A novel lanthanum-based phosphorus-containing flame retardant agent and its application in polylactic acid

Currently, intumescent flame retardants (IFR) are often used in the flame retardant modification of polylactic acid (PLA). Due to the high loading, it will weaken the mechanical properties of PLA. In this study, lamellar lanthanum-based DOPO derivative (La@DDP) is prepared by solution method, and it acts as a flame retardant agent was added into PLA with IFR. The results show that PLA composite passes the UL94 V-0 rating with a limiting oxygen index (LOI) of 32.0, in the addition of 4.5 wt% IFR and 1.5 wt% La@DDP. Moreover, the peak heat release rate (PHRR) and total heat release (THR) of the PLA composite reduces by 31.0% and 23.2% compared to pure PLA, respectively. IFR/La@DDP agents assign the PLA composite with excellent thermal stability and carbon-forming ability. Through the analysis of residual char, the synergistic flame retardant mechanism between IFR and La@DDP in PLA composite is discussed. Notably, the tensile strength and elongation at break of the PLA composites are only reduced by 4.03% and 9.51% compared to pure PLA. This work provides a novel lanthanum-based flame retardant agent for designing PLA composites with good fire safety and mechanical properties, and it will broaden the application range of PLA.     

Effect of phosphorus–nitrogen compound on flame retardancy and mechanical properties of polylactic acid

A phosphorus-nitrogen flame retardant (PN) was synthesized by using cytosine and diphenylphosphinic chloride. The flame retardancy and thermal stability of polylactic acid (PLA)/PN composites were investigated by the UL-94 vertical burning test, limited oxygen index (LOI), cone calorimeter test, and thermogravimetric analysis. The PN performs efficiently on improving the flame retardancy of PLA. The PLA composite achieves the UL-94 V-0 rating and its LOI increases to 30.4 vol% by adding 0.5 wt% PN. The flame retardant mechanism analysis showed that PN catalyzes the degradation of PLA to improve the flame retardancy by melting-away mode. Meanwhile PN reduces the release of flammable gasses during thermal degradation of PLA by promoting the transesterification of PLA, which is helpful for extinguishing flame. Moreover, triglycidyl isocyanurate (TGIC) was used as a micro-crosslinking agent to reduce the loss of mechanical properties of PLA/PN composites caused by degradation. Adding 0.1 wt% TGIC and 1.0 wt% PN into PLA, the tensile strength and elongation at break of PLA/PN are increased to the same level as that of PLA. Therefore, PLA with excellent comprehensive performance can be obtained.     

磷腈/三嗪双基分子复配阻燃聚乳酸

将磷腈/三嗪双基分子阻燃剂（HTTCP）分别与六苯氧基环三磷腈（HPCTP）和季戊四醇磷酸酯（PEPA）按不同配比复配,采用熔融共混法制备了阻燃聚乳酸（PLA）的复合材料。采用热失重分析仪、极限氧指数仪、垂直燃烧试验箱和锥形量热仪研究了2种复配阻燃体系及其配比对PLA阻燃复合材料热稳定性和阻燃性能的影响,并采用扫描电子显微镜对材料的残炭形貌进行了分析,探究了其阻燃机理。结果表明,PEPA/HTTCP复配阻燃剂的阻燃效果优于HPCTP/HTTCP复配阻燃剂。当PEPA/HTTCP的质量比为3/1,总添加量为20 %时,阻燃PLA的极限氧指数最高,为27.2 %,热释放速率峰值、平均热释放速率以及热释放总量达到最小值,且能够达到UL 94 V-0级。     

Polydopamine modified ammonium polyphosphate modified shape memory water-borne epoxy composites with photo-responsive flame retardant property

