Flame Retardant Properties Of Composites Research Articles

Investigation on flame‐retardant, thermal and mechanical properties of glass fiber reinforced polyimide composites

AbstractComposites with excellent flame retardant and mechanical properties are in high demand in the aerospace and various industrial fields. Glass fiber (GF) reinforced polyimide (PI) composites (GFRPCs) were fabricated using a simple ball milling and hot pressing technique. The effect of GF content on the thermal stability, mechanical and flame retardant properties of composites has been systematically studied. The Rockwell hardness of GFRPCs increase with increasing GF content, while the compressive strength, impact strength and flexural strength initially show an increase followed by a decrease due to the excellent dispersibility of the fillers and the strong interfacial interaction between the one‐dimensional GF and PI matrix. Thermogravimetric analysis results show that the addition of GF with very low thermal conductivity and excellent temperature resistance can effectively improve the thermal stability of PI. Adding GF into PI can obviously improve the limiting oxygen index value. Moreover, as the GF content increased, the time to ignition of the composites prolonged while total heat release decreased. These findings suggest a viable solution for enhancing both the flame retardance and mechanical properties of PI‐based composites.Highlights GFRPCs with high GF content fabricated via ball milling‐hot pressing method. Silane modified GF obviously improves the thermal stability of PI matrix. GFRPCs‐28 exhibits superior mechanical properties. An increases in time to ignition (TTI) and mass residual rate (MRR) of the GFRPCs was observed on adding GF.

Effects of intumescent flame retardant based on THEIC-based oligomeric ester as char forming agent on thermal，mechanical and flame retardant properties of HDPE composites

In this study, a new phosphor-ester (TPE) was prepared by one-spot polycondensation of tris (2-hydroxyethyl) isocyanurate (THEIC) and phenyl phosphonic dichloride (PPDC) and used as a charring agent in combination with ammonium polyphosphate (APP) to develop new intumescent flame retardant (IFR) for high-density polyethylene (HDPE). The thermal and flame retardant properties of composites were investigated by thermogravimetric analysis (TGA), limiting oxygen index measurement (LOI), and cone calorimetry (CCT). At the same time, the morphology and chemical structure of the char residue were analyzed by scanning electron microscopy, Fourier transfer infrared spectroscopy, and laser Raman spectroscopy. The results showed the LOI value of the composite HD/APP/TPE containing 25 wt. % of APP/THE reaches 28.2 %. The CCT test suggested that the peak heat released rate (PHRR) of the flame retardant composite is decreased by 37 % compared to that of pure HDPE. The use of IFR based on APP and TPE produces a compact char residue that acts as a barrier for heat, oxygen, and volatile combustibles and protects the underlying polymer. Besides TPE can produce the PO-type radicals that show some gas phase flame retardant action. However, the tensile strength of the composites is still lower than that of pure polymer.

Synergistic Effects of Expandable Graphite and Ammonium Polyphosphate on Flame-Retardant Property of Composites

Synergistic Effects of Expandable Graphite and Ammonium Polyphosphate on Flame-Retardant Property of Composites

Preparation and Properties of Bio-Based Flame Retardant L-APP/Poly(L-lactic acid) Composites

Poly(L-lactic acid) (PLLA) is a thermoplastic material with complete degradability, high biocompatibility and excellent mechanical properties. It can replace petroleum-based polymers are currently being used in the fields of packaging, agriculture, textiles, medical and so on. However, PLLA’s extremely flammability greatly limits its wider application. An bio-based flame retardant L-APP/PLLA composites was prepared by melt blending of the L-APP and PLLA. The morphology, impact properties, thermal properties and flame retardant properties of composites were investigated by field emission scanning electron microscope (SEM), impact tester, differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), limiting oxygen indexer (LOI) and horizontalvertical burning tester. The results showed that the degree of crystallization (Xc) and LOI of L-APP/PLLA composites increased as increasing of L-APP content. What’s more, the impact strength first increased and then decreased, the glass transition temperature (Tg) and melting temperature (Tm) do not changed significantly. The impact strength of composites was 9.1 kJ/m2 at a 5 wt% loading for L-APP, which was the highest level. When the content of L-APP was 20%, the LOI was 30.8%, the Xc was 42.3% and the UL-94 level was V-0. This research can promote the value-added utilization of lignin and the application of PLLA in the fields of flame retardant materials.

