Study of using aluminum hypophosphite as a flame retardant for low‐density polyethylene

Aluminum hypophosphite (AHP) was first used to improve the flame retardance of low‐density polyethylene (LDPE). The flame‐retardant properties of LDPE composites were investigated by the limiting oxygen index, vertical burning test (UL‐94), microscale combustion calorimetry, and cone calorimeter tests. The results showed that the incorporation of AHP could improve the flame retardancy of LDPE dramatically, the limiting oxygen index of LDPE containing 50 phr AHP reached 27.5%, and the UL‐94 could pass V‐0 rating. The cone calorimeter test results indicated that PP/AHP composite exhibited superior performance, and the heat release rate and the total heat release of composites were significantly reduced. In addition, the strength of the char was improved with the load of AHP increased. The structure of the char was researched by Fourier transform infrared spectrometry (FTIR) and scanning electron microscope‐energy dispersive spectrometer, and the results revealed that AHP promoted the formation of compact char layer. The TG‐FTIR analyses proved that AHP could react with LDPE to reduce the production of olefin in gas phase. Moreover, the structure of P–O–C was found, and the effective mechanism of AHP in LDPE composites was also hypothesized in this work.     

Fire performance of brominated and halogen‐free flame retardants in glass‐fiber reinforced poly(butylene terephthalate)

This paper investigates the effects of brominated and halogen‐free fire retardants on the fire performance of glass‐fiber (GF) reinforced poly(butylene terephthalate) (PBT). Brominated polystyrene was used as the brominated fire retardant, whereas aluminum diethylphosphinate with/without nanoclay as halogen‐free fire retardants (HFFRs). Tests were conducted by using thermogravimetric analysis, limiting oxygen index (LOI), UL94, and the cone calorimeter. Thermogravimetric analysis results show that decomposition of GF plus PBT (PBT + GF) starts earlier in the presence of all fire retardants (FRs). In the cone calorimeter, all FRs reduce significantly the heat release rate (HRR) compared with PBT + GF, with brominated polystyrene achieving lowest HRR primarily because bromine released in the pyrolysis gases inhibits combustion. Brominate polystyrene does not, however, affect the mass loss rate. Aluminum diethylphosphinate alone has significant effects on reduction of both HRR and mass loss rate, which become considerably more when combined with nanoclay. It was also found that the combustion efficiency of the brominated polystyrene compound is much lower than that of HFFRs, indicating that brominated polystyrene has higher gas phase flame retardant efficiency compared with HFFRs because the bromine radicals released during degradation of brominated polystyrene effectively quench the chemical reactions of the pyrolysis gases due to degradation of PBT.     

Investigation on phosphorus halogen‐free flame‐retardancy systems in short glass fiber‐reinforced PC/ABS composites under rapid thermal cycle molding process condition

In this study, standard test specimens with flame‐retarded short glass fiber‐reinforced PC/ABS materials were fabricated under rapid thermal cycle injection molding condition by selecting a potassium perfluorobutane sulfonate flame retardant specially used for PC, FR2025, and two kinds of aryl phosphorus halogen‐free flame retardants, UN707 and PX‐220. The flame‐retardancy effect of the above different flame retardants on the studied systems was compared through combustion tests of the specimens. Meanwhile, the thermal and mechanical properties of flame‐retarded composites were studied by using the thermogravimetry analysis, dynamic mechanical thermal analysis (DMTA), and universal testing machine. The results show that the “candlewick effect” of fibers exacerbates the fire behavior of composites. With the increase of the aryl phosphorus halogen‐free flame retardants, the flame‐retardancy effect of composites is obviously improved, and the maximum thermal degradation rate of composites is significantly decreased. The UL94 combustion rating is improved, and the time of residual flame is substantially reduced with the increase of PC content under the same content of flame retardant. The DMTA results show that the flame retardants have a reinforcement action on PC/ABS matrix. However, the macroscopic mechanical properties are slightly decreased in the glass fiber‐reinforced composites because of the destructive effect of the flame retardants on the interface compatibility between matrix and fibers; the scanning electron microscopic micrographs of tensile fracture fully prove this action mechanism of flame retardants. In addition, the addition of toughener and antidripping additive significantly affects the flame retardancy and mechanical properties of composites. POLYM. COMPOS., 36:1653–1663, 2015. © 2014 Society of Plastics Engineers     

