase. The SEM images showed that IFR system had toughening effect and could improved the strength of fibre-matrix interface. Based on the mechanical properties and the flame retardancy, when the matrix contains 30 wt% IFR system, the CGF/PE/IFR composite laminate had the best comprehensive performance. Image 1 [ABSTRACT FROM AUTHOR]