Fire safety of thermoplastic polyurethane based on pyromellitic dianhydride

In this paper, pyromellitic dianhydride (PMDA) was firstly used as fire safety agent for thermoplastic polyurethane (TPU). And, the fire safety improvement of PMDA in TPU was intensively investigated by limiting oxygen index (LOI), smoke density test (SDT), cone calorimeter test, and thermogravimetric/infrared spectroscopy, respectively. It has been found that PMDA could significantly improve the ignition level, and the LOI value increase to 28.5% when 8.0 wt% PMDA was incorporated into TPU; PMDA also could effectively suppress the smoke production and heat release during the combustion process. The peak heat release rate and total smoke release of the sample with 8.0 wt% PMDA were decreased by 68% and 22% compared with pure TPU in cone calorimeter test. The thermogravimetric/infrared spectroscopy results showed that PMDA could improve the thermal stability of TPU composites at high temperature and increased the release of CO₂, H₂O, and so on. All results confirmed that PMDA would have a good prospect in reducing the fire hazard of TPU.     

芳香族支链聚酰胺6的制备及共混纺丝研究

通过添加均苯四甲酸二酐水解聚合工艺制备芳香族支链聚酰胺6(PA6),采用熔融共混制备芳香族支链PA6/Ti O2母粒,然后与线型PA6共混纺丝,经拉伸后得到含芳香族支链PA6的共混纤维;研究了均苯四甲酸二酐含量对芳香族支链PA6流动性及热学性能的影响,以及芳香族支链PA6对芳香族支链PA6/Ti O2共混物结晶行为、可纺性及纤维力学性能等的影响。结果表明:随着均苯四甲酸二酐含量的添加,芳香族支链PA6的相对黏度逐渐降低,熔体流动指数增大,流动性增加,而结晶熔融温度逐渐降低;含芳香族支链PA6的共混体系纺丝温度较纯PA6降低4℃,芳香族支链PA6有助于提高PA6的可纺性,且纤维力学性能较好,含质量分数8%芳香族支链PA6的共混纤维的断裂强度为2.8 c N/dtex,断裂伸长率为45.4%。     

Colorless polyimides derived from 1S,2S,4R,5R-cyclohexanetetracarboxylic dianhydride,self-orientation behavior during solution casting,and their optoelectronic applications

A novel cycloaliphatic monomer for polyimides (PI), 1S,2S,4R,5R-cyclohexanetetracarboxylic dianhydride (H′-PMDA) is proposed in this work. H′-PMDA shows high polymerizability with various diamines in contrast to its isomer, i.e., conventional hydrogenated pyromellitic dianhydride (H-PMDA) and leads to highly flexible and colorless PI films with very high T_g's. In particular, the combinations with rigid structures of diamines give rise to PIs with significantly decreased coefficients of thermal expansion (CTE) owing to high extents of in-plane chain orientation induced by thermal imidization, whereas the H-PMDA-based counterparts do not. The decreased CTE reflects structural rigidity/linearity of the H′-PMDA-based diimide units as supported by liquid crystallinity observed in the corresponding model compound. Solution casting of a chemically imidized PI derived from H′-PMDA and 2,2′-bis(trifluoromethyl)benzidine (TFMB) results in a lower CTE than that of the thermally imidized counterpart, suggesting the presence of a self-orientation phenomenon during solvent evaporation. The mechanism is proposed in this work. H′-PMDA/TFMB and its copolymer systems can be useful as plastic substrates in image display devices and/or novel coating-type optical compensation films.     

Organosoluble semi-alicyclic polyimides derived from 3,4-dicarboxy-1,2,3,4-tetrahydro-6-tert-butyl-1-naphthalene succinic dianhydride and aromatic diamines: Synthesis,characterization and thermal degradation investigation

Semi-alicyclic polyimides (PI-1–PI-4) have been prepared from a newly-developed alicyclic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-6-tert-butyl-1-naphthalene succinic dianhydride (TTDA) and various aromatic diamines. The asymmetrical alicyclic tetralin structure in TTDA endowed the derived PI resins good solubility in various organic solvents. They were soluble not only in polar aprotic solvents but also in solvents with low boiling points including dichloromethane and tetrahydrofuran. Flexible and tough PI films were successfully cast from their N-methyl-2-pyrrolidone (NMP) solution except PI-1 derived from TTDA and 4,4′-oxydianiline (ODA). The PI films exhibited good optical transparency in the ultraviolet and visible light region with optical transmittances around 80% at a wavelength of 400 nm. The PI films showed good thermal stability up to 400 °C in nitrogen, after that they thermally decomposed rapidly. The thermal degradation behaviors of the PIs were investigated by means of thermogravimetric analysis-mass spectrometry (TG-MS), thermogravimetric analysis-Fourier transform infrared spectrometry (TG-FTIR) and the real time FTIR spectra (RT-FTIR) analysis techniques. The results revealed that the decomposition of PI-1 (as a representative) took place mainly in the range of 450–550 °C. The major degradative fragments at 500 °C were clearly identified as the tert-butyl-substituted tetralin moiety and its dealkylation products. Therefore, it can be deduced that for the TTDA-PIs, the single bond bridge attached the maleic anhydride and tetralin anhydride units in TTDA moiety might break first during the heating; thus producing the tetralin fragments.     