Flame retardancy of glass fiber reinforced high temperature polyamide by use of aluminum diethylphosphinate: thermal and thermo‐oxidative effects

Glass fiber reinforced polyamide (PA) 6 T/DT flame retarded with aluminum diethylphosphinate (AlPi) was tested to assess its flame retardant properties. Models for the decomposition of PA 6T/DT with and without AlPi are presented. Thermal decomposition was measured by performing TGA with Fourier transform infrared (FTIR) spectroscopy and FTIR spectroscopy in the condensed phase. Fire behavior was studied using a cone calorimeter and flammability was tested with UL 94 and the limiting oxygen index. AlPi works as an effective flame retardant for glass fiber reinforced PA 6T/DT materials, acting in the gas phase. Also observed was condensed‐phase action, which occurs especially under oxidative conditions before the samples ignite. © 2013 Society of Chemical Industry     

Phosphorus‐Containing Polymer Flame Retardants for Aliphatic Polyesters

Polyesters with 9,10‐dihydro‐9‐oxy‐10‐phosphaphenanthrene‐10‐oxide‐containing comonomers are synthesized aiming to improve the flame retardancy of aliphatic polyesters such as poly(butylene succinate) and poly(butylene sebacate). The influence of the chemical structure on the thermal decomposition and pyrolysis is examined using a combination of thermogravimetric analysis (TGA), TGA‐Fourier transform infrared (FTIR) spectroscopy, pyrolysis‐gas chromatography/mass spectrometry, and microscale combustion flow calorimetry. Thermal decomposition pathways are derived and used to select suitable candidates as flame retardants for PBS. The fire behavior of the selected polymers is evaluated by forced‐flaming combustion in a cone calorimeter. The materials show two modes of action for flame retardancy: strong flame inhibition due to the release of a variety of molecules combined with charring in the solid state.     

Pyrolysis and flammability behavior of long (Glass fiber)‐Reinforced polyamide 6 by aluminum alkylphosphinate‐based flame retardants in combination with organic montmorillonite

The pyrolysis and flammability behavior of long (glass fiber)‐reinforced polyamide 6 containing aluminum alkylphosphinate‐based flame retardant in conjunction with montmorillonite or organic montmorillonite (OMMT) were investigated by using thermal gravimetry, limiting oxygen index, vertical burning test, and cone calorimeter measurements. The results revealed that the incorporation of OMMT in (aluminum alkylphosphinate)‐containing long (glass fiber)‐reinforced polyamide 6 did not significantly affect the thermal stability; however, they showed an obvious synergy on the char yield. The components from the flame retardant, especially phosphorus, acted in the gas phase and condensed phase simultaneously. Substitution of part of flame retardants with OMMT helped keep more phosphorus in the solid phase at the expense of gas‐phase activity, as demonstrated in scanning electron microscopy‐energy‐dispersive X‐ray characterization of the residue. This substitution constructed an impermeable barrier on the burning surface, which was responsible for the improvements in the vertical burning test classification and limiting oxygen index test. J. VINYL ADDIT. TECHNOL., 24:27–36, 2018. © 2015 Society of Plastics Engineers     

Thermal degradation and combustion behaviors of flame retarded glass fiber reinforced polyamide 6 composites based on cerium hypophosphite

