Thermal stability of aromatic polyesters prepared from diphenolic acid and its esters

The thermal performance of aromatic polyesters (poly(DPA-IPC), poly(MDP-IPC) and poly(EDP-IPC)) prepared from isophthaloyl chloride (IPC) with diphenolic acid (DPA) and its esters were studied with DSC and TG, and the decomposition mechanism of poly(DPA-IPC) were investigated using FTIR and integrated TG/FTIR analyses. As compared with ordinary aromatic polyesters, poly(DPA-IPC) has lower glass transition temperature (159 °C) and much lower thermal stability. It starts to decompose at about 210 °C and is characterized by two-stage thermal decomposition behavior, with active energies of decomposition of 206 kJ/mol and 389 kJ/mol, respectively. The analyses of the decomposition process and products indicate that the pendent carboxyl groups in poly(DPA-IPC) are responsible for its low thermal stability. Accordingly, a decomposition mechanism for the first stage is proposed. With this knowledge in mind, we capped the carboxyl groups in DPA with methyl and ethyl groups to prepare poly(MDP-IPC) and poly(EDP-IPC) from methyl diphenolate and ethyl dipenolate. As expected, these two polymers exhibit obviously improved thermal stability, with onset decomposition temperature of about 300 °C.     

SYNTHESIS AND PROPERTIES OF NOVEL POLY(IMINO KETONE)S AS HIGH-PERFORMANCE POLYMERS

Di(4-bromophenyl)ketone and various aromatic diamines as the monomers,a series of novel poly(imino ketone)s (PIKs)have been synthesized via palladium-catalyzed aryl amination,which is Hartwig-Buchwald polycondensation reaction.The structures of PIKs are characterized by means of elemental analysis,FT-IR,~1H-NMR and UV-Vis spectroscopy. The results show a good agreement with the proposed structure.The general properties of PIKs are studied by DSC,TG and wide-angle X-ray diffraction,the solubility behavior...     

聚氨酯胶粘剂的热分解动力学研究

采用热分析技术考察了通用型聚氨酯胶粘剂在空气中的热解过程, 并通过TG方法和动力学方法研究了各步反应的活化能E、指前因子A等动力学参数. 通过等失重转化率法校验了两种方法所获得的E和A值. 结果表明, 聚氨酯胶粘剂有三个主要降解阶段, 第一降解阶段的活化能为144.31-148.35 kJ·mol^-1, 第二个降解阶段的活化能为196.96-204.26 kJ·mol^-1, 第三个降解阶段的活化能为202.97-205.27 kJ·mol^-1; 热降解过程为一级反应, 随着失重百分率的增大, 热分解反应活化能增大. 此外, 聚氨酯胶粘剂具有较高的热稳定性, 预测其在35 ℃的空气中失重5%时的热老化寿命为10年.     

聚亚胺酮的合成与性能研究

聚酰胺(PA)、聚醚酮(PEK)和聚酰亚胺(PI)等作为高性能材料已被开发并得到应用.这些高性能材料可用于航空、航天、微电子等高新技术领域[1~5].与此同时,为了满足人们对新材料的需求,科学界对新型高性能材料的开发和应用始终没有停止,且备受关注.本文首先通过傅-克酰基化反应合成     

Kinetics Analysis of the Thermal Decomposition of Poly(Butylene Adipate) Ionomers by Thermogravimetry (TG) and Derivate (DTG) Analysis

Kinetics analysis and thermal decomposition study of poly(butylene adipate) ionomers (PBAi) synthesized using the dimethyl 5‐sulfoisophthalate sodium salt (DMSI) of the diacid monomer were carried out by thermogravimetry (TG) and derivate (DTG) analysis. The decomposition kinetic parameters (activation energy, frequency factor) were calculated. The activation energy values of the PBAi‐2, PBAi‐3 and PBAi‐5 ionomers were respectively found as 164.51, 141.91 and 78.07 kJ/mol. The influence of DMSI content on the decomposition of the ionomers was investigated. The activation energy values decrease with increasing the content of DMSI. This suggests that increasing the content of DMSI makes the thermal decomposition of the ionomers easier.     

