固相缩聚法合成双酚A型聚碳酸酯的催化剂筛选

采用固相缩聚(SSP)法,以双酚A(BPA)和碳酸二苯酯(DPC)为原料,在不同催化剂的作用下,反应得到双酚A型聚碳酸酯(BAPC)。测定了产物的特性黏数和色差,并对产物进行了傅立叶变换红外光谱(FTIR)、核磁共振氢谱(1H–NMR)和热重(TG)分析。结果表明,四苯硼钠(Na TPB)为较优的催化剂,在1 mol的BPA中加入催化剂Na TPB用量为1×10–4 mol时,通过非光气熔融酯交换法合成并经部分结晶处理、筛分得到180~250μm预聚物颗粒,其在210℃、近真空(压力100 Pa)条件下,采用SSP法,反应3 h,可得色差较小(0.52%)、特性黏数为90.36 m L/g、热稳定性良好的BAPC。     

结晶态双酚A型聚碳酸酯固相缩聚的研究

在自制的反应器中将结晶态、无定形两种双酚A型聚碳酸酯(BAPC)预聚体固相缩聚合成了高摩尔质量的双酚A型聚碳酸酯.采用DSC、IR对双酚A型聚碳酸酯(BAPC)的熔融行为和结构进行了表征.结果表明,BAPC在固相缩聚后,玻璃化转变温度升高,热稳定性增强,其中BAPC为结晶态时固相缩聚的温度低于无定形态BAPC的固相缩聚温度,且结晶态BAPC固相缩聚后为无定形态.     

双酚A型聚碳酸酯合成工艺研究进展

介绍了光气法，酯交换法和氧化羰化法合成聚碳酸酯的工艺及催化剂，分析了三种方法的优缺点，侧重探讨了催化剂的选择。     

聚碳酸酯应用与合成工艺进展

聚碳酸酯是综合性能极为优异的工程塑料品种，在电子，建材，汽车，航天，医疗器械及信息领域，均以其独特的性能显示了十分广阔的应用前景，并长期保持着较高的增长速度，本文重点阐述了聚碳酸酯在各领域的应用现状及合成工艺进展。     

界面缩聚法合成四溴双酚A聚碳酸酯的工艺研究

以光气和四溴双酚A(TBBPA)为原料经光气界面缩聚,合成了四溴双酚A聚碳酸酯,并对四溴双酚A与光气投料比、催化剂种类及其用量、分子量调节剂用量4个因素进行考察。优化工艺条件为:四丁基氢氧化铵为催化剂,对叔丁基酚(TBP)为分子量调节剂,n(四溴双酚A)∶n(光气)=1∶1.3,n(四溴双酚A)∶n(对叔丁基酚)=1∶0.028,n(四溴双酚A)∶n(四丁基氢氧化铵)=1∶0.022。该方法操作简单,产品分子量分布窄,易于工业化生产。     

聚碳酸酯完全无光气合成技术的研究动态

介绍了由二芳基碳酸酯，二甲基碳酸酯，苯酚等非等气单体制备聚碳酸酯的方法以及甲醇羟基氧化，甲基亚硝酸酯法制二甲基碳酸酯，苯酚法制二苯基碳酸酯等非光气单体的方法，并就实现多步反应，改变反应官能团，提高催化效率，改变生产工艺等途径阐述了目前科学家在提高聚磷酸酯摩擦质量方面所进行的研究。     

三光气法合成双酚S/双酚A共聚碳酸酯

以双酚A、双酚S和三光气为单体,通过界面缩聚合成了共聚碳酸酯。研究了聚合反应温度、三光气、氢氧化钠及催化剂用量以及油水比等因素对聚合反应的影响,得到特性粘数为1．28 dL/g的聚碳酸酯共聚物。采用FT-IR确定了产物的结构;共聚碳酸酯的玻璃化转变温度为157．9℃,极限氧指数为0．32。     

聚碳酸酯合成新方法面世

最近，国外发明了一种聚碳酸酯合成的新方法，涉及芳香族聚碳酸酯的合成方法。     

Two-component initiator systems for the ring-opening polymerization of oligomeric cyclic bisphenol-A carbonates: The in situ cleavage of disulfides by triarlyphosphines