In this work, cerium hypophosphite (CeHP) was synthesized and characterized by scanning electron microscope (SEM) and thermogravimetric analysis (TGA) test. CeHP presented rod‐like morphological feature with good thermal stability. Subsequently, CeHP was added into glass fiber reinforced polyamide 6 (GFPA) to develop flame retardant glass fiber reinforced polyamide 6 composites (FR‐GFPA). The flame retardancy of FR‐GFPA composites was characterized by limiting oxygen index (LOI), Underwriters Laboratories 94 testing (UL‐94), microscale combustion calorimeter, and cone calorimeter test. FR‐GFPA composite with 20 wt% CeHP loading passed UL‐94 V0 rating with a high LOI of 26.5 vol%. Cone Calorimeter test showed that peak of heat release rate (PHRR) and total heat release (THR) of FR‐GFPA composites were reduced 27.1% and 21.1% compared with those of GFPA. The mechanical measurement revealed that the tensile strength first increased and then decreased with the increase of CeHP loading. With 15 wt% CeHP loading, the tensile strength of FR‐GFPA composite was 43.0% higher than GFPA. TGA and char residue characterization revealed that the addition of CeHP could significantly promote the formation of condensed char residue. The FR‐GFPA composites obtained herein exhibited superior combined properties of fire resistance, thermal stability, and mechanical properties, demonstrating that CeHP will be a promising candidate for preparing high performance polyamide composites. POLYM. COMPOS., 37:3073–3082, 2016. © 2015 Society of Plastics Engineers     

Investigations of thermal degradation behavior and fire performance of halogen‐free flame retardant poly(1,4‐butylene terephthalate) composites

This work aims to develop halogen‐free poly(1,4‐butylene terephthalate) (PBT) composites with enhanced flame retardancy using ecofriendly flame retardants, aluminum hypophosphite (AHP) and melamine derivatives (melamine polyphosphate and melamine cyanurate). Microscale combustion calorimetry and thermal gravimetric analysis/infrared spectrometry (TG‐IR) technique were used to investigate the potential fire hazards of these PBT composites. For the PBT composites with the incorporation of AHP and melamine derivatives, the heat release capacity (HRC) which is an indicator of a material fire hazard was significantly reduced, and the intensities of a variety of combustible or toxic gases detected by TG‐IR technique were remarkably decreased. Moreover, a loading of 20 wt % flame retardant mixture fulfilled the PBT composites high limited oxygen index (LOI) and V‐0 classification in UL 94 testing. An intumescent flame retarded mechanism was speculated in this work, because numerous bubble‐like char residues were found on the surface of the samples containing flame retardant mixture after LOI testing. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis,characteristic of a novel flame retardant containing phosphorus and its application in poly(ethylene‐co‐vinyl acetate)

A novel flame retardant (SPDH) containing phosphorus was synthesized through the reaction of 10‐(2, 5‐dihydroxyphenyl)‐9, 10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO‐HQ) and synthesized intermediate product 3, 9‐dichloro‐2, 4, 8, 10‐tetraoxa‐3, 9‐diphosphaspiro(5.5)undecane‐3, 9‐dioxide (SPDPC). The structure and properties of SPDPC and SPDH were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy and thermogravimetric analysis (TGA). After blending with poly(ethylene‐co‐vinyl acetate) (EVA), the flame‐retardant properties of EVA/SPDH composites were estimated by cone calorimeter, limited oxygen index (LOI) and UL‐94 tests, whereas the thermal stabilities were investigated using TGA. The morphological microstructure of the char formed by EVA/SPDH composite after combustion in cone calorimeter was investigated by scanning electron microscopy (SEM). The results indicate that the flame retardant and thermal stability were improved by incorporation of SPDH. The rich foamy char layers were observed from the residues after combustion in a cone calorimeter, which exactly benefits the improvement of thermal stability and flame retardant property of materials. Copyright © 2010 John Wiley & Sons, Ltd.     

Pyrolysis of epoxy resins and fire behavior of epoxy resin composites flame‐retarded with 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide additives

The pyrolysis of an epoxy resin and the fire behavior of corresponding carbon fiber‐reinforced composites, both flame‐retarded with either 10‐ethyl‐9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide or 1,3,5‐tris[2‐(9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide‐10‐)ethyl]1, 3,5‐triazine‐2,4,6(1H,3H,5H)‐trione, are investigated. The different fire retardancy mechanisms are discussed, and their influence on the fire properties assessed, in particular for flammability (limiting oxygen index, UL 94) and developing fires (cone calorimeter with different external heat fluxes of 35, 50, and 70 kW m^?2). Adding the flame retardants containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide affects the fire behavior by both condensed phase and gas phase mechanisms. Interactions between the additives and the epoxy resin result in a change in the decomposition pathways and an increased char formation. The release of phosphorous products results in significant flame inhibition. The fire properties achieved are thus interesting with respect to industrial exploration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2260–2269, 2007     

