侧基含磷共聚酯的热降解动力学及热稳定性

采用不同的升温速率,用Kissinger法研究了聚酯(PET)和侧基含磷共聚酯(FR-PET)在氮气气氛中热降解动力学,采用时-温等效原理对其热稳定性进行了深入研究,等温热失重法和Kissinger法将寿命方程及动力学参数联系起来,确定了它们之间的关系。结果表明,阻燃剂的引入降低了PET整个热降解过程的平均活化能,并改变了反应级数,但使PET的热稳定性有所提高。两种方法所确定的寿命方程较为接近,Kissinger法更为简便、迅速,为材料寿命的预测提供了捷径。     

聚苯硫醚砜的热老化

采用热分析的方法对高性能材料聚苯硫醚砜(PPSS)在氮气气氛和空气气氛中的热老化寿命进行了研究。通过Kissinger方法分别求得材料在氮气中的活化能为E=214．24kJ／mol,在空气中的活化能E=258．64kJ／mol,由Coats—Redfern法确定了材料在氮气和空气中热分解的第一个阶段都为一级反应,并根据Dakin提出的经验关系式作出老化寿命曲线,由此得出聚苯硫醚砜(PPSS)在氮气气氛和空气气氛中使用十年的上限温度为254℃和388℃。     

热致液晶共聚酯60PHB/PEN的热降解动力学研究--(Ⅰ) 非等温热降解动力学

在氮气氛中采用热重分析的方法对热致液晶共聚酯60PHB／PEN的热降解动力学进行了研究。采用Friedman和Chang两种单一加热速率方法对活化能Ea、反应级数n和频率因子Z等降解反应动力学参数进行了分析。讨论了加热速率和计算方法对热稳定性及降解动力学参数的影响。     

氯磺化聚乙烯在不同气氛中的热降解行为

利用热重分析仪（TGA）研究了氯磺化聚乙烯（CSM）在氮气和空气中的热降解行为,探讨了气氛对CSM热降解的影响。研究表明,CSM的热分解过程分为两个失重平台,随着升温速率的升高,聚合物的分解温度逐渐升高。分别用Kissinger和Flynn-Wal-lOzawa方法对CSM中第一个失重平台（磺酰氯基团）的降解行为进行了...     

新型含磷阻燃共聚酯热降解动力学

利用F lynn-W a ll-O zaw a方法,对纤维用聚酯(PET)及二羧乙基苯基氧化磷(BCPO)改性的阻燃聚酯(FR-PET)的热失重(TG)降解行为进行了研究,发现聚酯和阻燃聚酯的热降解过程相近,热降解活化能没有较大的变化,阻燃剂BCPO的引入对热降解过程无显著影响。     

阻燃PET的热降解动力学

利用双螺杆挤出机挤出造粒制备了共混型阻燃PET材料,并利用TG方法研究了PET和阻燃PET在N2气氛下以一定升温速度时的热降解动力学行为,以此探讨阻燃性能与热降解行为的关系。试验发现．加入阻燃荆后材料的初始分解温度提前,在失重20％以前,阻燃PET的活化能低于PET的活化能,当失重超过30％以后,阻燃PET的活化能超过了PET,说明阻燃刺使PET提前分解成发,隔热、隔氧阻止了材料的进一步氧化分解;阻燃荆的加入使同一温度下PET的不同失重率所对应的时间缩短,在同一温度下阻燃PET失重一半的时间t0．5也有较大幅度的缩短,即热稳定性下降,这一点与阻燃荆能够降低PET初始分解温度、提前分解成发有密切的关联。     

聚酰胺对聚甲醛的稳定化作用

采用220℃等温热失重、等速升温热重分析(TGA)分别研究了以聚酰胺为稳定剂的聚甲醛体系POM／COPA、POM／SAN／PA在氮气和空气气氛中的热稳定性,同时用Coats-Redkrnd法计算了各体系在空气中的降解动力学参数。结果表明,加入稳定剂COPA、PA的聚甲醛体系在220℃等温热降解1h的失重率远小于空白POM;TG分析数据也显示改性后的聚甲醛体系在氮气中的Tonset明显高于空白POM.空气中空白POM的活化能及分解温度均低于改性聚甲醛。     

