Development of heat shrinkable and flame‐retardant EVA/CSM blends

A plastic (EVA) was blended with elastomer (CSM) with and without curatives. The elastomer phase (amorphous) contributed markedly to the shrinkability and most important is, took up a major amount of additive flame‐retarding agent thus not affecting much the heat shrinkability of the plastic i.e. as a whole the blend. When the elastomer phase was crosslinked the flame‐retardancy, due to a reduction of combustible volatile product, was increased. Additive flame‐retardants hamper the heat‐shrinkability of the blend to some extent depending on various factors such as blend composition, temperature, curing etc. The depression of shrinkability in the presence of flame‐retarding agent was less for the cured sample and elastomer‐rich blend compared with the uncured and plastic‐rich blend, respectively. It was found that with an increase in the cure time and elastomer content the shrinkability as well as flame‐retardancy was increased. At high temperature the sacrifice of the shrinkability in the presence of flame‐retardants increased, for a particular blend. The shrinkability and flame‐retardancy of a cured sample was higher than that of an uncured sample. The highest flame‐retardancy was obtained in the presence of Sb₂O₃/Chlorohor. Copyright © 2002 John Wiley & Sons, Ltd.     

Effect of cure systems on shrinkability of polyolefin–EPDM blends

Effects of cure systems on shrinkability of polyolefin and EPDM blends have been studied as a function of cure time and amount of elastomers added. During measurement one of the parameters is kept constant while the other varies. The shrinkability of the blends increases with the increase in cure time when elastomer content is fixed. Similarly, at constant cure time higher loading of elastomer increases the shrinkability of the blends. Samples stretched under high temperature show higher shrinkability than those stretched under room temperature. Dicumylperoxide (DCP) is a more effective curing agent for making a particular set of blends more shrinkable than the sulfur. The changing morphological pattern with DCP-cured shrunk samples from those of sulfur cured samples is corroborated by the SEM studies where the elastomer phase appears to be globular in nature. The crystallinity of the blend depends on the dose and type of the elastomer used in polyolefin. The curing efficiency of the elastomerphase depends on the polyolefin used as blend partner. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 597–603, 1998     

Heat‐shrinkable polymer blends based on grafted low‐density polyethylene and polyurethane elastomer. Part I

Blends prepared by melt‐mixing of thermoplastic material‐elastomer have gained considerable attention in recent years. Heat‐shrinkability of polymer, which is dependent on elastic memory, can be introduced into the system in the form of an elastomeric phase. The present study deals with the measurement of the heat‐shrinkability of the blend of grafted polyethylene and polyurethane elastomer. Interchain crosslinking between grafted polyethylene and elastomer improves shrinkability. High‐temperature performance of the sample depends on the degree of interchain crosslinking. Probable interactions between the rubber and plastic phase are confirmed by IR spectroscopy. Extraction of the elastomeric phase is restricted due to interchain crosslinking as confirmed by SEM study. © 2000 Society of Chemical Industry     

PP/EPDM热塑性弹性体动态硫化阻燃材料制备及性能研究

研究了聚丙烯/三元乙丙橡胶(PP/EPDM)体系在过氧化二异丙苯(DCP)、硫磺(S)和酚醛树脂(PF)三种不同硫化条件下的动态硫化过程。探讨了膨胀型阻燃剂三聚氰胺磷酸盐(MP)和双季戊四醇(DPER)对PP/EPDM动态硫化体系力学性能和阻燃性能的影响。结果表明:在加入阻燃剂的情况下,PP/EPDM体系的阻燃性能得到了改善,但体系的力学性能下降较多。     

Effect of trace chloride on the char formation and flame retardancy of the LLDPE filled with NiAl‐layered double hydroxides