Shape memory epoxy (SMEP) is a high performance shape memory polymer; however, is extremely flammable which severely restricts its applications. In this work, a novel polydopamine modified ammonium polyphosphate (PDA@APP) flame retardant was prepared to improve the flame retardant and enrich the response method of SMEP. Through flame retardancy test confirmed that the flame retarding properties of the PDA@APP/WEP composites significantly improved than the APP/WEP composites, the limiting oxygen index (LOI) values of the APP/SMEP and the PDA@APP/SMEP samples increased by 29.8% and 32.2%, respectively. Moreover, the PDA@APP/WEP composites had excellent light response shape-memory performance. Interestingly, the PDA@APP/WEP treated polyester fabric exhibited excellent light crease recovery performance and excellent flame retardant property. This work develops a new method for fabric crease recovery and will help broaden the application of WEP and its composites.     

EP/MOC复合材料热分解动力学与阻燃性能研究

采用Kissinger法和Crane法对环氧树脂/氯氧镁(EP/MOC)阻燃复合材料在空气中不同升温速率下的热重(TG)和差热(DTA)曲线进行了热解动力学研究。测定了EP/MOC复合材料中EP起始分解和终止分解放热峰的特征温度。结果表明:EP/MOC复合材料中的EP活化能高于纯EP,说明MOC增强了EP的热稳定性,提高了热解温度;EP/MOC中的EP热分解反应级数和纯EP基本相同,说明同条件下的EP和MOC对热分解速率的影响是相同的;另外,该EP/MOC复合材料具有良好的阻燃性能。     

Mechanical,thermal and combustion properties of intumescent flame retardant biodegradable poly (lactic acid) composites

ABSTRACT

Despite extraordinary mechanical properties and excellent biodegradability, poly (lactic acid) (PLA) still suffers from a highly inherent flammability, restricting its applications in the electric and automobile fields. Although a wide range of flame retardants have been developed to reduce the flammability, they normally compromise the mechanical strength of PLA. In this study, a series of composites based on PLA, have been prepared by melt-blending with intumescent flame retardants (IFRs). The morphology, thermal stability and burning behaviour of the composites were investigated using a scanning electron microscope–energy dispersive spectrometer (SEM–EDS), thermogravimetric analysis (TGA), the limiting oxygen index (LOI), vertical burning (UL-94) and the cone calorimeter test (CCT). The LOI value reached 38.5% and UL-94 could pass V-0 for the PLA/IFR composite containing only 12 wt-% IFR. The dispersion of IFR in PLA was observed using SEM–EDS. A significant improvement in fire retardant performance was observed for the PLA/IFR composite from the CCT (reducing the heat release rate and the total heat release). More importantly, compared to pure PLA, the addition of IFR did not seriously deteriorate the mechanical properties of the material.     

Flexible and flame resistant poly(lactic acid)/organomontmorillonite nanocomposites

The PLA/OMMT nanocomposites were produced using a melt compounding technique with isopropylated triaryl phosphate ester flame retardant (FR; 10–30 parts per 100 resin). The flammability of the PLA/OMMT composites was evaluated with an Underwriter Laboratory (UL‐94) vertical burning test, and their char morphology was studied using scanning electron microscopy (SEM). The thermal properties of the PLA/OMMT were characterized with a thermogravimetric analyzer (TGA) and a differential scanning calorimeter (DSC). The thermal analyses showed that adding FR reduced the decomposition onset temperature (T_o) of PLA/OMMT. Both PLA/OMMT/FR20 and PLA/OMMT/FR30 showed excellent flame retardant abilities, earning a V‐0 rating during the UL‐94 vertical burning test. A compact, coherent and continuous protective char layer was formed in the PLA/OMMT/FR nanocomposites. Additionally, the DSC results indicated that the flexibility of the PLA/OMMT composites increased after adding FR due to the FR‐induced plasticization. The impact strength of PLA/OMMT was greatly increased by the addition of FR. Flexible PLA nanocomposites with high flame resistance were successfully produced. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41253.     