共聚甲醛的热降解行为及动力学

TGA结果表明三种CPOM(Y—M90、D-90EM和B—M90S)降解特征温度在氮气氛中均比空气氛中高70℃～100℃。这主要是由于在空气氛中聚甲醛的降解行为除了热裂解外,还存在自动氧化降解和氧化降解产物导致的酸解水解等降解方式,在较低的温度下由于空气中氧的作用,降解产物甲醛可被氧化成甲酸进而强化酸解水解作用,使CPOM的降解温度明显降低。用Freeman—Carroll方法研究了CPOM热降解动力学,计算得到的活化能和反应级数等参数在氮气氛中主要适用于350℃～385℃,质量损失区间在主要分解行为阶段(20％～70％);在空气和氮气氛中,D-90EM的n分别为0．36和1．06,差别最大,而Y—M90的n值分别为0．73和0．83,反应机制最为接近;三种CPOM在空气中n值以D-90EM和Y—M90差别最大,分别为0．36和0．73,而在氮气中B—M90S和D-90EM热降解接近一级反应,n值分别为1．08和1．06,降解机制最为相近。     

气氛对侧链型质子交换膜材料降解行为的影响

利用缩聚反应合成了不同磺化度的侧链型磺化聚芳醚酮(SPAEK)质子交换膜材料,红外光谱与氢核磁谱图证实所合成产物为目标产物。通过热重分析仪(TGA)对SPAEK在氮气和空气中的热性能研究发现,SPAEK在氮气中的热稳定性要好于在空气中的。通过Friedman方法计算得到了不同磺化度SPAEK分别在氮气和空气氛围下的活化能E和相关系数r。利用Coats-Redfern方法探讨了SPAEK的降解机理,结果表明SPAEK的降解机理为F1机理。     

氯磺化聚乙烯的热行为和热降解过程

用TG、DTG和DSC研究了氯磺化聚乙烯(CSM)的热行为和热降解过程。结果表明:CSM的热降解温度和失重50％的温度均随升温速率升高而增高;在氮气氛和空气中,CSM分别为三步和四步降解。     

Thermal degradation behavior and kinetic analysis of poly(L-lactide) in nitrogen and air atmosphere

The non-isothermal and isothermal degradation behaviors and kinetics of poly(L-lactide) (PLLA) were studied by using thermogravimetry analysis (TGA) in nitrogen and air atmosphere, respectively. At lower heating rate ((5–10)°C/min), PLLA starts to decompose in air at lower temperature than those in nitrogen atmosphere; however, at higher heating rate ((20–40)°C/min), the starting decomposition temperature in air are similar to those in nitrogen atmosphere, not only showing that PLLA has better thermal stability in nitrogen than in air atmosphere, but also suggesting that the faster heating rate will decrease the decomposition of PLLA in thermal processing. Whether in air or in nitrogen atmosphere, the decomposition of PLLA has only one-stage degradation with a first-order decomposed reaction, suggesting that the molecular chains of PLLA have the similar decomposed kinetics. The average apparent activation energy of non-isothermal thermal degradation (Ē_non) calculated by Ozawa theory are 231.7kJ·mol⁻¹ in air and 181.6kJ·mol⁻¹ in nitrogen; while the average apparent activation energy of isothermal degradation (Ē_iso) calculated by Flynn method are 144.0kJ·mol⁻¹ in air and 129.2kJ·mol⁻¹ in nitrogen, also suggesting that PLLA is easier to decompose in air than in nitrogen. Moreover, the decomposed products of PLLA are also investigated by using thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS). In air atmosphere the volatilization products are more complex than those in nitrogen because the oxidation reaction occurring produces some oxides groups.     

