双苯环长碳链半芳香尼龙的合成与表征

利用本体聚合方法，通过4，4′-二羧基联苯醚和4，4′-二羧基联苯砜分别与十二碳二胺的缩聚反应，制备了两种新型的半芳香尼龙：聚联苯砜二甲酰十二碳二胺(PA12-S)和聚联苯醚二甲酰十二碳二胺(PA12-0)。研究了反应时间和反应温度对聚合物摩尔质量的影响，并以IR、^1H NMR表征了两种聚合物的结构；利用DSC、TG研究了聚合物的热性能。结果表明：在一定范围内，升高反应温度和增加反应时间会提高产物的摩尔质量，两种半芳香尼龙具有较高的玻璃化转变温度，热分解温度比脂肪族尼龙高约20℃，同时两种半芳香尼龙均具有良好的耐溶剂性能。     

聚D,L-丙交酯的常压微波辐射合成

研究了常压下微波辐射开环聚合制备聚D,L-丙交酯(PDLLA)。考察了单体纯度、微波辐射时间、催化剂用量和体系真空度对聚合反应的影响。采用气相色谱(GC)测定丙交酯纯度;FTIR和1H-NMR表征产物结构;GPC测定分子量分布。实验结果表明:重结晶4次后的丙交酯,在催化剂辛酸亚锡用量为0.15%,常压下经微波辐射30min,可获得分子量为21.87×104的PDLLA。反应时间与传统法相比大大缩短。与传统合成法的不同还表现为,随丙交酯纯度的提高,最佳聚合时间延长;体系真空度对反应无影响。GPC结果表明聚合产物的分子量分布较窄。     

反应挤出己内酰胺阴离子开环聚合尼龙6的研究进展

作为一种可连续化生产,残留单体易于脱除,产物分子量高,分子量分布窄,产品性价比高的制备方法,反应挤出阴离子聚合法在尼龙6的研究中应用广泛。简要介绍了反应挤出阴离子聚合尼龙6的反应机理、工艺流程,并对国内外研究现状及发展趋势进行了分析,详细综述了反应挤出阴离子聚合尼龙6在纳米复合材料、尼龙6为基体的合金以及尼龙6为分散相的合金研究中的最新进展。     

用不同方法制备聚天冬氨酸的比较

通过以L-天冬氨酸为原料的热缩催化聚合、以马来酸酐和碳酸铵为原料的常规合成和微波幅照合成等不同方法制备了聚天冬氨酸。分别通过红外光谱技术和粘度法对产物进行了结构和分子量的表征,并研究了每种制备方法对产物的产率、分子量及其阻垢性能的影响。结果表明所有聚合产物均具有聚天冬氨酸的结构特征。虽然由L-天冬氨酸法制备的产物产率和分子量最高,但是由微波辐照合成所得产物的阻垢性能最佳。     

用不同方法制备聚天冬氨酸的比较

通过以 L-天冬氨酸为原料的热缩催化聚合、以马来酸酐和碳酸铵为原料的常规合成和微波幅照合成等不同方法制备了聚天冬氨酸.分别通过红外光谱技术和粘度法对产物进行了结构和分子量的表征,并研究了每种制备方法对产物的产率、分子量及其阻垢性能的影响.结果表明所有聚合产物均具有聚天冬氨酸的结构特征.虽然由L-天冬氨酸法制备的产物产率和分子量最高,但是由微波辐照合成所得产物的阻垢性能最佳.     

煤催化微波热解技术及其碳基吸波催化剂研究进展

微波技术与煤热解技术结合而成的煤微波热解技术可高效地治理传统煤热解技术中环境污染高和资源利用效率低的难题,为低变质煤的清洁高效利用和分级提质利用提供了新的思路。煤催化微波热解技术能有效改善热解升温特性和产物分布,从而受到较多学者的关注。本文从低变质煤催化微波热解技术发展历程着手,概述了国内外煤催化微波热解研究技术进展,通过加入Fe、Co、Ni和Cu等金属化合物或焦炭、活性炭等碳材料作为吸波剂,能显著增强煤对微波的吸收能力,提高热解升温速率、产物收率及产物质量,而有些金属化合物在微波热解反应中不仅起到吸波作用,还具有催化作用。碳基吸波催化剂作为一种性能优越的煤微波热解催化剂,具有优越的电磁和吸波性能、较好的催化性能和高经济性等优点,本文在煤催化微波热解技术研究现状的基础上,对碳基吸波催化剂进行了较为详细地分析,概述了碳基吸波催化剂的碳基体和催化活性组分的研究进展,对比了3种常见碳基吸波催化剂制备方法的优劣势。最后,总结了碳基吸波催化剂在研发过程中存在的难题,并展望了低变质煤催化微波热解技术的应用前景。     

