PETG树脂热分解稳定性研究

研究了不同1,4-环己烷二甲醇(CHDM)含量的PETG树脂在氮气和空气两种气氛中的热分解稳定性。结果表明:在氮气中,PETG树脂只有一个热失重台阶,相应的热分解温度分别为Tdi383.1～412.4℃,Tdp425.7～427.8℃,Tdi448.4～459.7℃,总失重84.7%～92.1%,这个结果可以作为PETG热分解稳定性的表征;CHDM含量对PETG树脂的热分解稳定性有一定影响,随着CHDM含量增加,PETG树脂的热分解稳定性有所降低。在空气气氛中,PETG树脂存在两个热失重台阶,第二失重台阶是残留物进一步氧化燃烧过程的体现。所以,第一失重台阶的热分解参数,可以作为PETG热氧化分解稳定性的表征。PETG的热氧化分解稳定性较其热分解稳定性要差,但两者相差不大。     

简单有机化合物的水热分解

为了了解醇、醛、酸和其它有机化合物在无氧水中的稳定性,研究了它们在２０－４０ＭＰａ,５７３－６７３Ｋ温度范围内的水热反应。测定和比较了有机化合物的一级分解速度常数。还测定了某些动力学参数。讨论了低分子量化合物在无氧水中的分解反应机理。     

改性双马来酰亚胺树脂热氧化性能研究

本文分析了ＢＰＰＤＰＳ改性双马来酰亚胺树脂的热氧化性分解特性,固化树脂分解速率低,有优良的抗氧化性;并推导出树脂的热分解动力学方程,符合一级反应历程。     

橡胶发泡剂热分解反应动力学研究方法

本文综合介绍了橡胶发泡剂分解过程动力学研究方法。包括升温和恒温下橡胶发泡剂分解放气量压力和体积测试方法,在橡胶介质中发泡剂分解特性的研究方法。并自行设计了一套较为简单实用的实验装置,这些测试方法的建立可为橡胶的实际生产提供一定的参考价值。     

抗氧剂对PMMA树脂热氧化稳定性的影响及动力学分析

采用热重分析,研究了抗氧剂种类及用量对聚甲基丙烯酸甲酯(PMMA)热氧化稳定性的影响,并采用Kis-singer、Flynn-Wall-Ozawa和Flynn法对其热氧化降解行为进行了动力学分析。结果表明,抗氧剂1010、1076、702和BHT的用量为0.5‰时就能够显著提高PMMA热氧化稳定性,使其起始热分解温度提高70℃左右,而抗氧剂用量进一步提高对改善PMMA的热稳定性意义不大;动力学分析表明,抗氧剂的加入能够提高PMMA质量损失率小于30%时的热降解活化能,而热分解后期由于降解温度高于抗氧剂熔点,抗氧剂气化逸出,抗氧剂不能有效提高PMMA后期热降解活化能,未能达到提高PMMA整体热稳定性的目的。     

稳定性PZT溶胶的制备及其热分解动力学分析

采用Sol–gel法制备了[Pb(Zr_0.53Ti_0.47)O₃](PZT)溶胶,并对PZT溶胶稳定性进行120 d跟踪表征。结果发现:随时间演化PZT溶胶pH值保持在4.81～5.52,溶胶粒径1.3～17.1 nm时,Zeta电位处于–10.23～–17.57 m V之间,PZT溶胶存储稳定性能良好。通过同步热分析、热重–红外联用分析、X射线衍射和X射线能谱分析,发现PZT溶胶热分解过程分为3个阶段;经透射电子显微镜与选区电子衍射分析,进一步表明热处理产物暴露晶面族为(110)和(101)。最后,通过热失重–微商热重法并结合Flynn–Wall–Ozawa法、Achar法和Satava法对PZT溶胶热解机理和动力学进行研究,结果表明:第1阶段活化能E_α=58.24 k J·mol^–1,遵循一级Mample单行法则;第2阶段活化能E_α=171.46 k J·mol^–1,遵循三维扩散(Jander)法则;第3阶段活化能E_α<...     

火药热分解特性与燃烧稳定性间相关性的分析

火药热分解过程的复杂性与其燃烧稳定性之间,存在有某种统计性的增函数关系。火药热分解特性对其燃烧特性的影响,是通过燃烧过程中亚表面热分解表观活化能的变化来实现的,当环境温度和压力较低时,亚表面的热分解特性,与常规条件下该火药的热分析结果相近。对于热分解过程较为复杂的火药,随着环境压力和温度的升高,其亚表面的分期机理和表观分解活化能将发生改变,亚表面分解速率随压力的变化规律也要发生变化,这就导致了燃烧过程的不稳定性,而对于那些热分解过程较为简单的火药,则不会出现这种情况,此外,本文还提出,火药中某些组分的爆燃是导致一些火药燃速压力指数较高的原因。     

