用玻璃化转变评价氟橡胶的低温性

针对普通氟橡胶耐低温性差的缺点,以低温性好的PL855、GLT两种牌号氟醚生胶为基体制备了氟醚硫化胶。阐述了用玻璃化转变评价氟橡胶低温性的原理,采用差示扫描量热仪测试了不同升温速率下氟醚生胶的玻璃化转变温度,采用动态热机械分析仪测试了不同频率下氟橡胶的玻璃化转变温度,根据所得数据计算玻璃化转变活化能。结果表明,PL855氟醚生胶的玻璃化转变温度和玻璃化转变活化能均比GLT氟醚生胶低,耐低温性更好;用两种氟醚生胶硫化而成的橡胶的耐低温性均比普通氟橡胶的耐低温性好,其中以PL855氟醚生胶制成的橡胶的耐低温性最好。该方法的评价结果与实际应用情况相符合。     

THV三元共聚物/PMMA共混物相容性研究

将四氟乙烯-六氟丙烯-偏氟乙烯三元共聚物(THV)与聚甲基丙烯酸甲酯(PMMA)进行熔融共混,考察了共混物THV/PMMA的组成对流变特性、动态力学行为和热力学行为的影响。结果表明,共混物的组成对共混物的平衡扭矩值和平衡温度影响不大。共混物组成对共混物中THV的结晶和PMMA树脂的玻璃化转变过程没有影响。随组成不同,共混物熔融行为在两个不同组分的典型熔融特征之间逐渐变化。不同组成的THV/PMMA共混物均呈现两个玻璃化转变温度,分别对应于两组成各自的玻璃化转变温度(Tg)位置。在THV/PMMA质量比为70/30的共混物中,PMMA呈球状分散在连续相THV基体中,分散相粒子的尺寸在1~10μm之间。二者为典型的不相容体系。     

溶聚丁苯橡胶/白炭黑复合材料的热历史行为

用动态力学分析仪研究了溶聚丁苯橡胶/白炭黑复合材料在不同的热历史条件下,温度和频率对其黏弹性能的影响。结果表明,预加热历史使得溶聚丁苯橡胶/白炭黑复合材料的玻璃化转变温度升高,预冷却历史则使其降低。复合材料具备热记忆效应,温度越接近于玻璃化转变温度则该效应越明显。温度低于频率敏感温度时,频率对复合材料分子的小尺寸运动产生影响,损耗因子随频率的升高而减小;而温度高于频率敏感温度时,频率对分子的小尺寸运动和主链刚性运动均有影响,复合材料的损耗因子随频率的升高而增大。     

POE-g-GMA对聚丙烯／聚磷酸铵复合材料玻璃化转变活化能的影响

以熔融反应挤出得到的POE-g-GMA作为增容剂，制备了增韧PP／APP复合材料。采用动态力学的方法，计算得到不同POE-g-GMA含量的PP／APP复合材料的玻璃化转变活化能。结果表明，在相同的测试频率下，接枝物POE-g-GMA的加入会导致PP／APP复合材料的内耗峰的峰温降低，而内耗峰的强度增加；降低复合材料的玻璃化转变活化能。这说明在PP／APP复合体系中加入POE-g-GMA可以改善PP和无机填料APP之间的相容性，使复合材料中的PP分子链段在进行玻璃化转变时更加容易。只需要较低的活化能就可以了。从中可以判断出接枝物POE-g-GMA对于PP／APP共混体系来说是很好的相容剂。     

环氧树脂与氰酸酯共固化反应的研究Ⅱ.固化反应动力学参数及固化物性能

用DSC，介电和动态力学等分析方法研究了组成对乙酰丙酮过渡金属络合物催化促进的环氧树脂与氰酸酯共固化反应体系反应动力学参数，固化产物力学，电气和耐热性能以及玻璃化转变温度的影响。结果表明，随着共固化反应体系中氰酸酯含量的增加，其表观反应活化能和频率熵因子均随之升高；在相同的固化条件下，共固化产物中三嗪环结构含量增加，聚醚结构减少，玻璃化转变温度升高，耐热性能，介电性能提高。     

