可再分散乳胶粉的研究进展及应用前景

介绍了可再分散乳胶粉的研究进展、性能特点以及在现实中的应用。随着对可再分散乳胶粉研究的深入，可再分散乳胶粉的应用因其优良的性能已从原来在建筑材料行业的应用扩展至许多新的领域。     

Crystallization of Amorphous Components in Spray-Dried Powders

Spray-dried powders are typically produced as amorphous particles. Long storage of the particles tends to crystallize the powders, a reaction affected by moisture, time, and temperature. This work has examined partial crystallization from amorphous spray-dried powders by moisture sorption. Powders of citrus fiber with hibiscus extract, maltodextrin, coffee, tea, skim milk, and sucrose were produced with a laboratory-scale spray dryer. The powders were exposed to ambient temperature and various relative humidities, with weight measurements recorded over time. It has been found that, in different materials, the amorphous to crystalline state change is observed at varying rates depending on the relative humidities and molecular weights. This observation may be associated with all amorphous spray-dried materials.     

玄武岩纤维聚合物水泥混凝土干缩性能试验研究

通过玄武岩纤维聚合物水泥混凝土干缩性能试验,研究了玄武岩纤维掺量和聚合物乳液掺量对混凝土干缩性能的影响.研究结果表明,单掺玄武岩纤维对混凝土的干缩存在负面作用,随着玄武岩纤维掺量的增加,混凝土的干缩率增大;单掺丁苯乳液聚合物时,随着丁苯乳液聚合物掺量的增加,混凝土的干缩率呈现明显的增大趋势;玄武岩纤维和聚合物乳液复掺使用可以减少混凝土的干缩,其改善效果优于两者单掺的情况,复掺对混凝土干缩起到了双重改性的效果.     

红外干燥高玻璃化温度乳液的成膜研究

采用具有核壳结构的丙烯酸酯自交联乳液,研究其在红外干燥下的成膜及性能,并利用Routh-Russel模型优化确定其成膜机理,优化了成膜条件。研究表明,通过红外干燥可以实现高玻璃化温度(Tg)乳液的快速成膜。聚合物乳液Tg和湿膜厚度H能够改变Routh-Russel模型的参数λ和Pe,继而影响乳胶粒子的成膜性能。Tg58℃及H≤400μm时,乳胶粒子受毛细管力变形,形成连续透明的聚合物膜,其硬度相比于室温自然干燥的涂膜高出2~5倍,且耐水性显著增加。原子力显微镜(AFM)表征证实红外干燥确实能够促进乳胶粒子的融并变形。     

Aqueous re-dispersibility characterization of spray-dried hollow spherical silica nano-aggregates

Hollow spherical aggregates of biocompatible silica nanoparticles are produced by the spray drying technique to facilitate the delivery of the nanoparticles to the lung for potential drug delivery applications. The large geometric size (d_G > 5 µm) and the low density (ρ_eff ≈ 0.3 g/cm³) of the nano-aggregates are specifically formulated to achieve high aerosolization efficiency and an effective lung deposition. The nano-aggregates must readily re-disperse into the primary nanoparticles in an aqueous medium for the nanoparticles to perform their intended therapeutic functions. An aqueous re-dispersibility characterization technique based on the turbidity level measurement is developed for this purpose. A water-soluble excipient (i.e. mannitol), which forms “excipient bridges” interconnecting the nanoparticles, is included in the spray-drying formulation to produce readily re-dispersible nano-aggregates. The nano-aggregate aqueous re-dispersibility depends on (1) the silica: mannitol concentration ratio and (2) the degree of hollowness, where nano-aggregates with a higher shell thickness to particle radius ratio exhibit weaker re-dispersibility due to the poor particle wetting. The spray-drying condition and the silica: mannitol ratio, which lead to the production of highly re-dispersible nano-aggregates having the desired morphology, are determined. The promising results signify the potential application of hollow spherical silica nano-aggregates as an inhaled drug delivery vehicle.     