Melamine poly(metal phosphates) as flame retardant in epoxy resin: Performance,modes of action,and synergy

Melamine poly(metal phosphates) (MPMeP) are halogen‐free flame retardants commercialized under the brand name Safire. Melamine poly(aluminum phosphate) (MPAlP), melamine poly(zinc phosphate) (MPZnP), and melamine poly(magnesium phosphate) (MPMgP) were compared in an epoxy resin (EP). The thermal decomposition, flammability, burning behavior, and glass transition temperature were investigated using thermogravimetric analysis, pyrolysis combustion flow calorimeter, UL 94 testing, cone calorimeter, and differential scanning calorimetry. While the materials exhibited similarities in their pyrolysis, EP + MPZnP and EP + MPMgP showed better fire behavior than EP + MPAlP due to superior protective properties of the fire residues. Maintaining the 20 wt % loading, MPZnP was combined with various other flame retardants. A synergistic effect was evident for melamine polyphosphate (MPP), boehmite, and a derivative of 6H‐Dibenzo[c,e][1,2]oxaphosphinine‐6‐oxide. The best overall performance was observed for EP + (MPZnP + MPP) because of the best protection effectiveness of the fire residue. EP + (MPZnP + MPP) achieved V1/V0 in UL 94, and an 80% reduction in the peak heat release rate. This study evaluates the efficiency of MPMeP in EP, alone and in combination with other flame retardants. MPMeP is a suitable flame retardant for epoxy resin, depending on its kind and synergists. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43549.     

A phosphorus‐containing inorganic compound as an effective flame retardant for glass‐fiber‐reinforced polyamide 6

A novel inorganic compound, aluminum hypophosphite (AP), was synthesized successfully and applied as a flame retardant to glass‐fiber‐reinforced polyamide 6 (GF–PA6). The thermal stability and burning behaviors of the GF–PA6 samples containing AP (flame‐retardant GF–PA6) were investigated by thermogravimetric analysis, vertical burning testing (with a UL‐94 instrument), limiting oxygen index (LOI) testing, and cone calorimeter testing (CCT). The thermogravimetric data indicated that the addition of AP decreased the onset decomposition temperatures, the maximum mass loss rate (MLR), and the maximum‐rate decomposition temperature of GF–PA6 and increased the residue chars of the samples. Compared with the neat GF–PA6, the AP‐containing GF–PA6 samples had obviously improved flame retardancy: the LOI value increased from 22.5 to 30.1, and the UL‐94 rating went from no rating to V‐0 (1.6 mm) when the AP content increased from 0 to 25 wt % in GF–PA6. The results of CCT reveal that the heat release rate, total heat release, and MLR of the AP‐containing GF–PA6 samples were lower than those of GF–PA6. Furthermore, the higher additive amount of AP affected the mechanical properties of GF–PA6, but they remained acceptable. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Flame retarded epoxy resins by adding layered silicate in combination with the conventional protection‐layer‐building flame retardants melamine borate and ammonium polyphosphate

The pyrolysis and flammability of phosphonium‐modified layered silicate epoxy resin nanocomposites (EP/LS) were evaluated when LS was combined with two flame retardants, melamine borate (MB) and ammonium polyphosphate (APP), that also act via a surface protection layer. Thermogravimetry (TG), TG coupled with Fourier Transform Spectroscopy (TG‐FTIR), oxygen index (LOI), UL 94 burning chamber (UL 94) and cone calorimeter were used. The glassy coating because of 10 wt % MB during combustion showed effects in the cone calorimeter test similar to nanodispersed LS, and somewhat better flame retardancy in flammability tests, such as LOI and UL 94. Adding APP to EP resulted in intumescent systems. The fire retardancy was particularly convincing when 15 wt % APP was used, especially for low external heat flux, and thus, also in flammability tests like LOI and UL 94. V0 classification is achieved when 15 wt % APP is used in EP. The flame retardancy efficiency of the protection layers formed does not increase linearly with the MB and APP concentrations used. The combination of LS with MB or APP shows antagonism; thus the performance of the combination of LS with MB or APP, respectively, was disappointing. No optimization of the carbonaceous‐inorganic surface layer occurred for LS‐MB. Combining LS with APP inhibited the intumescence, most probably through an increase in viscosity clearly above the value needed for intumescent behavior. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Flame retardant effect of polyhedral oligomeric silsesquioxane and triglycidyl isocyanurate on glass fibre‐reinforced epoxy composites