Layered double hydroxides (LDHs) have received intensive attentions for the potential as flame retardants of polyolefin. In the work, trace amounts of chloride were investigated for their synergistic effects on the char formation and flame retardancy of the linear low‐density polyethylene (LLDPE) filled with NiAl‐LDHs. Results showed that 0.5 wt% of NH₄Cl incorporation enabled the char yield of 20%LDH/LLDPE (20 wt% of NiAl‐LDH) increase from 10.4% to 49.6%. Other chlorides likewise offered significant increase in the char yield of 20%LDH/LLDPE. With the flame‐retardant measurements of cone calorimeter and limiting oxygen index device, it is revealed that the flame retardancy of LLDPE filled with NiAl‐LDHs could be greatly improved when trace amounts of NH₄Cl were further introduced. Thermal stability analysis illustrated that the presence of NiAl‐LDHs or NH₄Cl all had positive effects on the thermal stability of LLDPE, in which the chlorides influenced the LLDPE thermal stability via direct participation in the degradation of LLDPE. The synergetic mechanism analysis reveals that the introduction of chloride enabled the LLDPE decomposed products have more tendency to grow carbon nanotubes with the presence of NiAl‐LDH catalysts. Finally, the mechanical properties of LLDPE filled with NiAl‐LDHs and NH₄Cl were also investigated.     

Flame retardant cotton

The water‐soluble organophosphorus compound, namely, hexahydroxymethylamidocyclotriphosphatriazatriene (HHMAPT) was synthesized by reacting phosphonitrile chloride with liquid ammonia followed by reaction with formaldehyde. It is rich in phosphorus and nitrogen and as a polyfunctional compound it can undergo several reactions with itself forming an in situ polymer or with cotton cellulose similar to conventional N‐methylol finishing agents. It was successfully used as a flame retarding agent in the absence and presence of etherified methylolated melamine (EMM). Investigations into the different factors that affect these reactions and the effect of these on the properties of the finished fabrics give rise to the following points; (1) P%, N% and crease recovery increase by increasing the curing time and temperature; (2) the most effective catalyst is NH₄Cl; P% and N% increase by increasing the concentration of NH₄Cl from 5 to 12.5 g/l (3) an increase in EMM and HHMAPT concentrations is accompanied by enhancement in P%, N% and crease recovery; (4) the fabric samples exhibit durable flame retardancy at temperatures higher than 120°C in the absence of EMM while in the presence of EMM, all samples exhibit durable flame retardancy properties, regardless of the temperature of curing; (5) the durable flame retardancy is achieved at concentrations higher than 60 g/l HHMAPT and 7.5 g/NH₄Cl. All samples exhibit loss in tensile properties but within an acceptable range (20%), crease recovery is improved in all samples. Copyright © 1999 John Wiley & Sons, Ltd.     

Evaluation of PP/EPDM nanocomposites filled with SiO2, TiO2 and ZnO nanofillers as thermoplastic elastomeric insulators

Abstract

Thermoplastic elastomer, which has important characteristics for cable insulation, was developed by melt blending of polypropylene (PP) with ethylene propylene diene monomer (EPDM) at various blend ratios together with SiO₂, TiO₂ and ZnO nanofillers at fixed loading of 2 vol.-%. The influence of EPDM content and the presence of nanofillers in the blend on burning rate, hydrophobicity and dielectric breakdown strength were investigated. Burning rate of PP/EPDM/ZnO was significantly reduced, implying that there was an improvement in fire retardancy with the addition of ZnO nanofillers in the polymer blend. Both SiO₂ and ZnO filled system showed an improvement in hydrophobicity. Furthermore, dielectric breakdown strength showed higher value in EPDM rich blends. In addition, the presence of nanofillers deteriorated the dielectric breakdown strength of PP/EPDM nanocomposites.     

Application of chlorinated waste rubber as a flame retardant of low density polyethylene

For the reuse of the abundant waste rubber (WR), chlorinated waste rubber (Cl‐WR) was prepared by a water‐based chlorination method using chlorine gas as the chlorinating reagent. The resultant Cl‐WR was used as a flame retardant of low density polyethylene (LDPE) matrix. The properties of WR and Cl‐WR were characterized by thermogravimetric (TG) and Fourier transform infrared (FTIR) spectrometer. The results indicated that the Cl‐WR with a 42% chlorine content had a higher char residue than WR. The limiting oxygen index (LOI) value can be increased up to 27.2 and the flame retardancy reached to the maximum (V‐0) grade for the LDPE/Cl‐WR‐Sb blends with mass ratios of Cl‐WR/LDPE and Cl‐WR/Sb₂O₃ being 80/100 and 1.5/1, respectively. The improvement of the flame retardancy and thermal properties of the LDPE/Cl‐WR‐Sb blends were attributed to the char formation and synergistic effect between Cl‐WR and Sb₂O₃ in a high temperature region, although the mechanical properties of the said blend decreased in comparison with that of the neat LDPE. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Poly(aryloxyphosphazenes) and a flame retardant foam

