聚苯硫醚合成宏观动力学探讨

聚苯硫醚(PPS)的合成是特殊的缩聚反应[1],在合成过程中存在快慢不同的两个反应,快反应是低分子缩合,慢反应是AB型自缩聚,因此可称为(A2B2)→AB型缩聚反应。本文探讨生产聚苯硫醚时温度等反应条件对反应程度和产物熔点的影响。1　实验合成实验的装置和产品的分析测试同前文[1]。所使用的两种溶剂(六甲基磷酰三胺和N 甲基吡咯烷酮)只能使阳离子溶剂化:Na2S+2xNMP2Na(NMP)+x+S2-(1)这一溶剂化作用的稳定常数较大,溶剂将钠离子包围起来,使硫离子充分裸露,具有更高的亲核性[2],这种高活性,促使它首先与对二氯苯进行反应,生成对氯硫…     

高分子量聚苯硫醚树脂合成方法的改进

以硫化氢，氢氧化钠和对二氯苯为原料，磷酸钠作助剂，在六甲基磷酰三胺中进行常压缩聚反应，所得产物以分析表明为线型结晶性高分子量聚苯硫醚树脂原粉，产率９１．４％～９７．５％，成本低，易大于规模生产，产品直接作抽丝试验以了高分子量聚苯硫醚纤维。     

同步辐射X光散射方法研究聚苯硫醚（PPS）的结晶动力学

本文报道了用同步辐射X光散射方法研究聚苯硫醚(PPS)等温过程结晶动力学,测定了在不同结晶温度Tc下,小角和广角散射强度曲线、散射峰极大值随结晶温度的升高而向小角度移动。由小角和广角测得的一系列不同Tc温度的时间解析谱图,计算出PPS结晶速度(?)1/2最小值为0.47min,相对应的Tc为189℃,低于100℃和高于250℃结晶速度极为缓慢。长周期随结晶温度升高而增大,接近250℃时减小;密度随结晶温度升高而增加,接近熔融时,则有较大的增加;由PPS 30～225℃之间Q随温度变化曲线上的折点,求出T_g=89±5℃(加热速度10℃/min);并计算出在T_g温度时PPS两相热膨胀系数差为:     

片状催化剂F-T合成宏观动力学

采用固定床积分反应器,在工业条件下,对压片Ｆｅ－Ｃｕ－Ｋ催化剂进行了Ｆ－Ｔ合成宏观动力学考查。在稳态下,用集总的方法,在保持一定的轴向温度分布及取其平均温度条件下,求得两组宏观动力学方程,两者分别与实验数据吻合较好,同时两者之间也存在较好的一致性。     

硝酸分解磷矿的宏观动力学研究

在间歇反应器中 ,反应温度为 30～ 6 0℃ ,硝酸初始浓度 30～ 5 4 % ,磷矿初始粒径 0 .375～ 1.0 75毫米 ,搅拌强度 4 0 0转 分的条件下研究了硝酸分解磷矿的反应过程机理及宏观动力学。结果表明 ,磷矿分解速率及转化率随着搅拌强度、反应温度、硝酸浓度和颗粒细度的增加而增加 ;氢离子通过液膜的扩散传质是该过程的速率控制步骤。应用固体粒径减小的缩芯模型 ,将上述各影响因素的实验数据回归得到如下的宏观动力学模型 :1- (1-xB) 2 3=8.36 6exp - 6 .198× 10 3RT c1 .31 1AO R- 0 .1 0 91S lnτ活化能Ea=6 .198kJ mol,属液膜扩散传质控制     

聚苯硫醚及其聚醚砜共混物结晶动力学的研究

本文采用DSC方法,研究了聚苯硫醚及其聚醚砜共混物的等温结晶动力学。结果表明,经α-氯代萘处理后的聚苯硫醚原粉结晶速率常数有明显提高;聚苯硫醚/聚醚砜共混物的Avrami指数较纯聚苯硫醚低,共混物的结晶速率常数随共混组成变化出现最低值;共混物存在明显的二次结晶现象,t_(?)与t_(max)之间存在线性关系。     

B108中温变换催化剂宏观动力学的研究

常压下以内循环无梯度反应器研究了B108铁基中温变换催化剂上水煤气变换反应宏观动力学。测定了反应速率,并用马夸特非线性参数估值法获得了幂函数宏观动力学模型r_s=37.67exp(-43982/RT)y_(CO)~(0.7552)y_(H_2O)~(-0.0367)Y_(CO_2)~(-0.4874)y_(H_2)(1-β)根据方差分析和残差分析,证实模型是高度显著的。由实验数据计算出相应反应条件下的效率因子。内扩散对原粒度B108催化剂上的反应具有严重影响。模型用于工业变换炉催化剂的用量核算,模型值与实际值符合良好。     

丙烯在NiSO4催化剂上的液相齐聚—集总宏观动力学与反应器分析

以负载在γ－Ａｌ２Ｏ３上的ＮｉＳＯ４为催化剂，在微分反应器中进行了以壬烯与十二烯为目的产物的丙烯液相催化齐聚的研究。在２７３￣３１３Ｋ及高于丙烯蒸气压的压力条件下齐聚产物主要为己烯、壬烯及十二烯，十五烯以上的含量极少。根据反应的热力学性质可知齐聚反应为一组双分子不可逆反应。按集总原则回归实验数据，得到了丙烯齐聚过程的宏观动力学方程组及有关参数。由于齐聚反应的热效应较大，工业规模的丙烯齐聚只有在壁冷     

Reactive Blends of Poly(phenylene sulfide)/Hyperbranched Poly(phenylene sulfide)

Summary: Polymer blends consisting of linear poly(phenylene sulfide) (PPS) and hyperbranched PPS (HPPS) were obtained in melt. The solid-state properties of PPS and their blends were investigated by scanning electron microscopy (SEM), thermogravimetric analyzer (TGA), extraction measurement, differential scanning calorimetry (DSC) and dynamical mechanical analysis (DMA). Blends prepared by melt mixing turned out to be reactive as shown by the TGA and extraction measurement. SEM indicated that no phase separation occurs in PPS/HPPS blends. The degree of crystallization of the blends decreased with increasing HPPS content. Both the storage modulus and loss modulus increased as HPPS content increasing.     