Polyhedral oligomeric silsesquioxane (POSS) and triglycidyl isocyanurate (TGIC) were added to an aerospace grade epoxy resin (EP) individually or in combinations at low concentrations. The EP samples containing additives were cast into resin laminates and also used to produce glass fibre‐reinforced composite laminates. The flammability of the two types of laminates was studied by limiting oxygen index, UL‐94 and cone calorimetry. The cone results indicated that the use of POSS (10 wt%) in EP can significantly decrease resin/composite's peak heat release rate, total heat release, and CO production. The mechanical performance in flexural modes of the fibre‐reinforced composite laminates was not adversely affected by the addition of POSS and TGIC in the resin. POSS containing samples had better retention of mechanical properties after exposure to radiant heat in a cone calorimeter compared with other samples. The results of thermogravimetry (TG), TG‐FTIR, and dynamic FTIR indicated that the thermal degradation behavior of the EP is significantly changed by the addition of POSS. POSS can get grafted on the EP's main chain during earlier stages of decomposition and form a stable char layer to protect the underlying material from further decomposition. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers     

Red phosphorus–controlled decomposition for fire retardant PA 66

The thermal degradation and the combustion behavior of glass fiber–reinforced PA 66 materials containing red phosphorus were investigated. Thermogravimetry (TG), TG coupled with FTIR, and TG coupled with mass spectroscopy were used to investigate the thermal decomposition. The flame retardant red phosphorus was investigated with respect to the decomposition kinetics and the release of volatile products. The combustion behavior was characterized using a cone calorimeter. Fire risks and fire hazards were monitored versus external heat fluxes between 30 and 75 kW/m². Red phosphorus acts in the solid phase and its efficiency depends on the external heat flux. The use of red phosphorus results in an increased amount of residue and in a corresponding decrease in total heat release. The decrease of the mass loss rate peak results in a corresponding decrease of the peak heat release. With increasing external heat flux applied the first effect on the total heat release decreases linearly, whereas the second effect on the peak heat release expands linearly. The investigation provides insight into the mechanisms of how the fire retardant PA 66 is achieved by red phosphorus controlling the degradation kinetics. Taking into account that a decrease of the volatile products also leads to a decrease of heat production in the flame zone and that the char acts as heat transfer barrier, a reduced pyrolysis temperature is suggested as a further feedback effect. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2060–2071, 2002     

An easy‐to‐obtain silicone‐containing flame retardant and its effects on the combustion of polycarbonate

A novel silicone‐containing flame retardant (HSOBA) synthesized from hydrogen‐containing silicone oil and Bisphenol A via a simple approach has been incorporated into polycarbonate (PC) matrix to study its effects on the flame retardancy. The flame retardancy of PC/HSOBA composites is investigated by limiting oxygen index (LOI), vertical burning tests (UL‐94), and cone calorimeter measurement. The LOI value of the composites is 31.7 and the UL‐94 rating reaches V‐0, when the content of HSOBA is 3 wt %. Cone calorimeter data confirm that the HSOBA acts as an effective additive functioning both as flame retardants and as smoke suppressant. Evolution of the thermal behaviors of the composites tested by TGA, the morphological structures, and the constituent of char residue after LOI tests characterized by scanning electronic microscopy‐energy‐dispersive X‐ray analysis were used to explain the possible flame‐retardant mode. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermal degradation of flame‐retarded polyethylene/magnesium hydroxide/poly(ethylene‐co‐propylene) elastomer composites

