聚合物系脱挥研究进展

综述了聚合物系脱挥中脱挥表征方法、影响因素基本规律、脱挥基本理论和超泡脱挥动力学及脱挥设备等方面的研究现状,指出了今后可能的发展趋势。     

工业聚合反应装置：Ⅲ.均相本体聚合反应器（下）

论述了聚酯，聚酰胺缩聚反应装置及高粘流体脱挥设备。在简述其选型原理及设备结构的基础上，介绍和推荐了一些新型缩聚反应器和脱挥装置。     

聚合物高效脱挥技术进展

聚合物中挥发分含量的不同导致聚合物脱挥过程遵循不同的热质传递机理，基于脱挥过程关键机制开发高能效的聚合物脱挥技术与装备具有重要工程意义。本文分别简述了闪蒸脱挥、起泡脱挥以及扩散脱挥3种脱挥方式的传递机理、过程特征以及过程模型，在此基础上从脱挥工艺和装备两个方面综述了近年来聚合物脱挥过程强化的手段与方法，并系统介绍了栅缝降膜脱挥、超重力旋转强化脱挥、超临界流体辅助脱挥、超声空化强化脱挥等过程强化新技术及其应用现状，提出了未来聚合物脱挥理论与工程实践的研究方向：一方面仍需深入研究扩散脱挥与起泡脱挥的耦合作用机制，建立精准、普适的脱挥过程模型；另一方面指出立式降膜脱挥技术因其能效优势，有望成为未来大规模工业脱挥器的重要选择。     

苯乙烯-丁二烯嵌段共聚透明抗冲树脂的工业化试验研究

以n-BuLi/THF为引发体系，以苯乙烯、丁二烯为原料，以中型试验条件为依据，合成了具有嵌段结构的共聚合物即丁苯透明抗冲击树脂，实现了工业化试验研究。采用双螺杆蒸发挤出机组进行脱挥脱溶剂处理，实现了脱挥、输送、塑化、压缩挤出的一机多用功能。试验考察了反应温度、系统微量杂质含量和双螺杆工艺条件对产品质量的影响。     

水溶性丙烯酸树脂双螺杆脱挥挤出设备及工艺技术研究

综述了水溶性丙烯酸树脂的使用情况和生产工艺,重点介绍了其脱挥工艺及设备,分析了双螺杆脱挥挤出机的国内外发展概况、脱挥原理、优点和主要技术参数等,并提出了关于双螺杆脱挥挤出机传热设计、脱挥口及真空度设计、螺杆元件及组合设计等方面的建议。     

高黏聚合物系脱挥设备研究进展

聚合物脱挥对产品性能和缩聚反应过程具有十分重要的影响。脱挥设备是实现聚合物高效脱挥的关键手段。针对高黏聚合物系脱挥过程特性,指出增大气液相界面积和提高界面更新速率是改进脱挥设备的关键。综述了刮板式薄膜脱挥器、螺杆挤出机、卧式圆盘反应器和卧式捏合反应器等脱挥强化设备的技术特性和应用现状,并介绍了以旋转填充床为代表的新型脱挥强化设备的研究进展,为实现高黏聚合物系高效脱挥提供了新途径。     

氯磺化聚乙烯高温水射流法破乳脱挥动力学模型的建立及应用

建立了氯磺化聚乙烯(CSM)胶乳破乳脱挥过程的总动力学模型,并采用高温水射流法对CSM胶乳进行脱挥实验,通过体视显微镜分析了CSM胶乳的颗粒形貌,考察了热水温度和流速对脱挥效率的影响。结果表明,在CSM胶乳脱挥的总动力学模型中,热水流速和温度是影响脱挥效率的关键因素;在水射流实验过程中,随着热水流速和温度的增加,脱挥效率提高,与脱挥动力学模型的结论相吻合,从而验证了动力学模型的正确性。     

超重力旋转填充床用于高黏聚合物脱挥的研究进展

针对高黏聚合物体系脱挥过程的特点,指出聚合物脱挥技术推广的关键是开发高速表面更新的新型高效传质设备。工业上常规的脱挥设备存在不同的使用限制,本文提出了设计新型旋转填充床用于高黏聚合物脱挥的可能性,并类比螺杆挤出机结构介绍其脱挥机理。结果表明,相比常规的脱挥设备,旋转填充床脱挥效率高,能耗低。采用该技术对丙烯腈系聚合物进行两次循环脱挥处理,丙烯腈脱除率达到99%以上。在脱挥过程中,解吸的挥发分气体在第一时间离开填料层,并迅速由真空泵抽走,防止了挥发分的二次溶解。     

