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LOI
Kinds of LOI Terms modified by LOI Selected AbstractsGraft copolymerization modification of silk fabric with an organophosphorus flame retardantFIRE AND MATERIALS, Issue 5 2010Guan Jinping Abstract This paper mainly deals with flame retardance of a silk fabric treated with a vinyl phosphate dimethyl 2-(methacryloyloxyethyl) phosphate (DMMEP) onto silk fabric by a graft copolymerization technique. This paper also explores the relationship between limiting oxygen index (LOI) and weight gain of DMMEP treated silk fabric. The paper also investigates the whiteness, handle, tensile strength and laundering durability of treated silk fabric. Microscale combustion calorimetry (MCC) is applied to test the heat release rate of silk fabric. Thermal gravimetric analysis (TG) and differential thermal analysis (DTA) are carried out to investigate the thermal decomposition behavior of DMMEP treated silk fabric. The kinetic parameters, activation energy and pre-exponential factor are determined using the Kissenger method. Copyright © 2009 John Wiley & Sons, Ltd. [source] Flame retardation and thermal degradation of flame-retarded polypropylene composites containing melamine phosphate and pentaerythritol phosphateFIRE AND MATERIALS, Issue 5 2008Shun Zhou Abstract The flame retardation of polypropylene (PP) composites containing melamine phosphate (MP) and pentaerythritol phosphate (PEPA) was characterized by limiting oxygen index (LOI) and UL 94. The morphology of the char obtained from the combustion of the composites was studied by scanning electron microscopy (SEM). The thermal degradation of the composites was investigated using thermogravimetric (TG) analysis and real-time Fourier transform infrared (RTFTIR) spectroscopy. It has been found that the PP composites containing only MP do not show good flame retardancy even at 40% additive level. Compared with the PP/MP binary composites, all the LOI values of the PP/MP/PEPA ternary composites at the same additive loading increase, and UL 94 ratings of the ternary composites at suitable MP/PEPA ratios are raised to V-0 from no rating (PP/MP). The TG and RTFTIR studies indicate that the interaction occurs among MP, PEPA and PP. Copyright © 2008 John Wiley & Sons, Ltd. [source] Flame retardancy finish with an organophosphorus retardant on silk fabricsFIRE AND MATERIALS, Issue 6 2006Jin-Ping Guan Abstract The paper mainly deals with flame retardancy of silk fabrics treated with a commercial organophosphorus flame retardant [N-hydroxymethyl (3-dimethyl phosphono) propionamide (HDPP), also known as Pyrovatex CP], using the pad-dry-cure-wash method. The structures and properties of the treated and control sample are discussed. The Limiting Oxygen Index (LOI) value of the modified sample is above 30%. After 50 laundry cycles, it still has some flame retardancy left. HDPP and a cross-linking agent (HMM) were bound to silk fabrics which is confirmed by FT-IR spectra and amino analysis. The reaction degree of the flame retardant with silk is also high; almost all the tyrosine units have reacted, which can be confirmed by amino acid analysis. The reaction between flame retardant and silk only occurs in the amorphous region of silk fibre, which is confirmed by X-ray diffraction analysis and amino acid analysis. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis show that the flame retardant causes silk fabrics to decompose below its ignition temperature (600°C) and formed carbonaceous residue or char when exposed to fire. The char behaves as a thermal barrier to fire, so silk fabrics show good flame retardancy. The treatment has a little effect on the whiteness of the silk fabrics and the tensile strength of treated silk fabrics slightly decreased; both effects are negligible. Copyright © 2006 John Wiley & Sons, Ltd. [source] Flame retardant performance of various UL94 classified materials exposed to external ignition sourcesFIRE AND MATERIALS, Issue 1 2004Sanghyun Hong Abstract The flammability of eight halogen-free styrene resins and one halogen-containing styrene resin was characterized by UL 94 VB, LOI and cone calorimeter tests. Their burning behaviour was also measured when exposed to three external ignition sources (methenamine tablet, candle, paper ball). Five resins were used for 19, monitor housings and the others for 25, TV. The LOI values of UL 94 V-2, V-1 and V-0 rated resins were higher than that of HB. The heat release rate decreased as the UL 94 ratings increased from HB to V-0. When these resins were exposed to three external ignition sources, UL 94 V-1 and V-0 rated resins showed a self-extinguishing property after removal of the fire and did not cause fire growth in either 19, monitor or the 25, TV housings in all cases. However, UL 94 V-2 and HB rated resins were easily ignited and spread fire by dripping burning trickles. The burning rate of V-2 resin was slower than that of HB. Copyright © 2004 John Wiley & Sons, Ltd. [source] Genetic evidence for a maternal effect locus controlling genomic imprinting and growthGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 4 2005Amanda R. Duselis Abstract Crosses between two species of deer mouse (Peromyscus) yield dramatic parent-of-origin effects. Female P. maniculatus (BW) crossed with male P. polionotus (PO) produce animals smaller than either parent. PO females crossed with BW males yield lethal