Flame-retardant and thermal properties of highly efficient water-resistant intumescent flame-retardant polypropylene composites

Journal of Thermal Analysis and Calorimetry - The more efficient and hydrophobic modificated ammonium polyphosphate (M-APP) and charring agent (M-CA) were prepared based on sol–gel method,...     

The influence of silicone shell on double-layered microcapsules in intumescent flame-retardant natural rubber composites

The mechanisms of the thermal degradation of polyhedral oligomeric octaphenylsilsesquioxane (OPS), octa(nitrophenyl)silsesquioxane (ONPS), and octa(aminophenyl)silsesquioxane (OAPS) were investigated. The –NO₂ or –NH₂ substituents on the phenyl group affected the mechanism of the POSS thermal degradation. The thermal stabilities of OPS, ONPS, and OAPS were characterized by TG and FTIR. Thermal degradation of OPS included mainly the degradation of caged polyhedral oligomeric silsesquioxane structures and phenyl groups. Nitro or amino substituents decreased its thermal stability. The thermal degradation processes of OPS, ONPS, and OAPS differed. Phenyl groups and cyclobutadiene were observed in the OPS degradation products. Oxygen radicals that caused intensive CO₂ release between 350 and 450 °C were generated by the degradation of ONPS –NO₂. OAPS released mainly aminophenyl groups at 370 °C, whereas a small number of phenyl groups decomposed at 500 °C. The OAPS reactivity could enhance the thermal stability of POSS structure in the polyimide OAPS composites.     

Influence of ferrocene on smoke suppression properties and combustion behavior of intumescent flame-retardant epoxy composites

Journal of Thermal Analysis and Calorimetry - This article mainly studies smoke suppression properties and synergistic flame-retardant effects of ferrocene (Fe(C5H5)2) on intumescent...     

Combustion properties and thermal degradation behavior of polylactide with an effective intumescent flame retardant

An intumescent flame retardant spirocyclic pentaerythritol bisphosphorate disphosphoryl melamine (SPDPM) has been synthesized and its structure was characterized by Fourier transformed infrared spectrometry (FTIR), ¹H and ³¹P nuclear magnetic resonances (NMR). A series of polylactide (PLA)-based flame retardant composites containing SPDPM were prepared by melt blending method. The combustion properties of PLA/SPDPM composites were evaluated through UL-94, limiting oxygen index (LOI) tests and microscale combustion calorimetry (MCC) experiments. It is found that SPDPM integrating acid, char and gas sources significantly improved the flame retardancy and anti-dripping performance of PLA. When 25 wt% flame retardant was added, the composites achieved UL-94 V0, and the LOI value was increased to 38. Thermogravimetric analysis (TGA) showed that the weight loss rate of PLA was decreased by introduction of SPDPM. In addition, the thermal degradation process and possible flame retardant mechanism of PLA composites with SPDPM were analyzed by in situ FTIR.     

Mechanical and thermal properties of green polylactide composites with natural fillers

Green composites of PLA with micropowders derived from agricultural by-products such as oat husks, cocoa shells, and apple solids that remain after pressing have been prepared by melt mixing. The thermal and mechanical properties of the composites, including the effect of matrix crystallization and plasticization with poly(propylene glycol), have been studied. All fillers nucleated PLA crystallization and decreased the cold-crystallization temperature. They also affected the mechanical properties of the compositions, increasing the modulus of elasticity but decreasing the elongation at break and tensile impact strength although with few exceptions. Plasticization of the PLA matrix improved the ductility of the composites.     

Preparation and expansion properties of a novel UV-curable intumescent flame-retardant coating

Journal of Thermal Analysis and Calorimetry - N,N′-bis(2,4-di(acryloyloxyethyl)-[1,3,5]-triazin-2-yl)-hexane-1,6-diamine(BDAETH) and 2,2-dimethyl-1,3-propanediol glycerol-methacrylate...     

The effects of irradiation cross-linking on the thermal degradation and flame-retardant properties of the HDPE/EVA/magnesium hydroxide composites

High-density polyethylene/ethylene vinyl-acetate copolymer/magnesium hydroxide composites were crosslinked via high-energy electron beam irradiation in the presence of triallylisocyanurate. The structure of the cross-linking network was determined with the help of rheological measurements through advanced rheological extended systems (ARES). The thermal and flame-retardant properties of the irradiated composites were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and cone calorimetry. Results showed that the cross-linking network structure could enhance the thermal stability of composites, and did favor to smoke suppression. However, the peak heat release rate (PHRR) increased and the time to PHRR shortened, inferring that the composites after irradiation cross-linking were easier to combust. The char microstructure after cone calorimetry test was observed and used to give explanation of the above results.     