PLA/BF/ATH阻燃复合材料的性能研究

将氢氧化铝(ATH)作为阻燃剂与聚乳酸(PLA)、竹粉(BF)共混,得到PLA/BF/ATH阻燃复合材料,并对该复合材料的性能进行了测试与表征。结果表明:随着ATH用量的增加,PLA/BF/ATH阻燃复合材料的力学性能有所降低,但复合材料的热稳定性和残炭率相对提高,而且ATH的引入对复合材料燃烧过程中热量和烟气的释放产生了一定的抑制作用;另外,当ATH用量为25 phr时,复合材料具有最佳综合性能。     

Polylactic acid flame-retardant composite preparation and investigation of flame-retardant characteristics

Polylactic acid (PLA) is a new type of biodegradable material with good mechanical properties, and is widely used in many fields. However, as PLA is highly flammable, it is necessary to conduct flame-retardant modification research on PLA. Phosphorus heterophilic flame retardants are low smoke, non-toxic and have high flame-retardant efficiency, and also have broad application prospects. In this study, a phosphazene flame retardant, 9,10-dihydro-9-oxa-10-phosphazene-10-yl-hydroxy-phenol (abbreviated as DOPO-PHBA), was synthesized. The PLA/ECE/DOPO-PHBA flame-retardant composites were prepared by adding DOPO-PHBA and epoxy chain extender (ECE) into PLA. Thermal, mechanical, and flame-retardant properties, as well as microscopic morphology of the PLA flame-retardant composites were characterized and analyzed, and the flame-retardant mechanism was discussed. Results show that when the flame-retardant DOPO-PHBA is added at 5 wt%, the PLA composites can reach the V-0 level of combustion, and the corresponding LOI value is 30.0% at this time, and the LOI value increases from 22.5% to 33.6% with the increase of the flame-retardant content. In addition, PLA composites still have good mechanical properties, and the cone heat, carbon residue and the thermal decomposition process shows that the flame-retardant causes a two-phase flame-retardant mechanism on PLA with the gas and condensed phases acting in synergy. High flame retardancy is mainly attributed to free radical quenching, gas dilution, and the thermal barrier caused by the carbon layer. This work provides a simple and scalable method for the preparation of high-performance flame-retardant PLA materials.     

Preparation and characterization of straw/magnesium cement composites with high-strength and fire-retardant

To fully exploit the abundant bioresource crop straw, a straw-based composite with excellent fire retardant, high strength and dimensional stability was successfully prepared for use in building applications. The subject composite was composed of rice straw/magnesium cement (SMC) adhesive, with glass fiber as a reinforcement agent. The mechanical strength, dimensional stability, flame retardant, smoke suppression, and thermal stability of the material were used to evaluate its performance as a potential construction material. The effect of the addition of glass fiber and the pavement structure of straw and glass fiber were also characterized. The experimental results showed that the mechanical strength and rigidity of SMC composite were increased by the addition of 9% glass fiber to the total mass of the filler. Glass fibers reinforced and reduced the volume of the filler, while increasing the dimensional stability of the composites. The strength of the mixed structural composites was higher than layered structural composites, which is benefits the preparation of the composites. Compared to other straw/cement composites, glass-fiber reinforced SMC composites exhibited better strength, dimensional stability, flame retardant, smoke suppression and thermal stability. These superb properties make these novel composites an ideal candidate for use in the field of interior decoration, particularly in public venues.     

Improvement of the flame retardancy of plasticized poly(lactic acid) by means of phosphorus‐based flame retardant fillers

