Impact of antimony trioxide on the physico‐mechanical and flammability properties of irradiated recycled rubber powder and waste polyethylene composites

The physicomechanical behavior and flammability properties of waste polyethylene and recycled waste rubber powder blend (WPE/RWRP/MA) filled with antimony trioxide (Sb₂O₃), at different contents 5, 10, 15, and 20 wt %, and irradiated with different gamma radiation doses, namely 50, 75, 100, and 150 kGy, were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and limiting oxygen index (LOI) measurements. Tensile strength, elongation at break, elastic modulus, hardness, swelling properties, and electric conductivity behaviors were also investigated. Experimental results emphasized that Sb₂O₃ particles retard degradation and flammability of the composite. The LOI increases from 16 to 20.9 with 20 wt % Sb₂O₃ specimen irradiated with 150 kGy. Improvement in thermal stability at conditions of 15 wt % Sb₂O₃ and a dose of 75 kGy was demonstrated by TGA.DSC measurements showed that T_m significantly increased in the presence of the filler. Mechanical characterization tests showed a significant increase in tensile strength within the range 5–10 wt % Sb₂O₃. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Intumescent char structures and flame‐retardant mechanism of expandable graphite‐based halogen‐free flame‐retardant linear low density polyethylene blends

The structures of the intumescent charred layers formed from expandable graphite (EG)‐based intumescent halogen‐free flame retardant (HFFR) linear low‐density polyethylene (LLDPE) blends and their flame‐retardant mechanism in the condensed phase have been studied by dynamic Fourier transform infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (LRS), scanning electron microscopy (SEM), differential thermal analysis (DTA) and thermal conductivity (TC) measurements. The dynamic FTIR, XPS and LRS data show that the carbonaceous structures of intumescent charred layers consist of EG and various numbers of condensed benzene rings and/or phosphocarbonaceous complexes attached by the P? O? C and P? N bonds or quaternary nitrogen products. The addition of EG can hasten the formation of these phosphocarbonaceous structures. The above results show that the flame‐retardant mechanism in the condensed phase is that the compact char structures, as observed by SEM, slow down heat and mass transfer between the gas and condensed phase and prevent the underlying polymeric substrate from further attack by heat flux in a flame. The DTA and TC data show that carbonaceous charred layers are good heat‐insulating materials, the TC value of which is only about one‐tenth of that of the corresponding blend and that they increase the oxidization temperature and decrease thermal oxidization heat of the LLDPE/EG/HFFR systems. © 2003 Society of Chemical Industry     

Toughening study of fire‐retardant high‐impact polystyrene

Fire‐retardant high‐impact polystyrene (HIPS) was modified by melt blending with varying amounts of three types of tougheners. The effects of the tougheners on the properties of the fire‐retardant HIPS were studied by mechanical, combustion tests, and thermogravimetric analysis. The morphologies of fracture surfaces and char layers were characterized through scanning electron microscopy. The results show that the impact properties of styrene–butadiene–styrene (SBS)‐containing composites were better than those of ethylene–propylene–diene monomer (EPDM)‐containing or ethylene–vinyl acetate copolymer (EVA)‐containing composites. The tensile strength and flexural modulus of the fire‐retardant HIPS decreased evidently with the addition of tougheners. It is found that the compatibility between SBS copolymer and HIPS matrix was best among the three types of tougheners. The addition of SBS had little influence on the thermal property, residue, flammability, and morphology of char layer of the fire‐retardant HIPS, but the addition of EPDM rubber or EVA brought adverse influence on the residue, flammability, and morphology of char layer of the fire‐retardant HIPS, especially for EPDM. Copyright © 2009 John Wiley & Sons, Ltd.     

Flame‐retarded polyethylene terephthalate with carbon microspheres/magnesium hydroxide compound flame retardant

A novel compound flame retardant (carbon microspheres/magnesium hydroxide, abbreviated as CMSs/MH) was used to improve the fire performance of polyethylene terephthalate (PET). LOI, UL94, and Cone test results showed that CMSs/MH/PET composites obtained the best fire performance at the mass ratio of CMSs to MH, which was 5:5, where the CMSs/MH content was 1.0 wt. % of PET. The Py‐CS‐MS, TGA‐DSC results, and morphology of char residue revealed the flame‐retardant mechanism. CMSs/MH increased the thermal stability of PET by increasing the activation energy at the initial combustion stage. At the second stage of combustion, CMSs/MH increased the chance of recombination of free radicals and slowed the combustion. Additionally, CMSs/MH promoted the cross‐linking of pyrolysis products and further improved the continuity of the char layer. Thus, a dense and continuous char layer of CMSs/MH/PET composites was produced; this char layer reduced the heat release rate and increased the amount of char residue.     

