PP/Al(OH)_3/Mg(OH)_2复合材料的导热性能

制备了PP（聚丙烯）/Al(OH)₃/Mg(OH)₂导热复合材料,并用稳态平板导热系数测试仪在不同测试温度下测定该复合材料的导热系数。结果表明,加入Al(OH)₃和Mg(OH)₂使PP导热系数提高。复合材料的导热系数随着填料含量的增加而非线性提高,随着测试温度的升高而非线性提高,随着填料粒径的增大而非线性增大。     

Thermal degradation of flame‐retarded polyethylene/magnesium hydroxide/poly(ethylene‐co‐propylene) elastomer composites

Magnesium hydroxide‐based halogen‐free flame retarded linear low‐density polyethylene (LLDPE) composites containing poly(ethylene‐co‐propylene) (EP) elastomer were prepared by a melt process and subsequently vulcanized thermally. The thermal degradation of the composites was studied using thermogravimetric (TG) analysis and real‐time Fourier transform infrared (RT‐FTIR) spectroscopy. The combustion residues from the composites were characterized by Raman spectroscopy and X‐ray photoelectron spectroscopy (XPS). The results from TG and RT‐FTIR tests show that the incorporation of a suitable amount of the elastomer into polyethylene/magnesium hydroxide composites after vulcanization increases the thermal stability. A graphite‐like char was found for the composites with EP elastomer, from Raman spectroscopy studies. XPS results indicate that there are several forms of carbon present in the combustion residues of the composites with EP elastomer, compared with only one form of carbon in the residues of the composites without the elastomer. Copyright © 2003 Society of Chemical Industry     

PP/AI(OH)_3/Mg(OH)_2复合材料阻燃性能研究

制备了PP(聚丙烯)/Al(OH)_3/Mg(OH)_2/硼酸锌和PP/Al(OH)_3/Mg(OH)_2阻燃复合材料,并测定了复合材料的氧指数(OI)、水平燃烧速度和烟密度。结果表明,OI随着阻燃剂质量分数的增加而升高,随着粒径的增大而降低;燃烧速度随着阻燃剂用量的增加而下降,随着粒径的增大先升后降;烟密度随着阻燃剂用量的增加而降低,随着粒径的增大而增大;添加硼酸锌后具有显著的抑烟效果。     

Copolymerization kinetics of poly(acrylonitrile‐ran‐2‐ethenyl‐pyridine) and its degradation apparent activation energy

2‐Ethenyl‐pyridine (EPD) was first used to successfully copolymerize with acrylonitrile (AN) in a H₂O/dimethyl formamide (DMF) mixture by using azobisisobutyronitrile as the initiator. Kinetics of copolymerization and degradation of poly(AN‐ran‐EPD) were discussed. The kinetic equation of copolymerization and the apparent activation energy of degradation of poly(AN‐ran‐EPD) were obtained. In H₂O‐rich reaction medium, copolymerization followed the suspension polymerization more, but in DMF‐rich reaction medium, copolymerization followed the solution polymerization more. Increase in DMF concentration in the solvent mixture lead to a rapid increase in the degradation apparent activation energy. The apparent activation energy decreased quickly with an increase in EPD concentration, and such a change became less prominent as the molar ratio of EPD/AN went beyond 3/100. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal degradation behaviors of phosphorus–silicon synergistic flame‐retardant copolyester

A novel phosphorus‐containing poly (ethylene terephthalate) (PET) copolyester/nano‐SiO₂ composite (PET‐co‐DDP/SiO₂) was synthesized by in situ polycondensation of terephthalic acid (TPA), ethylene glycol (EG), [(6‐oxide‐6H‐dibenz[c,e] [1,2]oxaphosphorin‐6‐yl)‐methyl]‐butanedioic acid (DDP), and nano‐SiO₂. The morphology of PET nanocomposites was observed by using transmission electron microscope and scanning electron microscope. It was found that the SiO₂ nanoparticles were dispersed uniformly at nanoscale in the copolyesters with content 2 wt %. The thermal degradation behavior of PET nanocomposites was investigated by thermogravimetric analysis performed with air and nitrogen ambience. The activation energies of thermal degradation were determined using Kissinger and Flynn–Wall–Ozawa methods, respectively. The results obtained from Kissinger method showed that the activation energy was increased with the introduction of SiO₂. Moreover, the activation energy is decreased for PET‐co‐DDP system in nitrogen and air. The results also indicated that the SiO₂ and DDP had synergic effect on the early decomposition and the late charring in air. Furthermore, in the PET‐co‐DDP/SiO₂ system, the activation energy increased when the DDP component increased. However, the opposite results were obtained when the Flynn–Wall–Ozawa method was used. That was because the Doyle approximation stands correct as the conversion degree is from 5% to 20%. The effects of SiO₂ and DDP on the PET thermal degradation were lower in nitrogen than in air. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Studies on compatibilization of intumescent flame‐retardant/PP composites based on etched PP