干法腈纶纺丝油剂单体的国产化研究

通过试验产品与国产其它同类产品分析数据的对比,试验产品在理化指标和复配及腈纶丝上油使用测试指标上达到了进品４１２ ＃ 单体的指标要求,可以替代进口产品。还讨论了本项目工业化生产的可行性与经济效益预测。     

乳液触变性对流平性的影响研究

乳液的流平性是乳液应用性能中的一个重要项目。目前,评价乳液的流平性主要采用刮涂法、刷涂法和目测法,前者简单、方便和实用,而且还能定量地评定出流平性等级,但耗时较长,且定量比较粗略;而后两种方法虽然简单、方便、快捷,但人为影响因素较大且定量不准。采用流变仪测定乳液的触变环的面积可较好的评价乳液的流平性,且该方法具有准确、方便、快捷等优点。     

Microwave Pretreatment of Backsawn Messmate Boards to Improve Drying Quality: Part 1

The findings of an investigation into the microwave (MW) modification and conventional kiln drying of backsawn/flatsawn messmate stringybark (Eucalyptus obliqua L'Herit) are summarized. The project was conducted in two parts. Part 1, the subject of this article, investigates whether low-intensity microwave modification results in more or less check formation than occurs during conventional drying of eucalypts. Part 2 of the investigation will determine the acceleration in kiln drying that can be achieved through microwave modification of the wood structure and in turn improving permeability.

Significant improvement in microwave modified samples compared to controls in relation to check (internal/honeycombing and surface) formation during drying was observed, with Schedule 1 (70 kWh/m³) having 55% of samples without checks compared to the control samples at 31%.

The study also found that there is a significant reduction in surface checking (number and depth) in MW modified boards compared to the controls. The control samples exhibited the highest proportion of surface checking, with 65% possessing one or more surface checks, of which 82% extended more than one quarter the width of the sample. This was in marked contrast to Schedule 2 (75 kWh/m3), which resulted in 43% having one or more surface checks, of which 25% extended more than one quarter the width of the sample.

The control samples also returned the highest rate of internal/honeycombing checking with 28% of samples affected, while samples pretreated according to MW Schedule 2 yielded the lowest rate, with 11% affected.     

Discovery of a Flavonoid FM04 as a Potent Inhibitor to Reverse P-Glycoprotein-Mediated Drug Resistance in Xenografts and Improve Oral Bioavailability of Paclitaxel

Biotransformation of flavonoid dimer FD18 resulted in an active metabolite FM04. It was more druggable because of its improved physicochemical properties. FM04 (EC₅₀ = 83 nM) was 1.8-fold more potent than FD18 in reversing P-glycoprotein (P-gp)-mediated paclitaxel (PTX) resistance in vitro. Similar to FD18, FM04 chemosensitized LCC6MDR cells towards multiple anticancer drugs by inhibiting the transport activity of P-gp and restoring intracellular drug levels. It stimulated the P-gp ATPase by 3.3-fold at 100 μM. Different from FD18, FM04 itself was not a transport substrate of P-gp and presumably, it cannot work as a competitive inhibitor. In the human melanoma MDA435/LCC6MDR xenograft, the co-administration of FM04 (28 mg/kg, I.P.) with PTX (12 mg/kg, I.V.) directly modulated P-gp-mediated PTX resistance and caused a 56% (*, p < 0.05) reduction in tumor volume without toxicity or animal death. When FM04 was administered orally at 45 mg/kg as a dual inhibitor of P-gp/CYP2C8 or 3A4 enzymes in the intestine, it increased the intestinal absorption of PTX from 0.2% to 14% in mice and caused about 57- to 66-fold improvement of AUC as compared to a single oral dose of PTX. Oral co-administration of FM04 (45 mg/kg) with PTX (40, 60 or 70 mg/kg) suppressed the human melanoma MDA435/LCC6 tumor growth with at least a 73% (***, p < 0.001) reduction in tumor volume without serious toxicity. Therefore, FM04 can be developed into a novel combination chemotherapy to treat cancer by directly targeting the P-gp overexpressed tumors or potentiating the oral bioavailability of P-gp substrate drugs.     

