Flame retardation of polypropylene: Effect of organoantimony compounds on the melt flow behavior

The melt flow behaviour of polypropylene filled with organoantimony compounds, triphenylstibinedibromide and its derivatives with tribromo-, trichloro-, and pentachloro-phenols, as flame retardants has been studied in the temperature range of 180 to 220°C, and at shear rates of 29.5 to 588.8's^?1, using a capillary rheometer. A decrease in the melt viscosity at all shear rates and temperatures was noticed on addition of these flame retardants, The melt viscosity further decreased upon increasing the concentration (from 5 to 20 phr) of the flame retardants. The die swell was measured in order to determine the melt elasticity of the filled systems. The minimum melt viscosity of filled propylene was observed approximately where the maximum die swell (melt elasticity) occurred.     

Flame retardation of polypropylene: Effect of organoantimony compounds on the flammability and thermal behavior

Triphenylstibinedibromide and its derivatives with tribromo-, and pentachlorophenols have been used as flame-retardant additives for polypropylene. Maximum limiting oxygen index of 31.5 against 18.2 for unfilled polypropylene was obtained in a sample containing 10 phr of triphenylstibinedibromide. However, V-0 rating in UL-94 test was observed in 20 phr flame-retardant-filled polypropylene sample, while V-2 rating was obtained even at 5 phr flame-retardant level. Thermal behavior of flame-retardant-filled polypropylene was also studied in air atmosphere by thermogravimetric analysis, and an attempt has been made to correlate the flammability with the thermal behavior. The residue obtained in isothermal treatment at 450°C for 1/2 hour in air was analyzed for antimony and halogen which establishes the role of these flame retardants in vapor phase.     

Effect of surface coverage of silane treated CaCO3 on the tensile properties of polypropylene composites

Polypropylene (PP) composites were prepared with a constant volume fraction of a CaCO₃ filler, which was treated with eight trialkoxy functional silane coupling agents and the routinely used stearic acid, as comparison, The tensile properties of the composites were determined as a function of surface coverage and the chemical composition of the coupling agent. Significant differences were detected in the effect of the silane coupling agents on the tensile properties of the composites studied. They could be classified into groups of reactive, nonreactive and inactive compounds, in accordance with an earlier study. Moreover, tensile properties proved to be very sensitive to surface treatment. Reactive coupling leads to a maximum in tensile strength, while the use of nonreactive agents decreases strength rapidly with increasing surface coverage. The rate of strength decrease slows down above the concentration necessary for the formation of a monolayer coverage. Treatment influences deformability accordingly, it decreases on reactive coupling, while agents with a surfactant effect increase elongation. Amino functional silanes show a strong reactive coupling effect. A trialkoxy derivative of stearic acid, (3-stearyloxy-propyl-triethoxy-silane), synthesized the first time in our laboratory, has an outstanding surfactant effect; its use increases both the elongation and the tensile strength of the composites. Both characteristics exceed the corresponding properties of the reference composite containing the filler treated with stearic acid.     

Flame surface modification of polypropylene film

Contact-angle measurements, the ASTM standard wetting test for polyolefin films, and X-ray photoelectron spectroscopy (XPS or ESCA) were used to characterize flame-treated polypropylene (PP) films. Two combustion models, STANJAN and PREMIX, were then used to determine the chemical and physical properties of the flames used to treat the PP films. Both the flame equivalence ratio and the position of the PP film in the flame are important variables in determining the extent of oxidation and improvement in wettability obtained by flame treating. The optimal equivalence ratio for the flame treatment of PP is 0.93, while the optimal luminous flame-to-film distance is 0-2 mm. Modeling of the combustion processes occurring in the flame provides evidence that the extent of treatment correlates closely with the concentrations of H, O, and OH radicals present in the flame. The extent of surface modification of the flame-treated PP does not appear to correlate with either the flame temperature or the concentraion of oxygen molecules. The mechanism of surface oxidation by flame treatment probably involves polymer-radical formation by O and OH, followed by rapid reaction of the polymer radicals with O, OH, and O₂.     