羟基聚硅氧烷在单螺杆挤出机中的脱挥

研究了α,ω-二羟基聚二甲基硅氧烷在单螺杆挤出机中的脱挥,分析了影响脱挥效果的因素。结果表明,温度与真空度是影响脱挥效果的关键参数。温度升高,脱挥效果提高,最佳温度200～220℃;真空度升高,脱挥效果提高,但同时增加了冒料的可能性,适宜的真空度为24～28kPa。得出了实验范围内的挥发分最终质量分数与螺杆转速及进料流量的关联式。     

排气式双螺杆混炼挤出装置及方法

正本发明通过从设置在缸体的最前端节缸上的脱挥助剂注入喷嘴注入脱挥助剂,提高由聚合物或合成橡胶构成的合成树脂的脱挥能力,并进行低温发泡。本发明的排气式双螺杆混炼挤出装置及方法为,由最前端脱挥助剂注入喷嘴(1)将脱挥助剂分散到由最前端节缸(2)内的熔融树脂中,同时通过最前端混炼部(3)进行混炼,通过所述脱挥助剂使所述熔融树脂发泡并挤出,最前端脱挥助剂注入喷嘴(1)设置在由位于缸     

Continuous production of solid polystyrene in back‐mixed and linear‐flow reactors

A mathematical model has been developed to predict the steady state performance of a continuous bulk styrene polymerization process with catalytic initiation for solid polystyrene. The polymerization section contains one boiling CSTR, followed by multiple linear‐flow reactors. The devolatilization section consists of two polymer pre‐heaters and two high‐solids flashes. The polymer moment equations were solved simultaneously with the reactor modeling equations. The non‐linear algebraic equations were solved by a Newton‐Raphson iteration technique to give the steady‐state styrene monomer weight fraction in a CSTR. The coupled, non‐linear ordinary differential equations were numerically integrated using a single‐step, 4th‐order Runge‐Kutta technique, followed by a multi‐step Adams‐Moulton technique. The resulting computer simulation model is capable of evaluating how the production rate and product quality are affected by feed composition, temperature, initiator type, initiator concentration, and residence time. Several case studies were given for commercially important crystal‐clear and impact‐resistant resins. A binary initiation system gives a good balance of monomer conversion, polymer molecular weights, and rubber grafting compared to a single initiation system. The styrene dimer/trimer occur in low concentrations but can be substantially reduced with a low temperature initiator. The ideal mean residence time is approximately one minute or less in a shell‐and‐tube devolatilization pre‐heater. Low flash chamber vacuum is more effective than high polystyrene melt temperature to reduce the volatile content of the final product. The water injected to the low volatile melt shows promising improvement in the second‐stage polystyrene devolatilization.     

红外光谱法分析苯乙烯系树脂组分含量

采用本体聚合法分别制备了聚苯乙烯和聚丙烯腈的均聚物、共聚物及其共混物,用红外光谱对其组分进行了分析。以朗伯-比尔定律为依据,建立了标准工作曲线。结果表明:与核磁共振法和元素分析法相比,红外光谱法对苯乙烯类二元共聚物的组成分析的误差在1.0%左右,在聚合配方已知的前提下,对苯乙烯类三元共聚物的组成分析误差在4%之内。     

本体法与悬浮法PVC树脂生产工艺的比较及在管件生产中的优势

比较了本体法PVC7型树脂与悬浮法PVC-SG7型的生产工艺,介绍了本体法PVC树脂的质量、塑化性能和加工性能等在管件生产中的优势。     

Hybrid polymer latexes

Hybrid polymer latexes will be defined here as colloidal dispersions in which at least two distinct polymers exist within each particle. The two polymers may form a homogenous blend within the particle or microphase separation may occur. There are two general routes for their preparation. The first involves the use of a mini-emulsion polymerization process, in which a first polymer, most often prepared via polycondensation (or polyaddition), is dissolved in an unsaturated monomer (or a mixture of monomers). The solution is first emulsified into small droplets under a high shear process and then polymerized through a radical polymerization process. A variation of this route involves the synthesis of the polycondensate directly in the mini-emulsion. The second route involves a seeded emulsion polymerization of unsaturated monomer(s), in which the polycondensate is modified for use as a seed in the emulsion polymerization. Most often, styrenic and acrylic monomers are used, while the polycondensate may be alkyd resins, polyesters, epoxy resins, polyurethanes, or other polymers. The two routes are described in detail, as are the properties of the resulting materials (mostly as films). Up to now, there have been very few trials for the comparison of the two main routes. Most often the comparison is related to blends of the two kinds of emulsified polymers.     