热老化时间对PA66动态力学性能影响的研究

用动态力学热机械分析(DMA)仪研究了热老化时间对PA66玻璃化转变温度、储能柔量及表观活化能的影响,并分析了产生这些影响的原因。通过试样动态力学性能参数和活化能的突变点确定了PA66的临界失效时间,依据所得的临界失效时间和活化能,以及动态力学性能得到的寿命方程预估了PA66在25℃下的贮存期为40.9年。     

LLDPE-g-GMA对PET/LLDPE性能的影响

自制了线性低密度聚乙烯与甲基丙烯酸缩水甘油酯接枝物(LLDPE-g-GMA)，研究了LLDPE-g-GMA对聚对苯二甲酸乙二酯／线性低密度聚乙烯(PET／LLDPE)合金体系力学性能、结晶行为及玻璃化转变活化能的影响。结果表明，LLDPE-g-GMA有效地改善了PET／LLDPE的拉伸性能、弯曲性能及冲击性能；同时LLDPE-g-GMA的加入提高了PET的结晶速率，两者有较好的相容性；动态力学试验结果也证明了LLDPE-g-GMA与PET有较好的相容性。LLDPE-g-GMA可以作为PET／LLDPE体系的反应性增容剂。     

聚氨酯松弛活化能的计算及其与微相分离结构的关系

本文以聚四氢呋响(PTMG)、4,4′-二苯基甲烷二异氰酸酯(MDI)和1,4-丁二醇(BD)为原料,采用一步法合成聚氨酯样品,用DDV-Ⅱ动态粘弹仪测定了样品的动态力学图谱.首次建立了一套利用动态力学图谱计算聚氨酯松弛活化能的方法,并用活化能大小定量地表征了聚氨酯的微相离结构.     

粉末涂料

00021 05具有良好耐候性、耐沾污性、光泽和贮存稳定性的无有机溶剂的含氟聚合物粉末涂料组合物:护99一60646[日本专利公开]/日本:Central Glass Co.,Ltd.(Mae(Ia,Kazuhiko等)一1999.3.2一10页一97/2 30986(19978.27);IPC C08F259/08 题述组合物含有固化剂和接枝氟聚物。该氟聚物是通过将l~300份单体接枝聚合于roo份氟聚物(由氟烯烃和含过氧基的单体制得)上而制得的,含有OH、C02H、缩水甘油基、氨基和/或烷氧基甲硅烷基团,玻璃化温度几)56℃,数均相对分子质量Mn《巧000。例如,将新戊酸乙烯醋1939.叔碳酸9乙烯醋889、乙二醇单烯丙基醚…     

增容作用对PVDF/PET共混物性能的影响

通过溶液聚合方法合成了甲基丙烯酸甲酯(MMA)与甲基丙烯酸缩水甘油酯(GMA)共聚物(MG),将其应用到聚偏氟乙烯(PVDF)/聚对苯二甲酸乙二醇酯(PET)共混物中,考察了MG共聚物的增容作用对PVDF/PET共混物性能的影响。采用扫描电镜(SEM)、差示扫描量热分析(DSC)、动态机械分析(DMA)、力学测试等测试方法对共混物进行表征。结果表明,PVDF/PET共混物为不相容体系,随着MG共聚物含量的增加,PVDF/PET共混物的两相玻璃化转变温度差值变小,分散相尺寸变小,共混物的断裂伸长率和屈服强度明显升高;MG共聚物显著增强了PVDF/PET共混物间的相容性,提高了共混物的性能。     

Structural Carbon/Epoxy Prepregs Properties Comparison by Thermal and Rheological Analyses

Two different carbon/epoxy prepreg materials were characterized and compared using thermal (DSC, TGA, and DMA) and rheological analyses. A prepreg system (carbon fiber preimpregnated with epoxy resin F584) that is currently used in the commercial airplane industry was compared with a prepreg system that is a prospective candidate for the same applications (carbon fiber prepreg/epoxy resin 8552). The differences in the curing kinetics mechanisms of both prepreg systems were identified through the DSC, TGA, DMA, and rheological analyses. Based on these thermal analysis techniques, it was verified that the curing of both epoxy resin systems follow a cure kinetic of n order. Even though their reaction heats were found to be slightly different, the kinetics of these systems were nevertheless very similar. The activation energies for both prepreg systems were determined by DSC analysis, using Arrhenius's method, and were found to be quite similar. DMA measurements of the cured prepregs demonstrated that they exhibited similar degrees of cure and different glass transition temperatures. Furthermore, the use of the rheological analysis revealed small differences in the gel temperatures of the two prepreg systems that were examined.     