Effect of polymeric silane coupling agents on adhesion of polypropylene and polystyrene to glass

The coupling performance of some polymeric silane compounds was compared with that of the monomeric silanes for adhesion of polypropylene (PP) and polystyrene (PS) to glass. A silylated poly-1,2-butadiene was found to be effective for PP and, on the other hand, some copolymers derived from styrenyl triethoxysilane or γ-methacryloxypropyl trimethoxysilane for PS. Benzoyl peroxide also showed a pronounced effect on the adhesion of PP, rather than that of PS. The adhesion strength was approximately correlated with the contact angles of the resin melts on the coated glass, intensively suggesting the dependence of compatibility between resinous matrix and coupling agent on the adhesion. Their critical surface tensions, thermal behavior, and infrared spectra were also measured to discuss the relationship between the surface constitution and the adhesion effect.     

Properties of polypropylene structural foam crosslinked by vinyltrimethoxy silane

Polypropylene containing the blowing agent azodicarbonate was first grafted with vinyl trimethoxy silane, then crosslinked using the hot water treatment. Two heating stages initiated the blowing agent and formed polypropylene structural foam. The effects of such reaction variables as initiator, cross-linking agent, cross-linking accelerator, and blowing agent on the gel fraction, density, and expansion ratio of polypropylene foam were studied. Furthermore, cell dimension, compression strength, and volume resistivity were also measured and analyzed.     

The retardation of reinforcing steel corrosion by alkyl-alkoxyl silane

The effectiveness of an alkyl-alkoxy silane treatment of concrete on reducing the rate of corrosion of reinforcing steel in the presence of chloride ions was investigated. First, the penetrating characteristics of the alkyl-alkoxy silane into dried concrete were determined. Then, the corrosion currents of 90 corrosion specimens, some of which were dried and silane-impregnated, were measured using an impressed current, accelerated corrosion technique. The penetration of alkyl-alkoxy silane into dried concrete followed an approximate linear square root time relationship. Comparisons of corrosion currents showed that alkyl-alkoxy silane showed that allowing time after treatment for the They also showed that allowing time after treatment for the ethanol carrier to evaporate and exposing the treated surface to water for a short period of time were beneficial.     

Effect of titanium compounds on thermooxidative properties of stabilized polypropylene

The effect of titanium compounds on thermooxidation stability of stabilized polypropylene was studied. It was found that the presence of titanium compounds shortens the induction period of PP oxidation. This phenomenon is brought about by the thermal reactions of titanium compounds with antioxidants which take place during polymer processing. The first step is the reaction of Ti? Cl with OH groups of phenolic antioxidant, which gives rise to a colored titanate and HCl. Hydrogen chloride functions as a Friedel-Crafts catalyst for degradation and dealkylation of phenolic antioxidants. The products of degradation have a very low stabilization efficiency. Hydrogen chloride acceptors suppress antioxidant degradation and increase the polymer stability even in the presence of small amounts of titanium compounds.     

硅烷接枝聚丙烯对GMTPP的增容作用及增容机理

为了获得高刚性和高韧性的玻璃纤维毡增强聚丙烯(GMT-PP),首先制备了硅烷接枝聚丙烯(PP-g-Si),研究了PP-g-Si对GMT-PP的增容作用及增容机理.结果表明质量分数低于20%的PP-g-Si,可以提高GMT-PP的拉伸和弯曲性能,而冲击强度几乎没有变化;PP-g-Si对GMT-PP的增容机理为PP-g-Si的甲硅烷基氧与结合在玻璃纤维上的氨基硅烷的氨基相互吸附形成了氢键.     

Evaluation of interfacial compatibility in wood flour/polypropylene composites by grafting isocyanate silane coupling agent on polypropylene

In this paper, the polypropylene was functionalized by isocyanate silane coupling agent grafted polypropylene (IS-g-PP), various characterization methods were conducted to evaluate the interfacial compatibility of WF/PP. The results indicated that IS-g-PP remarkably enhanced the interfacial adhesion between WF and PP with improved mechanical property, tensile strength was improved by 96.1%, and flexural strength was also increased apparently. According to the DSC results, the crystallization temperature of PP was decreased due to its enhanced interfacial adhesion. Most importantly, the use of IS-g-PP reinforced the storage modulus, loss modulus, and complex viscosity of WF/PP. These results demonstrated that IS-g-PP enhanced the interfacial interaction, and the mobility of PP chain was restrained, and was further confirmed by SEM analysis.     