用于稳定Pickering乳液的氨基化明胶纳米颗粒的制备

以氨基化改性的B型明胶为原料,通过二次去溶剂法可制得具有良好单分散性(PDI≈0.068)的氨基化明胶纳米颗粒(Aminated gelatin nanoparticles,AGNPs),其粒径约为240 nm,表面带正电荷(ζ≈35 mV),并考察了制备过程中溶液pH对AGNPs粒径以及分散性的影响。结果表明:当pH≈4.0时,制备的AGNPs粒径较小(≈240nm),分散较为均匀。SEM、AFM及TEM测试结果表明:AGNPs为一种粒径窄分布的球形纳米颗粒;相比明胶纳米颗粒(Gelatinnanoparticles,GNPs),AGNPs刚性结构特点增强,且质地较为均匀。颗粒表面润湿性测试结果显示,AGNPs的三相接触角(θow=67?±5?)比GNPs(θow=31?±6?)显著增大,表明AGNPs的表面疏水性有所增强。以AGNPs为稳定剂制备的水包油(O/W)型Pickering乳液4℃下储存9个月未出现分层,表现出较高的稳定性。     

乳化燃油火焰温度测定的简易方法

为弥补一般光度法测乳化燃油火焰温度的不足,本文结合最新国外文献,设计了一种测定乳化燃油火焰温度的简易方法,以活塞式燃烧管为燃烧器,用细丝热电偶测火焰温度,利用小烟囱减少外界风及气流对火焰的影响,促使火焰正常燃烧。文中给出了试验装置图,并对此法的特点进行了比较和讨论     

Emulsion polymerization of an epoxy–acrylate emulsion stabilized with polyacrylate. II. Using the results of statistically designed experiments to deduce a possible polymerization mechanism

Epoxy–acrylate composite emulsions such as the one in this study can be used as metal coatings, etc. Many factors can influence the final quality of the product, and it is the aim of this study to highlight some of these factors. Statistically designed experiments were performed to investigate the influence of monomer level, the polymeric dispersant level, epoxy level, and the initiator level on particle size (light scattering), particle size distribution, and fractional conversion. It was found that the monomer level significantly influenced particle size and particle size distribution. The epoxy level and the monomer level influenced fractional conversion significantly. A qualitative model based on these observations is put forward to describe the mechanism of particle formation and polymerization. This model states that the high internal viscosity of the initial dispersed epoxy phase inhibits the formation of smaller particles and accelerates the polymerization rate during the first few minutes of polymerization by inducing a gel effect that inhibits termination and chain transfers of radical species. The addition of a monomer lowers the internal viscosity of the particles and causes them to break up into droplets containing dissolved epoxy, polyacrylate, and monomer. At the same time, radical species inside the smaller droplets can now undergo termination and chain transfer reactions. To confirm this model, polyacrylates of varying molecular masses were synthesized. Variation of the molecular masses of these polyacrylates resulted in variation in the viscosity of the dispersed phase. Polymerizations conducted with the polyacrylates confirmed the model observations. A dispersed phase with a high viscosity results in an increased polymerization rate, larger overall particle size, and a higher mass average molecular mass copolymer compared to lower molecular mass polyacrylates. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 368–381, 2000     

静电植绒胶粘剂的研制

本文介绍了静电植绒胶粘剂的研制方法,并讨论了单体、乳化剂、引发剂、交联剂及温度对产品性能的影响。     

Artificial Neural Networks Associated to Calorimetric Measurements Used as a Method to Predict Polymer Composition of High Solid Content Emulsion Copolymerizations

Summary: Inspired by biological systems, artificial neural networks (ANN) have demonstrated to be powerful tools to model non‐linear systems, such as high solid content latexes produced by emulsion polymerization which have a great importance in the polymeric industry, essentially for environmental reasons, since they usually have water as a continuous phase. The quality of the produced polymer is closely related to the structure of the polymeric chain. In order to propose technical and economically feasible alternatives to control a polymeric structure, this work is aimed to develop a new methodology based on ANN associated with calorimetry to predict the polymeric structure. The designed ANN presented excellent results when tested with process condition variations (such as temperature and reaction time) as well as when they were submitted to test concerning the variation on the proportion of monomers in the latex formulation. Hence, it was possible to conclude that ANN, associated to calorimetry, lead to an efficient method to predict the polymer composition in emulsion copolymerizations.