Thermal degradation behaviour of a nearly alternating copolymer of vinylidene cyanide with 2,2,2-trifluoroethyl methacrylate

The thermal decomposition under non-oxidative conditions of a copolymer of vinylidene cyanide (VCN) and 2,2,2-trifluoroethyl methacrylate (MATRIF) was investigated by thermogravimetry (TG) and Pyrolysis-GC-MS. The type and composition of the pyrolytic products and the shape of the TG curve indicate that both the main thermal degradation process, with onset at 368 °C, and a minor weight loss at around 222 °C are mainly associated with random main-chain scission. The kinetic parameters were determined by means of dynamic and, in the case of the main degradation stage, also isothermal methods. The results obtained from the dynamic methods (Friedman, Flynn-Wall-Ozawa, and Kissinger, respectively) are in good agreement with those obtained from isothermal TG data. The activation energy was in the 177-213 kJ/mol range for the first stage, and 224-295 kJ/mol for the second stage, the highest respective values being determined from the kinetic analysis according to the Kissinger method.     

聚芳醚醚酮的热老化寿命研究

本工作用热重法(TG)研究了聚芳醚醚酮(PEEK)在空气和氮气中的热分解反应过程;确定了PEEK在这两种气氛中的热分解反应模型均符合无规引发断裂模型;在空气中PEEK的热分解显示两个过程,由此计算其在空气中第一阶段的热分解和氮气中的热分解反应活化能分别为214.7kJ/mol和232.2kJ/mol;由热分解反应动力学参数推算出热老化寿命曲线,并讨论了实验条件对结果的影响,进而以失重5%作为材料寿终指标估算出PEEK在氮气和空气中使用10年的最高温度分别为307℃和274℃。     

SYNTHESIS AND PHOTOPHYSICAL PROPERTIES OF POLY(ARYL IMINO) CONTAINING ACRIDINE UNITS(PAIA)

1,4-Bis-(4-bromobenzoyl)benzene and proflavine,3,6-diaminoacridine free base were synthesized first.Using 1,4- bis-(4-bromobenzoyl)benzene and proflavine,3,6-diaminoacridine free base as the monomers,poly(aryl imino) containing acridine units(PAIA) was synthesized via palladium-catalyzed amination.The structure of PAIA was characterized by means of FTIR,~1H-NMR spectroscopy and elemental analysis,the results show an agreement with the proposed structure.The UV absorption and photoluminescence spectra wer...     

Studies on multistep thermal decomposition behavior of polytriazole polyethylene oxide‐tetrahydrofuran elastomer

Polytriazole polyethylene oxide‐tetrahydrofuran (PTPET) is an energetic propellant elastomer that is prepared using glycidyl azide polymer and trifunctional alkynyl‐terminated polyethylene oxide‐tetrahydrofuran. Its thermal decomposition, determined using thermogravimetic analysis, showed two mass‐loss peaks largely related to the decomposition of azide groups and the main chain. Flynn‐Wall‐Ozawa and Kissinger‐Akahira‐Sunose methods were deployed to obtain kinetic triplet parameters of PTPET thermal decomposition by the traditional model‐free method; the Coats‐Redfern approach was used as the model‐fitting method. Kinetics analysis indicated that the mechanism of the two‐step reactions were the primary‐reaction of first order and the power‐law phase reaction of the 2/3 order. The first decomposition stage of PTPET had an activation energy (E_a) of 113 to 116 kJ/mol while the second was 196 to 210 kJ/mol. The thermal decomposition of PTPET with different heating rates and mechanisms showed good kinetic compensation effects, the gas products being further studied with TG‐FTIR.     

