“Bishydrazid A2”: A new semiaromatic film and fiber-forming polymer based on bisacid A2

We report the preparation of the dihydrazide of bisacid A2 (“bisdihidrazide A2”). Its composition and structure have been verified by elemental analysis and by means of infrared and NMR spectra. This material was then converted into a polyhydrazide (“bishydrazid A2”) in an HCl-accepting solvent. The polymer was converted to fiber by wet spinning the dope obtained during the polycondensation reaction without prior neutralization or dilution. Film was cast from a solution of the precipitated and washed polymer which had an inherent viscosity of about 0.8; mechanical tests on the film—both before and after treatment with formic acid—were carried out. Differential scanning calorimetry showed an α/β transition comparable to that shown by bisacid A2 polyaramides and described in preceding papers^1,2. Wide-angle x-ray scattering showed that the polymer is amorphous. Scanning electron micrographs revealed the physical structure of wet-spun fiber and the probable mechanism of fiber formation by dope extrusion into a water bath.     

Cured polyesters based upon bisacid A2: Water absorption,toluene resistance,and resistance to 5% aqueous HNO3 and NaOH

Earlier papers have described the preparation and purification of bisacid A2,^1,2 the preparation and cure of crosslinkable polyesters,³ the thermal properties of cast sheet,⁴ and the mechanical properties of glass fiber laminates⁵ which were made from reactants that included bisacid A2 in two series of cocondensates. The present paper details the water absorption and the long-term effects (up to 12 months) of toluene, 5% aq. HNO₃, and 5% aq. NaOH. The effects of the last two were found to be negligible, but the water absorption and the toluene resistance appeared to be capable of correlation with the known composition and the inferred structure of the copolyesters.     

The stability of solutions in reactive monomers of crosslinkable polyesters containing bisacid A2

Earlier papers^1–6 have dealt with the synthesis and purification of bisacid A2; the preparation of unsaturated polyesters by cocondensing bisacid A2 with maleic anhydride in varying proportions in the presence or absence of phthalic anhydride as a further modifying acid, using propylene glycol as the polyesterification diol; the hardness and the thermal and mechanical properties of cast, cured resins and glass fiber-reinforced laminates; and the water and chemical resistance of the cured resins. This paper deals with the solution stability of the liquid resins prior to cure and, in particular, with the observed fact that solutions containing esters of bisacid A2 in sufficient quantity do not require the addition of stabilizers commonly needed for commercial polyesters in order to impart an acceptable shelf life to the liquid resins.     

Polyesters from bisacid A2. Electrical properties of glass fiber laminates

The preparation and purification of bisacid A2, the preparation of crosslinkable polyesters from bisacid A2, and some of the properties of the resulting resins and laminates have been reported in earlier communications.^1–7 This paper reports the surface and volume resistivities of laminates according to B.S. 2782 as well as their dielectric loss and permittivity at 23°C over a frequency range of about 9 decades and discusses the significance of the results.     

A polyamide from bisacid A2 and p-phenylenediamine: Synthesis,properties, and fiber formation

The synthesis, characterization, and processing of a new polyamide which is formed from bisacid A2 and p-phenylenediamine are reported. The polymer is synthesized using low-temperature solution polycondensation methods. The conditions for producing high molecular weight polymer are described. The polymer produced is amorphous, but lower molecular weight varieties may be crystallized with a formic acid treatment. Differential scanning calorimetry indicates a transition in the range of 180–190°C. Mechanical properties of films are measured. Fibers have been produced by both melt and wet spinning.     

Thermal properties of unfilled cast cured sheets of polyesters based on bisacid A2

The synthesis of bisacid A2 in a high state of purity, the preparation of unsaturated copolyesters therefrom, the preparation of solutions of the latter in suitable monomers, followed by casting of those solutions after addition of catalysts and curing of the material to obtain crosslinked polyester sheet, has been described in earlier communications.^1–3 This paper deals with the heat distortion temperatures⁴ and the (modified) Vicat softening points⁵ of the cast sheets of various copolyesters at various monomer contents.     

