水溶性聚酯的热降解动力学研究

水溶性聚酯的热降解动力学研究应宗荣李瑞霞吴大诚（四川联合大学轻纺学院成都６１００６５）关键词水溶性聚酯，热降解，动力学，活化能高聚物的热稳定性直接影响高聚物的应用和加工成型．高聚物在高温时易发生热降解，导致分子链断裂，分子量降低，性能劣化．研究...     

气氛对尼龙1010热降解的影响

利用ＴＧ和ＤＴＡ研究了尼龙１０１０在Ｎ２气和空气流巾的降解过程和动力学，考察了反应气氛对降解步骤．降解温度、降解率和动力学参数的影响，分析了两者降解机理的可能差别．发现空气中的热氧降解为多步反应，而Ｎ２气中的热降解为一步反应Ｚ降解温度和降解率，Ｎ２气中均高于空气中；表观反应级数Ｎ２气中为１．０，空气中为１．１级．     

阻燃共聚酯/粘土复合物热降解动力学研究

用插层共聚方法合成了含磷共聚酯／粘土复合物。用热重(TG)方法考察热降解动力学。通过在空气中以不同的升温速率升温至设定温度,用Kissinger法和Hymn-Wall-Ozawa法对数据进行处理。结果表明,粘土组分含量较高的反应活化能较大,热稳定性较好。     

酚醛树脂中亚甲基对热降解的影响

将固化后的酚醛树脂在不同温度下进行热处理,对固化后的样品进行热重分析,对热处理后的试样进行傅立叶红外光谱分析.实验结果表明,酚醛树脂的热降解与亚甲基的取代位有关.酚醛树脂中的亚甲基分两个阶段进行热解降,350~450℃的温度区间主要是部分邻-邻(o-o′)位亚甲基和邻-对(o-p)位亚甲基的分解,400~620℃温度区间为对-对(p-p′)位亚甲基的分解,p-p′位亚甲基比o-o′位亚甲基的起始热分解温度高50℃左右.     

基于TGA-FTIR联用技术研究ABS树脂的热氧降解行为

采用热失重-傅立叶变换红外光谱(TGA-FTIR)联用技术研究了空气气氛下ABS树脂的热稳定性及热氧降解失重情况。研究了ABS在4个不同升温速率下的失重情况;采用TGA-FTIR联用技术对10℃/min等速升温下ABS失重过程的逸出气体进行分析;采用热分解动力学方法分析ABS的热氧降解过程,计算热分解活化能。结果表明,ABS的TGA曲线有两个失重区间:第一区间是ABS的急剧氧化降解过程,活化能(Ea)为191.8~262.8 kJ.mol-1,第二区间是成炭产物的氧化,Ea约为139.7 kJ.mol-1;升温速率越小,ABS热氧降解速率越慢,交联成炭产物越多,有利于抑制ABS的降解;由FTIR测试和Ea变化发现,热氧降解反应为多步复杂反应,初期时氧化反应和氧化断链同时进行,并以氧化断链反应为主,随着分子链上产生的双键增多发生交联反应,失重率大于80%时开始炭化反应,最终交联炭层发生氧化反应生成CO2。     

人胎盘胶原热变性的量热法研究

本文用差示扫描量热计,在274—345K温度范围内,研究了Ⅰ型人胎盘胶原在各种水介质中的热变性过程,测得这些过程的热力学参数。在pH3.7无盐水溶液中,该胶原的平均变性温度T_d为47.1℃,变性焓△H_d为8.43kJ/mol残基。得到各种胶原的△H_d-T_d的线性函数关系,指明人胎盘胶原结构稳定化的各种因素。用热力学事实判定水-羰基模型是更可取的。通过van’t Hoff焓的计算估计出入胎盘胶原分子中有5个合作块,每个合作块包含600个残基,是多区域蛋白质。     

生物质热反应机理与活化能确定方法Ⅰ.干燥段研究

干燥段是生物质热解的第一个过程.采用热分析仪研究了杉木木屑干燥段质量和热量的变化,推导了非等温干燥动力学模型,探讨了热质传输机理.结果表明,随着温度的升高,木屑含湿量迅速下降,80℃左右出现一个明显的失重峰;非等温干燥动力学Page模型能很好地模拟木屑干燥过程,木屑干燥活化能为12.6 kJ/mol;水分传输与热量传递...     

热塑弹性体热寿命和热降解动力学

利用热重法研究了聚苯乙烯/聚二烯烃/聚苯乙烯三嵌段共聚物(SIS,SBS,SI/BS)在氮气气氛条件下以不同升温速率β时热降解动力学及其热寿命。确定了热降解温度与升温速率的关系,求得了热降解过程的表观活化能和热降解速率常数,得到了不同失重率时的热寿命方程,计算出三种化合物在不同温度下的寿命。     

氧化铜和聚磷酸铵对聚酰胺6热降解行为的影响

氧化铜和聚磷酸铵对聚酰胺6热降解行为的影响     

粘土中金属组分对粘土胶热降解的影响

天然橡胶;粘土中金属组分对粘土胶热降解的影响     

聚氨酯的热分解研究进展

介绍了有关聚氨酯热性能研究的状况,着重阐述了聚氨酯在不同气氛下的热解机理及热解动力学的内容,同时也阐述了聚氨酯今后热解研究的发展方向。     

Thermal and mechanical properties of UV irradiated collagen/chitosan thin films

The thermal and mechanical properties of collagen/chitosan blends before and after UV irradiation have been investigated using thermal analysis and mechanical (Instron) techniques. Comparisons were made with the thermal and mechanical properties of both collagen and chitosan films. Air-dried collagen, chitosan and collagen/chitosan films were exposed to UV irradiation (wavelength 254 nm) for different time intervals. Thermal properties of collagen/chitosan blends depend on the composition of the blend and are not significantly altered by UV irradiation.Mechanical properties such as ultimate tensile strength and ultimate percentage of elongation were much better for collagen films than for collagen/chitosan films. The results have shown that the mechanical properties of the blends were greatly affected by the duration of UV irradiation. Ultimate tensile strength and ultimate percentage elongation decreased after UV irradiation of the blend. Increasing UV irradiation leads to an increase in Young's modulus of the collagen/chitosan blend.     