Ultraviolet-induced graft reaction of quinoid compounds onto polypropylene films: Effect of synthesis conditions on hydroquinone-g-polypropylene

The liquid-phase graft reaction of hydroquinone (HQ) was carried out onto the surface of medical-grade polypropylene (PP) films with the photosensitizer, benzophenone (BP). The effects of various reaction conditions on the graft yield of the samples and the changes in physicochemical properties of the surface of the samples were determined by FTIR/FMIR and surface tension measurements. As BP concentration was increased, the graft yield increased up to a maximum at 2.5 wt % of BP and then decreased. Graft yield was increased with irradiation time and HQ concentration before leveling at 3.5 wt %, in 150 min. The surface tension of samples were increased of graft yield up to 37 dyn/cm. © 1995 John Wiley & Sons, Inc.     

笼状磷酸酯微胶囊/聚磷酸铵阻燃聚丙烯

将笼状磷酸酯微胶囊(ET)与聚磷酸铵(APP)复配用于阻燃聚丙烯(PP)。采用氧指数和UL 94评价了阻燃PP的阻燃性能,采用热重分析、扫描电子显微镜照片、傅里叶变换红外光谱及X射线电子能谱研究了阻燃剂的协同效应和阻燃机理。结果表明:ET与APP有较好的复配协同效应,ET/APP的阻燃性能随m(ET)/m(APP)的不同而变化。当m(ET)/m(APP)为1∶2时,阻燃效果最好。w(ET/APP)为30%时,氧指数达29.7%,且达到UL 94 V-0级。     

锑类化合物对聚氨酯弹性体性能的影响

以锑类化合物(乙二醇锑或氧化锑)作为PUE(聚氨酯弹性体)的改性剂,探讨了改性剂含量对PUE的合成工艺、性能及结构等影响。结果表明:随着体系中乙二醇锑含量的不断增加,PUE复合材料的密度、硬度和拉伸强度逐渐增大,但断裂伸长率呈先升后降态势,PUE基体中乙二醇锑的结晶结构遭到破坏;随着氧化锑含量的不断增加,PUE复合材料的密度、硬度和拉伸强度缓慢上升,而断裂伸长率显著下降,氧化锑的结晶结构依然存在;当乙二醇锑和氧化锑含量相同时,乙二醇锑对PUE表现出较高的催化活性,对PUE复合材料的性能影响较大;乙二醇锑对PUE复合材料的阻燃效果略逊于氧化锑。     

Flame retardancy of polypropylene and impact polystyrene: Phosphonium bromide/ammonium polyphosphate system

The individual and the combined effects of the phosphonium salt Cyagard RF-1 and ammonium polyphosphate on the oxygen index of polypropylene and high-impact polystyrene have been studied. The synergistic action of the two flame retardant components is evaluated quantitatively, and a correlation between char yield and synergism is discussed. The chars are characterized in terms of their elemental composition.     

The nature of silane at the interface of treated fillers

Silane coupling agents have been traditionally used to modify the surface properties of finely divided solids — ‘fillers’ such as powdered minerals and fibrous materials — in order to control their dispersion properties in various liquid media and resins. A number of techniques, including electrokinetic, contact angle, microscopic and the ‘desorption’ test, have been used to study the nature of filler surfaces treated with these agents.     

The electric resistivity of compacts of graphite intercalation compounds with antimony pentafluoride and with antimony pentachloride

The electric resistivities were measured for textured compacts of the intercalation compounds of graphite with SbF₅ and with SbCl₅. Starting materials were coarse flakes of natural graphite and graphite foils (0.35 and 2 mm thick). First stage compounds and mixtures of first and second stage compounds were studied. The resistivities of the compacts from flakes were strongly pressure dependent, maximum conductivity was not yet reached at 600 bar. The resistivities of preparations from graphite foils were much less pressure dependent. The resistivity of the foils decreased to 36 × 10^?8 Ωm, that is 3–4% of the resistivity of the parent foils. In general, the intercalation compounds with SbF₅ showed somewhat higher resistivities than the SbCl₅ compounds. This seems to be caused by formation of an insulating layer on the surface of the particles due to partial fluorination of carbon atoms with SbF₅. CF bonds were detected by IR spectroscopy and by XPS. The first stage SbF₅ compound is formed already at room temperature, contrary to literature reports, provided sufficient time is given.     