Double-layered co-microencapsulated ammonium polyphosphate and mesoporous MCM-41 in intumescent flame-retardant natural rubber composites

Double-layered co-microencapsulated ammonium polyphosphate (APP) and mesoporous MCM-41 (M(A&M)) were prepared using melamine–formaldehyde resin and zinc borate by in situ polymerization. The structure of the microcapsules was characterized by particle size analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy. Double-layered microencapsulation gave APP narrow particle size distribution. The flame-retardant and mechanical effects of M(A&M) in natural rubber (NR) were evaluated using the limiting oxygen index, UL 94 test, thermogravimetric analysis, and tensile test. Results indicated that the NR/M(A&M) composites had much better flame-retardant and mechanical properties than the NR/APP/MCM-41 composites. The limited oxygen index value of the NR/M(A&M) composite reached the maximum, and the UL-94 ratings were increased to V-0 when the ratio of APP to MCM-41 was 39:1 in microcapsule. The occurrence of a synergistic effect between MCM-41 and intumescent flame-retardant in the NR composites was proved. This investigation provided a promising formulation for flame-retardant NR composites.     

Mechanical, thermal, and fire properties of polylactide/starch blend/clay composites

Polylactide (PLA)/starch blend/clay and PLA/clay composites are prepared by melt blending. Structural and thermal characterizations are performed by differential scanning calorimetry, X-ray diffraction analysis, and thermogravimetric analysis. The fire properties are assessed on a dual cone calorimeter. Combustion residue and char formation is characterized by optical microscopy and attenuated total reflection infrared spectroscopy. Although the clay is not fully intercalated/exfoliated, the composites exhibit a higher thermal stability and much reduced peak heat release rate, and the PLA/starch blend composite retains its mechanical properties. For the PLA/starch blend composite, smoke release is also considerably reduced. Catalyzed, oxidative decomposition is shown to occur early in the thermal decomposition of the composites, prior to increased thermal stability. The inclusion of clay promotes char formation and increases the quantity of carbonaceous char in the combustion residue. There is minimal migration of the clay to the surface prior to ignition and char is formed mainly after ignition and during burning. During the later stages of burning some of the char formed is converted to CO₂.     

The production and properties of polylactide composites filled with expanded graphite

Composites have been produced by melt-blending biodegradable polylactide (PLA) with commercially available expanded graphite (EG). Using different techniques of addition, the manifold effects of EG on PLA molecular, thermo-mechanical and fire-retardant properties were evaluated. The EG nanofiller provides PLA composites with competitive functional properties. They have a high rigidity, with Young's modulus and storage modulus increasing with EG content. They also have excellent thermal stability while preserving the glass transition and melting temperature of the original PLA matrix. Purification and pre-dispersion of EG nanofiller proved beneficial for preserving PLA molecular weights and led to improved mechanical performance. The presence of dispersed graphene nanolayers in PLA significantly accelerated the polyester crystallization process. The flame retardant properties also displayed improvements with a large decrease in the maximum rate of heat release as recorded by cone calorimetry, whereas the horizontal burning test (UL94 HB) was successfully passed revealing non-dripping and char formation.     

Study of thermal properties of intumescent additive

Bicyclic compounds containing phosphorus on their skeleton such as 2,4,6-trioxa-1-phosphabicyclo[2,2,2]octane-4-methanol phosphate (PEPA) having three active ingredients required for intumescence have been synthesized. The structural characterization of PEPA was carried out by FT-IR, ¹H and ¹³C NMR. The thermal behaviour of the material was studied using TGA, TGA–MS and pyrolysis GC–MS. Thermogravimetric analysis reveals that PEPA undergoes several stages of degradation with a char of about 12% at 800 °C. The TGA–MS studies indicate that the material degrades with the liberation of water, formaldehyde, alkene and alcohols as the major degradation products. Pyrolysis GC–MS results reveal that PEPA isomerizes in the acidic medium. PEPA and/or isomers of PEPA react with formaldehyde, one of the degradation products, to form cross-linked structure and cyclic products with the elimination of water molecule. The thermal degradation mechanisms for PEPA are presented and discussed.     

Rheological and thermal properties of stereocomplexed polylactide films

Poly(l-lactide) (PLLA) and Poly(d-lactide) (PDLA) blended films (PLLA/PDLA) were prepared (5/95; 25/75; 50/50, and 75/25) by solvent casting method. Blend of PLLA and PDLA of medium molecular mass led to the formation of stereocomplex which was evidenced by differential scanning calorimetry, rheological measurement and Fourier transform infrared spectroscopy. The stereocomplex had a higher melting temperature (T _m) (more than 50 °C) and crystallized at higher temperature (T _c) (more than 25 °C) from the melt compared to neat PLLA and PDLA. The T _m and T _c gradually decreased with increasing the number of thermal scans. The enthalpy of fusion (?H_m) for stereocomplex crystallites in 50/50 blend films was the highest than that of homo-crystallites. Rheological measurement at a temperature of 180–195 °C revealed that the neat PLA was predominantly liquid-like behavior (G″ > G′) which transformed to extreme solid-like behavior by incorporation of PDLA into PLLA. Among blends, 50/50 PDLA/PLLA showed the maximum mechanical strength (G′) followed by 25/75, 75/25, and 5/95 blends. The significant increase in mechanical strength is believed to be attributed by stereocomplex formation by blends. Thermal and rheological data supported higher mechanical strength and an increase in melting and crystallization temperature adequately.     