overgrowth that has been associated with loss-of-imprinting (LOI). Previously, we mapped two loci influencing fetal growth. These two loci, however, do not account for the LOI, nor for the dysmorphic phenotypes. Here we report that maternal genetic background strongly influences the LOI. Analyses of crosses wherein maternal genetic background is varied suggest that this effect is likely due to the action of a small number of loci. We have termed these putative loci Meil. Estimation of Meil loci number was confounded by skewed allelic ratios in the intercross line employed. We show that the Meil loci are not identical to any of the DNA methyltransferases shown to be involved in regulation of genomic imprinting. genesis 43:155,165, 2005. © 2005 Wiley-Liss, Inc. [source] Widespread disruption of genomic imprinting in adult interspecies mouse (Mus) hybridsGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 3 2005Wei Shi Abstract Mammalian interspecies hybrids exhibit parent-of-origin effects in that offspring of reciprocal matings, even though genetically identical, frequently exhibit opposite phenotypes, especially in growth. This was also observed in hybridization with the genus Mus. These parent-of-origin effects suggested that imbalance in the expression of imprinted genes, which are expressed differentially, depending on their transmission through the maternal or paternal germline, and/or differential loss-of-imprinting (LOI) could underlie these opposite growth phenotypes in reciprocal mammalian hybrids. Here we report that tissue-specific LOI occurs in adult Mus hybrids. Contrary to expectations, LOI patterns were not consistent with a direct influence of altered expression levels of imprinted genes on growth. Bisulfite sequencing revealed that reactivation of maternal alleles of Peg3 and Snrpn in specific tissues was accompanied by partial demethylation at their potential imprinting control regions. We propose that abnormal reprogramming after fertilization and during preimplantation development is in part responsible for hybrid dysgenesis, for which a strong epigenetic basis has been demonstrated. genesis 43:100,108, 2005. © 2005 Wiley-Liss, Inc. [source] The dynamics of unattached benthic macroalgal accumulations in the Swan,Canning EstuaryHYDROLOGICAL PROCESSES, Issue 13 2001Helen Astill Abstract It has been suggested that macroalgal accumulations may impact on benthic nutrient cycling by promoting remineralization of sedimentary nutrients, otherwise inaccessible, and act as sinks/sources for dissolved nutrients in the water column. However, little consideration has been given to the time taken for these impacts to occur, and if accumulations persist long enough in a region for impacts to occur. In this study, accumulations were characterized seasonally, according to biomass, height relative to water depth, and organic content of the underlying sediment, from November 1996 to August 1997, in the Swan,Canning Estuary. Persistence of accumulations was measured from late summer to mid-winter in 1997, by tagging individual plants and recording the time tagged plants persisted at 10 sites. In summer 1998, physicochemical profiles of accumulations were measured over 24 h, at two locations: one with relatively low sediment organic content (SOCn) (1·5% LOI) and one with relatively high SOC (6% LOI). Accumulations rarely exceeded 25 cm in height, regardless of water column depth, and ranged between 100 and 500 g dwt m,2. Macroalgae persisted between one week, in relatively well-flushed regions, to one month in areas with poor flushing. Over the entire diurnal period, almost 100% of incident light was attenuated at the bottom of all accumulations. Dissolved oxygen levels at the bottom of accumulations were generally depressed, particularly at night, with hypoxia (1 mg l,1) recorded at the high SOC site at 03 : 00 h. No significant differences in FRP concentrations (approximately 30,60 µg l,1) were recorded between sites, or within accumulation profiles. Ammonium levels were greatly raised inside accumulations at the high SOC site by 03 : 00 h (10 and 300 µg l,1, inside and outside, respectively). The results show that, where SOC is high, conditions within accumulations are affected. Impacts occurred within 24 h; well within the period for which accumulations persist. These results also indicate that regulation of hydrological regimes in estuarine systems may result in increased persistence of macroalgal accumulations, and associated water quality problems. Copyright © 2001 John Wiley & Sons, Ltd. [source] Metallic oxides as fire retardants and smoke suppressants in flexible poly(vinyl chloride)JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Antonio Rodolfo Jr. Abstract Combustion and smoke emission properties of PVC compounds, modified with copper (II), molybdenum, and zinc oxides, were studied using cone calorimeter, limiting oxygen index (LOI) and thermogravimetry coupled with mass spectrometry (TG/MS). Results showed that the metal oxides have a very significant effect on the combustion and smoke suppression properties of the PVC compounds. The results also confirmed the anticipation mechanisms of the dehydrochlorination reactions, reductive coupling, and elimination of benzene resulting from the presence of copper (II), molybdenum, and zinc, indicated by the increasing content of postcombustion char residue and the significant reduction in benzene production, indicated by the MS measurements performed. The results also provide indications that the combination of the copper (II) and molybdenum oxides is the one with the best balance of combustion properties, as it reduced the heat released and promoted the suppression of smoke more efficiently. The formulations containing ZnO, because of their strong Lewis acid character, indicated a less pronounced reduction of smoke released during the combustion process, when compared with copper (II) and molybdenum oxides. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effect of boron-containing materials on the flammability and thermal degradation of polyamide 6 composites containing melamineJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Mehmet Do Abstract Three different boron-containing substances,zinc borate (ZnB), borophosphate (BPO4), and a boron- and silicon-containing oligomer (BSi),were used to improve the flame retardancy of melamine in a polyamide 6 (PA-6) matrix. The combustion and thermal degradation characteristics of PA-6 composites were investigated with the limiting oxygen index (LOI), the UL-94 standard, thermogravimetric analysis (TGA)/Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). A slight increase was seen in the LOI values of a sample containing BSi (1 wt %). BPO4 at high loadings showed a V0 rating (indicating the best flame retardancy) and slightly lower LOI values in comparison with samples with only melamine. For ZnB and BSi, glassy film and char formation decreased the dripping rate and sublimation of melamine, and this led to low LOIs. According to the TGA,FTIR results, the addition of boron compounds did not change the decomposition product distribution of melamine and PA-6. The addition of boron compounds affected the flame retardancy by physical means. The TGA data showed that boron compounds and melamine reduced the decomposition temperature of PA-6. According to the DSC data, the inclusion of boron compounds increased the onset temperature of sublimation of melamine and also affected the flame retardancy negatively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Flammability and mechanical properties of wood flour-filled polypropylene compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010M. B. Abu Bakar Abstract Polypropylene (PP) composites filled with wood flour (WF) were prepared with a twin-screw extruder and an injection-molding machine. Three types of ecologically friendly flame retardants (FRs) based on ammonium polyphosphate were used to improve the FR properties of the composites. The flame retardancy of the PP/WF composites was characterized with thermogravimetric analysis (TGA), vertical burn testing (UL94-V), and limiting oxygen index (LOI) measurements. The TGA data showed that all three types of FRs could enhance the thermal stability of the PP/WF/FR systems at high temperatures and effectively increase the char residue formation. The FRs could effectively reduce the flammability of the PP/WF/FR composites by achieving V-0 UL94-V classification. The increased LOI also showed that the flammability of the PP/WF/FR composites was reduced with the addition of FRs. The mechanical property study revealed that, with the incorporation of FRs, the tensile strength and flexural strength were decreased, but the tensile and flexural moduli were increased in all cases. The presence of maleic anhydride grafted polypropylene (MAPP) resulted in an improvement of the filler,matrix bonding between the WF/intumescent FR and PP, and this consequently enhanced the overall mechanical properties of the composites. Morphological studies carried out with scanning electron microscopy revealed clear evidence that the adhesion at the interfacial region was enhanced with the addition of MAPP to the PP/WF/FR composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Investigation of flame retardancy and physical,mechanical properties of zinc borate/boric acid polyester compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2010Miyaser Demirel Abstract The glass fiber reinforced polyester composite materials were prepared with varying contents of boric acid, zinc borate, and magnesium hydroxide as flame retardants to improve the flame retardancy of the composites. Experimental results showed that boric acid exhibited a good flame retardant effect on the polyester composite. When boric acid content is used as 15 wt %, the Limiting Oxygen Index (LOI) value of the composite reached upto 25.3. The increase in boric acid content from 15 to 30 wt %, the LOI values of composite were enhanced from 25.3 to 34.5 by 9.2 units. The LOI values of the composite samples increased with increasing boric acid content. The smoke density results showed that the addition of glass fiber and flame retardants decreased the smoke density of the unreinforced polyester resin. The mechanical properties of the composites have decreased by the addition of flame retardants. The scanning electron micrographs taken from fracture surfaces were examined. The flame retardants, such as boric acid, were well dispersed in the glass fiber reinforced polyester composites and obviously improved the interfacial interaction between glass fibers and polyester composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] A study of the novel intumescent flame-retarded PP/EPDM copolymer blendsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Shun