二苯胺型重氮盐的光、热分解及其树脂的复合物和自组装研究

本论文分为两部分 ,第一部分为二苯胺型重氮盐的光、热分解及其树脂复合物的研究 .合成了 4种二苯胺型重氮盐 (咔唑 3 重氮盐 ,Ｃ 3 ＤＳ ;Ｎ 乙基咔唑 3 重氮盐 ,ＮＥＣ 3 ＤＳ ;Ｎ 苄基咔唑 3 重氮盐 ,ＮＢＣ 3 ＤＳ ;Ｎ 甲基 二苯胺 2 硝基 4 重氮盐 ,ＭＮＤＤＳ)及其与甲醛缩合的树脂 .研究了二苯胺型重氮盐的光、热分解 ,结果表明 :在醇中 ,二苯胺型重氮盐的光解主要生成重氮基被乙氧基取代的产物 ;热解几乎生成唯一的重氮基被氢取代的产物 .而硝基取代的二苯胺 4 重氮盐 ,在水中 ,无论是光解还是热解 ,其产物基本相同 .对重氮…     

硫酸铵分解过程及其热分解动力学研究

硫酸铵热分解能为硫酸氢铵溶液浸出粉煤灰提取氧化铝工艺过程提供硫酸氢铵溶液和氨水,研究硫酸铵热分解过程的机理和热分解动力学具有重要意义。通过X射线衍射、质谱和傅里叶变换红外光谱等对硫酸铵热分解过程的产物进行了表征,结果表明硫酸铵的热分解产物为硫酸氢铵、焦硫酸铵、氨气、水、氮气和二氧化硫。采用X射线衍射、质谱和傅里叶变换红外光谱等表征方法并与热重分析技术联用对硫酸铵进行了分析,结果发现硫酸铵的热分解过程分为3个阶段：硫酸铵分解形成硫酸氢铵和氨气;硫酸氢铵脱水形成焦硫酸铵;焦硫酸铵分解。采用Ozawa-Flynn-Wall和Kissinger-Akahira-Sunose无模型方法计算每个阶段的活化能。采用Coats-Redfern方法确定每个阶段最可能的机理函数。结果表明：第一阶段的平均活化能（E）为125.21 kJ/mol,ln A为18.46;第二阶段的平均活化能（E）为110.21 kJ/mol,ln A为13.94;第三阶段的平均活化能（E）为97.70 kJ/mol,ln A为8.44。     

不同结构二苯胺重氮盐及重氮树脂的光，热分解

对二苯胺－4－重氮盐（DS）,邻－甲氧基二苯胺－4－重氮盐（MDS）和N－甲基－间硝基二苯胺－4重氮盐（NDS）及它们的重氮树脂（DR,MDR,NDR）在水溶液中的光,热分解研究表明,这些重氮盐和树脂的光分解性质,即感光灵敏性差别不大,而热分解性质,即热稳定性差别很大,MDS的热稳定性最好,固相膜中3种树脂的光分解亦差别不大,但N－甲基－间硝基二苯胺－4－重氮树脂（NDR）固相膜的热稳定性出乎预料地好,从疏水性的角度对NDR固相膜突出的热稳定性作了初步解释。     

Thermal stability of poly(trimethylene terephthalate)

The first-order thermal degradation rates of poly(trimethylene terephthalate) [PTT] at 240-280 °C under non-oxidative conditions have been determined from the increase in allyl endgroups (¹H NMR) which closely match the rates determined from the decrease in molecular weight (intrinsic viscosity). Consequently, the predominant thermal degradation mechanism of PTT is consistent with concerted, electrocyclic oxo retro-ene chain cleavage under conditions pertinent to viable polymerization processes and efficient downstream extrusion and spinning into fiber. Although catalysts, additives and other reaction variables can influence the thermo-oxidative stability of polyesters including PTT, these factors have been found to have little or no effect on PTT thermal degradation rates under non-oxidative environments. The thermal stability of poly(butylene terephthalate) [PBT] has also been determined from butenyl endgroups (NMR) and molecular weight (IV). The activation energies (E_a) for both PTT and PBT thermal chain cleavage are similar to the reported E_as for poly(ethylene terephthalate) [PET] degradation, which is further supported by semi-empirical molecular orbital calculations on model compounds. However, both PTT and PBT undergo molecular weight decrease faster than PET. The apparent slower chain cleavage of PET is attributed to the contribution of productive chain propagation reactions due to unstable vinyl endgroups which alters the equilibrium stoichiometry compared to the relatively stable endgroups of PTT and PBT.     