阻燃共聚酯/粘土复合物热降解动力学研究

用插层共聚方法合成了含磷共聚酯／粘土复合物。用热重(TG)方法考察热降解动力学。通过在空气中以不同的升温速率升温至设定温度,用Kissinger法和Hymn-Wall-Ozawa法对数据进行处理。结果表明,粘土组分含量较高的反应活化能较大,热稳定性较好。     

Effect of Fe3O4‐doped sepiolite on the flammability and thermal degradation properties of epoxy composites

As‐received sepiolite/epoxy systems and Fe₃O₄‐doped sepiolite/epoxy systems were prepared, and the contents of sepiolite and Fe₃O₄‐doped sepiolite were kept as 2 and 4 wt%, respectively. Compared with sepiolite, the effect of Fe₃O₄‐doped sepiolite on the flame retardancy, combustion properties, thermal degradation, thermal degradation kinetics and thermomechanical properties of epoxy resin was investigated systematically by limiting oxygen index (LOI), cone calorimeter (Cone), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Some interesting results had been acquired. The addition of sepiolite decreased heat release rate, total smoke production and smoke production rate, and obviously improved LOI values of epoxy composites. Compared with sepiolite, the addition of Fe₃O₄‐doped sepiolite further reduced parameters mentioned above of epoxy composites, and further enhanced LOI values and char residues after cone test. There might be a synergistic effect between sepiolite and Fe₃O₄ on flame retardant epoxy composite. TGA results indicated that the addition of sepiolite had a slight effect on the thermal degradation of epoxy composites; however, the addition of Fe₃O₄‐doped sepiolite accelerated the thermal degradation of epoxy composites. DMA results showed that the addition of both sepiolite and Fe₃O₄‐doped sepiolite increased the glass transition temperature (T_g) of epoxy composite. The results obtained in this paper supplied an effective solution for developing excellent flame retardant properties of polymeric materials. Copyright © 2015 John Wiley & Sons, Ltd.     

Influence of cotton waste and flame-retardant additives on the mechanical,thermal, and flammability properties of phenolic novolac epoxy composites

Cellulose - Phenolic novolac-type epoxy (EPN) resin composites were fabricated by reinforcing with cotton waste (CtW), along with aluminum hydroxide (AH), and boric acid (BA) particles under...     

Preparation and thermal properties of a novel flame-retardant coating

A novel silicone and phosphate modified acrylate (DGTH) was synthesized and characterized by ¹H NMR and FTIR. It was found that DGTH could be cured both by UV radiation and moisture mode with FTIR. The flammability and thermal behavior of the cured film were studied by the limited oxygen index (LOI), thermogravimetric analysis (TG) and real time Fourier transform infrared (RT-FTIR). The LOI value of the cured film is 48 and the TG data shows that the cured film has three characteristic degradation temperature regions, attributing to the decomposition of phosphate and polyurethane to alcohols and isocyanates, thermal pyrolysis of alkyl chains, and decomposition of unstable structures in char, respectively. The RT-FTIR data implies that the degraded products of phosphate form poly(phosphoric acid) further catalyse the breakage of carbonyl groups to form an intumescent char, preventing the samples from further burning.     

Synergistic effects and mechanism of ZnCl2 on intumescent flame-retardant polypropylene

The synergistic effects of ZnCl₂ on polypropylene (PP)/ammonium polyphosphate/pentaerythritol have been studied. The cone calorimeter test, limiting oxygen index, and UL-94 data show that suitable amount of ZnCl₂ can greatly increase the flame-retardant property of PP/intumescent flame retardant (IFR)/ZnCl₂ blends, however, the corresponding smoke release increased for PP/IFR/ZnCl₂ blends when compared with PP/IFR without ZnCl₂. The dynamic Fourier transfer infrared spectra reveal that the ZnCl₂ accelerated the formation of charred layers with P–O–P and P–O–C complexes which formed from burning of polymer materials. The morphological structures of charred residues observed by scanning electron microscopy give the positive evidence that ZnCl₂ can promote the formation of compact intumescent charred layers and prevent the charred from cracking, which effectively protects the underlying polymer from burning. The thermogravimetric analysis data show that the PP/IFR/ZnCl₂ sample has higher thermal stability than that of PP/IFR and PP/IFR/ZnO samples. However, the corresponding charred residues are much lower than that of PP/IFR/ZnO sample. All the above data indicated that the synergistic mechanism of ZnCl₂ with IFR in PP system can be ascribed to catalyze effects in condense phase and serve as a radical scavenger in vapor phase.