Magnesium hydroxide‐based halogen‐free flame retarded linear low‐density polyethylene (LLDPE) composites containing poly(ethylene‐co‐propylene) (EP) elastomer were prepared by a melt process and subsequently vulcanized thermally. The thermal degradation of the composites was studied using thermogravimetric (TG) analysis and real‐time Fourier transform infrared (RT‐FTIR) spectroscopy. The combustion residues from the composites were characterized by Raman spectroscopy and X‐ray photoelectron spectroscopy (XPS). The results from TG and RT‐FTIR tests show that the incorporation of a suitable amount of the elastomer into polyethylene/magnesium hydroxide composites after vulcanization increases the thermal stability. A graphite‐like char was found for the composites with EP elastomer, from Raman spectroscopy studies. XPS results indicate that there are several forms of carbon present in the combustion residues of the composites with EP elastomer, compared with only one form of carbon in the residues of the composites without the elastomer. Copyright © 2003 Society of Chemical Industry     

Synthesis of tris(2‐hydroxyethyl) isocyanurate homopolymer and its application in intumescent flame retarded polypropylene

A macromolecular homopolymer (named as Homo‐THEIC) was synthesized through self‐etherification of tris(2‐hydroxyethyl) isocyanurate (THEIC) molecules and used as charring agent. Its chemical structure was characterized by FTIR and ¹³C‐NMR. The charring agent was mixed with ammonium polyphosphate (APP) and applied in flame retarded polypropylene (PP). Results of UL‐94, LOI, and cone calorimeter test showed that the LOI of flame retarded PP can reach 32.8% and UL‐94 V‐0 rating can be achieved at 30 wt % loading. The heat release rate and smoke production rate during the combustion of PP were substantially reduced. TGA results indicated that the synergistic effect between APP and Homo‐THEIC existed and the addition of intumescent flame retardant (IFR) dramatically enhanced the thermal stability of PP. According to the results of TGA, SEM, TG‐FTIR, FTIR, and Raman, the char forming process of IFR can be separated into three stages: the formation of viscous phosphate ester (T _onset?330 °C), the expanding process along with the decomposition of phosphate ester and the release of a large amount of gases (330–480 °C), and the final formation of graphitic‐like char without any expanding feature (480–670 °C). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44663.     

阻燃聚丁二酸丁二醇酯复合材料的制备及其阻燃性能研究

采用熔融共混技术,将次磷酸铝(AHP)和三聚氰胺氰尿酸盐(MC)引入聚丁二酸丁二醇酯(PBS),制备了一系列阻燃PBS复合材料,并采用极限氧指数、垂直燃烧、微型量热测试以及热失重分析研究了复合材料的阻燃性能以及热稳定性。结果表明,AHP可以有效提高PBS复合材料的阻燃性能;AHP与MC复配可以进一步提高复合材料的阻燃性能,两者质量比为2∶1,添加量为20 %（质量分数,下同）即可使复合材料达到UL 94 V 0级别,极限氧指数达到29 %;AHP以及复合阻燃体系可以有效提高复合材料初始分解温度及其高温稳定性。     

阻燃玻璃纤维增强PA6的紫外光稳定性

分别将三聚氰胺氰尿酸盐、十溴二苯乙烷、溴化聚苯乙烯和次磷酸盐作为阻燃剂对尼龙6(PA6)进行阻燃玻璃纤维增强改性,采用热失重分析仪、水平垂直燃烧测定仪、分光测色仪对PA6复合材料的热降解行为、阻燃性能和紫外光老化后色差值(ΔE)进行了分析。结果表明,阻燃剂的引入提升了PA6复合材料的阻燃性能,但是降低了复合材料的热稳定性。阻燃剂类型对PA6复合材料紫外光黄变的影响程度依次是溴化聚苯乙烯>十溴二苯乙烷>三聚氰胺氰尿酸盐、次磷酸盐。通过将紫外光吸收剂和中性受阻胺光稳定剂复配使用可以有效抑制溴化聚苯乙烯阻燃增强PA6材料的紫外光黄变。