纳米金属粉对高氯酸铵热分解动力学的影响

The thermal decomposition characteristics of general ammonium perchlorate (g-AP) influenced by the addition of aluminum, nickel with different particle sizes (general and nano) are studied by TG and DSC. The results show that aluminum powders (both general and nano size) are nearly uninfluenced. Nano nickel powders have the greatest influence on the decomposition properties of g-AP among metal powders. Such accelerating effects of nanonickel powders are more apparent on the stage of high temperature decomposition than low temperature decomposition of g-AP and will be weakened with the decrease of the content of nanonickel. Nanonickel powders are also more effective than super fine nickel powders on accelerating the thermal decomposition of superfine AP (s-AP). The kinetic parameters of the thermal decomposition of s-AP and mixture of s-AP and nano nickel powders are obtained from the TG-DTG curves bythe integral method based on the Coats-Red fern equation. Nanonickel powders reduce the apparent activation energy of the thermal decomposition of s-AP from 157.9 kJ/mol to 134.9 kJ/mol. The most probable mechanism functions of the thermal decomposition reaction for s-AP and mixture of s-AP and nano nickel powders both belong to systems of Avrami-Erofeev equations. The mechanism of such accelerating effects has been discussed.     

Synthesis, characterization and thermal degradation mechanism of three poly(alkylene adipate)s: Comparative study

Three high molecular weight aliphatic polyesters derived from adipic acid and the appropriate diol - poly(ethylene adipate) (PEAd), poly(propylene adipate) (PPAd) and poly(butylene adipate) (PBAd) - were prepared by two-stage melt polycondensation method (esterification and polycondensation) in a glass batch reactor. Intrinsic viscosities, GPC, DSC, NMR and carboxylic end-group measurements were used for their characterization. Mechanical properties of the prepared polyesters showed that PPAd has similar tensile strength to low-density polyethylene while PEAd and PBAd are much higher. From TGA analysis it was found that PEAd and PPAd have lower thermal stability than poly(butylene adipate) (PBAd). The decomposition kinetic parameters of all polyesters were calculated while the activation energies were estimated using the Ozawa, Flynn and Wall (OFW) and Friedman methods. Thermal degradation of PEAd was found to be satisfactorily described by one mechanism, with activation energy 153 kJ/mol, while that of PPAd and PBAd by two mechanisms having different activation energies: the first corresponding to a small mass loss with activation energies 121 and 185 kJ/mol for PPAd and PBAd, respectively, while the second is attributed to the main decomposition mechanism, where substantial mass loss takes place, with activation energies 157 and 217 kJ/mol, respectively.     

聚碳酸亚丙酯马来酸酐的热分解动力学(英文)

通过热重分析研究了新型三元共聚物聚碳酸亚丙酯马来酸酐(PPCMA)在不同升温速率下的热分解动力学.设计并引入一种新的计算方法,非线性约化法(NLA),对共聚物热分解过程中的表观活化能进行了计算.研究发现,虽然用非线性约化法计算的表观活化能相对误差值稍大于用传统计算方法Flynn-Wall-Ozawa(FWO),Tang和Kissinger-Akahira-Sunose(KAS)计算的相对误差值,但其分析合理且计算过程更为简便.此外,固态反应模型拟合方法计算结果表明,共聚物的热分解过程对应多个反应机理.整个热分解过程,表观活化能值处于70-135kJ·mol-1之间,指前因子处于5.24×104-9.89×107min-1之间.同时,通过对表观活化能值的比较,初步解释了聚碳酸亚丙酯(PPC)与PPCMA热解温度差异的原因.     

阻燃共聚酯的热降解动力学研究——Ⅰ.含磷共聚PET和PET的比较

1　前言ＰＥＴ(聚对苯二甲酸乙二醇酯 )由于具有优良的综合性能 ,被广泛地应用于合成纤维、薄膜和工程塑料等领域 ,但由于它的可燃性 ,在火灾事故中 ,由其着火所致占有较大比例 ,因此它的阻燃化更加引起了世界范围内学者的广泛关注[1 ] 。由于磷是对聚酯的最有效阻燃元素 ,采用共聚法制备含磷ＰＥＴ的报道较多 ,也有关于其热降解动力学研究的报道[2～ 1 0 ] 。但本文所采用的单体羟基苯氧膦丙酸 (ＣＥＰＰ)和ＰＥＴ共聚所得产物的热降解动力学研究 ,尚未见报道。研究该种含磷ＰＥＴ的热稳定性和热降解行为对研究该材料的使用范围和成型加工…     

