Modification of layer charge in smectites by microwaves

The layer charge reduction of two Li-saturated montmorillonites is referred to application of microwave radiation at 2.45 GHz for dispersions and 30.0 GHz for the solid powders. Efficiency of these treatments was compared to the same conditions applying conventional heating. The samples were heated in the temperature and time windows corresponding to 190–270 °C and 30–120 min, respectively. Changes in the mean layer charge were monitored by the determination of cation exchange capacity values using exchange of triethylene tetraamino copper ions. The charge reduction of the montmorillonites in aqueous dispersions was rather low (< 30%) despite the fact, that high Li⁺ concentration dissolved in solution was selected (1 mol L^− 1). This behaviour was attributed to the very high water content in used dispersions and high hydration enthalpy of Li⁺ cations. Nevertheless, the microwave heated dispersions (2.45 GHz) showed detectable layer charge reduction as compared to conventionally heated dispersions, where no significant changes were found.Solid powders with different content of exchangeable lithium ions were prepared with solutions having different molar fraction of Li⁺ and Na⁺ cations (0%, 20%, 40%, 60%, 80%, 100% of Li⁺). Final composition of interlayer cations was analysed with ICP-OES. In contrary to dispersions, the microwave treatment of the prepared powders revealed high layer charge reduction, which was much higher than for conventionally heated powders. The efficiency was enhanced with increasing interlayer lithium content but reached a limiting value depending on the montmorillonite used. Migration of the lithium into the structure of the montmorillonite supported with microwaves was extremely fast, finished probably within the few minutes of the treatments. The exchangeable Li⁺ cations are accelerated through alternating electric field of microwaves and highly efficient layer charge neutralisation occurs. Infrared spectroscopy showed that the products obtained with microwave treatments correspond to the materials heated conventionally for much longer periods of time. Hence, applying microwaves the time and energy requirement can be significantly reduced. The X-ray diffraction showed that montmorillonite layers were able to swell in ethyleneglycol upon charge reduction, if the cation exchange capacity was not reduced more than 20–40%.     

聚氨酯泡沫材料的性能研究

聚氨酯泡沫具有多孔性、相对密度小、比强度高等特点,根据所用原料的不同和配方的变化可制成阻尼减震性能优异的材料。为了满足铝型材内填充材料的阻尼减震的要求,通过改变原料的组成和配比,制备了一种密度低、阻尼性能优异的聚氨酯泡沫材料。研究了发泡剂、N220和环氧树脂的含量对泡沫材料性能的影响,结果表明调节发泡剂用量可以改变材料的密度和粘接性能,N220和环氧树脂的加入可以提高聚氨酯泡沫的阻尼性能,所制得的聚氨酯泡沫材料可以满足铝型材填充材料的要求。     

Mechanical properties and microstructure evaluation of fly ash - Slag geopolymer foaming materials

The existing fly ash-slag foaming geopolymer materials generally have the shortcomings of low fly ash content and low porosity. It is urgent to develop geopolymer foaming materials with high fly ash content and high porosity. Using fly ash and slag as the main raw materials, geopolymer foaming materials were prepared by alkali activation. The effects of activator content and sodium silicate modulus on the macroscopic mechanical properties, pore structures and microstructures of geopolymer foaming materials were studied. The experimental results showed that when the activator content was 21% (wt.) and the modulus of sodium silicate was 1, the specimen exhibited the best performance. The compressive strength of the specimen reached 2.18 MPa at 28 d, the porosity was 63.07%, and the average pore sizes of macroscopic pores were 920 μm. Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and Scanning Electron Microscopy and Energy Dispersive Spectrometer (SEM-EDS) analysis showed that when the content of activator was 21% and the modulus of sodium silicate was 1, the reaction grade of the system was the highest, reached 55.12%, meanwhile the main product Sodium silicate hydrate (N-A-S-H) gel produced the largest amount. The fractal dimension calculations showed that the spatial complexity of a specimen with large pores was greater than that of a specimen with small pores. This study can provide a basis for the design of geopolymer foaming materials with high proportion of fly ash and high porosity.     