Zhou Abstract Flammability of polypropylene/ethylene,propylene-diene copolymer (PP/EPDM) filled with melamine phosphate (MP) and pentaerythritol phosphate (PEPA) was studied by limiting oxygen index (LOI), UL 94, and cone calorimetry. The thermal degradation of the composites was investigated using thermogravimetric analysis (TG) and real-time Fourier transform infrared spectrum (RT-FTIR), and the mechanical properties of the materials were also studied. It had been found that the PP/EPDM/PEPA/MP composites (PEPM series) showed better flame retardancy than that of the PP/EPDM composites containing MP or PEPA. TG and RT-FTIR studies indicated that the interaction occurs among MP, PEPA, and PP/EPDM. The incorporation of the flame retardants deteriorated the mechanical properties of the materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis and characterization of dicyanate monomers containing methylene spacersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008G. Anuradha Abstract The bisphenols containing methylene spacer were prepared by treating eugenol/2-allyl phenol with 2,6-dimethyl phenol/guiacol/o -cresol in the presence of AlCl3. All the bisphenols were converted to their respective cyanate esters by treating with CNBr. The structural confirmation was done by FTIR, 1H NMR, 13C NMR spectral methods, and elemental analysis. Thermal characterization was done by DSC and TGA. DSC transition shows that the Tg is in the range of 208,239°C. The Tg is highest for the cyanate ester Cy(b) with symmetric structure. The Tg of the cured network depends on the length and symmetry of the monomer, Tg being higher for shorter and the para-substituted monomers. The T10 values are in the range of 364,381°C. The char yield is in the range of 47,53%. From the char yield, the limiting oxygen index (LOI) value was determined, which is used to confirm the flame retardancy of the cyanate ester resins. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis of a magnesium/aluminum/iron layered double hydroxide and its flammability characteristics in halogen-free, flame-retardant ethylene/vinyl acetate copolymer compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2008Chuan-Mei Jiao Abstract Mg,Al,Fe ternary hydrotalcites were synthesized by a coprecipitation method and characterized with powder X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The flame-retardant effects of Mg/Al,CO3 layered double hydroxides (LDHs) and Mg/Al/Fe,CO3 LDHs in an ethylene/vinyl acetate copolymer (EVA) were studied with the limited oxygen index (LOI), the UL-94 test, and the cone calorimeter test (CCT), and the thermal degradation behavior of the composites was examined by thermogravimetric analysis. The results showed that the LOI values of the EVA/(Mg/Al/Fe,CO3 LDH) composites were basically higher than those of the EVA/(Mg/Al,CO3 LDH) composites at the same additive level. In the UL-94 test, there was no rating for the EVA/(Mg/Al,CO3 LDH) composite at the 50% additive level, and a dripping phenomenon occurred. However, the EVA/(Mg/Al/Fe,CO3 LDH) composites at the same loading level of LDHs containing a suitable amount of Fe3+ ion reached the V-0 rating, the dripping phenomenon disappearing. The CCTs indicated that the heat release rate (HRR) of the EVA composites with Mg/Al/Fe,CO3 LDHs containing a suitable amount of Fe3+ decreased greatly in comparison with that of the composites with Mg/Al,CO3 LDHs. The introduction of a given amount of Fe3+ ion into Mg/Al,CO3 LDHs resulted in an increase in the LOI, a decrease in the HRR, and the achievement of the UL-94 V-0 rating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Reactive extrusion to synthesize intumescent flame retardant with a solid acid as catalyst and the flame retardancy of the products in polypropyleneJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Yuan Liu Abstract Reactive extrusion and solid acid catalysis technologies were adopted in the pentaerythritol,melamine phosphate (PER-MP) reaction to synthesize intumescent flame retardant, melamine salt of pentaerythritol phosphate (MPP), which was applied in flame retardant polypropylene (PP). This environment-friendly synthesis method provided a solution to the problems of conventional methods. On one hand, reactive extrusion in a twin screw extruder can effectively mix and transfer viscous materials that usually results in a tough stir in a conventional reactor, and achieve a continuous synthesis process. On the other hand, the solid acid, silicotungstic acid (STA) serving as a catalyst, can maintain a satisfactory conversion even with a low extrusion temperature and a short residence time, thus effectively suppressing foaming in the process of the reaction. Furthermore, without removal like other catalysts in general chemical reactions, STA was kept in produced MPP to constitute a synergism flame retardant system, therefore further improved the flame retardancy. LOI and UL94 test showed that the STA-catalyzed MPP (by reactive extrusion) possessed much better flame retardancy in PP when compared with the noncatalyzed MPP (by reactive extrusion), as well as present commercial MPP (by POCl3 method). In our investigation, the catalytic and synergistic effects of STA, as well as the related factors of the reactive extrusion affecting the conversion of the PER-MP reaction, flame retardancy and mechanical performance of the corresponding flame retardant PP, were systematically investigated. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Blends of triazine-based hyperbranched polyether with LDPE and plasticized PVCJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Jyotishmoy Borah Abstract Triazine-based hyperbranched polyether was obtained by earlier reported method and blended with low density polyethylene (LDPE) and plasticized poly(vinyl chloride) (PVC) separately to improve some desirable properties of those linear polymers. The properties like processability, mechanical properties, flammability, etc. of those linear polymers were studied by blending with 1,7.5 phr of hyperbranched polyether. The mechanical properties were also measured after thermal aging and leaching in different chemical media. SEM study indicates that both polymers exhibit homogenous morphology at all dose levels. The mechanical properties like tensile strength, elongation at break, hardness, etc. of LDPE and PVC increase with the increase of dose level of hyperbranched polyether. The flame retardant behavior as measured by limiting oxygen index (LOI) for all blends indicates an enhanced LOI value compared to the polymer without hyperbranched polyether. The processing behavior of both types of blends as measured by solution viscosity and melt flow rate value indicates that hyperbranched polyether acts as a process aid for those base polymers. The effect of leaching and heat aging of these linear polymers on the mechanical properties showed that hyperbranched polyether is a superior antidegradant compared to the commercially used N -isopropyl- N -phenyl p -phenylene diamine. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 648,654, 2007 [source] Immobilization of flame retardant onto silica nanoparticle surface and properties of epoxy resin filled with the flame retardant-immobilized silicaJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2009Takeshi Yamauchi Abstract To prepare silica nanoparticle having flame retardant activity, the immobilization of flame retardant onto hyperbranched poly(amidoamine) (PAMAM)-grafted silica was investigated. Grafting of PAMAM onto a silica surface was achieved in a solvent-free dry-system using PAMAM dendrimer synthesis methodology. The immobilization of bromine flame retardant, poly(2,2,,6,6,-tetrabromobisphenol-A) diglycidyl ether (PTBBA), was successfully achieved by the reaction of terminal amino groups of PAMAM-grafted silica (Silica-PAMAM) with epoxy groups of PTBBA. The immobilization of PTBBA was confirmed by FTIR and thermal decomposition GC-MS. The amount of PTBBA immobilized onto Silica-PAMAM was determined to be 60 wt %. PTBBA-immobilized Silica-PAMAM (Silica-PAMAM-PTBBA) was dispersed uniformly in a epoxy resin, and the epoxy resin was cured in the presence of hexamethylenediamine. Flame retardant activity of the epoxy resin filled with Silica-PAMAM-PTBBA was estimated by limiting oxygen index (LOI). The LOI of epoxy resin filled with Silica-PAMAM-PTBBA was higher than that filled with untreated silica and free PTBBA. It was confirmed that the flame retardant activity of epoxy resin was improved by the addition of the Silica-PAMAM-PTBBA. The elimination of PTBBA from the epoxy resin filled with Silica-PAMAM-PTBBA into boiling water was hardly observed by immobilization of PTBBA onto silica surface. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6145,6152, 2009 [source] Preparation and properties of high performance epoxy,silsesquioxane hybrid resins prepared using a maleimide,alkoxysilane compound as a modifierJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2005Ying-Ling Liu Abstract An alkoxysilane compound possessing maleimide moiety (MSM) was prepared from N-(4-hydroxyphenyl)maleimide and 3-glycidoxypropyltrimethoxysilane and was used as a modifier of epoxy resins. In situ curing epoxy resins with MSM resulted in epoxy resins with good homogeneity. Just 5,10 wt % of MSM is sufficient to yield high glass transition temperature (165 °C), good thermal stability above 360 °C, and high flame retardancy (LOI = 30) to bisphenol-A-based epoxy resins. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5787,5798, 2005 [source] Synergistic Effect of the Charring Agent on the Thermal and Flame Retardant Properties of PolyethyleneMACROMOLECULAR MATERIALS & ENGINEERING, Issue 2 2004Xiao-Ping Hu Abstract Summary: A new charring agent (CA), a derivative of triazines, was synthesized. The flame retardancy and thermal behavior of a new intumescent flame-retardant (IFR) system for PE (PE-IFR) were investigated by limited oxygen index (LOI), UL-94 test, thermogravimetric analysis (TGA), and FTIR spectroscopy. The TG curves shows that the amount of residue of IFR-PE system are largely increased compared to those of PE at temperatures ranging from 350 to 700,°C. The new PE-IFR system can apparently reduce the amount of decomposing products at higher temperatures and promotes the formation of carbonaceous charred layers. It showed a distinct synergistic flame retardant effect (SE) between nitrogen and phosphorus. The flame retardant PE composition was optimized to achieve a LOI value of 31.2 and UL-94 V-0 performance with the synthesized charring agent, ammonium polyphosphate (APP). TG curves of PE, APP, CA, and different PE/CA/APP systems. [source] Frequent loss of imprinting of IGF2 and MEST in lung adenocarcinomaMOLECULAR CARCINOGENESIS, Issue 4 2001Masakazu Kohda Abstract