The phosphoric acid–pentaerythritol–melamine copolymer was selected as an intumescent flame retardant (IFR). The influence of dicromate acid–etching polypropylene (EPP) on the properties and compatibility of IFR/PP composites was studied. The results obtained from mechanical tests and SEM showed that EPP was a true coupling agent for IFR/PP blends, but without changing the necessary flame retardancy. The cocrystallization between bulk PP and PP segments of EPP was proved by WAXD analysis. Flow tests showed that the flow behavior of composites in the melt is that of a pseudoplastic liquid, which is almost insignificant for EPP affecting the rheological behavior of an IFR/PP composite. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 522–527, 2002; DOI 10.1002/app.10261     

Thermal degradation kinetics and lifetime estimation for polycarbonate/polymethylphenylsilsesquioxane composite

The thermal degradation behaviors of polycarbonate/polymethylphenylsilsesquioxane (FRPC) composites were investigated by thermogravimetric analysis (TGA) under isothermal conditions in nitrogen atmosphere. The isothermal kinetics equation was used to describe the thermal degradation process. The results showed that activation energy (E), in the case of isothermal degradation, was a quick increasing function of conversion (α) for polycarbonate (PC) but was a strong and decreasing function of conversion for FRPC. Under the isothermal condition, the addition of polymethylphenylsilsesquioxane (PMPSQ) retardanted the thermal degradation and enhanced the thermal stability of PC during the early and middle stages of thermal degradation. It also indicated a possible existence of a difference in nucleation, nuclei growth, and gas diffusion mechanism in the thermal degradation process between PC and FRPC. Meanwhile, the addition of PMPSQ influenced the lifetime of PC, but the composite still met the demand in manufacturing and application.     

Thermal degradation kinetics of para‐substituted poly (styrene peroxide)s in solution

The thermal degradation of three polymeric peroxides of styrene monomers with substituents in the para position was studied at various temperatures (65, 75, 85, and 95°C). A continuous distribution model was used to evaluate the rate coefficients for the random‐chain and chain‐end scission degradation from the evolution of molecular weight distributions with time. The activation energy determined from the temperature dependence of the rate coefficients was in the range 18–22 kcal mol^?1. This result suggests that the thermal degradation of polyperoxide is controlled by the dissociation of the O—O bonds in the polymer backbone. The thermal stability for poly(p‐methylstyrene peroxide) lies in between that of poly(p‐tert‐butylstyrene peroxide) (highest) and poly(p‐bromostyrene peroxide) (lowest). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 957–961, 2002     

A study of the flame‐retardant properties of polypropylene/Al(OH)3/Mg(OH)2 composites

Polymeric materials are used extensively, but their applications are limited because many of them are flammable. Therefore ways to make them flame retardant have received much attention. In this work, polypropylene (PP) was used as the matrix resin, aluminium hydroxide (Al(OH)₃) and magnesium hydroxide (Mg(OH)₂) as flame‐retardant additives and zinc borate (ZB) as a flame‐retardant synergist. PP/Al(OH)₃/Mg(OH)₂ and PP/Al(OH)₃/Mg(OH)₂/ZB flame‐retardant composites were prepared with a twin‐screw extruder. The flame‐retardant properties, i.e. oxygen index (OI), burning velocity and smoke density, of the composites were measured. The results showed that OI increased with an increase of the filler content and decreased with an increase of the filler particle diameter. The burning velocity decreased with an increase of the filler content, while it first increased and then decreased with an increase of the filler particle diameter. The smoke density decreased with an increase of the filler content and increased with an increase of the filler particle diameter. There was a flame‐retardant synergy between Al(OH)₃/Mg(OH)₂ and ZB in the composites, and the smoke suppression effect was marked when ZB was added. Copyright © 2009 Society of Chemical Industry     

Thermal and microwave‐assisted oxidative degradation of poly(ethylene oxide)

The kinetics of the thermal and microwave‐assisted oxidative degradation of poly(ethylene oxide) were determined with potassium persulfate as the oxidizing agent. Gel permeation chromatography was used to determine the variation of the molecular weight with time. The degradation was studied as a function of the temperature and persulfate concentration, and it was found that the degradation rate increased with the temperature and concentration of persulfate. Continuous distribution kinetics were used to determine the rate coefficients for the degradation process, and the activation energies were obtained. The results indicated that the microwave‐assisted process had a lower activation energy of 10.3 kcal/mol, whereas that of the thermal degradation was 25.2 kcal/mol. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2090–2096, 2005     