聚苯硫醚反应淤浆的处理工艺

综述了聚苯硫醚反应淤浆的处理工艺，包括聚苯硫醚树脂的收集，溶剂的回收和反应助剂的回收两部分，并展望了聚苯硫醚反应淤浆处理工艺的发展趋势。     

聚亚苯基苯并二噁唑缩聚反应动力学

以4,6-二氨基间苯二酚磷酸盐(DAR.2HP3O4)和对苯二甲酸(TA)为原料经非均相逐步缩聚反应制得聚亚苯基苯并二噁唑(PBO)。该反应可分为溶解控制(齐聚合)、反应动力学控制(预聚合)以及高分子链段扩散控制(后聚合)3个阶段。探讨了各阶段的反应过程,并对PBO预聚合反应动力学进行了研究。结果表明:其动力学符合不可逆二级反应机理,反应活化能为51.9 kJ/mol。     

重铬酸钾电化学合成反应表观动力学

针对重铬酸钾传统生产技术存在的高污染、高消耗等问题,研究了用电化学合成绿色技术.由在自制电解槽中以铬酸钾为原料电化学合成重铬酸钾的反应动力学实验,测得不同反应条件下的动力学数据.结果表明,电化学合成反应过程表现为拟零级反应动力学特征.建立了电化学合成反应表观动力学方程和阳极电解液体积随转化率的变化方程,求得了动力学参数...     

The Synthesis and Characterization of High Molecular Weight Poly（phenylene sulfide/ether）

Poly(p-phenylene sulfide) (PPS) is a high performance engineering thermoplastic with high temperature resistance, good chemical resistance and mechanical properties. Since it was commercialized by Phillips Petroleum Company in 1973, it has been widely use…     

Crystallization and melting of cold-crystallized poly(phenylene sulfide)

In this study, we report the melting behavior of poly(phenylene sulfide), PPS, which has been cold-crystallized from the rubbery amorphous state. We find that the crystallization kinetics are faster for cold-crystallized PPS than for melt-crystallized material, due to formation during quenching of a short-range ordered, but noncrystalline, structure. We observe that the endothermic response of cold-crystallized PPS at a large undercooling consists of a low temperature endotherm, followed by an exothermic region, and by the main higher melting endotherm. The lower melting peak temperature of cold-crystallized PPS increases as the crystallization temperature increases, but the main upper melting peak temperature remains almost the same. The size of the exothermic region is strongly related to the degree of undercooling, and must be taken into account in order properly to determine the degree of crystallinity of the material prior to the scan. When the crystallization time is varied, we see a systematic decrease in the size of the main endotherm, and an increase in size of the lower melting endotherm. This suggests that a portion of the main endothermic response is due to reorganization during the scan. Annealing will not only increase the degree of crystallinity but also improve the crystal perfection; therefore the ability of an annealed sample to reorganize decreases as the annealing time increases. However, an additional third melting peak is seen when a cold-crystallized sample is annealed at high temperature for a sufficiently long residence time. The existence of the third melting peak suggests that more than one kind of distribution of crystal perfection may occur when PPS has been cold-crystallized and subsequently annealed.     

Poly(p‐phenylene sulfide) nonisothermal cold‐crystallization

The poly(p‐phenylene sulfide) (PPS) nonisothermal cold‐crystallization behavior was investigated in a wide heating rate range. The techniques employed were the usual Differential Scanning Calorimetry (DSC), and the less conventional FT‐IR spectroscopy and Energy Dispersive X‐ray Diffraction (EDXD). The low heating rates (Φ) explored by EDXD (0.1 K min^?1) and FT‐IR (0.5–10 K min^?1) are contiguous and complementary to the DSC ones (5–30 K min^?1). The crystallization temperature changes from 95 °C at Φ = 0.05 K min^?1 to 130 °C at Φ = 30 K min^?1. In such a wide temperature range the Kissinger model failed. The model is based on an Arrhenius temperature dependence of the crystallization rate and is widely employed to evaluate the activation energy of the crystallization process. The experimental results were satisfactorily fit by replacing in the Kissinger model the Arrhenius equation with the Vogel–Fulcher–Tamann function and fixing U* = 6.28 k J mol^?1, the activation energy needed for the chains movements, according to Hoffmann. The temperature at which the polymer chains are motionless (T_∞ = 42 °C) was found by fitting the experimental data. It appears to be reasonable in the light of our previously reported isothermal crystallization results, which indicated T_∞ = 48 °C. Moreover, at the lower heating rate, mostly explored by FT‐IR, a secondary stepwise crystallization process was well evidenced. In first approximation, it contributes to about 17% of the crystallinity reached by the sample. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2725–2736, 2005     

Apparent Kinetics for Electrosynthesis Process of Chromic Acid

A new green technique for producing chromic acid via an electrosynthesis method was studied.The kinetic experiments were carried out on the direct electrosynthesis reaction of chromic acid from sodium dichromate in a self-made electrosynthesis reactor with a multiple-unit metal oxides combination anode,a stainless steel cathode,and a reinforcing combination Nafion?324 cation exchange membrane.The apparent kinetic data were experimentally measured at different reaction time under different reaction condition...