Toward living radical polymerization

Radical polymerization is one of the most widely used processes for the commercial production of high-molecular-weight polymers. The main factors responsible for the preeminent position of radical polymerization are the ability to polymerize a wide array of monomers, tolerance of unprotected functionality in monomer and solvent, and compatibility with a variety of reaction conditions. Radical polymerization is simple to implement and inexpensive in relation to competitive technologies. However, conventional radical polymerization severely limits the degree of control that researchers can assert over molecular-weight distribution, copolymer composition, and macromolecular architecture. This Account focuses on nitroxide-mediated polymerization (NMP) and polymerization with reversible addition-fragmentation chain transfer (RAFT), two of the more successful approaches for controlling radical polymerization. These processes illustrate two distinct mechanisms for conferring living characteristics on radical polymerization: reversible deactivation (in NMP) and reversible or degenerate chain transfer (in RAFT). We devised NMP in the early 1980s and have exploited this method extensively for the synthesis of styrenic and acrylic polymers. The technique has undergone significant evolution since that time. New nitroxides have led to faster polymerization rates at lower temperatures. However, NMP is only applicable to a restricted range of monomers. RAFT was also developed at CSIRO and has proven both more robust and more versatile. It is applicable to the majority of monomers subject to radical polymerization, but the success of the polymerization depends upon the selection of the RAFT agent for the monomers and reaction conditions. We and other groups have proposed guidelines for selection, and the polymerization of most monomers can be well-controlled to provide minimal retardation and a high fraction of living chains by using one of just two RAFT agents. For example, a tertiary cyanoalkyl trithiocarbonate is suited to (meth)acrylate, (meth)acrylamide, and styrenic monomers, while a cyanomethyl xanthate or dithiocarbamate works with vinyl monomers, such as vinyl acetate or N-vinylpyrrolidone. With the appropriate choice of reagents and polymerization conditions, these reactions possess most of the attributes of living polymerization. We have used these methods in the synthesis of well-defined homo-, gradient, diblock, triblock, and star polymers and more complex architectures, including microgels and polymer brushes. Applications of these polymers include novel surfactants, dispersants, coatings and adhesives, biomaterials, membranes, drug-delivery media, electroactive materials, and other nanomaterials.     

Waste liquors from cellulosic industries. III.. Lignin from soda-spent liquor as a component in phenol-formaldehyde resin

Lignin separated from soda-spent liquor of rice straw pulping was used to replace some of the phenol condensed with formaldehyde to form phenol-formaldehyde resins (PF). The phenol-lignin-formaldehyde resin was obtained through two stages, namely adduct and polymerization stage. In the adduct stage, lignin: phenol ratio, time and temperature were studied. The produced phenol-lignin was condensed with formaldehyde to produce phenol-lignin-formaldehyde resins. The ratio of phenol-lignin to formaldehyde during the condensation, temperature and time of polymerization were also studied. In each case the yield, viscosity, solubility, and the softening point of the resins were determined. Lignin can replace up to 25% of the phenol without affecting the physical properties of the produced phenol-lignin-formaldehyde resins. IR-spectra showed a structural similarity of phenol formaldehyde and phenol-lignin-formaldehyde resins.     

苯乙烯树脂抗老化研究进展

综述了苯乙烯树脂老化机理进展,重点详述了有机稳定剂、无机纳米氧化物、无机纳米氧化物与有机稳定剂复合、接枝改性对苯乙烯树脂抗老化的影响,并提出了苯乙烯树脂抗老化技术发展的方向。     

Synthesis of versatile TIPNO-based alkoxyamines

The versatile chloromethyl TIPNO-based alkoxyamine was efficiently transformed into other valuable functionalised TIPNO-based alkoxyamines such as amino alkoxyamines which are interesting initiators for block copolymers and bisalkoxyamines in good yield and in two steps at the most. One bisalkoxyamine has allowed to prepare well-defined polystyrene-b-poly(n-butyl acrylate)-b-polystyrene symmetrical triblock copolymer. The last representative example of such alkoxyamines is a styrenic alkoxyamine which was copolymerized with styrene to afford branched polystyrene. Finally, for the first time branched poly(n-butyl acrylate) by nitroxide mediated radical polymerization was obtained and was a efficient macroinitiator of styrene, which indicates that the radical polymerization mediated by this styrenic alkoxyamine is living.     

ABS树脂生产技术现状及技术经济评估

阐述了ＡＢＳ树脂乳液接枝混法，连续本体法、乳液接接枝悬浮法接枝连连续本地生产技术的新进展，并对该４种方法进行了技术经济评估。