热重分析法研究氢氧化镁纳米粉体的非等温分解动力学

以白云石为原料,盐酸酸溶后得到CaCl₂-MgCl₂滤液,采用氨水直接沉淀法制备出符合HG/T 3607-2000Ⅰ型标准的六方片状的纳米氢氧化镁。六方片厚度为25～30 nm,直径为0.3～0.4 mm。利用热重分析法对纳米氢氧化镁在不同升温速率下的热分解动力学进行研究,以期深入了解纳米氢氧化镁热分解制备纳米氧化镁粉体过程的物理化学本质。采用Kissinger法和Ozawa法计算出氢氧化镁热分解反应活化能分别为115.47 kJ·mol^-1和126.04 kJ·mol^-1。对热重分析数据进行处理和拟合,判断纳米氢氧化镁粉体热分解反应机理函数为Avrami-Erofeev（n=1.5）的随机成核和随后生长机理。指前因子为3.077×10¹⁰ s^-1。纳米氢氧化镁经煅烧制备得到的氧化镁纳米球的直径为80～100 nm。     

Thermal degradation kinetics of poly(O,O‐diethyl‐O‐allylthiophosphate‐co‐acrylonitrile) in nitrogen

The nonisothermal degradation kinetics of the copolymer poly(O,O‐diethyl‐O‐allylthiophosphate‐co‐acrylonitrile), which was synthesized with O,O‐diethyl‐O‐allylthiophosphate and acrylonitrile, were studied by thermogravimetry/derivative thermogravimetry techniques. The kinetic parameters, including the activation energy and the pre‐exponential factor of the copolymer degradation process, were calculated by the Kissinger and Flynn–Wall–Ozawa methods. The thermal degradation mechanism of the copolymer was also studied with the Satava–Sestak method. The results show that the activation energies were 138.17 kJ/mol with the Kissinger method and 141.63 kJ/mol with the Flynn–Wall–Ozawa method. The degradation of the copolymer followed a kinetic model of a phase boundary reaction and the kinetic equation could be expressed as G(α) = 1 ? (1 ? α)⁴ [where G(α) is the integral function of conversion and α is the extent of conversion of the reactant decomposed at time t]. The reaction order was 4. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Durable flame‐retardant finished cotton fabrics characterized by thermal degradation behaviors

After a series of investigations on the durable flame‐retardant finishes, it was thought to be important to study these durable flame‐retardant finished materials from the thermal analytical standpoint. Accordingly, cotton fabric was finished with N‐methylol dialkyl phosphonopropionamide (Pyrovatex C) by thermofixation and tetrakis (hydroxymethyl) phosphonium sulfate (THPS) precondensate by ammonia cure (Proban), as well as with THPS monomer by heat cure under various conditions, and subjected to the thermogravimetry (TG) to observe thermal degradation behaviors and obtain apparent activation energy (E_a). TG curves of Proban‐finished samples showed the largest shift to lower temperatures with a steep slope; thermofixed THPS‐finished sample gave a smaller shift with similar steep slope, whereas Pyrovatex‐finished samples exhibited a similar shift but with a gradual slope. E_a versus residual ratio curves led us to conclude that C N bond‐rich Proban polymer requires the highest E_a and decomposes with considerable rapidity, whereas ethylene‐bond‐rich Pyrovatex‐finished samples with melamine crosslinking decompose gradually with the lowest E_a. As for the relationship between flame retardance and E_a distribution in the process of thermal degradation, typical differences among the above three kinds of finished samples were found, which are compared and discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 975–987, 1999     

Study on flame‐retardancy and thermal degradation behaviors of intumescent flame‐retardant polylactide systems

Two intumescent flame‐retardant (IFR) additives, IFR‐I and IFR‐II, were synthesized and their structure was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. Polylactide (PLA) was modified by the two IFRs to obtain flame‐retardant composites. The flammability of the PLA/IFR composites was characterized by the vertical burning test UL‐94 and limiting oxygen index. The limiting oxygen index values of the PLA composites increased with increase of IFR content. The PLA composite with 20 wt% IFR‐I could pass the UL‐94 V0 rating, while the composite with 30 wt% IFR‐II could not. The results of pyrolysis combustion flow calorimetry showed that the heat release capacity of PLA composites with 30 wt% IFR‐I decreased 43.1% compared with that of pure PLA. The thermal degradation and gas products of PLA/IFR‐I systems were monitored by thermogravimetric analysis and thermogravimetric analysis infrared spectrometry. Scanning electron microscopy was used to investigate the surface morphology of the char residue. Copyright © 2011 Society of Chemical Industry     