The aim of this study is to improve the flame resistance and toughness of poly(lactic acid) (PLA) with the addition of low amount of flame retardant fillers and plasticizer simultaneously. Poly(ethylene glycol) (PEG) was used as plasticizer for PLA. Ammonium polyphosphate, boron phosphate, and tri‐phenyl phosphate (TPP) were used as flame retardant additives. Among these flame retardant additives, boron phosphate was synthesized from its raw materials by using microwave heating technique. Characterization of PLA/PEG‐based flame retardant composites was performed by conducting tensile, impact, differential scanning calorimeter, thermal gravimetric analysis, scanning electron microscope, limiting oxygen index, and UL‐94 vertical burning tests. Mechanical tests showed that the highest tensile strength, impact strength, and elongation at break values were obtained with the addition of ammonium polyphosphate and TPP into PLA/PEG matrix, respectively. Scanning electron microscopy analysis of the composites exhibited that the more homogeneous filler distribution in the matrix was observed for TPP containing composite. The best flame retardancy performance was also provided by TPP when compared with the other flame retardant additives in the plasticized PLA‐based composites.     

A novel bio-based charcoal-forming agent based on chitosan and phytate@Mg to improve the flame retardancy of poly(lactic acid)

A novel bio-based carbon forming agent (Mg@PA-CS) containing P and N elements was were synthesized using the complexation characteristics of chitosan (CS) and phytate (PA). The flame retardant behavior of poly(lactic acid) (PLA)/Mg@PA-CS/APP composites (addition of 20 wt% of different ratios of Mg@PA-CS and APP to polylactic acid composites) were investigated by the limiting oxygen index (LOI), vertical burning test (UL-94), cone calorimetry test (CCT), and thermogravimetric analysis (TGA). Due to the biphasic flame retardant and synergistic effect, since the 20 wt% flame retardant system (Mg@PA-CS:APP = 1:2), PLA composites passed the UL-94 test V-0 rating, reached 34% LOI value. The peak heat release rate (PHRR) and total heat release rate (THR) were reduced to 1/2 of the pure PLA, char residue could be as high as 11.49% at 800°C. Moreover, the flame-retardant mechanism of PLA composites during thermal decomposition was analyzed using a scanning electron microscope (SEM) and the coupling techniques of TGA linked with FT-IR (TG-FTIR).     

Flame retardant and antibacterial properties of PLA/PHMG-P/APP composites

Poly(lactic acid) (PLA) has evolved into a commodity polymer with numerous applications. However, its high flammability limits its viability as a perfect alternative to petrochemical engineering plastics. In this study, PLA was modified using polyhexamethyleneguanidine phosphate (PHMG-P) and ammonium polyphosphate (APP). The flame retardant performance of PLA/PHMG-P/APP was investigated based on the limiting oxygen index (LOI), vertical burning test (UL-94), thermogravimetric analysis (TGA), cone calorimetry (CC), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and Raman Spectrometry. Qualitative and quantitative methods were used to determine the antibacterial properties of PLA composites. The LOI of PLA-10% (P:A = 1:4) was 31.7% and was rated V-0 in the UL-94 V-0 test. The antibacterial properties of the composites reflected the antibacterial effects of PLA-10% (P: A = 1:4) against Escherichia coli and Staphylococcus aureus, with the antibacterial rates reaching 93.41% and 93.26%, respectively. PHMG-P and APP had a synergistic flame-retardant effect and improved the flame retardancy of PLA while exhibiting excellent antibacterial properties.     

Improve the mechanical property and flame retardant efficiency of the composites of poly(lactic acid) and resorcinol di(phenyl phosphate) (RDP) with ZnO‐coated kenaf

The kenaf coated with zinc oxide (ZnO) was prepared and characterized by X‐ray diffraction, scanning electron microscopy, and X‐ray photoelectron spectroscopy. The ZnO‐coated kenaf and the flame retardant resorcinol di(phenyl phosphate) were blended with poly(lactic acid) (PLA) by solution compounding and melt blending to prepare the flame‐retarded PLA composites. The thermal stability, the mechanical property, and the flame retardancy of the PLA composites were improved evidently. The tensile strength of the prepared PLA composites could reach up to 62.3 MPa in comparison with 55.4 MPa of the pure PLA. The dense and compact char residues were observed after the combustion of the PLA composites containing ZnO‐coated kenaf, whereas there were serious dripping phenomena and no char formation during the combustion of the pure PLA. The use of ZnO‐coated kenaf could increase flame retardant efficiency obviously. The mechanism of flame retardancy was discussed. Copyright © 2014 John Wiley & Sons, Ltd.     