Fire‐retardant poly(ethylene terephthalate) by combination of expandable graphite and layered clays for plastics and textiles

Expandable graphite (EG) and polyethylene terephthalate (PET) were melt blended to develop a new nanocomposite intumescent flame retardant in which the effect of combination of EG with nanoclays would be exploited with sodium and organo‐modified montmorillonites, namely Cloisite^®Na, Cloisite^®10A and Cloisite^®30B. X‐ray diffraction analysis coupled to transmission electron microscopy and rheology shows that PET–EG–clay compounds are characterized by an exfoliated and/or intercalated morphology as a function of the type of clay. Thermal stability of composites is enhanced in nitrogen and air by filler adding as compared with neat PET, while combustion rate is decreased both in the bulk material and in textiles made of fibers spun from the compound. Copyright © 2010 John Wiley & Sons, Ltd.     

阻燃聚乙烯复合材料的制备及其性能研究

用磷酸、季戊四醇和三聚氰胺为原料,在其物质量比为n(磷酸)∶n(季戊四醇)∶n(三聚氰胺)=3∶1∶2的条件下制备了阻燃剂季戊四醇磷酸蜜胺盐,把该阻燃剂和高密度聚乙烯熔融共混制得复合材料。结果表明,当阻燃剂含量为15%时,复合材料的拉伸强度和熔融指数比聚乙烯略有下降,但复合材料的极限氧指数却比聚乙烯提高很多,并从理论上给出相应解释。     

有机膦系阻燃剂改性再生聚酯纺丝及性能研究

采用有机膦系阻燃剂(OP)对再生聚酯(RPET)进行熔融共混挤出造粒,将切片干燥,熔融纺丝制备改性RPET纤维,研究了改性RPET的性能。结果表明:在RPET中加入阻燃剂OP,得到的改性RPET熔点下降,玻璃化转变温度和结晶温度上升,改性RPET纤维强度下降,阻燃性能提高;当阻燃剂OP质量分数为4.7%,拉伸倍数为3.3时,制得的改性REPT纤维的断裂强度为2.2 cN/dtex,断裂伸长率为44%,极限氧指数为27.1%;当OP质量分数为5.9%时,改性RPET纤维的极限氧指数为28.3%。     

Microencapsulation of hydrophilic solid powder as fire retardant agent with epoxy resin by droplet coalescence method

To give water resistance to Bistetrazol–diammonium (BHT–2NH₃) as a fire retardant agent, microencapsulation with epoxy resin was tried by the droplet coalescence method. In this method, two kinds of epoxy resin droplets were prepared; one is the larger epoxy resin droplet containing BHT–2NH₃ as a core material and the other the smaller droplets containing Imidazole as a gelation agent. The larger epoxy resin droplets were made to coalesce with the many smaller droplets during the microencapsulation process to prepare microcapsules. In the experiment, the agitation velocities for preparation of the droplets and for coalescence were mainly changed. With increase in the impeller speed, the content of core material increased, became maximum because of increase in the coalescence frequency, and then decreased because of breakup of droplets. With increase in the impeller speed, the leakage ratio of core material decreased, became minimum, and then increased. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Durable flame‐retardant treatment of polyethylene terephthalate (PET) and PET/cotton blend using dichlorotribromophenyl phosphate as new flame retardant for polyester

Dichlorotribromophenyl phosphate (DCTBPP) was synthesized via the reaction of tribromophenol and phosphorous oxychloride and characterized by elemental analysis, IR, ¹H‐NMR, thermogravimetric analysis, and differential scanning calorimetry. To impart durable flame retardancy the poly(ethylene terephthalate) (PET) fabric was treated with DCTBPP via pad–dry–thermosol fixation and the PET/cotton (50/50) blend fabric was treated with both DCTBPP and tetrakis(hydroxymethyl) phosphonium chloride (THPC)/urea precondensate via a two‐bath sequential treatment. The treated PET fabric's increased limiting oxygen index value was proportional to the increasing DCTBPP application level and showed self‐extinguishing properties at 8.1% add‐on, even after 50 washes. The blend fabric treated with 15% DCTBPP and 30% THPC/urea precondensate became self‐extinguishable and durable to 50 washes, and the treated fabric retained over 85% of its breaking strength without excessive stiffness. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 793–799, 2001     

Synergistic effect of intumescent flame retardant and zinc borate on linear low-density polyethylene