Molecular mobility in polymers studied with thermally stimulated recovery. II. Study of the glass transition of a semicrystalline PET and comparison with DSC and DMA results

The glass transition of a semicrystalline PET is studied by dynamic mechanical analysis (DMA) and thermally stimulated recovery (TSR). The DMA results allowed us to construct a master curve for E′ and D′, where the shift factors were modelled with the Vogel-Fulcher-Tamman-Hesse (VFTH) equation above T_g. Using the thermal sampling procedure, the TSR technique allowed us to decompose the complex distribution of retardation times into a set of quasi-elementary processes. At the compensation point a broad distribution of retardation times is observed using DSC data. The TSR results show a typical increase of the activation energies in the glassy state, followed by a decrease above T_g that may be modelled with the VFTH equation. This observation was explained taking into account both the typical time scale range of TS experiments and the evolution of the retardation times distribution with temperatures below and above T_g, under the Adams-Gibbs theory. The evolution of the activation energies from the TSR results was shown to be compatible with the DMA and DSC data.     

聚氨酯/环氧树脂互穿网络聚合物反应动力学

通过共混法制备了聚氨酯(PU)/环氧树脂(EP)互穿网络聚合物(IPN),采用示差扫描量热法(DSC)和动态机械分析(DMA)对IPN形成过程中的固化反应动力学及产物IPN的相容性进行了研究,结果表明,m(PU)/m(EP)=10∶6的IPN体系的反应级数为0.95,表观活化能为169.23 kJ/mol;PU/EP IPN只有1个玻璃化转变温度,相容性好。     

ACR中壳层PMMA相对分子质量对PVC／ACR共混物性能的影响

采用种子乳液法制备了核壳型聚丙烯酸酯(ACR),并分别采用十二烷基硫醇和正辛基硫醇作为链转移剂对 ACR壳层的聚甲基丙烯酸甲酯(PMMA)进行相对分子质量调节,并用于PVC共混改性。黏度法对PMMA的相对分子质量测定表明,正辛基硫醇的相对分子质量调节能力较强。采用差示扫描量热分析测定PMMA的玻璃化转变温度(Tg),并对共混树脂进行动态力学性能测试。当ACR壳层PMMA平均相对分子质量低于12×104时,PVC/ACR 共混树脂的缺口冲击强度大大提高。与纯PVC相比,共混树脂的Tg均略有提高,其增量随ACR壳层PMMA平均相对分子质量的降低而减小。动态力学性能测试结果表明,ACR壳层聚合物平均相对分子质量越低,共混物分子链段运动活化能提高越少。     

Comparison of thermal techniques for glass transition measurements of polystyrene and cross-linked acrylic polyurethane films

There are few quantitative comparisons in the literature between glass transitions (T_g) measured by differential scanning calorimetry (DSC) and by dynamic mechanical analysis (DMA). Also, in the case of DMA, two different operational definitions have been used to obtain the glass transition, namely, the loss modulus (E″) and damping (tan δ) peak temperatures. We propose a new DMA definition of T_g and demonstrate that it agrees with DSC T_g measurements within ±2°C for both thermoplastic polystyrene and thermoset cross-linked acrylic polyurethane films with measurable tan δ peaks. The glass transitions for a single polystyrene standard and several cross-linked acrylic polyurethane films were measured by DSC. Additionally, E″ and tan δ peak temperatures were measured by DMA as a function of frequency and temperature. Empirically, it was determined that the average of the E″ and tan δ peak temperatures measured at 1 rad/s oscillation frequency corresponds to the glass transition measured by the ASTM E1356 DSC test method. © 1994 John Wiley & Sons, Inc.     