Genomic imprinting is a parental origin,specific chromosomal modification that causes differential expression of maternal and paternal alleles of a gene. Accumulating evidence suggests that deregulation of imprinted genes, including loss of imprinting (LOI), plays a role in oncogenesis. In the present study, we investigated allelic expression of six imprinted genes in human lung adenocarcinomas as well as in matched normal lung tissue. Informative cases showing heterozygosity for the gene of interest were selected from 35 patients. LOI of the insulin-like growth factor 2 gene (IGF2) and mesoderm-specific transcript (MEST, also known as paternally expressed gene 1) was noted in 47% (seven of 15) and 85% (11 of 13) of informative cases, respectively. Monoallelic expression was maintained in all the matched normal tissues examined. LOI of IGF2 was seen more frequently in moderately to poorly differentiated adenocarcinomas. In contrast, H19, small nuclear ribonucleoprotein,associated polypeptide N gene (SNRPN), necdin gene (NDN), and long QT intronic transcript 1 (LIT1) exhibited consistent monoallelic expression in all the informative samples. These findings indicated that independent deregulation took place in imprinted genes and suggested that aberrant imprinting of IGF2 and MEST was involved in the development of lung adenocarcinoma. © 2001 Wiley-Liss, Inc. [source] Flame resistance and foaming properties of NBR compounds with halogen-free flame retardantsPOLYMER COMPOSITES, Issue 12 2009SungCheal Moon Acrylonitrile butadiene rubber (NBR) foams compounded with various halogen-free flame retardants were prepared. The influence of nonhalogen flame retardants on the flame resistance and foaming properties of the NBR compounds were investigated. The foaming properties (expandability 980%,1050%, closed-cell structure) of NBR compounds with expandable graphite (EG) and ammonium polyphosphate (APP) flame retardants were similar to the NBR base compounds which contained primarily aluminum hydroxide (ATH). The heat release capacity (HRC) ranged from 10 to 74 J/g-K, the average heat release rate (A-HRR) ranged from 8 to 60 kW/m2, and the total heat release (THR) ranged from 2.6 to 7.3 MJ/m2 for the nonhalogenated NBR foams with closed-cell structure and were significantly decreased upon increasing the amounts of flame retardants. This reduction is attributed to the hard char formation and production of water from the interaction with ATH. The limiting oxygen index (LOI) and time to ignition (TTI) show opposite results. The smoke density (0.050,0.037) of the NBR foams with EG flame retardant was decreased when compared to the NBR foam (0.107). The EG flame retardant was more effective than the phosphorus/nitrogen flame retardants in reducing the HRR and smoke density. The use of both ATH and EG is very effective in improving flame resistance. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers [source] Microencapsulation of ammonium polyphosphate: Preparation, characterization, and its flame retardance in polypropylenePOLYMER COMPOSITES, Issue 8 2008Kun Wu Microencapsulated ammonium polyphosphate (MCAPP) with a melamine,formaldehyde (MF) resin coating layer was prepared by in situ polymerization. MCAPP was characterized by Fourier transform infrared, X-ray photoelectron spectroscopy, and so on. The results show that the microencapsulation with MF resin leads to a decrease in the particles' size and water absorption. The flame retardant action and mechanism of MCAPP and ammonium polyphosphate (APP) in polypropylene are studied using limiting oxygen index (LOI) and UL 94 test, and their thermal stability is evaluated by thermogravimetric analysis. The LOI value of the PP/MCAPP composite at 30 wt% loading is 30.5%, whereas the corresponding value of the PP/APP composite is only 20%. Moreover, the LOI values of the PP/MCAPP/PER composites are higher than the ones of the PP/APP/PER composites. In the UL 94 test, the PP/MCAPP/PER composites with suitable ratios of MCAPP to PER can reach the V-0 rating, and the best rating of the PP/APP/PER composites is V-1. V-1. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers [source] Effects of synthesis conditions on crystal morphological structures and thermal degradation behavior of hydrotalcites and flame retardant and mechanical properties of EVA/hydrotalcite blendsPOLYMER COMPOSITES, Issue 2 2007Longchao Du The effects of synthesis methods and reaction conditions on the crystal morphological structures and thermal degradation behavior of hydrotalcites have been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), particle size analysis (PSA), and differential thermal analysis (DTA). The flame retardant and mechanical properties of ethylene,vinyl acetate (EVA) blends with the corresponding hydrotalcites have been estimated by limiting oxygen index (LOI), UL-94, and mechanical measurements. The results from the XRD, TEM, and PSA demonstrate that the hydrotalcites synthesized by ultrasound method have larger crystal sizes and particle size distribution than those by mechanical stirring method. Higher reaction temperature, longer dripping time, and lower solution concentration can increase the crystal and particle sizes of ultrasound-synthesized hydrotalcites, whereas the longer ultrasound aging time can increase the crystal sizes and decrease the particle sizes of hydrotalcites because of the smashing conglomeration. The