钯催化胺化反应合成高性能材料——聚亚胺砜

利用三(二亚苄基丙酮)二钯(Pd2(dba)3)与1.1′-联萘-2.2′-二苯膦(BINAP)组成的催化体系,高效地催化4,4′-二氯二苯砜和芳香二胺的Buchwald-Hartwig交叉偶联反应,制备出新型聚亚胺砜.聚合物结构通过核磁氢谱、红外谱图、凝胶渗透色谱和元素分析等方法进行表征,表征结果与目标产物相吻合,并具有较高的分子量(Mw>2.5×104).利用DSC、TG和XRD等对其性能进行测试,结果表明,该类聚合物为无定形态,具有较高的玻璃化转变温度(Tg>200℃)、良好的热稳定性(Td>400℃)和溶解性能.其中含异丙基的PIS-3不仅可溶解在强极性溶剂中,并且在室温条件下(25℃)可溶于四氢呋喃中.     

Thermal Behavior,Specific Heat Capacity and Adiabatic Time-to-explosion of GDN

A new compound,[(NH2)2C=NH2]+N(NO2)2-(GDN),was prepared by mixing ammonium dinitramide(ADN) and guanidine hydrochloride in water.The thermal behavior of GDN was studied under the non-isothermal conditions with DSC and TG/DTG methods.The apparent activation energy(E) and pre-exponential constant(A) of the exothermic decomposition stage of GDN were 118.75 kJ/mol and 1010.86 s-1,respectively.The critical temperature of the thermal explosion(Tb) of GDN was 164.09 ℃.The specific heat capacity of GDN was determin...     

新型侧基含磷共聚酯的阻燃和热降解动力学

利用动态热重分析法(TG)研究了聚酯(PET )及侧基含磷共聚酯(FR-PET)在不同升温速率下的热稳定性及热降解动力学, 并通过极限氧指数法(LOI)考察了FR-PET的阻燃性能; 采用Flynn-Wall-Ozawa方法分析了PET和FR-PET的热降解表观活化能; 利用Coast-Redfern方法通过对不同机理模型的选取, 确定了PET和FR-PET热降解动力学机理及其模型, 得出了主降解阶段的非等温动力学方程及热降解速率曲线图. 研究结果表明, 侧基含磷单元的引入提高了聚酯的阻燃性能, 侧基上的P—C和P—O键易断裂, 从而降低了聚酯的热稳定性. PET和FR-PET的热降解表观活化能(0.1≤α≤0.85)分别为194-227和184-209 kJ/mol; PET和FR-PET热降解反应均属于受减速形α-t曲线控制的反应级数机理, 其机理函数为f(α)=3(1-α)2/3(0.1≤α≤0.85). 侧基含磷单元的引入对PET的主降解阶段的热降解速率并无实质上的影响. 侧基含磷共聚酯的凝聚相阻燃作用有限, 可能以气相阻燃机理为主发挥阻燃作用.     

Thermal Decomposition and Glass Transition Temperature of Poly(methyl Methacrylate) and Poly(isobutyl Methacrylate)

Abstract

The thermal decomposition and the glass transition temperatures of poly(methyl methacrylate) (PMMA) and poly(isobutyl methacrylate) (PiBuMA) were studied with a differential scanning calorimeter (DSC). The undecomposed and decomposed polymers were analyzed by gel permeation chromatography (GPC) for molecular weight distributions and by DSC for changes in the thermal properties and glass transition temperatures, T. In the isothermal decomposition of PMMA and PiBuMA, depolymerization reactions exclusively are operative. During low temperature decompositions, longer PMMA chains depolymerize first. These are followed by the shorter chains. In the case of PiBuMA, the shorter chains depolymerize first. Some of these undergo chain recombinations to yield very high molecular weight products. For identical values of weight loss, the respective decomposition temperatures for PiBuMA are 40 to 70 K lower than those for PMMA. The activation energies of decomposition (42 kJ/mol for PMMA and 67 kJ/mol for PiBuMA) have been found to be lower than those reported in the literature. Although T_g∞ of PiBuMA (331 K) agrees well with the literature value (326 K), T_g∞ of atactic PMMA (394 K) is higher than the reported value (378 K).     