Plastics and elastomers were prepared, physical state determined by the side chains attached to the phosphorus–nitrogen backbone. The poly(aryloxyphosphazenes) displayed a high degree of flame retardancy in the uncured, unfilled state. Limiting oxygen index (LOI) values varied from 27 to 33 for nonhalogenated materials and from 38 to 65 for halogenated materials. These values qualify all poly(aryloxyphosphazenes) studied as flame retardants according to the generally accepted definition (LOI ≥ 27). Materials subjected to the National Bureau of Standards Smoke Test gave encouraging results. The [(C₆H₅O)₂PN-(4-C₂H₅C₆H₄O)₂PN]n elastomer was investigated for application as a fire retardant insulating foam. Closed-cell foams produced from this copolymer showed much improved fire retardancy and smoke generation compared to commercially available fire retardant foam insulations.     

A novel phosphorus‐containing copolyester with low melting temperature and high flame retardancy

BACKGROUND: The increasing uses of non‐woven fabrics need the development of a kind of novel flame‐retardant polyester with low melting temperature. Neopentyl glycol (NPG) and 3‐(hydroxyphenylphosphinyl)propionic acid (HPPPA) were used as the third and fourth comonomer to synthesize phosphorus‐containing poly[(ethylene terephthalate)‐co‐(neopentyl terephthalate)] (PENT) with both flame retardancy and low melting temperature. RESULTS: The chemical structure of PENT was confirmed using Fourier transform infrared, ¹H NMR, ¹³C NMR and ³¹P NMR spectroscopy. PENT displays a monomodal gel permeation chromatography curve. When the content of NPG was kept at 10 wt% and the content of HPPPA increased to 5 wt%, the melting temperature (T_m) of the resulting PENT5/10 decreases to 171.2 °C, a 34.6 °C decrease compared to that of PENT0/10 (containing no HPPPA). The flammability of the PENTs was characterized with the limiting oxygen index (LOI) test, the UL‐94 vertical test and the cone calorimeter test. The incorporation of HPPPA can significantly improve the flame retardancy of the PENTs, the LOI values of the PENTs increasing from 24.4 to 37.6, as the loading of HPPPA increases from 0 to 5 wt%. CONCLUSION: The PENTs possess both low melting temperatures and excellent flame retardancy. HPPPA can be used as fourth comonomer to improve the flame retardancy of the PENTs, while decreasing the T_m value of the copolyester. Copyright © 2009 Society of Chemical Industry     

Study of Fire Retardancy and Thermal and Mechanical Properties of HDPE-Wood Composites

This article reports a study of flame retardancy and thermal and mechanical properties of wood-plastic composites (WPCs) based on high-density polyethylene and pine flour. The study shows that sample composition plays an important role in WPCs' properties. The influence of additives like fillers (SiO₂ or CaCO₃) and flame retardants ammonium polyphosphate (APP) and pentaerythritol (PER) on WPCs' properties has been considered. The best properties are shown in samples using SiO₂ as filler and treated with the intumescent fire retardant APP/PER. Such samples have excellent fire retardancy with V-0 rating (UL-94 test) and imply that APP/PER fire retardant ensures effective fire retardancy for WPCs.     