聚氨酯/微米Si_3N_4复合材料的性能研究

对聚氨酯/微米Si3N4复合材料的性能进行了研究,实验表明：聚氨酯/Si3N4复合材料具有优异的性能,聚氨酯/微米Si3N4复合材料,其硬度、力学性能和抗冲蚀磨损性能比纯聚氨酯优异;在微米Si3N4含量为3%时,其硬度、力学性能最佳;在微米SiN含量为5%时,其抗冲蚀磨损性能最佳。     

有机硅改性聚氨酯合成革涂饰剂的合成及性能

用聚醚多元醇(PPG)、聚二甲基硅氧烷(PDMS)、异佛尔酮二异氰酸酯(IPD I)、1,4-丁二醇(BDO)等为主要原料,合成了有机硅改性聚氨酯溶液。通过对合成条件的考察发现,反应温度为65℃,反应4 h,采用m(丁酮)∶m(二甲苯)=1∶1作溶剂,可得到黏度适中、性能良好的产品。考察了聚二甲基硅氧烷质量分数〔w(PDMS)〕对有机硅改性聚氨酯溶液及其成膜性能的影响。结果发现,随着w(PDMS)增加,溶液的黏度降低,成膜的热稳定性提高,当w(PDMS)=10%时成膜的水接触角达到最大值102.6°。     

木质素网状聚氨酯泡沫的制备及初步应用

介绍了木质素网状聚氨酯泡沫的制备方法,着重讨论了溶剂对木质素在聚氨酯基体中分布的影响、木质素对聚氨酯软质泡沫的泡孔和力学性能的影响。实验结果表明:木质素的加入可以提高聚氨酯软质泡沫的开孔率,当木质素的质量分数在2%时,可使网化泡沫拉伸强度最高达0.12MPa;当木质素的质量分数在5%时,可使网化泡沫伸长率最高达374.3%;木质素质量分数为5%和8%的聚氨酯软质泡沫经过30d的挂膜测试,最终挂膜量分别达10000mg/L和12100mg/L,可以作为污水处理填料使用。     

Properties of segmented polyurethanes derived from different diisocyanates

Various segmented polyurethane materials with a polyurethane hard segment (HS) content of 40 wt % were prepared by bulk polymerization of a poly(tetramethylene ether) glycol with M_n of 2000, 1,4‐butanediol, and various diisocyanates. The diisocyanates used were pure 4,4′‐diphenylmethane diisocyanate (MDI), 2,4‐toluene diisocyanate (T100), toluene diisocyanate containing 80% 2,4‐isomer and 20% 2,6‐isomer (T80), isophorone diisocyanate (IPDI), hydrogenated 4,4′‐diphenylmethane diisocyanate (HMDI), and 1,6‐hexane diisocyanate (HDI). The segmented polyurethane materials were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), tensile properties, tear strength, and Shore A hardness. The DSC and DMA data show that the thermal transitions are influenced significantly by the diisocyanate structure. In the segmented polyurethane materials with aliphatic HS, the polyether soft segment (SS) is immiscible with the HS. However, in the segmented polyurethane materials with aromatic HS, the SS is partially miscible with the HS. The diisocyanate structure also influences the mechanical properties significantly and is described as the effect of symmetry and chemical structure of the HS. Various solution polymerized polyurethane resins with solid content of 30 wt % were also prepared and their thickness retention, water resistance, and yellowing resistance were determined for the evaluation of their usage as wet process polyurethane leather. The polyurethane resin with aliphatic HS show poorer thickness retention but better yellowing resistance. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 167–174, 2000     

单组分聚氨酯乳液制备及其结构与性能研究

采用预聚合法,以聚酯二元醇(PEA)、甲苯二异氰酸酯(TDI)、二羟甲基丙酸(DMPA)为基本原料合成了分子链上带有亲水基团(-COOH)的聚氯酯预聚体。以特殊的水化方式制得聚酯型水性聚氨酯乳液。讨论了温度、-NCO-与-OH的物质的量之比(R)、亲水基团含量、合成工艺分别对材料力学性能、耐水性、玻璃化转变温度(Tg)等的影响。研究发现,采用前中和工艺、在高速搅拦下将预聚物加入到水中的水化方式,当R值为1．2,羧基含量为1．6％时,合成的聚酯型水性聚氨酯乳液具有较好的贮存稳定性,且涂膜的耐水性和力学性能良好。     