机械力改性芦苇纤维及其对聚乳酸复合材料的阻燃性能研究

采用机械力化学法对芦苇纤维（RF）进行磷酰化改性,并将改性后的磷酰化芦苇纤维（MPRF）与聚乳酸（PLA）共混制备复合材料,研究了MPRF对复合材料热稳定性、阻燃性、燃烧性能以及力学性能的影响。结果表明,磷元素成功接枝到芦苇纤维表面,800 ℃时的残余质量增加;随着MPRF添加量的提高,PLA复合材料的阻燃性能随着MPRF的加入而逐渐增加,当MPRF添加量为40 %（质量分数,下同）时,其弯曲强度和拉伸强度可达266.9 MPa和44.7 MPa,极限氧指数为24.6 %;最大热释放峰值下降到366.9 kW/m²,与PLA相比下降了39.3 %,有效降低复合材料的火灾危险性。     

Influences of high-impact polystyrene loading on the foaming behavior and flame-retardant properties of polyphenylene oxide composites blown with CO2

Polymeric foam with high expansion ratio, well-defined cell structure, and excellent flame retardant properties is essential for broadening its applications. Polyphenylene oxide (PPO) is a kind of cost-effective engineering plastic with excellent flame retardancy, anti-dripping behavior, and good mechanical strength, but suffers from its poor processability. In this study, microcellular PPO composite foams were fabricated by applying a solid-state foaming technology using compressed CO₂ as the blowing agent. High-impact polystyrene (HIPS) phase was introduced with the aim to improve the fluidity and foaming ability of PPO composites. It was interesting to find that the 18–48% HIPS loading significantly increased the expansion ratio, that is, 1.8–3.3 versus, 10.8–14.3, and broadened the optimum foaming temperature of PPO composite foams, attributing to the miscible character between PPO and HIPS and excellent foaming ability of HIPS. Furthermore, the as-prepared PPO/HIPS composite foams exhibited high limited oxygen index (LOI) of 22.0–29.9%, low horizontal flammability rate (HFR) of 60.5–141.2 mm/min, and anti-dripping behavior, and the void fraction was verified to be a critical parameter to determine the flame retardant performance of the composite foam. Besides its lightweight and excellent flame retardant properties, PPO composite foams also presented uncompromised tensile properties and well-defined thermal insulation properties.     

改性凹凸棒土对PBAT阻燃性能的影响

用费托蜡（FTW）对凹凸棒土（ATP）进行表面改性制备了阻燃剂F-ATP，并对其形貌、结构及其热稳定性进行了表征。将阻燃剂F-ATP加入到聚己二酸/对苯二甲酸丁二醇酯（PBAT）基体中制备了PBAT/F-ATP复合材料。采用极限氧指数测定仪（LOI）、垂直燃烧测试（UL-94）、锥形量热仪（CCT）、TG-IR、拉曼光谱仪和SEM对复合材料的阻燃性能进行了分析。结果表明，改性后的ATP团聚现象消失且热稳定性明显提高。阻燃剂F-ATP质量分数为10%的PBAT/F-ATP复合材料（PBAT-3）阻燃效果最佳，其LOI值达到23.5%,UL-94等级达到V-1级，熔滴现象得到明显改善。与ATP质量分数为10%的PBAT/ATP复合材料相比，PBAT-3复合材料的峰值热释放速率值（PHRR）、总热释放量（THR）分别降低了4.99%和26.11%。PBAT-3复合材料气态产物的释放量在整个燃烧过程中均降低，起到了很好的气相阻燃效果，这主要归因于阻燃剂F-ATP的加入使PBAT/F-ATP复合材料形成致密且连续性好的炭层结构，有效地隔绝了复合材料内部与外界的热量/质量传递。     