Study of the miscibility and crystallization behavior of poly(ethylene oxide)/poly(vinyl alcohol) blends

The miscibility and crystallization behavior of poly(ethylene oxide)/poly(vinyl alcohol) (PEO/PVA) blends were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and polarizing optical microscopy. Because the glass‐transition temperature of PVA was near the melting point of PEO crystalline, an uncommon DSC procedure was used to determine the glass‐transition temperature of the PVA‐rich phase. From the DSC and DMA results, two glass‐transition temperatures, which corresponded to the PEO‐rich phase and the PVA‐rich phase, were observed. It was an important criterion to indicate that a blend was immiscible. It was also found that the preparation method of samples influenced the morphology and crystallization behaviors of PEO/PVA blends. The domain size of the disperse phase (PVA‐rich) for the solution‐cast blends was much larger than that for the coprecipitated blends. The crystallinity, spherulitic morphology, and isothermal crystallization behavior of PEO in the solution‐cast blends were similar to those of the neat PEO. On the contrary, these properties in the coprecipitated blends were different from those of the neat PEO. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1562–1568, 2004     

阻燃韧性不饱和聚酯树脂的粘弹性研究

对用己二酸-二溴新戊二醇-丙二醇-顺酐合成的阻燃韧性不饱和聚酯树脂进行了动态力学测试及分析，确定了该树脂的玻璃化转变温度(Tg)，分析了温度对模量、内耗和玻璃化转变温度的影响，同时对其他影响因素进行了讨论。     

Synthesis and characterization of fluoropoly(amide–sulfonamide)s via polycondensation

Novel fluorine-containing polymers, fluoropoly(amide–sulfonamide)s were synthesized for the first time by polycondensation from β-hydroxytetrafluoroethanesulfonic acid sultone (TFE-sultone) and hexamethylenediamine. The chemical structures of the obtained F-PASAs were characterized by intrinsic viscosity measurements, GPC, FTIR, ¹H NMR, ¹⁹F NMR and element analysis in detail. Thermal properties and optical property of F-PASAs were investigated by DSC, DMA, TGA and UV–vis spectra, respectively. The investigation indicated that these functional fluoropolymers in which there are both amide and sulfonamide linkages along the polymer main chains possessed distinctive structure as well as unique properties such as thermal properties, clean and high transparency and compatibility with nylons.     

Film formation from surfactant-free,slightly crosslinked,fluorescein-labeled polystyrene particles

A steady state-fluorescence (SSF) technique for studying film formation from surfactant-free, slightly crosslinked polystyrene (PS) latex particles is reported. The powder films were prepared from fluorescein (F)-labeled PS particles at room temperature. The mechanically strong films were obtained by annealing these films at elevated temperatures in 5, 10, 20, and 30 min time intervals above the glass transition (T_g) temperature of polystyrene. Scattered light (I_s) and fluorescence (I_F) intensities from F were monitored after each annealing step to investigate the three different film formation stages called void closure, healing, and interdiffusion. The evolution of transparency of the latex films was monitored by using a photon transmission technique. Scanning electron microscopy (SEM) was employed to detect the variation in physical structure of the annealed latex films. Onset temperature for void closure, T_m’, and healing temperatures, T_h, were determined and corresponding activation energies were measured. Void closure and interdiffusion stages were also modeled and the related activation energies were also determined. It was observed that lower energy is needed for the void closure process than interdiffusion of chains across the particle-particle boundaries.     

Molecular dynamics simulation for fluoropolymers applied in ε-CL-20-based explosive

Herein, in order to design the formulation of fluoropolymer bonded explosives, common fluoropolymers were selected and added to the high energy density compound hexanitrohexaazaisowurtzitane (ε-CL-20). Molecular dynamics simulations were carried out on fluoropolymers (F2603, F2311, F2314, F2426, and PTFE) and fluoropolymers bonded ε-CL-20. Glass transition temperature (Tg) of fluoropolymers were calculated. Besides, the mechanical properties and physical compatibilities of ε-CL-20 based polymer bonded explosives were predicted. The calculated results show that the order of Tg of fluoropolymers is: PTFE > F2314 > F2311 > F2462 ≈ F2603 and Tg of F2603 increases as the degree of polymerization increases. The binding energy for fluoropolymers with ε-CL-20 is in the following order: ε-CL-20/F2462 > ε-CL-20/F2603 > ε-CL-20/F2314 > ε-CL-20/F2311. All fluoropolymers interact with ε-CL-20 mainly in vdW force. The order of tensile modulues is: ε-CL-20 > ε-CL-20/F2314 > ε-CL-20/F2311 > ε-CL-20/F2462 > ε-CL-20/F2603, the orders of Poisson’s ration (γ) and the quotient bulk modulus (K)/shear modulus (G) are opposite.