碳纤维复合吸波涂层材料的性能影响研究

以水性聚氨酯为基,碳纤维为填料,制备了碳纤维复合吸波涂层材料。采用扫描电镜、差示扫描量热仪、傅里叶红外光谱仪、X射线衍射仪和矢量网络分析仪对碳纤维复合吸波涂层材料的结构与性能进行了测试和表征。实验结果表明:碳纤维复合吸波涂层材料为碳纤维和水性聚氨酯的物理结合,随着碳纤维含量的增加和厚度的增大,碳纤维复合吸波涂层材料的反射率峰值均向低频移动,当碳纤维含量为0.8%,涂层厚度为1.2 mm时,碳纤维复合吸波涂层的反射率峰值达到-6.01 dB,小于-5 dB的带宽为4.2 GHz,涂层面密度为1.02kg/m~2。     

硅酸盐/聚氨酯弹性体制备及性能研究

以自制聚醚型聚氨酯预聚体、硅酸盐水溶液、乙二醇/丙三醇(质量比1:1)混合扩链交联剂、多亚甲基多苯基异氰酸酯(PAPI)等为原料制备了硅酸盐/聚氨酯弹性材料.探究了预聚体NCO基含量、乙二醇/丙三醇含量以及硅酸盐水溶液种类等因素对硅酸盐/聚氨酯弹性体力学性能的影响.结果表明:当B组分中预聚体质量分数为83.5％且其NC...     

Preparation and performance of lightweight porous ceramics using metallurgical steel slag

In this paper, porous ceramics with high porosity and low bulk density were prepared by using steel slag and kaolin as main raw materials and polyurethane sponge as template. The effects of steel slag particle size, zirconia addition, the solid content of the slurry, and the addition of polycarboxylic acid water-reducing agent on the properties of ceramics were studied. In addition, by adding a surfactant (Sodium dodecyl sulfate) to form fine pores on the original framework of the three-dimensional network porous ceramic, the shortcomings of the single as well as the uncontrollable density and porosity of the porous ceramic, which are produced by the template method, are improved. When the grinding time of steel slag is 90 min, the content of zirconia is 3% wt, the solid content of ceramic slurry is 64% wt, and 0.6% wt polycarboxylic acid water-reducing agent and 0.4% of surfactant are added, the prepared porous ceramic skeleton is clear and good. The porous ceramic has a low bulk density (as low as 157.869 kg/m³), high porosity (about 94.05%) and high compressive strength (0.2 MPa). The crystalline phase of it is mainly composed of anorthite, gehlenite, forsterite and quartz. The addition of zirconia, water-reducing agent and surfactant only changes the macrostructure of porous ceramics, and does not change its crystal phase composition. The preparation of porous ceramics from steel slag not only solves the recycling problem of steel slag, but also provides a good substitute for main raw materials of porous ceramics.     

桐油基水性聚氨酯乳液的合成及性能

采用从桐油自制的桐酸甲酯酸酐MEA和1,4-丁二醇反应,制备了桐油基多元醇TBPO,并进一步以TBPO、异佛尔酮二异氰酸酯和二羟甲基丙酸为原料,制备了桐油基水性聚氨酯乳液。采用红外光谱仪对MEA、TBPO和水性聚氨酯进行了表征,验证了产物的结构与预测相符,对水性聚氨酯的热性能及乳胶粒直径及分布进行了表征。结果表明,以桐酸甲酯酸酐为原料可以制备具有耐热性好、粒径分布窄的水性聚氨酯乳液,该水性桐油基聚氨酯可用作水性涂料。     