Vinyl polysiloxane microencapsulated ammonium polyphosphate and its application in flame retardant polypropylene

Vinyl polysiloxane microencapsulated ammonium polyphosphate (MAPP) was prepared by a sol-gel method using vinyltrimethoxysilane as a precursor to improve its thermal stability and hydrophobicity. The MAPP was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and thermogravimetric analyzer (TGA). The results showed that ammonium polyphosphate (APP) was successfully coated with vinyl polysiloxane. MAPP and pentaerythritol (PER) were used together to improve the flame retardancy of polypropylene (PP). The flame retardant properties of PP composites were investigated by limiting oxygen index (LOI), UL-94 test, TGA and SEM. When the MAPP was added as a flame retardant, with PER as a char forming agent, the LOI of PP/MAPP/PER composites was 33.1%, and it reached the UL-94 V-0 level. The results also demonstrated that the flame retardant properties of PP/MAPP/PER composites were better than those of PP/APP/PER composites at the same loading. Moreover, the addition of flame retardant and carbon forming agent could promote the crystallization behavior of PP.     

Reactable versus soluble DOPO derivatives in poly(lactic acid)/poly(butylene adipate-co-terephthalate) composites: Flame retardance,mechanical properties and morphology

Flame retardant poly(lactic acid)/poly(butylene adipate-co- terephthalate) (PLA/PBAT) composites containing 9,10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO) derivatives (phosphorus-containing diol compound of DOPO-HQ, and bis DOPO phosphonates of DIDOPO) were systematically and comparatively investigated. Results showed that the different structures of the two derivatives with reactable or soluble characteristics display different effects. DIDOPO endows a higher limiting oxygen index and a better UL-94 rating for PLA/PBAT composites compared with DOPO-HQ. Compared with that of PLA/PBAT, the peak heat release rate of PLA/PBAT/DIDOPO-12.5 is 8.4% lower and that of PLA/PBAT/DOPO-HQ-12.5 is 30.6% lower. The flame retardant mechanism of the main gaseous and minor condensed phases is evident for the flame retardant PLA/PBAT composites. In comparison, DIDOPO displays a greater flame inhibition effect, and DOPO-HQ shows better barrier and protective functions in PLA/PBAT composites. Besides, the elongation at break of the composites with DOPO-HQ is slightly superior to that of PLA/PBAT/DIDOPO. After the introduction of flame retardant, the blends show dispersed particles with size reduction relative to those of PLA/PBAT. This work provides a guidance to design PLA composites with simultaneously improved flame retardancy and toughness.     

Influence of ammonium polyphosphate on the flame retardancy and mechanical properties of ramie fiber‐reinforced poly(lactic acid) biocomposites

Fully degradable natural fiber/degradable polymer composites have received much research attention and have various applications such as in automotive components. But flammability limits their application; it is important to improve the flame retardancy of fully degradable composites with environmentally friendly flame retardants. Flame‐retarded ramie fiber‐reinforced poly(lactic acid) (PLA) composites were prepared using three processes: (1) PLA was blended with ammonium polyphosphate (APP), and then the resulting flame‐retarded PLA was combined with ramie fibers; (2) ramie fibers underwent flame‐retardant treatment with APP, which were then compounded with PLA; and (3) PLA and ramie, both of which had been flame‐retarded using APP, were blended together. The APP in the composites is shown to be very effective in improving flame retardancy according UL94 test and limiting oxygen index measurements. Thermogravimetric analysis shows that the improved flame retardancy is due to increased char residue at high temperature. The loading of APP disturbs the compatibility between PLA and fibers, which can be directly observed using scanning electron microscopy. Furthermore it has an influence on the dynamic mechanical properties and mechanical properties according dynamic mechanical analysis and mechanical measurements. The results show that composites produced using the third process not only have the best flame retardancy but also comparatively better mechanical properties. Copyright © 2009 Society of Chemical Industry