DTA data give a positive evidence that the hydrotalcite samples prepared by mechanical stirring method with longer alkaline dripping time have higher thermal degradation temperature than those by ultrasound method, since the ultrasound-synthesized hydrotalcites have more lattice defects than stirring-prepared hydrotalcites. The data from LOI, UL-94, and mechanical tests show that the ultrasonic-synthesized hydrotalcites have better flame retardant properties, whereas the stirring-synthesized hydrotalcites have better tensile strength in the EVA/hydrotalcite blends. POLYM. COMPOS., 28:131,138, 2007. © 2007 Society of Plastics Engineers [source] Study on flame retardance of co-microencapsulated ammonium polyphosphate and dipentaerythritol in polypropylenePOLYMER ENGINEERING & SCIENCE, Issue 12 2008Zhengzhou Wang Co-microencapsulated ammonium polyphosphate and dipentaerythritol [M(A&D)] was prepared using a melamine-formaldehyde (MF) resin by in situ polymerization method, and characterized by XPS. The co-microencapsulation of ammonium polyphosphate and dipentaerythritol (DPER) leads to a great improvement in water solubility of the additives. The flame retardant effect of M(A&D) in polypropylene (PP) is evaluated using limiting oxygen index (LOI) and UL 94 test, and the water resistance of the PP/M(A&D) composites is also studied. The flame retardant properties and water resistance of the PP/M(A&D) composites are much better than the ones of the PP/APP/DPER composites. Moreover, the thermal stability of the PP/M(A&D) composites is improved compared with the PP/APP/DPER composites. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers [source] Preparation and characterization of microcapsulated red phosphorus and its flame-retardant mechanism in halogen-free flame retardant polyolefinsPOLYMER INTERNATIONAL, Issue 8 2003Qiang Wu Abstract Microcapsulated red phosphorus (MRP), with a melamine,formaldehyde resin coating layer, was prepared by two-step coating processes. The physical and chemical properties of MRP were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) and other measurements. The flame retardant action and mechanism of MRP in the halogen-free flame retardant (HFFR) polyolefins (PO) blends have been studied using cone calorimeter, limiting oxygen index (LOI), thermogravimetric analysis (TGA) and dynamic FTIR spectroscopy. The results show that the MRP, which is coated with melamine,formaldehyde resin, has a higher ignition point, a considerably lower amount of phosphine evolution and of water absorption compared with red phosphorus (RP) itself. The data observed by cone calorimeter, LOI and TGA measurements from the PO/HFFR blends demonstrated that the MRP can decrease the heat release rate and effective heat of combustion, and increase the thermostability and LOI values of PO materials. The dynamic FTIR results revealed the flame-retardant mechanism that RP can promote the formation of charred layers with the P,O and P,C complexes in the condensed phase during burning of polymer materials. Copyright © 2003 Society of Chemical Industry [source] Fireproofing of polyurethane elastomers by reactive organophosphonatesPOLYMER INTERNATIONAL, Issue 1 2003Wassef El Khatib Abstract Polyurethane elastomers were prepared with hydroxytelechelic polybutadiene (HTPB) as polyol, modified 4,4,-diphenylmethane diisocyanate (modified MDI) as liquid polyisocyanate, and phosphonate diols as chain extenders and flame retardant compounds. These phosphonate diols were synthesized by radical thiol,ene addition of allyl or vinyl dialkyl phosphonate to 3-mercapto-1,2-propanediol. For various percentages of phosphorus (0 to 3%, w/w), polyurethane elastomers remain stable up to 250,°C. The percentage of residual char at 600,°C increases with increasing phosphorus content. For the soft segments, no variation in the glass transition temperature (Tg) is observed as the percentage of P increases, whereas the Tg of hard segments increases. Above 0.5% phosphorus content, the limiting oxygen index (LOI) becomes higher than the percentage of oxygen in the air. © 2003 Society of Chemical Industry [source] Synergistic effects of , -cyclodextrin containing silicone oligomer on intumescent flame retardant polypropylene systemPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2010Huanfeng Wang Abstract The effects of , -cyclodextrin containing silicone oligomer(CDS), as a synergistic agent, on the flame retardancy and mechanical properties of intumescent flame retardant polypropylene composites were studied by adding different amounts of CDS in intumescent flame retardants. The limiting oxygen index (LOI), UL-94 test, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) were utilized to evaluate the synergistic effects of CDS in the composites. It was found that after a little amount of CDS partially replaced a charring-foaming agent (CFA) in IFR, LOI values of the composites were enhanced and they obtained a UL-94 V-0 rating. IFR system containing 6.25wt% CDS presented the best flame retardancy in PP. The experimental results obtained from LOI and UL-94, TGA, SEM, and mechanical properties indicated that the combination of CDS and CFA presents synergistic effects in flame retardancy, char formation, and mechanical properties of the composites. This is probably due to different structures of polyhydroxyl macromolecules (CDS and CFA), the existence of dimethyl