Preparation of dendritic waterborne polyurethane-urea/Ni–Zn ferrite composite coatings and investigation of their microwave absorption properties

This study shows the preparation of microwave absorbing composite material by using Ni–Zn ferrite filler and dendritic waterborne polyurethane-urea (WPU) polymer as a matrix. Initially, waterborne polyurethane prepolymers were synthesized by using PEG1500 (WPU1) and PPG1000 (WPU2) polyols via prepolymer mixing process. Then, chain extended with water in the presence of hexamethylenetetramine (HMTA) as crosslinker. Then, 1/1 (w/w) amount of Ni–Zn ferrite was dispersed in the WPU polymer to be converted into a microwave absorbing composite coating (CWPU1 and CWPU2). Structural, mechanical and morphological properties were investigated. The microwave absorption measurements were performed by using transmission/reflection method via waveguide method in the frequency range of 8.2–12.4 GHz. Permittivity and permeability measurements were performed in the frequency range of 8.2–12.4 GHz. It has been found that CWPU1 which was prepared by using WPU1 polymer indicated broader microwave absorption between 9.4 and 11.7 GHz due to its dendritic structure. Besides, permittivity and permeability results indicated that CWPU1 and CWPU2 have distinctive magnetic properties.     

Design and formulation of polyurethane foam used for porous alumina ceramics

The present work studied a simple direct foaming method for preparation of porous alumina ceramics by expansion of a ceramic suspension based on polyurethane (PU) foam system. The effects of polyurethane formulas including catalyst composition, blowing agent content, NCO index and solid content on the samples properties were investigated. The results showed that the homogeneity, porosity and mechanical properties are various for different formulas. The dried green bodies showed diametrical compressive strength in the range of 0.39–1.25 MPa and were amenable to machining operations such as milling, drilling and lathing. Meanwhile, PU formulas play an important role in the microstructures and mechanical properties of green bodies and sintered ceramic foams. Pyrolytic removal of polyurethane skeleton followed by sintering at 1550 °C produced alumina bodies with open cell porosity 54–75% and diametrical compressive strength 1.39–28.47 MPa. Microstructure showed both large (200–300 μm) and small (50–100 μm) pores all with various sizes of windows. Based on the optimization of polyurethane formulation, the porous alumina foam with porosity of 64% and compressive strength of 25.26 MPa was prepared. This polyurethane foam system is easily available and low-cost, which could be widely applied in preparation of other porous ceramics, such as ZrO₂, SiO₂, etc.     

Electrolyte and pH responsive surfactant association in ionic semi‐interpenetrating networks containing cellulose or chitin synthesized in lithium chloride–N,N‐dimethylacetamide

Semi‐interpenetrating networks (SIPNs) of N,N‐dimethylacrylamide (DMAm)–N,N‐dimethylamino‐ethylacrylamide (DMAEAm), or N,N‐dimethylacrylamide (DMAm)–2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) containing cellulose or chitin were synthesized in 9% LiCl–N,N‐dimethylacetamide (DMAc). The SIPNs were formulated to contain (1, 2, or 5% w/w) cellulose or 0.8% w/w chitin. Control systems (without polysaccharide) were also synthesized in 9% LiCl–DMAc. An acrylamide (Am)–AMPS hydrogel was synthesized for comparison with the SIPN composites. The swelling behavior of these materials was investigated as a function of pH (DMAEAm‐containing networks) or electrolyte concentration (AMPS‐containing networks). The DMAm–AMPS materials were found to have higher equilibrium water content (EWC) values in deionized water than the DMAm–DMAEAm materials. The EWC of the DMAm–DMAEAm materials was largest between pH 4 and 5 due to the protonation of the tertiary amine, with the chitin‐containing material exhibiting the largest EWC. The DMAm–AMPS materials exhibited a decrease in EWC values with an increase in electrolyte concentration. Polymer–surfactant interactions were shown to exist for surfactants of opposite charge of the ionic mer units incorporated into the polymeric network. Surfactant sequestration by the polysaccharide‐containing materials was greater than that of the control gels; however, the rates of surfactant binding were lower. Release of the bound surfactant was achieved by the disruption of the charge–charge interactions by changing the pH of the medium (DMAEAm‐containing networks) or by the addition of electrolyte (AMPS‐containing networks). The DMAm–DMAEAm SIPNs released only 4% of the surfactant originally sequestered. By contrast, the DMAm–AMPS SIPNs released approximately 80%. The control Am–AMPS hydrogel–surfactant complex collapsed in the presence of electrolyte, and no surfactant was released from the complex. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 989–998, 1999     