Vamac(R) 乙烯丙烯酸酯三元共聚物系列专题讲座(五)矿物填料填充的Vamac(R)胶料的耐燃性能

介绍了矿物填料对Vamac(R)胶料性能的影响,分析了阻燃剂及阻燃剂的并用对Vamac(R)耐燃性能影响.还阐述了杜邦耐燃测试的试验方法.     

Flame retardation of polyethylene: Effect of a phosphorus flame retardant having both hydrophobic and hydrophilic groups in the same molecule

The effect of phosphorylated cashew nut shell liquid prepolymer (PCNSL), a phosphorus‐based flame retardant (FR) possessing both hydrophobic and hydrophilic groups in the same molecule, on the processability, mechanical properties, thermal and flammability behavior, and aging characteristics of low‐density polyethylene (LDPE) was studied. TGA showed that PCNSL enhanced the thermal stability of LDPE, whereas limiting oxygen index (LOI) values increased from 17 to 24.5. The large increase in the LOI value could most probably be due to the possibility of PCNSL acting, apart from being a normal phosphorus‐containing FR, also as an antioxidant that might control the oxidative surface degradation of LDPE. The oxidative induction test (PE, 2.5 min, with 2% PCNSL, 225 min, and 2% Irganox®, 189 min) showed that the antioxidant property of PCNSL is better than that of Irganox®, a known antioxidant for polyethylene (PE) and the enthalpy of oxidation (PE 4.6 kJ/g, with 2% PCNSL 2.6 kJ/g and 2% Irganox®, 2.2 kJ/g) for the PCNSL/LDPE blend was less than that of LDPE and was comparable to that of the Irganox® system. Brabender Plasticorder traces of LDPE/PCNSL blends showed good processability and miscibility. The enhanced processability and miscibility between LDPE and PCNSL are attributed to the presence of the hydrophobic aliphatic segment in the FR. The SEM microstructure of the blend supported the above findings. Comparative evaluation with standard all‐aromatic FRs such as decabromodiphenyl oxide (DBDPO) and tricresyl phosphate (TCP) was carried out and the data supported the finding that FRs having both aliphatic and aromatic moieties with hydrophobic and hydrophilic characters in the same system can give better property profiles than those without these attributes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2631–2640, 2000     

Flame retardant and mechanical properties of a copolymer PP/PE containing brominated compounds/antimony trioxide blends and magnesium hydroxide or talc

The incorporation of two brominated compounds/antimony trioxide blends into a PP–PE copolymer were studied. Both brominated trimethylphenyl indane (FR 1808) and poly(pentabromobenzyl acrylate) (FR 1025) confer good flame retardancy at 40% loading. A comparison was made with the incorporation of magnesium hydroxide at higher loadings (up to 64%) in the same copolymer. The mineral filler improves both fire resistance and stiffness of the copolymer, nevertheless the high loading causes a dramatic decrease in impact resistance. Moreover, the necessary surface treatment of the filler significantly lowers the maximal tensile strength. In order to maximize both fire resistance and mechanical properties, we combined each brominated flame-retardant system (20% in weight) with magnesium hydroxide or talc (20% in weight). Talc is used as reference. These composites show interesting fire-retardant properties in comparison with the copolymers containing only 40% of the brominated flame-retardant systems. In addition, the mechanical properties are on the whole improved. © 1997 John Wiley & Sons, Ltd.     

Flame retardant mechanism of polymer/clay nanocomposites based on polypropylene

The combustion behavior and thermal-oxidative degradation of polypropylene/clay nanocomposite has been studied in this paper. The influence of compatibilizer, alkylammonium, organoclay, protonic clay and pristine clay is considered, respectively. The decrease of heat release rate (HRR) is mainly due to the delay of thermal-oxidative decomposition of the composites. The active sites on clay layers can catalyze the initial decomposition and the ignition of the composites. On the other hand, the active sites can catalyze the formation of a protective coating char on the samples. Moreover, the active sites can catalyze the dehydrogenation and crosslinking of polymer chains. Accordingly, the thermal-oxidative stability is increased and HRR is decreased.