半芳香聚酰胺热降解性能和非等温结晶动力学研究

在 N2气氛下,用热重分析法研究了半芳香聚酰胺的热降解行为和热降解动力学。并用经 Jeziorny 修正的Arami 方程对其非等温结晶动力学进行了研究。结果表明：半芳香聚酰胺的热降解过程为一步反应,用 Kissinger 方法和Flynn-Wall-Ozawa 方法求得半芳香聚酰胺的热分解活化能分别为258．37 kJ /mol 和227．41 kJ /mol;在非等温条件下,半芳香聚酰胺结晶时可能以片晶形式生长,随着降温速率增大,转变成三维球晶生长。     

Thermal degradation kinetics of polyethylene and silane‐crosslinked polyethylene

The thermal degradation of linear low‐density polyethylene (LLDPE) and linear low‐density silane‐crosslinked polyethylene (SXLPE) was studied. Kinetic evaluations were performed by model‐free kinetic analysis and multivariate nonlinear regression. Apparent kinetic parameters for the overall degradation were determined. The results show that the thermal stability of SXLPE was higher than that of LLDPE. Their decomposition reaction model was a single‐step process of an nth‐order reaction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1172–1179, 2005     

Thermal degradation kinetics of poly(N‐adamantyl‐exo‐nadimide) synthesized by addition polymerization

The thermal decomposition behavior and degradation kinetics of poly(N‐adamantyl‐exo‐nadimide) were investigated with thermogravimetric analysis under dynamic conditions at five different heating rates: 10, 15, 20, 25, and 30°C/min. The derivative thermogravimetry curves of poly(N‐adamantyl‐exo‐nadimide) showed that its thermal degradation process had one weight‐loss step. The apparent activation energy of poly(N‐adamantyl‐exo‐nadimide) was estimated to be about 214.4 kJ/mol with the Ozawa–Flynn–Wall method. The most likely decomposition process was an F1 deceleration type in terms of the Coats–Redfern and Phadnis–Deshpande results. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3003–3009, 2007     

Kinetic study of polypropylene nanocomposite thermo‐oxidative degradation

Polypropylene (PP) has wide acceptance for use in many application areas. However, low thermal resistance complicates its general practice. The new approach in thermal stabilization of PP is based on the synthesis of PP nanocomposites. This paper discusses new advances in the study of the thermo‐oxidative degradation of PP nanocomposite. The observed results are interpreted by a proposed kinetic model, and the predominant role of the one‐dimensional diffusion type reaction. According to the kinetic analysis, PP nanocomposites had superior thermal and fireproof behaviour compared with neat PP. Copyright © 2005 Society of Chemical Industry     

Melt shear viscosity of PP/Al(OH)3/Mg(OH)2 flame retardant composites at high extrusion rates

The melt apparent shear viscosity (η_a) of polypropylene (PP) composites filled with aluminum hydroxide [Al(OH)₃] and magnesium hydroxide [Mg(OH)₂] was measured by means of a capillary rheometer under experimental conditions of temperature ranging from 180 to 200°C and apparent shear rate varying from 10 to 2 × 10³ s⁻¹, to identify the effects of the filler particle content and size on the melt viscosity. The results showed that the melt shear flow of the composites obeyed the power law and presented pseudoplastic behavior. The dependence of η_a on temperature was consistent with the Arrhenius equation. The sensitivity of η_a for the composite melts to temperature was greater than that of the unfilled PP, and weakened with increasing apparent shear rate. The η_a increased linearly with an increase of the weigh fraction of the flame retardant, especially in the low apparent shear rate region. The η_a of the composites decreased slightly with an increase of particle size of flame retardant. Moreover, the variation for the η_a with particle size of flame retardant was much less than with apparent shear rate under these test conditions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

PP/MWNTs和PP/OMMT复合材料的热降解动力学研究

采用熔融共混法制备了聚丙烯/多壁碳纳米管(PP/MWNTs)与聚丙烯/纳米有机蒙脱土(PP/OMMT)复合材料,利用热重分析法研究了PP、PP/MWNTs及PP/OMMT在氮气气氛中的热降解过程,并采用Kissinger及Ozawa方法研究了复合材料的热降解动力学及热降解表观活化能.结果表明,MWNTs和OMMT的加入...