Flammability properties of paper coated with poly (methylenephosphine), an organophosphorus polymer

The flame retardant properties of paper coated with either poly(methylenephosphine) ( PMP ) or poly(methylenephosphine oxide) ( PMP‐O ) are evaluated. Paper sheets made from thermomechanical pulp were coated with PMP (M_n = 27,000 g mol^?1, polydispersity index (PDI) = 1.47), PMP‐O (M_n = 30,000 g mol^?1, PDI = 1.24), or monobasic ammonium phosphate (MAP) to achieve an approximate loading of 0.8 mmol P/g paper. Thermal stability studies by thermogravimetric analysis show that the paper degrades in two main stages, with the second thermo‐oxidative stage having a slower rate of degradation for paper treated with flame retardants. The flame retardancy of the sheets was evaluated by Technical Association of Pulp and Paper Industry Standard Method T461 cm‐00 and by limiting oxygen index (LOI) according to ASTM D2863. After leaching with water, samples coated with PMP or PMP‐O show no loss of flame retardancy, while those coated with MAP lose all flame retardancy. The LOI of paper coated with PMP (23.1%) or PMP‐O (25.9%) is higher than those of uncoated paper (19.6%), but lower than MAP‐coated paper (34.7%). Analysis of the char provided evidence that the flame retardant mechanism of PMP and PMP‐O involves the formation of phosphorus oxides and acids. Copyright © 2014 John Wiley & Sons, Ltd.     

Overview of recent developments in the flame retardancy of polycarbonates

This paper presents an overview of the recent literature on flame retardancy of polycarbonate (PC) and polycarbonate‐based resins. A brief survey of the major mechanisms of thermal decomposition of PC is also presented because it gives insight in the mechanisms of flame retardant action. Mostly industrial laboratories are involved in the development of new flame retardants for PC and, to a much lesser extent, academic laboratories are doing research on the mechanistic aspects of flame retardancy. The number of patents published annually on the flame retardancy of PC and its blends significantly exceeds the number of patents on flame retardancy of any other polymer. Because PC is a naturally high charring polymer, the condensed phase active flame retardants, in particular phosphorus‐based ones, are widely used in PC‐based blends. Plain PC can pass stringent flame retardant tests with very low additions of some sulfur‐ or silicone‐based flame retardants. Copyright © 2005 Society of Chemical Industry     

Flame retardancy in fabric consisting of cellulosic fiber and modacrylic fiber containing fine‐grained MoO3 particles

Flame retardancy of fabrics consisting of modacrylic fiber containing with various dispersed metal compounds and cellulosic fiber has been investigated by means of flame test (ISO15025 procedure A) and limiting oxygen index (LOI). It has been found that excellent flame retardancy is achieved by fine‐grained MoO₃ particles. The afterflame time in flame test and the LOI value are improved with decreasing particle size of MoO₃. The flame retardancy of MoO₃ (particle size; 0.1 µm) is comparable to that of Sb₂O₃. On the other hand, significant improvement in flame retardancy is not observed for other metal compounds although some metal oxides and a hydroxide in the present study are known as flame retardant or smoke suppressing agent in halogen containing polymer in previous studies. In order to clarify the mechanism of the observed flame retardancy by the addition of fine‐grained MoO₃, we have carried out X‐ray fluorescence spectrometry (XRF) measurement of the fabric specimen after the flame test and thermogravimetric analysis (TGA) of various types of samples. These analytical data indicated that MoO₃ works as halogen synergist in solid phase and the char of modacrylic fiber formed by addition of MoO₃ suppresses decomposition of the cotton blended in the fabric in the range of the ignition temperature. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and properties of novel phosphorus‐containing bismaleimide/epoxy resins

A novel soluble phosphorus‐containing bismaleimide (BMI) monomer, bis(3‐maleimidophenyl)phenylphosphine oxide (BMIPO), was synthesized by the imidization of bis(3‐aminophenyl) phenylphosphine oxide, in which its structural characterization was identified with ¹H‐NMR, ¹³C‐NMR, and Fourier transform infrared spectra. The BMIPO resin, with five‐membered imide rings and high phenyl density, was an excellent flame retardant with a high glass‐transition temperature (T_g), onset decomposition temperature, and limited oxygen index. In phosphorus‐containing BMI/epoxy/4,4′‐methylene dianiline (DDM)‐cured resins, homogeneous products were obtained from all proportions without phase separation. Because of the higher reactivity of BMIPO/DDM relative to that of 4,4′‐bismaleimidodiphenylmethane (BMIM)/DDM, the increase in the BMIPO/BMIM ratio in this blending resin increased the recrosslinking hazards of the postcuring stage and so lowered the T_g value and thermal stability. The thermal stability of the BMI/epoxy‐cured system was lower than that of the epoxy‐cured system because of the introduction of a phosphide group into BMIPO, whereas for the T_g value and flame retardancy, the former was significantly higher than the latter: the higher the BMIPO content in the blend, the higher the flame retardancy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2080–2089, 2002; DOI 10.1002/app.10607     