Crosslinked polyesters from “bisacid A2.” The mechanical properties of glass fiber-reinforced laminates

This paper reports the flexural and tensile test results on glass fiber laminates prepared from solutions in styrene of polyesters containing bisacid A2 and from standard commercial liquid polyester resins. The results are compared with each other. Suggestions are made for differences in strength, modulus, and strain. The results are presented in tables which give a statistical evaluation of numerous tests in terms of mean, range, and standard deviation.     

Isothermal crystallization behavior and melting characteristics of injection sample of nucleated polypropylene

The isothermal crystallization behavior and melting characteristics of pure polypropylene (PP) and PPs nucleated with a phosphate nucleating agent (A) and a sorbitol derivative (D) have been studied by differential scanning calorimetry (DSC). Compared with pure PP, nucleated PPs show a shorter half‐times of crystallization. Dependence of crystallization rate of nucleated PP on the crystallization temperature is stronger than that of pure PP at the higher crystallization temperature, whereas the opposite results are obtained at the lower crystallization temperature. Addition of nucleating agent shifts the temperature at the deviation from the baseline of DSC melting curve, T, and the temperature at the completion of melting, T, to higher temperatures, indicating that nucleated PPs exhibit a higher perfection of PP crystals. A shoulder peak in the high temperature range of melting peak of nucleated PP and a wider low temperature region in the melting peak of pure PP are observed. Obviously, PP and nucleated PPs form different distribution of crystal perfection in the isothermal crystallization process. According to the half‐time of crystallization, nucleating agent A is more effective than D. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2547–2553, 2000     

全氧燃烧熔制太阳能玻璃工程技术经济分析

简要介绍了太阳能玻璃的发展和应用、全氧燃烧熔制太阳能玻璃工艺技术具有节能减排、绿色环保的优越特性。主要对240t/d全氧燃烧熔制太阳能玻璃工程进行了技术经济分析.     

高孔隙率泡沫铜强化相变材料熔化特性

为了研究纯石蜡与泡沫铜/石蜡相变复合材料吸热熔化性能的不同,探究泡沫铜对石蜡熔化换热过程的影响,本文对纯石蜡和孔隙率为0.98的高孔隙率泡沫铜/石蜡复合材料的相变熔化过程进行了可视化实验研究,并数值模拟分析了纯石蜡及泡沫铜/石蜡复合材料熔化过程。结果表明：复合材料与纯石蜡的液相率变化出现交点,即临界液相率值,此时复合材料具有的液相占比与纯石蜡液相占比相同;泡沫铜的填充能明显改善纯石蜡传热系数低的问题,加快相变材料的整体熔化速率,当热通量为1200W/m2时,孔隙率为0.98的泡沫铜填充使纯石蜡完全熔化时间缩短了约12.5%,并使整体温度分布更均匀,改善热分层现象,且复合材料最大温差比纯石蜡最大温差低约27.5K。     

Further studies on polyamides from bisacid a2

Earlier work on the low temperature solution polyamidation of bisacid A2 has raised a number of structural problems. Work carried out more recently showed that the problem of apparent nonisostoichiometry could be reasonably satisfactorily explained. The present paper reports the synthesis and investigates the properties of a further series of polyamides based upon Bisacid A2. More importantly, however, a detailed characterization and evaluation of the new polymers with respect to their structures is presented. This enabled us to compare the various structures in the light of the experimental evidence provided by a number of analytical and spectroscopic techniques, solution behavior, molecular weight, and thermal, morphological, and mechanical properties. Some work was also done on the effect of incorporating a small amount of a trifunctional monomer into the polyamide system.     

Melting Point of Cryolite

The melting point of ultimate-purity cryolite was determined by evaluating the liquid fraction r of selected natural mineral samples over the melting range. A plot of the reciprocal of the liquid fraction l/r, as a function of the temperature T from which samples were quenched, gave a straight line that indicates a melting point for the sample of 1009.2°C at l/r = 1 and extrapolates to a value of 1012° f 2°C at l/r = 0 for pure cryolite.     