微波辅助合成5-[4-(4-溴代丁氧基)苯基]-10,15,20-三对甲氧基苯基卟啉

探讨采用微波辅助合成尾式卟啉（p-BrTMOPP）的制备工艺及其影响因素。以吡咯、对羟基苯甲醛和对甲氧基苯甲醛为原料,以丙酸为溶剂,制备得到p-HTMOPP;以1,4-二溴丁烷为原料,微波辅助加热条件下制备得到目标化合物尾式卟啉p-BrTMOPP;目标产物经过UV-vis、IR、ESI-MS等方法表征。在90℃、DMF溶剂条件下微波辐射加热30min,快速高效得到目标化合物,反应产率89.2%。和传统加热方法相比较,微波辅助合成尾式卟啉化合物明显缩短了反应时间,提高了反应效率。     

尼龙6连续聚合过程的流程模拟与调控

基于流程模拟软件Aspen Polymer Plus建立了己内酰胺水解聚合生产尼龙6的两段式工艺过程模型,利用该模型对某厂2万吨/年两段式生产工艺进行模拟,各聚合阶段内己内酰胺、环状二聚体含量、聚合物分子量,以及各聚合阶段温度分布和两聚合塔塔顶出水量等结果均与工业值吻合良好,模型可靠。在此基础上,进一步模拟考察了聚合反应过程中进料水含量、分子量调节剂含量、各聚合阶段温度和各聚合塔压力等因素对己内酰胺转化率、环状二聚体生成以及聚合产品分子量的影响,并进行了参数灵敏性分析。结果表明:较低的进料水含量、降低反应温度和前聚塔压力及提高后聚塔的真空度均有利于降低聚合产品中环状二聚体的含量;两个聚合塔下半段的温度变化对环状二聚体产生有显著影响,提高后聚塔真空度可显著提高聚合物分子量。以尼龙6连续聚合过程的环状二聚体含量调控为目标,在优化的操作条件下,尼龙6聚合物中环状二聚体的含量可降低约16%。     

乙酸乙烯酯的微波加热聚合

对乙酸乙烯酯甲醇溶液在微波加热条件下的聚合反应进行了研究,讨论了微波聚合条件、引发剂浓度、溶剂浓度和种类对聚合产物的转化率和分子量的影响。聚合物可以在较短时间内获得。且在同样的实验条件下,用不同的溶剂获得的聚合物的分子量不同。     

聚六亚甲基胍盐酸盐的合成研究

以盐酸胍和1,6-己二胺为主要原料,聚乙二醇400为溶剂,经高温热缩聚反应合成聚六亚甲基胍盐酸盐。考察了聚合工艺中反应温度、反应时间、投料比和溶剂用量等对产物数均分子量Mn和重均分子量Mw的影响,得到了较佳聚合反应条件。在较佳条件下合成的产品分子具有良好的线性分布,抗菌性能良好。     

Microwave assisted synthesis of high molecular weight polyvinylsilazane via RAFT process

The microwave-assisted synthesis of high molecular weight polyvinylsilazane (H-PVSZ) leads to a narrow molecular weight distribution at accelerated polymerization rates under controlled/living polymerization, while retaining the excellent controllability offered by reversible addition fragmentation chain transfer (RAFT) polymerization in a thermal reaction process. Under microwave irradiation, higher molecular weight H-PVSZ (6250 vs. 4370) was obtained with higher conversion (86.7 vs. 30.1%) than under conventional heating through a simple 3 h reaction of vinylcyclicsilazane with a molecular weight of 314 in the presence of dithiocarbamate derivatives (RAFT agent) and 2,2′-azobis-isobutyronitrile (AIBN, thermal initiator). H-PVSZ with a well-controlled high molecular weight is useful for synthesizing inorganic-organic diblock copolymer polyvinylsilazane-block-polystyrene (PVSZ-b-PS) with a higher molecular weight and lower polydispersity than by conventional heating of the PVSZ-derived product.     