1,4-二羟基丁烷-2-磺酸钠基磺酸型PUD膜性能研究

以自制1,4-二羟基丁烷-2-磺酸钠为亲水单体,聚己二酸己二醇新戊二醇酯(PHNA)、异佛尔酮二异氰酸酯(IPDI)、1,4-丁二醇(BDO)和乙二胺(EDA)为原料,采用丙酮法合成了固含量超过50%的PUD(聚氨酯分散体)。研究结果表明:PUD胶膜的断裂伸长率超过1 500%、最大拉伸强度为47.3 MPa,具有高强度、高弹性之特点;PUD胶膜具有良好的热稳定性(起始分解温度超过280℃,490℃完全分解)和耐水性(吸水率低于10%)。     

含马来酰亚胺环水性聚氨酯纸张表面施胶剂的制备及应用

以聚酯二元醇(PCL1000)、异佛尔酮二异氰酸酯(IPDI)、1,4-丁二醇(BDO)、二羟甲基丙酸(DMPA)、三羟甲基丙烷(TMP)、N-(4-羟基苯基)马来酰亚胺(4-HPM)为主要原料,合成了含马来酰亚胺环水性聚氨酯(MWPU)乳液,探讨了聚氨酯乳液对纸张的表面施胶性能,并优化了合成工艺条件。结果表明,当异氰酸酯指数R=1.4,w(COOH)=1.4%,w(4-HPM)=1.0%时,此时含马来酰亚胺环水性聚氨酯乳液具有优异的表面施胶性能。以质量分数为2%的含马来酰亚胺环的水性聚氨酯乳液进行表面施胶时,纸张施胶度达64 s,抗张指数达到57 N·m/g,耐折度达82次。     

环氧改性水性聚氨酯的合成工艺及性能

采用甲苯二异氰酸酯(TDI-80)、聚醚二醇(N220)、二羟甲基丙酸((DMPA)、环氧树脂和丙烯酸羟丙酯(HPA)为主要原料,合成了环氧改性的水性聚氨酯乳液。研究了反应温度、乳化分散速度、中和度和环氧树脂的用量对乳液及涂膜性能的影响。结果表明:当乳化分散速度为4 000~5 000 r/min,中和度为90%~95%,环氧树脂的添加量为4%~6%时,可得到性能较好的乳液。通过环氧树脂改性的水性聚氨酯涂膜具有硬度高、耐水性和力学性能好的特点。     

柔性印刷电路用聚酯覆铜板胶粘剂的应用与制备

聚酯覆铜板是一种新型ＦＰＣ板基材，所使用的胶粘剂具有比较特殊的性能。本文使用聚氨 酯改性环氧作聚酯覆铜板的胶粘剂，对配方中的组份进行了优选，当选用分子量大的聚醚聚氨酯、且－ＮＣＯ 含量为４％～６％、聚氨酯子聚体加入量为３０～４０价时，筛选出的胶粘剂适于制造聚酯覆铜板。     

可生物降解热塑性聚氨酯弹性体的合成与性能研究

以中等分子量聚碳酸亚丙酯多元醇作为软段,并与过量的甲苯二异氰酸酯生成预聚物,用1,4–丁二醇进行扩链制备热塑性聚氨酯弹性体,整个反应体系保持—NCO/—OH=1.2。研究了硬段含量变化对材料结构与性能的影响。结果表明,所得弹性体的拉伸性能随着硬段含量的增加而增大,这是微相分离变化的结果;弹性体具有较好的生物降解性,可用于潮湿恶劣环境。