A two-component initiator system based on the in situ cleavage of phenyl disulfide by a triarylphosphine has been developed for the ring-opening polymerization of cyclic bisphenol-A (BPA) carbonate oligomers. This development has potential use in composite applications such that the prepolymer can suitably wet the composite material before being converted to high-molecular-weight polymer. The initiator precursors (phenyl disulfide and triphenylphosphine) do not independently initiate significant ring-opening polymerization of the oligomeric cyclic BPA carbonate mixture. A mixture of cyclic BPA carbonate oligomers and one of the initiator components (phenyl disulfide), combined and heated at 300°C with a mixture of the cyclics and the other initiator component (triphenylphosphine), does produce a high-molecular-weight polymer (M_w = ∼ 70,000). The polymerization-initiating species is thought to be thiophenyltriphenylphosphonium thiophenoxide. The effects of concentration of the initiator components, reaction temperature, time, and so forth on polymerization were studied; in general, the degree of polymerization ranged from about 65 to 75%. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 2251–2255, 1997     

聚碳酸酯合成技术进展

综述了聚碳酸酯(PC)已经实现工业化的4种合成聚合工艺,按照各生产工艺的流程和特点对其进行了阐述。同时,介绍了非光气法缩聚阶段的关键设备。非光气法PC生产工艺已经在竞争中逐步占据优势,未来需要进一步优化酯交换反应和缩聚反应阶段的反应器设计。     

酯交换缩聚法合成聚碳酸酯的研究进展

聚碳酸酯的酯交换缩聚工艺具有绿色环保的特性,符合当今世界可持续发展的主题,相对于传统的光气法工艺更具有发展前途。综述了国内外在酯交换缩聚工艺的机理以及催化剂选择和工艺条件上取得的进展。指出碳酸二苯酯与双酚A酯交换反应是四面体机理,正反应是二级反应,逆反应是三级反应;以La(ACAC)_3作催化剂,得到的产品不但粘均分子量较高,而且热稳定性非常好;利用酯交换熔融聚合工艺可以解决传统光气法的环境问题,而固相聚合可以得到超高分子量的产品。     

聚四氢呋喃催化合成研究进展

主要论述和归纳了目前文献报道的能够催化四氢呋喃开环聚合的各类催化体系,并对不同催化体系的优缺点进行了评述     

Diluent effects on carbonate mobility in bisphenol-A polycarbonate in the solid state

The effect of miscible low molecular weight additives on the mobility of the carbonate group in bisphenol-A polycarbonate (BPAPC) has been studied using n.m.r. and dielectric relaxation experiments in the solid state. Proton-enhanced dipolar-decoupled carbon-13 n.m.r. spectra of BPAPC, isotopically enriched at the carbonate position, are obtained without magic-angle sample spinning. The resolved chemical shift anisotropy allows study of nuclear spin relaxation for the carbonate groups in the polymer that have different orientations relative to the static magnetic field in the laboratory frame. The spin-lattice relaxation time in the rotating frame (T_1?) is measured at a motional-probe frequency of 50 kHz for the undiluted polymer and for BPAPC-diluent blends containing either dibutylphthalate or dinitrobiphenyl. The T_1? exhibits some dependence on orientation in all systems studied. In the blend containing dibutylphthalate (DBP), T_1? is decreased by a factor of two for all orientations of the carbonate group. This implies that DBP substantially increases the spectral density of 50 kHz motions in the carbonate region of the polymer at ambient temperature. In contrast, dinitrobiphenyl does not significantly alter the Fourier component of thermal fluctuations at 50 kHz. Dielectric relaxation measurements at 10 kHz reveal that the primary (T_g) and secondary (β) motional processes in BPAPC are affected by low molecular weight additives. An intermediate relaxation process appears in the temperature interval between the glass transition temperature (T_g) and the sub-T_g β-relaxation (T_β) in the polymer-diluent blends. The n.m.r. spin-lattice relaxation rate in the rotating frame, T^?1_1?, correlates well with the relative magnitude of the dielectric dissipation factor (tan δ_ε) between T_g and T_β.     