Degradation of ROMP-based bio-renewable polymers by UV radiation

The degradation of a bio-renewable polymer under UV exposure was studied using various methods. Degradation of the bio-renewable polymer increased with increasing exposure time. Enhanced cross-link density in the early stage of degradation was confirmed by Soxhlet extraction. Tensile testing showed a transition from ductile failure to brittle fracture. Surface cracks and embrittlement were primary reasons for most reductions in mechanical properties, such as tensile strength and breaking strain. The effects of degradation were confined to the surface of thick bio-based polymer specimens, confirmed by both SEM and PAS-FTIR. Depth profile studies of degraded samples showed that the concentration of oxidation products, such as hydroxyl and carbonyl groups, varied with depth depending on the diffusion of oxygen.     

溶液pH值对二嗪磷紫外光降解产物及降解途径的影响

在低压汞灯(253.7 nm)光照条件下, 研究了溶液pH值对农药二嗪磷光降解产物及降解途径的影响. 结果表明: 不同溶液pH值条件下二嗪磷的光降解均符合一级反应动力学, 其在中性(pH=7.0, k=0.0234 min^-1)和碱性(pH=10.0, k=0.0236 min^-1)条件下的光降解速率基本相同, 且略高于酸性(pH=4.0, k=0.0193 min^-1)时的光降解速率. 通过UPLC-ESI-MS/MS对降解产物测定分析发现: 溶液pH值显著地影响了二嗪磷光降解产物的种类及生成量. 溶液pH=4.0、7.0和10.0的二嗪磷溶液分别UV光照60 min时分别检出了五种、八种和六种主要的光降解产物, 且同一产物在不同pH值条件下的生成量存在显著差异. 结合MS和MS/MS质谱图信息, 推导出了二嗪磷主要光降解产物的分子结构, 并根据光降解产物种类及生成量随光照时间的变化关系提出了不同溶液pH值时二嗪磷的可能降解途径.     

Thermal behavior and degradation mechanism of poly(bisphenyl acryloxyethyl phosphate) as a UV curable flame-retardant oligomer

Poly(bisphenyl acryloxyethyl phosphate) (BPAEP) was blended in different ratios with urethane acrylate EB220 to obtain a series of UV curable flame-retardant resins. The thermal degradation mechanisms of their cured films in air were studied by thermogravimetric analysis, in situ FTIR and direct pyrolysis/mass spectrometry measurements. The results showed that BPAEP/EB220 blends have lower initial decomposition temperatures (T_di) and higher char residues than pure EB220, while BPAEP has the lowest T_di and the highest char residue. The degradation process of BPAEP was divided into three characteristic temperature regions, attributed to the decomposition of phosphate, ester group and alkyl chain, and aromatic structure in the film.     

紫外光辐射对TiO2溶胶的影响研究

用紫外-可见吸收光谱、动态光散射与透射电镜研究紫外光辐射对T₂溶胶的影响,结果表明,光辐射使T₂溶胶在可见光区的吸收减少,紫外区吸收增加,吸收带隙增大.与非光辐射的T₂溶胶粒子相比,光辐射使T₂溶胶粒子分布均匀且平均粒径减小,提高了T₂纳米粒子在室温下的晶化程度.     

Photocatalytic degradation of azo dyes in aqueous solutions under UV irradiation using nano-strontium titanate as the nanophotocatalyst

Research on photocatalytic degradation rate of azo dyes using nano-strontium titanate in photocatalysis process was the main goal of present study. In this regard, the influence of the main operating parameters such a photocatalyst concentration, dye concentration, temperature, pH and the presence of hydrogen peroxide upon dye removal rate under UV irradiation was studied. The absorbance of samples was measured by a UV–Vis spectrophotometer. The structure and morphology of nano-powder were investigated using scanning electron microscopy and crystalline structure by X-ray diffraction spectroscopy. The results reveal that nano-strontium titanate has high and significant photocatalytic activity and in comparison with nano-titanium dioxide was superior photocatalyst.     

离子液体增塑生物基聚丁内酰胺的热分解机理

采用疏水性1-丁基-3-甲基咪唑六氟磷酸盐([BMIM]PF₆)和亲水性1-丁基-3-甲基咪唑四氟硼酸盐 ([BMIM]BF₄)两种咪唑类离子液体(IL)增塑聚丁内酰胺(PBL), 探讨了IL对PBL结晶性能及热性能的影响. 研究发现, 两种IL都会削弱PBL分子间氢键, 并抑制PBL晶体在(200)晶面的生长, 降低PBL结晶度. 当IL添加质量分数为5%时, 增塑膜熔点下降7~8 ℃. 与纯PBL膜相比, [BMIM]BF₄增塑PBL膜热稳定性下降, 而[BMIM]PF₆增塑PBL膜的热稳定性提高. [BMIM]PF₆增塑PBL膜热分解过程的热动力学分析结果表明, 其热分解反应活化能为46.68 kJ/mol, 反应级数为1, 热分解最概然机理函数模型符合Mampel单行法则(一级), 即PBL受到热刺激后, 在聚合物和分解产物界面无规律成核, 反应核心具备反应活性, 随后反应逐步扩大, 直至结束.