A series of novel intumescent flame retardant (IFR) based on melamine, neopentyl glycol, and aluminum diethylphosphinate were prepared and tested. In addition, the synergistic effect of the novel IFR and zinc borate (ZB) on the flame retardancy of LLDPE composites was investigated. The structures of novel IFR and ZB were characterized by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The limiting oxygen index (LOI) increased from 19.3% for the pure LLDPE to 27% for the 25 wt% IFR/5 wt% ZB composites and the composites achieved the desired V-0 rating in the UL-94 test. Thermogravimetric analysis showed that the addition of IFR/ZB reduced the pyrolysis rate of the LLDPE composites at high temperatures and increased the amount of the char residues, and the char residue of LLDPE-5 reached 12.1 wt% at 700°C. Cone calorimetry (CCT) data showed that the peak of total heat release, heat release rate, and fire growth index were comparatively reduced, indicating that the addition of IFR/ZB decreased the fire hazard of LLDPE composites. The formation of a compact and thermally stable char layer on the surfaces of LLDPE composites was revealed from the scanning electrone microscopy images and digital photographs of the char residue after the CCT tests.     

Fire‐retardant hybrid thermosetting resins from unsaturated polyesters and polysilazanes

This introduces an organic–inorganic thermosetting hybrid resin system based on unsaturated polyester and polysilazanes. It shows the chemical modification of unsaturated polyester structures by end capping to enable the combination of both components. In general, halogen‐free unsaturated polyesters are not fire‐retardant and have to be equipped with additives. Fillers and intumescent additives are preponderantly used in today's fire‐retardant formulations. In contrast to these fire‐retardants, polysilazanes act as ceramizing agents. Polysilazanes are suitable fire‐retardants for resin transfer molding due to their low viscosity. Both burning behavior and glass transition temperature (T_g) are investigated as important application properties. In contrast to state‐of‐the‐art fire‐retardant formulations polysilazane‐based thermosetting hybrid resins burn with high intensity and fast extinction. Therefore, total heat and smoke emission is decreased. The formation of ceramic structures during burning results in high residual mechanical properties and a low mass loss. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40375.     

纳米纤维素阻燃膜的制备及阻燃性检测概述

分别介绍了阻燃性能指标评价、阻燃纤维素纤维的制备、纳米纤维素的制备等方法,比较了阻燃防护服和森林防火服的阻燃性能指标评价国家标准,森林防火服的阻燃性能指标评价还另外采用了GB／T5454—1997纺织品燃烧性能试验氧指数法国家标准,探讨了纳米纤维素复合阻燃膜的制备方法及其应用前景。     

Fire‐resistant elastomers

The molecular design of semi‐inorganic polymers has produced polysilphenylene–siloxane and polyphosphazene elastomers having comparable fire safety to heat resistant engineering plastics. In flaming combustion a polyphosphazene rubber had a four times lower peak heat release rate than the polyurethane elastomer currently used in fire‐blocked aircraft seat cushions. The addition of expandable graphite flakes to polyurethane and polyphosphazene elastomers reduces their peak heat release rates by factors of seven and five, respectively. Published in 2003 by John Wiley & Sons, Ltd.     

无机阻燃剂对PVC/木粉复合材料性能的影响

分别采用A1(OH)3、ZB以及Sb2O3等无机阻燃剂对PVC/木粉复合材料改性,研究不同的阻燃剂配方及阻燃剂含量对PVC/木粉复合材料阻燃性能和力学性能的影响。结果表明:随着A1(OH)3,ZB以及Sb2O3添加量的增加,PVC/木粉复合材料的氧指数(LOI)呈逐渐增大的趋势。Sb2O3阻燃效率最高,当添加量为9份时,氧指数达到35.2%;无机阻燃剂的加入普遍降低了PVC/木粉复合材料的冲击韧性,但对拉伸强度起到了一定的增强作用。     

超细氢氧化铝粉末的制备及其阻燃性能

介绍了以硝酸铝、氢氧化钠为原料,用室温固相法制备了超细粉末氢氧化铝,并运用X射线粉末衍射（XRD）、粒度分析仪及电感耦合等离子发射光谱仪对超细粉末进行了分析和表征;并将超细氢氧化铝和普通氢氧化铝在氯化丁基橡胶（CIIR）中作为阻燃剂进行对比实验。结果表明：此方案可行,纯度较好,应用在氯化丁基橡胶中的阻燃性有一定的提高。     