Study of the Addition of a Thermoplastic Vulcanizate to a HDPE Composite Highly Filled with Magnesium Hydroxide and Its Effect on the Tensile and Flame Retardant Properties

A work was carried out in order to obtain a TPV based on HDPE and EPDM, studying the effect of three different peroxides. The effect of one mono- and two bifunctional peroxides was studied. In general, at equal wt% of peroxide, the bifunctional peroxides produced greater gel content, higher tensile stress, and higher elongation at break. Thereafter, the work was focused on studying the effect of this TPV, as well as a commercial TPO, on the tensile and flame retardant properties of composites based on blends of HDPE and a thermoplastic elastomer (either TPV or TPO), plus 130 phr of magnesium hydroxide (MH). The composites without the rubbery phase, but with 130 phr of MH, were highly brittle and fragile. The composites with the rubbery phase, on the other hand, (either TPO or TPV), were tougher and presented relatively much higher tensile properties. With regard to flame retardancy, the formulations containing the TPV showed better flame retardancy and passed as V-1 in the UL-94V. With respect to the cone calorimeter, those with TPO or TPV all generated a total of 80 MJ of heat energy. The compositions with TPV, however, generated this amount of heat over a larger period of time, i.e., showing less heat generated per second. In addition, the compositions with TPV presented a markedly lower pHRR, by an average of 15%. Thermogravimetric analysis (TGA) showed that the MH in the samples with a 40 wt% rubbery phase starts decomposing at 315°C. However, as the temperature increases, the MH in the TPV composite apparently decomposes at a slower rate than that in the TPO composite.

Influence of expandable graphite particle size on the synergy flame retardant property between expandable graphite and ammonium polyphosphate in semi-rigid polyurethane foam

Effect of the difference of expandable graphite (EG) particle size on the synergistic flame retardant effect between expandable graphite (EG) and ammonium polyphosphate (APP) in the semi-rigid polyurethane foam (SPUF) was studied for the first time. Three large-span particle sizes of EG were added into SPUF with different mass ratios of EG/APP. The synergistic effect between EG and APP on the flame retardant property of composites was investigated using the limiting oxygen index test, horizontal–vertical burning test, thermogravimetric analysis (TGA), scanning electron microscope (SEM), etc. Flammability performance tests indicated that the larger particle size the EG possessed, the more obvious will be the synergistic effect exhibited between EG and APP. SEM images and TGA results provided positive evidence for the combustion tests. Synergistic effect was strongly influenced by the compactness of united protective layer. The maximal rate of the degradation of the SPUF composite system further confirmed the relationship between the rate of the composites’ degradation and the compactness of united protective layer. Speculative reactions which were related to the changes of EG in the presence of APP under high temperature were discussed.

Investigation of flame-retarded poly(butylene succinate) composites using MHSH as synergistic and reinforced agent

Magnesium hydroxide sulfate whisker (MHSH) was used as flame-retarded synergistic agent of intumescent flame retardant (IFR), and to prepare flame-retarded PBS composites. The mechanical performance and flame-retardant properties of composites were investigated. Experimental data showed that an appropriate MHSH loading favored the mechanical performance and flame-retardant properties of composites. When IFR and MHSH loadings were 23 and 2 wt%, respectively, the limited oxygen index value of 39.8% and UL-94 V0 rate of composite could be achieved. The tensile strength increased by 33.3% in comparison with that of composite only prepared by 25 wt% IFR. XRD analysis indicated that the addition of MHSH significantly increased the crystallization of composites. FT-IR analysis demonstrated that P–O–Mg–O–P bonds could be generated during pyrolysis process. TG and cone calorimeter analyses both indicated that the incorporation of MHSH and IFR lowered the flammability of composites by limiting heat and mass transfer. Based on the experimental and analyses data, especially the SEM analysis, possible mechanism was proposed. The combustion products of MHSH and IFR provided a flame shield during combustion process. MHSH played a reinforcement effect in the shield. A more stable three-dimensional intumescent charred layer could not only effectually prevent the melt from dripping but also hinder the diffusion of oxygen and heat into the interior substrate.