     

Comments to “Analysis of constant rate period of spray drying of slurry” by Liang et al., 2001

In the study by Liang et al. [2001. Analysis of constant rate period of spray drying of slurry. Chemical Engineering Science 56, 2205-2213] the Darcy flow of liquid through a pore system of primary particles to the surface of a slurry droplet was applied for the constant rate period. Steep primary particle concentration gradients inside droplets with a primary particle size of were observed. Unfortunately, the boundary condition at the droplet surface for the parabolic second-order PDE did not conserve the solid mass in the droplet, and the plots for the primary particle concentration profiles in the droplets were incorrect. In this letter we derive the correct boundary condition equation. Furthermore, we show that the primary particle concentration profiles inside the droplets are flat when the primary particles have a size of . We conclude that the model presented by Liang et al. is unable to predict the formation of hollow particles.     

白乳胶微生物污染的控制及防腐防霉剂的选择

针对聚醋酸乙烯酯乳液含有PVA及添加淀粉等填充物类后不防霉的特点,根据其生产工艺及产品性能,分析微生物污染的来源、种类及危害,从微生物污染原理出发,利用防腐防霉剂的杀菌机理,建立适宜于产品的防腐防霉剂体系,控制微生物的污染。经应用于工业生产中,取得了良好的效果,解决了胶体霉变问题。     

Reactive surfactants in heterophase polymerization. XVI. Emulsion copolymerization of styrene–butyl acrylate–acrylic acid in the presence of simple maleate reactive surfactants

This study deals with the influence of a copolymerizable surfactant on the stability of lattices. Two main reactive surfactants, one anionic and one nonionic, both containing a reactive part issued from maleic anhydride, were engaged in seeded emulsion polymerizations of styrene‐co‐butyl acrylate‐co‐acrylic acid. The importance of the polymerization conditions clearly appears through the incorporation yield of the surfmers: When good conditions are used, this yield can be as high as 80%. Once stable lattices are synthesized, with a great incorporation of the surfactant, the stability of the colloid (against freeze–thawing cycles or in the presence of concentrated divalent electrolyte solutions) is then largely improved. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2768–2776, 2000     

pH敏感的水溶性氨基聚合物的制备及其对乳液成膜的影响

从乳胶粒的成膜驱动力入手,研究了在乳液中加入pH敏感的水溶性氨基聚合物,利用特定条件下,氨基聚合物破坏乳胶粒的双电层,从而克服乳胶粒聚结的斥力,促使乳胶粒快速聚结成膜。探讨了不同条件下氨基聚合物的制备、氨基聚合物与乳液稳定共存的条件以及对乳液干燥速度的影响。     

Spray Drying,a Versatile Synthetic Method to Control Purity in Single Phases and Mixed Phases of Bismuth Molybdates

The synthesis of pure bismuth molybdates (α, β and γ phases) using a novel method — spray drying — has been studied and successfully applied. It is shown that it is possible to control the synthesis of mixtures of different bismuth molybdates using spray drying. The influence of the relative molar ratio of bismuth to molybdenum constituents on the formation of different bismuth molybdate phases has been investigated. Starting from spray‐dried precursors, thermal details of the phase diagram of the Bi₂O₃‐MoO₃ system can be accurately reproduced and very pure phases can be easily obtained. Spray‐drying is compared to conventional precipitation and solid‐state reaction and the obtained products were characterized by XRD, IR, Raman, SEM, BET and DTA.     

0.3%印楝素乳油及其混配剂防治稻纵卷叶螟和三化螟的药效

研究结果表明：0．3％印楝素与20％三唑磷混配剂-楝唑乳油对稻纵卷叶螟、三化螟具有防效高、速效性持效性好的特点；印楝素和阿维菌素混合有一定的防效和持效性，但速效性差；印楝素单用速效性差、防效低，但持效性较好；在水稻露穗5％时喷施楝唑乳油2625ml／hm^2，15d后对四代稻纵卷叶螟的防效达95％、20d后对三代三化螟的防效达100％。