Kinetic model for short-cycle bulk styrene polymerization through bifunctional initiators

A model describing the kinetics of bulk styrene polymerization through bifunctional initiators has been developed. The diffusion-controlled propagation and termination reactions at high monomer conversions are modeled with the free volume theory for polymer solutions. Three different commercially available bifunctional initiators were experimentally evaluated for a wide range of polymerization conditions to study the effect of the reaction rate on the molecular weight and molecular weight distribution. The model predictions for the same polymerization conditions show excellent agreement with the experimental data, for the whole range of conversions, for both reaction rate and molecular weight distribution development, under all the conditions tested. It is demonstrated throughout this study that high molecular weights, very high reaction rates, and narrow molecular weight distributions can be achieved simultaneously by using bifunctional initiators. A comparison between monofunctionally initiated systems with the bifunctionally initiated ones shows that short-cycle reactions with reductions in polymerization time of up to 75% may be achieved with the bifunctional initiators for a wider range of conditions without significantly affecting the molecular weight and molecular weight distribution of the final product.     

Synthesis of succinic acid-based polyamide through direct solid-state polymerization method: Avoiding cyclization of succinic acid

Succinic acid is an important synthetic monomer but it is difficult to use it as a precursor for synthesizing high molecular weight polyamide, due to its tendency to perform intra-cyclization reaction at high temperature. In order to solve this problem, in this paper, the direct solid-state polymerization (DSSP) method with the initial reactant, nylon salt which was composed of 1, 5-diaminopentane, succinic acid, and terephthalic acid, was applied to synthesize the bio-based copolyamide PA 5T/54. In comparison with the conventional melting polymerization method, the DSSP method can prevent the cyclization reaction of succinic acid effectively due to the lower reacting temperature as well as the restriction effect of the nylon salt. As a result, the product fabricated by DSSP method has higher molecular weight and much lighter color from red to white. Therefore, the DSSP method is advantageous for the synthesis of the polymers or copolymers composed of the succinic acid as the monomer. Furthermore, the polymerization mechanism proposed in this work can serve as a guidance for the design of the molecular structure and control of the polymerization process.     

Reverse atom transfer radical polymerization of acrylonitrile under microwave irradiation

Reverse atom transfer radical polymerization was first used to successfully synthesize polyacrylonitrile under microwave irradiation. FeCl₃, coordinated by isophthalic acid, was used as the catalyst, and 2,2′‐azobisisoheptonitrilewas used as the initiator. N,N‐Dimethylformamide was used as the solvent to improve the solubility of the ligand. Under the same experimental conditions, the apparent rate constant under microwave irradiation was higher than that under conventional heating. The polymerization not only showed the best control of the molecular weight and its distribution but also provided a rather rapid reaction rate with the [acrylonitrile]/[2,2′‐azobisisoheptonitrile]/[FeCl₃]/[isophthalic acid] ratio of 300 : 1 : 1 : 2. The polymers obtained were used as macroinitiators to initiate the chain extension and successfully synthesize acrylonitrile polymers with a molecular weight higher than 50,000 and a narrow polydispersity as low as 1.30. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Free radical polymerization of butyl acrylate in monodispersed droplets: Comparison between two heating strategies

Monodispersed droplets could be easily generated in coaxial microdevice, and a reaction based upon these discrete droplets is an attractive approach thanks to isolated reaction units, efficient mixing, and precise residence time control. In this work, free radical polymerization of butyl acrylate was conducted in monodispersed droplets of several hundred microns. Two different heating methodologies, microwave heating and conventional heating with oil bath were adopted to initiate polymerization, respectively. The polymerization under conventional heating could be regarded as an isothermal process, while the polymerization under microwave heating gradually underwent a temperature increase. So the poly (butyl acrylate) obtained by microwave heating has larger average molecular weight and higher polydispersity index. Meanwhile, the conversion of butyl acrylate was significantly improved by microwave heating compared with conventional heating, even though the reaction temperature under microwave heating might be lower than the temperature of the oil bath. This remarkable enhancement was a direct proof of the nonthermal effect of the microwave field for free radical polymerization. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