Heat Shrinkable Polymer Blends Based on Grafted Polyethylene and Chlorosulphonated Polyethylene (Part I)

Abstract

Blend prepared by melt mixing of thermoplastic material-elastomer have gained considerable attention in recent years. Heat shrinkability of the polymer which depends on elastic memory can be introduced into the system in the form of an elastomeric phase. The present study deals with the measurement of heat shrinkability of the blend of grafted polyethylene with CSM. Interchain crosslinking between grafted polyethylene and elastomer improves the shrinkability. Crystallinity of the polymer blends also affected by interchain crosslinking, thus affecting the shrinkability. Probable interactions of the rubber and plastic phase are confirmed by IR spectroscopy. Extraction of the elastomeric phase is restricted due to interchain crosslinking as confirmed by SEM study.     

Synergistic effect of carbon and phosphorus flame retardants in rigid polyurethane foams

Two kinds of carbon and phosphorus synergistic system used to improve the flame retardancy of rigid polyurethane foams (RPUF) were studied. One is the synergistic effect of expandable graphite and guanidinium phosphate; the other is red phosphorus and guanidinium phosphate. The flame retardant properties and mechanical properties of these composites were investigated by limiting oxygen index, cone calorimeter test, as well as tension and compression test. These 2 groups of mixed inorganic flame retardants can greatly improve the flame retardancy of RPUF composites, as the limiting oxygen index increases from 20.1% to about 33% and the HRR reduces from 395 kW/m² to below 200 kW/m². It provides a convenient and inexpensive way to obtain RPUF with demanding properties.     

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     

Halogen‐free intumescent flame‐retardant ethylene‐vinyl acetate copolymer system based on organic montmorillonite and graphene nanosheets

Halogen‐containing flame retardants are not preferred for environmental reasons. Herein, a halogen‐free intumescent flame‐retardant ethylene‐vinyl acetate copolymer (EVA/IFR) system containing organic montmorillonite (OMMT) and graphene nanosheets (GNSs) is fabricated with well dispersion structure, enhanced thermal‐oxidative resistance at high temperature. Interestingly, the amount of residual chars from thermogravimetric analysis is increased to 12.7 wt % at 700 °C, the EVA/IFR composite containing both OMMT and GNSs exhibits the best flame retardancy with the lowest peak heat release rate value of 529.58 kW m^?2, and the highest limited oxygen index value of 24.8%. The excellent flame retardancy is attributed to the formation of complete and compact protective char layer. Furthermore, the decreases of the mechanical properties caused by the addition of IFR are relieved and a high volume resistivity is maintained when combining OMMT and GNSs in the EVA/IFR system together. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46361.     

Flame retardancy and thermal properties of organoclay and phosphorous compound synergistically modified epoxy resin

Phosphorous flame retardants (PFRs) are common halogen‐free flame retardants. However, the flame retardancy of PFRs has not been fully exploited. Herein, the synergistic flame retardant effect of a typical phosphorous compound, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO), and organoclay on epoxy is studied. Results show that the peak of heat release rate (pHRR) and smoke production rate of modified epoxy resin (EP) with both 2.0 wt % phosphorus and 4.0 wt % organoclay are only 40% and 46% of that of neat EP resin, respectively, while the sole use of 2.0 wt % phosphorus only decrease the pHRR to 59% of that of neat EP resin. The structure and thermal decomposition behavior of as‐prepared nanocomposites are analyzed, and a synergistic flame retardant mechanism is proposed. This investigation opens a new approach to obtain halogen‐free EPs with higher flame retardancy and better overall properties than the EPs loaded with DOPO only. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43367.