Thermal degradation behavior and kinetic analysis of poly(L-lactide) in nitrogen and air atmosphere

The non-isothermal and isothermal degradation behaviors and kinetics of poly(L-lactide) (PLLA) were studied by using thermogravimetry analysis (TGA) in nitrogen and air atmosphere, respectively. At lower heating rate ((5–10)°C/min), PLLA starts to decompose in air at lower temperature than those in nitrogen atmosphere; however, at higher heating rate ((20–40)°C/min), the starting decomposition temperature in air are similar to those in nitrogen atmosphere, not only showing that PLLA has better thermal stability in nitrogen than in air atmosphere, but also suggesting that the faster heating rate will decrease the decomposition of PLLA in thermal processing. Whether in air or in nitrogen atmosphere, the decomposition of PLLA has only one-stage degradation with a first-order decomposed reaction, suggesting that the molecular chains of PLLA have the similar decomposed kinetics. The average apparent activation energy of nonisothermal thermal degradation (Ē _non) calculated by Ozawa theory are 231.7 kJ·mol⁻¹ in air and 181.6 kJ·mol⁻¹ in nitrogen; while the average apparent activation energy of isothermal degradation (Ē _iso) calculated by Flynn method are 144.0 kJ·mol⁻¹ in air and 129.2 kJ·mol⁻¹ in nitrogen, also suggesting that PLLA is easier to decompose in air than in nitrogen. Moreover, the decomposed products of PLLA are also investigated by using thermogravimetry-differential scanning calorimetry-mass spectrometry (TGDSC-MS). In air atmosphere the volatilization products are more complex than those in nitrogen because the oxidation reaction occurring produces some oxides groups.     

新型阻燃剂-2-羧乙基苯基次膦酸及其阻燃共聚酯的制备、表征及热性能研究(英文)

制备了一种新型的含磷阻燃剂-2-羧乙基苯基次膦酸(CEPPA),并用FTIR、HNMR表征了其结构。当磷含量为0.6wt%时,其阻燃共聚酯的LOI可达29.4%。同时利用DSC、TGA研究了不同磷含量共聚酯的热性能。结果表明,共聚酯的玻璃化转变温度(Tg)、熔点(Tm)、热结晶温度(Tmc)、起始分解温度(Tid)随着磷含量的增加而降低,而冷结晶温度(Tcc)、最大分解速率(Tmax)、燃烧后炭层含量则随之增加。为了更好地解释阻燃剂的阻燃机理,利用FTIR研究了TGA测试后生成炭层的结构,结果表明燃烧后的炭层主要由含磷碎片组成。     

Viscosity and Thermal Conductivity Equations for Nitrogen, Oxygen, Argon, and Air

New formulations for the viscosity and thermal conductivity for nitrogen, oxygen, argon, and air are given. Air is treated as a pseudo-pure fluid using an approach adopted from previous research on the equation of state for air. The equations are valid over all liquid and vapor states, and a simplified cross-over equation was used to model the behavior of the critical enhancement for thermal conductivity. The extrapolation behavior of the equations for nitrogen and argon well below their triple points was monitored so that both could be used as reference equations for extended corresponding states applications. The uncertainties of calculated values from the equations are generally within 2% for nitrogen and argon and within 5% for oxygen and air, except in the critical region where the uncertainties are higher. Comparisons with the available experimental data are given.     

PVC搪塑粉的热降解特征及其动力学研究

粉末搪塑表皮被广泛应用在各种中高档汽车仪表板上.为了优化设计搪塑粉、提高热加工性能从而促进高档汽车国产化,本文首先利用热重分析和裂解气相色谱/质谱实验探讨搪塑粉的热降解失重特征,分析升温速率、实验气氛和搪塑加工对其热降解行为的影响,继而结合X射线荧光光谱实验对其热降解动力学进行研究.结果表明:搪塑粉的热降解过程可分为3个阶段,PVC和增塑剂的相互作用使其热降解过程更加复杂;随升温速率的增加,热降解失重曲线向高温区偏移;搪塑粉在有氧气氛中更易发生热降解,失重率较大;与搪塑粉相比,搪塑表皮的热稳定性能得到一定程度的提升;第1热降解阶段氮气条件下的热降解活化能和反应级数较小.     