无碱玻璃纤维池窑用高致密锆英石砖的研究

采用高纯锆英石为主要原料 ,研究了几个关键工艺因素对高纯高致密锆英石砖性能的影响。结果表明 ,原料纯度、外加物种类及其加入量和烧成温度是获得优质高致密锆英石砖的关键。显微结构分析结果显示 ,这种砖晶粒间呈交错网络结构 ,直接结合程度极高 ,并具有良好的抗玻璃液的侵蚀性和渗透性。扫描电镜检验发现 ,玻璃液渗入砖内与砖反应 ,首先溶解Al2 O3、R2 O等组分 ,然后溶解锆英石 ,并析出斜锆石晶粒 ,呈岛状分布于玻璃液中 ,破坏了砖的原始直接结合结构 ,导致砖的解体。     

PET/EN-MFMB增韧体系非等温结晶及熔融行为

用差热分析法研究了PET／EN-MFMB增韧体系逐渐升温和逐渐降温的结晶行为以及逐渐升温的熔融行为。结果表明:PET／EN-MFMB增韧体系中PET冷、热结晶开始结晶温度均比原料PET的有所降低,热结晶成核速率均比原料PET的有明显提高。HDPE的结晶过程受到了PET的阻隔、约束作用。PET结晶开始熔融温度一般都比原料PET 有所提高;HDPE结晶熔融峰顶温度比原料HDPE以及EN-MFMB中的HDPE的明显降低。     

基于热重差热分析研究玻璃熔制过程中碳酸钡的分解规律

纯碳酸钡的分解比一般的碳酸盐要复杂而且分解温度更高,尤其在含碳酸钡的硼硅酸盐玻璃熔制过程中碳酸钡的分解更为复杂,其直接影响到所熔制玻璃的质量和熔制工艺的优化.以中温固体氧化物燃料电池(简称IT-SOFC,Solid Oxide of Fuel Cell)封接玻璃BaO-CaO-Al2O3-B2O3-SiO2体系的某配方为对象进行研究,以探明含碳酸钡的硼硅酸盐玻璃熔制过程中碳酸钡的分解规律.本文设计了三种粉料,即原配方粉体记为A粉料,在原配方改动为只留下BaCO3、SiO2、Al2O3三种原料的配方记为B样,最后一种粉料为分析纯BaCO3.利用差热热重分析(DTA/TG)对这三种粉料进行分析测试与比对,同时利用X射线衍射技术(XRD)对A粉料所制备的玻璃粉体进行分析.实验结果表明:分析纯碳酸钡发生两步晶型转变后,在1010 ℃才开始分解.而含碳酸钡的硼硅酸盐玻璃熔制过程中一部分碳酸钡在相对低温条件下首先是与SiO2与Al2O3两种原料反应而分解,另一部分碳酸钡随着温度不断升高而自身分解.最终,A玻璃在1176.5 ℃时产生BaAl2Si2O8(钡长石)晶相.     

Preparation and purification of bisacid A2 (2,2-diphenylolpropane 4,4-dioxyacetic acid). II

In an earlier communication¹ the preparation of Bisacid A2 was described. This paper describes the attempts at spotting impurities in the products so obtained by subjecting them to thin-layer chromatography. No traces of impurities could be detected since no separation whatever was observed. Infrared spectra of pure Bisacid A2 were found to be identical with the spectrum of Nanu and Boboescu.² It was also seen that the product obtained by the standard preparation in 70–73% yield with a minimum melting point of 173°C could not be demonstrably improved by esterification and rehydrolysis. Second crops from first mother liquors from the aqueous acetic acid recrystallization of the crude precipitated product of the condensation reaction (as well as ether extracts from these mother liquors) showed that both contained material with phenolic OH groups. These are the inpurities in the crude product which must be completely removed during purification if the final material is to be used for the synthesis of unsaturated polyester resins for ultimate use as crosslinked reinforced plastics, as alkyd varnish bases, or as fiber-forming saturated polyesters and polyamides. The need for adhering to the standard synthetic procedure was confirmed, in particular the need for multistage condensation, giving an effective yield of 70–73% of pure material     

