Advanced Industrial and Engineering Polymer Research最新文献

Polyester-cotton fabrics (PTCO) have excellent properties and are ubiquitous in daily life, but their serious flammability brings great safety hazards to people's lives. This study used phenylphosphonic acid (PPOA) and urea as raw materials to prepare a flame retardant named POU. PTCO/POU was prepared by the pad-dry-cure technique, and the performance was compared with that of PTCO/PPOA, revealing many interesting phenomena. Based on the gas phase and condensed phase flame-retardant mechanism brought by P/N synergy, PTCO/POU had better flame retardancy than PTCO/PPOA did. The damaged length was 6.7 cm, and the limiting oxygen index (LOI) value was 30.1%. The char residues after burning were complete and denser with a higher degree of graphitization. Thermogravimetric analysis showed that POU can significantly reduce the R_max of PTCO, and improve its thermal stability in high temperature zones. The CCT results showed that PTCO/POU had the longest time to ignition and the smallest fire growth index, which was of great significance for reducing fire risk. The TG-FTIR results showed that the volatile products of PTCO/POU were greatly reduced, and during the burning process, NH₃ was produced to dilute the concentration of combustible gases. In addition, PTCO/POU also had better whiteness performance than PTCO/PPOA did. This work greatly improved the flame retardancy of PTCO in a simple way and expanded its application prospects.

Asphalt pavement is widely applied to the surface in high-grade highway tunnels due to its prominent preponderance in road performance. However, asphalt is flammable as the binder material to adhere the aggregates and other additives, resulting that a fire in the semi-closed space of the tunnel can ignite and burn asphalt pavement to generate a large amount of heat and smoke. Therefore, further promoting the advance of flame-retardant asphalt pavement is essential to ensure security in tunnels. We gathered the relevant standards or regulations of diverse nations and test methods concerning flame retardancy of asphalt. Then we reviewed the research status of flame-retardant asphalt mixture, including thermal characteristics of the asphalt and four fractions, the flame retardants applicable to asphalt, and effects on other components. This review demonstrated that establishing universal standards and test methods is a research basis specifically for flame-retardant asphalt pavement. To optimize the flame retardancy of asphalt pavement, it should focus on the synergy with diversified aspects such as asphalt binders, multiple flame retardants, aggregates, mineral powders, fibers, and other additives.

Polylactic acid/Polycarbonate (PLA/PC) blend was prepared via twin screw extruder by taking the bio-based content as much as possible and the better mechanical, thermal, and impact properties into consideration. Flame retardant (FR) performance of the PLA/PC blend was improved by using the mixture of ammonium polyphosphate, triphenyl phosphate, and zinc borate. FR properties of PLA/PC blend was evaluated according to the UL 94 test standard. The variations in tensile and flexural strength, and Izod-notched impact strength values were determined. In order to reduce the total amount of flame retardant additive, instead of using a mixture of TPP and APP (weight ratio of 2/1) at 21 wt% weight fraction, 1 wt% Zinc borate together with 18 wt% TPP-APP mixture was used and obtained V0 rating for the thickness of 1.5 mm. It was reported that weight fraction of flame retardant additives (APP and TPP) was successfully reduced by using a mixture of APP, TPP and ZnB without degrading the mechanical properties such as tensile and flexural strengths. Using less total FR additive weight (19 wt%) led to 15 and 24% higher tensile and flexural strength values, respectively, compared to higher FR additive weight (21 wt%).

Rapid development of energy, electrical and electronic technologies has put forward higher requirements for the thermal conductivities of epoxy resins and their composites. However, the thermal conductivity of conventional epoxy resins is relatively low, which could cause major heat dissipation issues. Therefore, the thermal conductivity enhancement of epoxy resins has long been a hot research topic in both academia and industry. In recent years, many promising advances have been made at the technical and mechanistic levels. This review includes the different approaches, the thermal conduction mechanisms implied, and the main research progresses. The research and academic achievements are mainly focused on the development of intrinsically liquid crystal epoxy resins and their composites, and the addition of fillers on amorphous epoxy resins. Finally, the challenges and prospects for thermal conductive epoxy resins are provided. Notably, this review can provide a more comprehensive understanding of thermally conductive epoxy resins and a guideline for the cutting-edge development direction of thermally conductive epoxy resins.

The fire performance durability of products containing flame retardants may be significantly affected after aging and mechanical recycling. Publications of the last ten years show that even under severe conditions simulating outdoor applications, progress has been made in using halogenated and halogenfree flame retardants with high temperature stability, stabilizers acting as flame retardants, improved coating formulations for wood and steel less sensible to hydrolysis by using topcoats and layer by layer approaches. Mechanical recycling is possible for halogenated and non-halogenated flame retardant systems, but has only been studied for virgin thermoplastics which may be available from post-industrial waste. Post-consumer waste is still unsuitable due to its mixed contents. Examples from practice show that the lifetime of products containing flame retardants may be durable for decades in indoor and probably for a much shorter time in outdoor applications.

The substitutional structure of cyclotriphosphazene derivatives significantly influences their flame-retardant effectiveness. A cyclotriphosphazene derivative with triazole group, referred to as hexa(1,2,4-triazol-3-ylamine) cyclotriphosphazene (HATA), was utilized to improve the flame retardancy of epoxy resin (EP). Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis were employed to characterize the thermal properties of EP/HATA thermosets. HATA facilitated the curing of EP due to its triazole and secondary amine structure. EP/HATA thermosets exhibited improved char-forming ability and storage modulus, attributed to the rigid cyclophosphonitrile structure of HATA. As a result of incorporating 5% HATA with 0.73 wt% phosphorus, EP passed UL-94 V-0 level. Subsequent analysis using a cone calorimeter revealed obvious reductions in the peak heat release rate, fire growth rate, and total smoke production of EP with the addition of HATA. Simultaneously, there was a significant enhancement in the char yield of EP during combustion, indicating notable improvements in fire safety. Additional investigations, including X-ray photoelectron spectroscopy, scanning electron microscopy, TG-FTIR, and pyrolysis gas chromatography/mass spectrometry, were employed to analyze the char residue and gaseous volatiles. HATA promoted the formation of a dense, continuous, and intumescent char layer containing cyclophosphonitrile structure in EP. Moreover, the decomposition of HATA released a notable quantity of nitrogen-containing volatiles, effectively mitigating flammable gases originating from the EP matrix in gaseous phase. A biphasic flame-retardant mode of action was proposed, underscoring cooperative flame-retardant effects arising from the interaction between triazole substituents and cyclophosphonitrile structure in HATA molecular for EP.