silicone group in CDS, and the toughness of epoxy silicon chain in CDS. SEM results proved that the interfacial compatibility between IFR and PP was improved by CDS. Copyright © 2009 John Wiley & Sons, Ltd. [source] A new intumescent flame-retardant: preparation, surface modification, and its application in polypropylenePOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2008Xingyi Wang Abstract Melamine salt of tripentaerythriol phosphate (MTP), as a new intumescent flame-retardant, was prepared from tripentaerythritol (TPE), polyphosphoric acid, phosphoric pentoxide, and melamine, and then incorporated into polypropylene (PP) to obtain flame-retarded PP-MTP. FT-IR analysis showed that MTP was in the form of cage structure. The flammability, combustion behavior, and thermal degradation and stability of flame-retarded PP were characterized by using LOI, UL-94 test, cone calorimetry, and TGA, respectively. By SEM, the char structure of PP-MTP was analyzed. XRD diffraction tests showed that PP-matrix of PP-MTP presented better crystallized phases, when MTP was modified by methyl hydrogen siloxane. The relations of the dispersion of MTP in PP matrix to the compatibility between PP and MTP, and to the flame retardancy were discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Flame retardancy mechanisms of metal phosphinates and metal phosphinates in combination with melamine cyanurate in glass-fiber reinforced poly(1,4-butylene terephthalate): the influence of metal cationPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2008Ulrike Braun Abstract The pyrolysis and fire behavior of glass-fiber reinforced poly(butylene terephthalate) (PBT/GF) with two different metal phosphinates as flame retardants in combination with and without melamine cyanurate (MC) were analyzed by means of thermogravimetry, thermogravimetry coupled with infrared spectroscopy, flammability, and cone calorimeter tests as well as scanning electron microscopy/energy dispersive X-ray spectroscopy and X-ray fluorescence spectroscopy. In PBT/GF, dosages of 13,20% of the halogen-free flame retardant aluminum phosphinate or aluminum phosphinate in combination with MC fulfill the requirements for electrical engineering and electronics applications (UL 94,=,V-0; LOI,>,42%), whereas the use of the same amount of zinc phosphinate or zinc phosphinate in combination with MC does not improve the fire behavior satisfactorily (UL 94,=,HB; LOI,=,27,28%). The performance under forced flaming conditions (cone calorimeter) is quite similar for both of the metal phosphinates. The use of aluminum and zinc salts results in similar flame inhibition predominantly due to the release of the phosphinate compounds in the gas phase. Both metal phosphinates and MC interact with the polymer changing the decomposition characteristics. However, part of the zinc phosphinate vaporizes as a complete molecule. Because of the different decomposition behavior of the metal salts, only the aluminum phosphinate results in a small amount of thermally stable carbonaceous char. In particular, the aluminum phosphinate-terephthalate formed is more stable than the zinc phosphinate-terephthalate. The small amount of char has a crucial effect on the thermal properties and mechanical stability of the residue and thus the flammability. Copyright © 2008 John Wiley & Sons, Ltd. [source] Comparison of loss on ignition and thermal analysis stepwise methods for determination of sedimentary organic matterAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2009Gretel Frangipane Abstract 1.Loss on ignition (LOI) is a widely used method to estimate organic matter (OM) in the sediment of marine and freshwater ecosystems. Thermogravimetric-differential thermal analysis (TG-DTA) of organic species provides information on thermal reactions, the amount and properties of clay structural water, organic species and carbonates. 2.The accuracy of LOI compared with that of TG-DTA was evaluated in 33 sediment samples from the Lagoon of Venice (Italy). 3.In all tests conducted with TG-DTA the mass loss of OM and the loss of clay structural water (LCSW) from oxidized samples were measured. The mass loss of OM at 350°C (TG-DTA 350 OM) and the total extraction of organic matter at 567°C (TEOM) calculated from the difference between natural state samples and oxidized samples highlight the presence of both thermally labile and thermally stable substances. 4.The grain size data of sediment samples from the Lagoon shows a variable distribution between slightly muddy sand and mud. Loss of clay structural water at 350°C (LCSW 350) and total extraction of clay structural water at 567°C (TECSW) both estimated by TG-DTA on oxidized samples, were found to correspond approximately to 6% and 10%, respectively of the clay fraction (<4 µm). This percentage may be used to correct LOI measurements of OM in sediments with high clay content. 5.LOI 350 (loss on ignition at 350°C) and LOI 550 (loss on ignition at 550°C) proved to be ,80% and ,200%, respectively, of total extraction of mass loss at 350°C (TG-DTA 350 tot) and at 567°C (TEML) estimated by TG-DTA on natural samples, meaning that the LOI 550 value represents a significant overestimate. The difference between the LOI 550 and TEML values indicates that the mass loss excess (MLE) may be accounted for by losses due to breakdown of carbonates. Copyright © 2008 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||