MİNERAL TAKVİYELİ KABLO TAVALARININ MEKANİK ÖZELLİKLERİNİ İYİLEŞTİRMEK İÇİN CAM ELYAFLARIN KULLANILMASI

Composite materials are able to improve the system performance by reducing redundancy. Different materials with the best characteristics can be combined to create a new material. In this study, a composite material was manufactured with glass fibre and inorganic mineral additives. It was aimed to produce strong, light-weight and flame retardant cable trays. Within this context, glass fibres were used to strengthen the mineral reinforced cable trays. Mechanical and flame retardant properties of composites were examined according to glass fibre loading and micro-nano size distribution of the mineral. Composite samples were prepared by adding glass fibres and huntite/hydromagnesite minerals with different ratios to poly vinyl chloride (PVC) matrix. Flame retardant property was studied through the limiting oxygen index (LOI) test. Mechanical effects of the glass fibre additives were investigated as a main objective of this work. It was observed that glass fibre additives improved the mechanical properties of the composites. Tensile strength increased from 38.4 to 65.8 MPa by adding 30% glass fibres. Keywords : Composites, cable trays, mechanical property, flame retardant, huntite/hydromagnesite

Synthesis and Characterization of Melamine Halogen Acid Salts and its Application as Flame Retardant

In this paper, a series of novel halogen compounds, melamine halogen acid salts were directly synthesized by melamine and halogen acid in water phase. The chemical structures of melamine halogen acid salts were characterized by Fourier-transform infrared spectroscopy (FT-IR), elemental analysis and 1H-NMR. Meanwhile, the thermal properties of compounds were investigated by thermogravimetric analysis (TGA). The TGA results showed that melamine halogen acid salts had good thermostability during polymer processing. Futhermore, limiting oxygen index (LOI) and vertical burning test were used to study the flame retardant properties of composites blended by melamine halogen acid salts and polymer. The results revealed good flame retardancy that flame retardant polyethylene with 2 wt% melamine hydrobromide in total 8 wt% flame retardants got LOI value of 29.7% and reached UL 94 V-0 rating.

Study on the Flame Retardant Property of Magnesium Hydroxide Whiskers/PE Composites

The magnesium hydroxide (MH) whisker/PE composites were prepared by melt-extrusion with modified whiskers and unmodified whiskers as fillers respectively. The flame retardant property of composites was tested by the oxygen index machine. The magnesium hydroxide whiskers could improve the flame retardant property of the composites. When the contents of the modified and unmodified whiskers increased from 10% to 60%, the oxygen index of the composites increased from 24.4% to 43.4%, 23.2% to 40.2% respectively. The flame retardant of the modified whiskers/PE composites was better than the unmodified. The morphology of fracture was analyzed by SEM: the modified whisker could be more evenly divided into PE matrix with better dispersibility and compatibility, for that there occurred organic molecule membranes on the surface of the crystal whiskers after being modified, which lowered the interfacial energy of whiskers.

Study on the Flame Retardant Property of Magnesium Hydroxide Whiskers/PE Composites

The magnesium hydroxide (MH) whisker/PE composites were prepared by melt-extrusion with modified whiskers and unmodified whiskers as fillers respectively. The flame retardant property of composites was tested by the oxygen index machine. The magnesium hydroxide whiskers could improve the flame retardant property of the composites. When the contents of the modified and unmodified whiskers increased from 10% to 60%, the oxygen index of the composites increased from 24.4% to 43.4%, 23.2% to 40.2% respectively. The flame retardant of the modified whiskers/PE composites was better than the unmodified. The morphology of fracture was analyzed by SEM: the modified whisker could be more evenly divided into PE matrix with better dispersibility and compatibility, for that there occurred organic molecule membranes on the surface of the crystal whiskers after being modified, which lowered the interfacial energy of whiskers.