Joining of aluminum and ceramic substrates by interposing molten aluminum–silicon alloy

The effects of interposing a molten aluminum alloy layer between pure aluminum and silicon nitride on the strength of joining and properties of the joined sample were investigated. An aluminum-based alloy containing 12 wt% silicon with a melting point lower than the 660°C melting point of pure aluminum was joined to pure aluminum and a silicon nitride substrate by using polymethylphenylsiloxane. A specimen with the same joining area (1600 mm²) and no alloy layer was prepared for comparison. In thermal cycling tests of Δ190 K, cooled at –40°C and heated at 150°C, the specimen without the alloy layer failed after 200 cycles, whereas the specimen with the alloy layer failed after 500 cycles. The bending strength of the sample with the alloy was approximately 1.5 times that of the sample without the alloy. These results indicate that the alloy layer facilitated the strong joining of the aluminum and substrate.     

聚乳酸/可反应性纳米SiO2复合材料的等温结晶动力学

采用熔融共混法制备了聚乳酸/可反应性纳米二氧化硅(PLLA/RNS)复合材料。利用差示扫描量热仪研究了RNS对PLLA等温结晶行为的影响;用Avrami 方程研究了PLLA及其复合材料的等温结晶动力学。结果表明,加入RNS对PLLA结晶起到了异相成核作用,随着RNS含量的增加,PLLA的结晶速率(K)提高,半结晶时间(t1/2)减小,而Avrami指数(n)变化不大,说明RNS没有改变PLLA结晶的成核机理;利用Arrhenius方程和Lauritzen-Hoffman理论分别对PLLA及其复合材料的结晶活化能(ΔE)、成核参数(Kg)和折叠链端表面自由能(σe)进行计算后发现,复合材料的ΔE比纯聚乳酸的小,Kg 、σe略有增加。这表明加入RNS降低了复合材料的ΔE,从而有效地促进了PLLA基体的结晶。     

热致相分离法iPP/nano-SiO2杂化中空纤维膜的结构与透过性能

通过熔融共混等规聚丙烯(iPP)/邻苯二甲酸二丁酯(DBP)/邻苯二甲酸二辛酯(DOP)/纳米二氧化硅(nano-SiO2)体系,采用热致相分离法(TIPS)制备了iPP中空纤维膜。对膜结构与透过性能进行了表征。用示差扫描量热仪(DSC)测定了体系的iPP动态结晶温度,融化峰值温度数值表明结晶只存在α晶型。X光电子能谱(XPS)表明nano-SiO2向膜表面发生了迁移,使得膜的亲水性有所提高,膜的接触角由120.05°降低到101.05°,降低了19.7%。随着nano-SiO2添加量的增加,膜的孔隙率和纯水通量均呈现先增大后减小的趋势。膜的孔隙率增加了20.2%,纯水通量增大了21.7%。经过拉伸后的杂化膜,孔隙率增大了27.4%,纯水通量增加了211%。研究表明:通过向铸膜液中添加nano-SiO2,可以优化膜结构,并改善膜的亲/疏水性以及透过性能。     

A DSC study of oriented samples of a blend of linear and branched polyethylene

Summary Differential scanning calorimetry (DSC) of cold-drawn samples of a blend of linear (LPE) and branched polyethylene (BPE) shows that the melting point of the high temperature peak decreases monotonically with increasing draw ratio. This is in apparent contradiction to the data obtained for pure LPE, for which quite unanimously the melting point has been shown to increase with increasing draw ratio. An explanation of this deviation in behaviour between the blend of LPE and BPE and the pure LPE is proposed based on the idea that the transformation of the lamellar structure to a fibrillar structure involves several kinds of rearrangement including a mixing on a supermolecular level of the originally segregated LPE and BPE components. The crystal rearrangements occurring on heating (in the DSC) in oriented pure LPE that are responsible for the high melting point of this system are thereby hindered.