Effect of physical ageing on enthalpy relaxation and isothermal contraction in bisphenol-A polycarbonate

The intention of this paper is to correlate the decrease of free volume and the enthalpy relaxation which occur in high polymers during annealing. We used a simple correlation relation, with one chief parameter (the ‘equilibrium temperature’ ?), which can be deduced from different models. Data on polycarbonate (PC) show no correlation between enthalpy relaxation and isothermal contraction using that relation: the assumption that the decrease of free volume in PC in the glassy state obeys a Williams-Landel-Ferry (WLF) type equation could not be confirmed. Moreover, it seems that the changes of configuration occurring during annealing cannot be described with only one parameter.     

酯交换法合成聚碳酸酯催化剂性能考察

以双酚A和碳酸二苯酯为原料,采用非光气熔融酯交换法合成聚碳酸酯。考察了氢氧化钾、氢氧化钠、四丁基氢氧化铵、碳酸钠、吡啶以及复合催化剂对聚碳酸酯合成反应速率及聚碳酸酯分子量和色差的影响。研究表明,氢氧化钾作为催化剂较适合于聚碳酸酯合成工艺,使用复合催化剂可以得到分子量较高、色差较低的聚碳酸酯。     

Novel intumescent flame retardants: synthesis and application in polycarbonate

Novel phosphorus‐containing and nitrogen‐containing intumescent flame retardants, bis‐aminobenzyl spirocylic pentaerythritol bisphosphonate (BASPB) and arylene‐N,N′‐bis(2,2‐dimethyl‐1,3‐propanediol phosphoramidate) (ABDPP), were synthesized, and their structures were characterized with Fourier transform infrared spectroscopy and ¹H and ³¹P nuclear magnetic resonance. The phosphorus compounds were used to impart flame retardancy to polycarbonate (PC). Combustion behaviors and thermal degradation properties of the flame‐retarded‐PC composites were assayed by limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter test, and thermogravimetric analysis. PC/5 wt.% BASPB and PC/5 wt.% ABDPP composites passed UL‐94 V‐0 rating; their LOI values were 35.5% and 34.7%, respectively. Scanning electron microscopy revealed that the char properties had crucial effects on the flame retardancy. The mechanical properties and water resistance of the PC/BASPB and PC/ABDPP composites were also measured. After water resistance test, PC/5 wt.% BASPB and PC/5 wt.% ABDPP composites kept V‐0 rating, and the mass loss was only 1.0%. Copyright © 2012 John Wiley & Sons, Ltd.     

Mechanism of octamethylcyclotetrasiloxane polymerization in the presence of siloxanediols

Polycondensation of tetramethyldisiloxanediol (HD ₂OH) by triflic acid (TfOH) in the presence of octamethylcyclotetrasiloxane (D₄) has been studied at 30°C in CH₂Cl₂ solution and in bulk at 80°C. The condensation follows a similar pathway, at a similar rate, in the presence or in the absence of D₄. Larger oligosiloxanediols and D₄ are formed first, and high polymer only after several hours. At 30°C, no polymerization of D₄ occurs, even 24 h after the total conversion of HD₂OH. In bulk at 80°C, polymerization of D₄ takes place when silanol concentration becomes very low at the end of the polycondensation, and is assumed to result from a reaction of D₄ with ester end-groups activated by hydrated acid at this temperature. Indeed, these results show that silanol groups activated by TfOH are not responsible for D₄ polymerization. Polymerization made in the presence of longer-chain oligosiloxanes HD_xOH (x ∼ 15) indicates that the presence of silyltriflates is a prerequisite of the propagation reaction. Polymerization of D₄ alone at 80°C also occurs in the presence of water in situ (0.9 mol litre⁻¹) after addition of pure triflic acid, and water cocatalyses the propagation reaction. However, the initiation reaction is almost completely inhibited when triflic acid is prehydrated.