A hybrid intumescent fire retardant coating from cake- and eggshell-type IFRC

In this study the applicability of flame retardant mixed with a carbon source (such as pentaerythritol) for the intumescent fire retardant coating (IFRC) daubed on the top of a piece of plywood was investigated. There are three kinds of flame retardants used in this study: (1) artificial mesophase graphite powder (MGP), (2) sericite (Al₄(OH)₄(KAlSi₃O₁₀)₂), and (3) graphite. The desirable sizes of graphite, MGP and sericite were obtained by sieving. The graphite, MGP and sericite were characterized using a scanning electron microscope (SEM) and an energy dispersive spectrum (EDS). The IFRC, which consisted of 19.8% of flame retardant (or flame retardant mixed with carbon source), 15% of dehydrate agent, 18% of foaming agent, 7.2% of resin binder, and 40% of solvent, was prepared and daubed on the top of plywood. The fire protection capability of IFRC was tested using a flammability 45° tester. A conventional IFRC (with the carbon source) was also prepared to study the effect of adding the mixture of flame retardant and carbon source on the fire protection capability of IFRC. The microstructures of the conventional IFRC, the IFRC with flame retardant, and the hybrid IFRC (with flame retardant and carbon source) were inferred and demonstrated using SEM micrographs of the cross-section of three kinds of burnt IFRC. Most interestingly, the fire protection capability of the hybrid IFRC exceeds that of the conventional IFRC even though the percentage of carbon in the burnt hybrid IFRC is less than that in the burnt conventional IFRC.     

Mechanical properties of commingled plastic from recycled polyethylene and polystyrene

The mechanical properties of commingled plastic in the form of thick beams prepared by the ET-1 process have been examined in flexure and compression. The mechanical properties were evaluated in relationship to the hierarchical morphology described in a previous study. It was found that the flexural modulus was dominated by the properties of the skin and was satisfactorily modeled by approaches based on the observed micro-morphology, such as the Nielsen and Davis models. It was not necessary to consider the skin–core macromorphology because the flexural modulus was dominated by the void-free skin. The compressive modulus was lower than the flexural modulus and was strongly affected by the skin–core macro-morphology. From the differences between the flexural and compressive moduli, it was determined that the core was essentially nonload-bearing in compression. Flexural fracture initiated on the tension side of the beam and propagated rapidly through the thickness, whereas compressive failure occurred by longitudinal splitting of the skin. © 1994 John Wiley & Sons, Inc.     

Bio-based compatibiliser enhancing the interface properties of CaCO3/recycled high-density polyethylene composites

The fabrication of composites of two or more materials with different polarities requires the use of compatibilisers to improve interface properties. However, most compatibilisers used for industrial production are derived from the cracking products of petroleum, which is a limited resource susceptible to price fluctuations and pollutes the environment. In this study, a new compatibiliser derived from renewable plant-oil-based products, ESO–G–OA, was designed and synthesized using epoxy soybean oil, oleic acid, and glycerol. Scanning electron microscopy results showed that ESO–G–OA can effectively improve the dispersion of CaCO₃ in a recycled high-density polyethylene (reHDPE) matrix and reduce the interfacial gap between the two phases. The analysis of the mechanical properties showed that the ESO–G–OA-modified composite has higher tensile and impact strength than unmodified samples. The ESO–G–OA modification improved the thermal stability and melt flow of the composite and reduced the energy consumption during processing. Moreover, the excellent compatibility of ESO–G–OA can improve the comprehensive properties of CaCO₃/reHDPE composites, compensating for the performance reduction caused by the multiple processing steps necessary to obtain reHDPE. This confirmed that ESO–G–OA has promising application prospects in the production of composites requiring compatibilisers.     

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.     

Creep resistance of wood‐filled polystyrene/high‐density polyethylene blends

Creep, the deformation over time of a material under stress, is one characteristic of wood‐filled polymer composites that has resulted in poor performance in certain applications. This project was undertaken to investigate the advantages of blending a plastic of lower‐creep polystyrene (PS) with high‐density polyethylene (HDPE) at ratios of 100:0, 75:25, 50:50, 25:75, and 0:100. These various PS–HDPE blends were then melt blended with a short fiber‐length wood flour (WF). Extruded bars of each blend were examined to measure modulus of elasticity and ultimate stress. Increasing the ratio of WF increased modulus of elasticity in all composites, except between 30 and 40% WF, whereas the effect of WF on ultimate stress was variable, depending on the composite. Scanning electron microscopic images and thermal analysis indicated that the wood particles interacted with the PS phase, although the interactions were weak. Finally, creep speed was calculated by using a three‐point bending geometry with a load of 50% of the ultimate stress. Creep decreased only slightly with increasing WF content but more significantly with increasing PS content, except at pure PS. The WF/75PS–25HDPE blend showed the least creep. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 418–425, 2001