聚酯热稳定性的研究

在合成聚酯试验之后,利用聚合试验装置搅拌器扭矩变化来表征聚酯加工过程中的热稳定性,比热失重法更接近聚酯加工过程,比粘度降法减少了干扰因素。研究结果表明:稳定剂种类、添加量和调配方式等均影响聚酯的热稳定性。     

聚对苯二甲酸丙二醇酯的热性能研究

研究了聚对苯二甲酸丙二醇酯 (PTT) ,PET ,CDP在不同温度和时间下的特性粘数和端羧基含量的变化。结果表明 ,一定温度下 ,PTT熔体特性粘数随熔融时间的延长而下降 ,一定时间下 ,随温度的升高而下降。PTT端羧基含量随温度升高而增大 ,PTT的热稳定性较PET明显下降。     

Spherulite morphology and crystallization behavior of poly(trimethylene terephthalate)/poly(ether imide) blends

The spherulite morphology and crystallization behavior of poly(trimethylene terephthalate) (PTT)/poly(ether imide) (PEI) blends were investigated with optical microscopy (OM), small-angle light scattering (SALS), and small-angle X-ray scattering (SAXS). Thermal analysis showed that PTT and PEI were miscible in the melt over the entire composition range. The addition of PEI depressed the overall crystallization rate of PTT and affected the texture of spherulites but did not alter the mechanism of crystal growth. When a 50/50 blend was melt-crystallized at 180 °C, the highly birefringent spherulite appeared at the early stage of crystallization (t < 20 min). After longer times, the spherulite of a second form was developed, which exhibited lower birefringence. The SALS results suggested that the observed birefringence change along the radial direction of the spherulite was mainly due to an increase in the orientation fluctuation of the growing crystals as the radius of spherulite increased. The lamellar morphological parameters were evaluated by a one-dimensional correlation function analysis. The amorphous layer thickness showed little dependence on the PEI concentration, indicating that the noncrystallizable PEI component resided primarily in the interfibrillar regions of the growing spherulites.     

PET/PTT共混聚酯的等温结晶行为

使用差示扫描量热仪(DSC)研究不同比例的PET/P1T共混聚酯在205℃的等温结晶行为,并使用Avrami方程对其等温结晶过程进行研究.结晶半周期t1/2,总结晶速率常数k和Avrami指数n的变化表明:在共混体系中,对于PET和PTT而言,另一组分的加入都会对结晶产生阻碍作用,PET与P1T相互影响成核与晶体生长机理.     

聚对苯二甲酸丙二醇酯的热降解性能

采用了旋转流变仪、凝胶色谱等仪器对聚对苯二甲酸丙二醇酯(PTT)的热降解性能进行了研究。研究表明:随着时间的延长,PTT熔体的相对分子质量和熔体黏度明显下降,而相对分子质量分布没有明显变化;随着温度的升高,PTT熔体的降解速度明显增大;在不同剪切速率下,两种国外PTT熔体的热降解速率基本相同;PTT相对分子质量越高,越易发生热降解。     

Studies of temperature influence on volatile thermal degradation products of poly(ethylene terephthalate)

The temperature influence on the thermal degradation products evolved from poly(ethylene terephthalate) (PET) was investigated. The experiments were carried out within the temperature range of 200–700°C in air. The main volatile toxic products and weight losses during thermal degradation of PET were determined. The results are presented on plots as a function of the degradation temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2377–2381, 1998     

Volatile products of poly(ethylene terephthalate) thermal degradation in nitrogen atmosphere

Thermal degradation of PET was studied in a nitrogen atmosphere at 200–700°C. The experiments were carried out in a tubular furnace under isothermal conditions. The volatile substances evolved from PET were identified and quantified. Weight losses of PET during the thermal degradation in different temperatures were determined. The results are presented on plots as a function of the degradation temperature. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1894–1901, 2000     

SBS/蒙脱土纳米复合材料耐热性能研究

采用溶液混合方法制备了苯乙烯/丁二烯三元嵌段共聚物（SBS）/有机蒙脱土（OMMT）纳米复合材料（NC）,对SBS/OMMT NC的热学性能进行了研究。结果表明,添加OMMT对于所有复合体系均提高了耐热性能,其中以SBS4402/OMMT-DK1B体系最为明显,热失重中心温度Tdc提高幅度达27℃;当OMMT用量为2.5质量份时,NC的Tdc最高,表明耐热性能最好,超过2.5质量份后,耐热性能下降;星型结构SBS耐热性能的提高明显高于线型SBS。     

Crystallization kinetics of poly(trimethylene terephthalate)

The bulk isothermal crystallization kinetics of poly(trimethylene terephthalate) (PTT) was studied using a differential scanning calorimeter. Avrami's theory was used to analyze the data. Based on crystallinity growth rate, Avrami rate constant, K, and crystallization half‐time, PTT's crystallization rate is between those of poly(butylene terephthalate) (PBT) and poly(ethylene terephthalate) (PET) when compared at the same degree of undercooling. PBT has the highest crystallization rate with K in the order of 10^?2 to 10^?1 min^?n. It is about an order of magnitude faster than PTT at 10^?3 to 10^?2 min^?n, which in turn is an order of magnitude faster than PET with K of 10^?4 to 10^?2 min^?n. Contrary to previous reports (PTT was not included in the study) that aromatic polyesters with odd numbers of methylene units were more difficult to crystallize than the even‐numbered polyesters, PTT did not fit in the prediction and did not follow the odd‐even effect.