1-甲基-1,2,3,4-四氢异喹啉的合成工艺改进

以苯乙胺为原料,经乙酰化反应得乙酰苯乙胺(3),在甲基磺酸的作用下环合得1-甲基-3,4-二氢异喹啉(4),经硼氢化钠还原得1-甲基-1,2,3,4-四氢异喹啉(1)。改进了合成工艺,总收率达80.8%。     

均苯四甲酸二酐的捕集方法

介绍了从均四甲苯固定床气相氧化法的高温反应气中捕集低浓度的均苯四甲酸二酐的各种方法.并从反应工艺条件、设备的占地面积、粗产品收率、均苯四甲酸二酐的纯度、均酐产品捕集器的种类、数量、工人劳动强度、劳动环境等方面阐述了间接冷却法和直接冷却法中各种均苯四甲酸二酐捕集方法的优缺点.通过比较、分析指出了直接冷却法中有机溶剂湿壁捕集法和水-空气捕集法是均苯四甲酸二酐捕集方法的研究和发展方向.     

PMDA-6FHP-DR1／SiO2杂化纳米材料的结构设计和合成

以含氟的二胺5，5′—(六氟异丙基)—二—(2—氨基苯酚)及均苯四甲酸酐(PMDA)为单体，首先合成了经酰胺化的主链上带有活性羟基的含氟聚酰亚胺，再通过Mitsunobu反应将活性生色分子分散红1(DR1)共价链接到聚酰亚胺的侧链骨架上，合成了含氟聚酰亚胺．采用溶胶—凝胶(SOl—Gel)技术，并利用偶联剂γ—氨丙基三乙氧基硅烷(AFTES)制备带有发色团的和含有硅氧烷端分子的聚酰胺酸，其中的Si(OR)3基经水解、缩合后，与正硅酸乙酯(TEOS)在催化剂作用下反应，经杂化、凝胶后，得到光学透明且热稳定性高的有机／无机杂化材料．将制得的含氟聚酰亚胺／SiO2杂化材料，采用红外光谱(FT—IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)、示差扫描量热法(DSC)，对材料的结构、表面形貌、热性能进行了表征．     

均苯四甲酸二酐的生产及其在涂料工业中的应用

简述了均苯四甲酸二酐任涂料工业中的主要用途。介绍了均四甲苯法、偏三甲苯烷基化法、一氧化碳法等均苯四甲酸二酐的生产方法，对各种生产方法进行了评述，同时对我国均酐生产提出了一些合理化建议。     

Synthesis and properties of polyimides derived from cis- and trans-1,2,3,4-cyclohexanetetracarboxylic dianhydrides

Cis-1,2,3,4-cyclohexanetetracarboxylic dianhydride (cis-1,2,3,4-CHDA) was synthesized. It was found that under such conditions as heating or boiling in acetic anhydride, cis-1,2,3,4-CHDA could be converted to its trans-isomer. The process of thermal isomerization was monitored by ¹H NMR spectra and the mechanism of conversion was proposed. Their absolute structures of cis- and trans-1,2,3,4-CHDAs were elucidated by single crystal X-ray diffraction. The polycondensations of cis- and trans-1,2,3,4-CHDAs with aromatic diamines such as 4,4′-oxydianiline (ODA), 4,4′-methylenedianiline (MDA), 4,4′-diamino-3,3′-dimethyldiphenylmethane (DMMDA), 4,4′-bis(4-aminophenoxy)benzene (TPEQ), 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) were studied. It is easy to obtain higher molecular weight polyimides from trans-1,2,3,4-CHDA using conventional one-step or two-step methods. However, higher molecular weight polyimides derived from cis-1,2,3,4-CHDA could not be prepared by the usual methods (solid content ca. 10%) owing to the trend of forming cyclic oligomers. Increasing the concentration of monomers could give higher molecular weight cis-polymers. All of the cis-polyimides were soluble at room temperature in aprotic polar solvents and phenolic solvents and some of them even soluble in chloroform and tetrahydrofuran, while the corresponding trans-polymers showed poor solubility as compared to cis-polymers. All of the polyimides showed good thermal stability with the 5% weight loss temperatures in air over 415 °C. Furthermore, polyimides derived from cis-1,2,3,4-CHDA have higher glass transition temperatures (T_gs) than corresponding trans-polyimides. The flexible polyimide films possessed a tensile modulus range of 2.1-3.6 GPa, a tensile strength range of 42-116 MPa, an elongation at break of 4-18%. These polyimides exhibited cutoffs at wavelengths around 270 nm and were entirely colorless. All the polyimides showed amorphous pattern according to Wide angle X-ray diffraction measurements. The differences of polymerization and properties were explained by the structural changes resulted from isomerism.     

均苯四酸二酐凝华结晶精制的最佳条件研究

研究了均苯四酸二酐（简称均酐或PMDA）凝华结晶精制的最佳条件,并以均酐在定温下的平衡蒸汽压为基础,推导出凝华结晶条件数学关系式．该式把氧化反应的空速,气相组成及捕集温度等工艺参数与捕集率关联起来,并制作出捕集温度对均酐凝华结晶效率和均酐纯度关系曲线图．同时讨论了拉乌尔数学关系式在处理本体系的适应范围．指出在低捕集率情况下,引入修正项后的拉乌尔数学关系式才能与实验值吻合．