聚合工艺对低不饱和度高相对分子质量聚醚性能的影响

采用双金属氰化络合物催化剂（DMC）合成了低不饱和度高相对分子质量聚醚（DL-4000D）,讨论了聚合温度、聚合压力、低聚物脱水时间等聚合工艺条件对DL-4000D及其制品性能的影响。结果表明,聚合温度在115~125℃、低聚物脱水时间在2 h左右,聚合压力小于100 kPa等工艺条件下,制备的聚醚不饱和度低,相对分子质量分布窄,由其制得的聚氨酯制品的综合性能好。     

Molecular Weights of Reactive Systems Employing Anionic Polymerization

Anionic polymerization has been successfully employed for reactive processing, the most notable example being that of nylon RIM [1] using caprolactam polymerization. Here, fast polymerization is achieved with the help of a combination of a catalyst and an initiator under practically anhydrous conditions. This polymerization method leads to a narrow molecular weight distribution and a Poisson distribution of the individual chain lengths. Analytical expressions for calculating the number-average and weight-average degrees of polymerization of the polymer chains from the degree of conversion have been derived based on this knowledge [2]. But in a reactive system where a substantial amount of monomer may be present during most of the processing time, the average must include the monomer units present. Only such averages will be of use in correlations of molecular weight with viscosity and degree of conversion with viscosity, which are of importance in the design of a reactive processing system. A method to compute such average molecular weights is presented here.     

Microwave-Irradiated Ring-Opening Polymerization of Octamethylcyclotetrasiloxane in the Presence of Water

α, ω-dihydroxyl polydimethylsiloxane (DHPDMS) was prepared via anionic ring-opening polymerization of octamethyl cyclotetrasiloxane (D₄) under microwave irradiation (MI) in the presence of water. The conversion and polymerization rate were calculated by the gravimetric method. The effect of microwave power on the polymerization was investigated. FTIR was used to verify the DHPDMS prepared at different irradiation times. The results show that the conversion is the highest when the initial microwave power is preset at 700 W. Compared with conventional heating (CH), the polymerization rate and equilibrium conversion are both enhanced by the introduction of microwave irradiation. The species and concentration of the cyclosiloxane mixture caused by backbiting reaction were determined by gas chromatography/mass spectrometry (GC/MS). The lower concentration of cyclosiloxane in the polymer prepared under MI indicates that side reactions have been reduced and a pure polymer obtained. The molecular weight and polydispersity index (PDI) measured by GPC show that under MI, the molecular weight of DHPDMS is lower and PDI is narrower than those under CH.     

Evolution to similarity solutions for polymerization and depolymerization with microwave radiation

The kinetics of polymerization and depolymerization are critical in understanding the stability and characterization of polymers. The kinetics of simultaneous polymerization and degradation of poly(methyl methacrylate) have been investigated by varying the initiator concentration and monomer concentration under the influence of microwave energy. Microwave radiation initially polymerizes the monomer, then degrades the resulting polymer and the polymer attains an equilibrium molecular weight distribution with a polydispersity of two. To understand more fully the kinetics, the molecular weight distribution (MWD) is represented as a gamma distribution; the random degradation rate coefficient is assumed to vary linearly with molecular weight and the polymerization rate coefficient is assumed to be independent of molecular weight. The change of the MWD with time is studied by continuous distribution kinetics; the solutions obtained depict the change of the average molecular weight, polydispersity and the gamma distribution parameters with time. Experimental data indicate that reaction rates are enhanced by microwave radiation and the MWD approaches a similarity solution within 10 min for all the investigated cases. The model satisfactorily predicts the change of the MWD with time. © 2001 Society of Chemical Industry     

尼龙6固相缩聚——实验数据与模型数据的比较

研究了不同起始相对分子质量、不同含水量的圆球状尼龙6切片在不同温度和反应时间下的连续固相缩聚行为.结果说明了起始相对分子质量和温度对尼龙6的固相增黏效果影响很大,和模型得出的结论一致;而不同含水量和反应时间同样也会影响尼龙6切片的固相增黏效果.此外,结果还发现在实际生产中,切片的起始氧化温度远远低于模型推断出的起始氧化温度.实验结果为今后的模型设计和改进提供了极有参考意义的数据,同时也为固相缩聚提出了新的研究方向.