含异亚丙基聚亚胺醚酮的合成与性能

首先通过Friedel-Crafts酰基化反应得到1,4-双-(4′-溴苯酰基)苯,经两步合成芳香二胺2,2-双-[4-(4-氨基苯氧基)苯基]丙烷,以1,4-双-(4′-溴苯酰基)苯和2,2-双-[4-(4-氨基苯氧基)苯基]丙烷为单体,以三(二亚苄基丙酮)二钯为催化剂,1.1′-联萘-2.2′-二苯膦(BINAP)为配体,由钯催化的胺基化反应缩聚合成了高分子量含异亚丙基聚亚胺醚酮(pr-PIEK),Mn=5.15×104、Mw=1.26×105.其结构由红外、核磁氢谱和元素分析表征,表征结果与目标结构吻合良好.通过XRD、DSC和TG等对pr-PIEK的主要性能进行分析,结果表明pr-PIEK为无定形态,表现出良好的热稳定性(高的热分解温度TD>450℃)、力学性能(拉伸强度为72.76 MPa、拉伸模量为1013.63 MPa、断裂伸长率为10.32%)和较好的溶解性能,pr-PIEK在室温条件下可溶解在普通有机溶剂氯仿中,50℃溶于丙酮.     

地开石热分解过程及非等温动力学研究

Fourier-transform infrared emission spectroscopy was used to study the dehydroxylation behavior of the thermal decomposition of dickite from Chenxi, Hunan Province, China. Dehydroxylation of dickite was followed by a loss of intensity of the 3620.73, 3695.34 cm-1 OH-stretching bands and 916.06, 1009.33 cm-1 OH bending bands. The thermal decomposition was investigated by thermogravimetric analysis (TGA). A good agreement is found with TG curves of dickite and the mass loss is 13.7% (close to the theoretical value). The non-isothermal kinetics of the thermal decomposition of dickite was studied in TG-DTG curves over the temperature range from 298 K to 1123 K by thermogravimetry and differential thermal analysis in air. Mathematical analysis of TG-DTG data using the integral methods (Coats-Redfern equation, HM equation, MKN equation) and differential method (Achar equation) shows that the thermal decomposition of dickite accords F2 mechanism. The kinetic parameters such as the activation energy (E=131.62 kJ/mol), pre-exponential factor (A=108.30 s-1) and reaction order (n=2.1) are reported. The Ozawa method was used to analyse the activation energy of the same sample at different heating rate and gave 133.07 kJ/mol. The kinetic parameters calculated from different equation are rather close to each other.     

Thermal degradation kinetics of the biodegradable aliphatic polyester, poly(propylene succinate)

The preparation of the biodegradable aliphatic polyester poly(propylene succinate) (PPSu) using 1,3-propanediol and succinic acid is presented. Its synthesis was performed by two-stage melt polycondensation in a glass batch reactor. The polyester was characterized by gel permeation chromatography, ¹H NMR spectroscopy and differential scanning calorimetry (DSC). It has a number average molecular weight 6880 g/mol, peak temperature of melting at 44 °C for heating rate 20 °C/min and glass transition temperature at −36 °C. After melt quenching it can be made completely amorphous due to its low crystallization rate. According to thermogravimetric measurements, PPSu shows a very high thermal stability as its major decomposition rate is at 404 °C (heating rate 10 °C/min). This is very high compared with aliphatic polyesters and can be compared to the decomposition temperature of aromatic polyesters. TG and Differential TG (DTG) thermograms revealed that PPSu degradation takes place in two stages, the first being at low temperatures that corresponds to a very small mass loss of about 7%, the second at elevated temperatures being the main degradation stage. Both stages are attributed to different decomposition mechanisms as is verified from activation energy determined with isoconversional methods of Ozawa, Flyn, Wall and Friedman. The first mechanism that takes place at low temperatures is auto-catalysis with activation energy E = 157 kJ/mol while the second mechanism is a first-order reaction with E = 221 kJ/mol, as calculated by the fitting of experimental measurements.