Environmental aging of high-performance polymeric composites: Effects on durability

The effect of sub-T_g environmental aging on the durability of two high-performance polymeric composites has been investigated. The material systems under study were a thermoplastic-toughened cyanate ester resin (Fiberite 954-2) and a semicrystalline thermoplastic resin (Fiberite ITX), and their respective carbonfiber composites, IM8/954-2 and IM8/ITX. Specimens were aged for periods of up to 9 months in environmental chambers at 150 °C and in one of three different gas environments: nitrogen, a reduced air pressure of 13·8 kPa (2psi air) or atmospheric ambient air (14·7psi air). The glass transition temperatures, T_g, of the two resin systems were monitored as a function of aging time and environment. The changes in T_g showed effects of both physical aging and chemical degradation; the latter appeared to be sensitive to the oxygen concentration in the aging environment. Flexure tests were performed on 8-ply unidirectional (90 °) IM8/954-2 and IM8/ITX composites, aged up to 6 months in the three gas environments at 150 °C. The samples showed a 30–40% loss in the bending strength after aging. These strength reductions were sensitive to the oxygen concentrations in the aging environment. Stress/strain tests were also conducted on the same composites to measure the ultimate properties of the materials before and after aging in the three different environments at 150 °C. The results showed a decrease of 40–60% in the ultimate strain to failure with aging. The modulus of both composite systems on the other hand increased by up to 20 % after aging for 6 months, possibly as a consequence of the physical aging phenomena. In both systems greatest reduction in ‘useful’ mechanical properties occurred in the ambient air environment, while the least reduction occurred in nitrogen. Weight loss in the plain resin and composite samples was monitored as a function of aging time and environment. Typically, all of the samples showed 1–2 % weight loss after 9 months of aging at 150 °C, and the composite samples lost much more weight (on a polymer basis) than unreinforced resin specimens over the same aging period. The weight loss data as well as all the above-mentioned observations were indicative of an oxidation process in the composites.     

甘蔗渣对聚甲基丙烯酸甲酯热降解的影响

目的分析生物质材料对塑料废弃物热降解的影响,以聚甲基丙烯酸甲酯(PMMA)为对象,探讨甘蔗渣对其热分解行为和动力学的作用。方法利用溶液共混法制备PMMA/甘蔗渣混合物,采用热失重法研究其在氮气中的热分解过程,通过最大失重速率法和Ozawa等失重法计算PMMA热分解反应的动力学参数活化能和频率因子。结果甘蔗渣使得PMMA的初期热分解温度明显降低,但是PMMA的热分解活化能和频率因子却都显著增加。最大失重速率法的计算结果表明,PMMA加入甘蔗渣后的热分解活化能增加了26.2 k J/mol,等失重法的结果显示活化能和频率因子分别为168.14 k J/mol和28.41 min-1,比纯PMMA相应地增大了72.6 k J/mol和12.52 min-1。结论甘蔗渣的加入对PMMA的热降解有显著的影响,使其热分解变得困难,因此有必要进一步探讨其他生物质对PMMA热分解的影响。     

PC/POSS复合材料的制备及热性能

合成及表征了八苯基倍半硅氧烷（PH-POSS）、γ-甲基丙烯酰氧丙基倍半硅氧烷（MA-POSS）,并利用差示扫描量热（DSC）和热重分析（TGA）分别研究其在聚碳酸酯（PC）体系中对体系热性能的影响。研究结果表明,复合材料Tg随着PH-POSS含量的增加而降低;而随着MA-POSS含量的增加基本不受影响。在氮气中,复合...