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Mayank Shah Edwin Zondervan Maarten Oudshoorn Andre de Haan 《Macromolecular Symposia》2011,302(1):46-55
Summary: Unsaturated polyester is traditionally produced in a batch wise operating reaction vessel connected to a distillation unit. An attractive alternative for the synthesis of unsaturated polyester is a reactive distillation. To value such alternative synthesis route reliable process models need to be developed. In this paper, the strategy is described for the development of the reactive distillation model. Essential parts of the reactive distillation model are kinetic and thermodynamic which are subsequently validated with the experimental data of the traditional batch process such as acid value of the polyester, weight of the distillate and glycol concentration in the distillate. We find that the models predict these important variables reliably. Unsaturated polyester production time is around 12 hours in the traditional batch process. However, the simulation study of the reactive distillation process shows that the total production time of unsaturated polyester in a continuous reactive distillation system is between 1.5 hours to 2 hours for the same product quality as during batch production. The equilibrium conversion is raised by 7% compared to the traditional batch process. The model demonstrated that reactive distillation has the potential to intensify the process by factor of 6 to 8 in comparison to the batch reactor. 相似文献
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Chebli K. Marais S. Saiter J. M. Pardo E. F. Grenet J. Metayer M. 《Journal of Thermal Analysis and Calorimetry》2000,62(3):657-664
Investigations involving thermally stimulated depolarization currents were performed on unsaturated polyester resins cured
with styrene. Samples containing different amounts of Co octoate promoter were studied. The complex spectra revealed the classical
β and the α dipolar relaxations. The peak characterizing the α dipolar relaxation was overlapped by a ρ peak of appreciable
magnitude, due to the presence of impurities in the promoter solution [1]. However, study of the elementary spectra as concerns
both α and β peaks for various samples containing different amounts of Co octoate demonstrated that the relaxation kinetics,
and particularly the values of the apparent activation energies, do not depend on these impurities.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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不饱和聚酯/聚氨酯互穿网络聚合物的合成 总被引:8,自引:1,他引:8
以醋酸酐封端的不饱和聚酯(FUPR)与交联聚氨酯预聚物制备了具有互穿聚合物网络(IPN)的不饱和聚酯/聚氨酯,通过红外,DSC和扫描电镜等分析了FUPR/PUIPN网络形成的动力学,微相分离行为及力学性能,结果表明,当FUPR/PU达到某一比值时,产生网络互穿效应,可改善聚氨酯的刚性,提高不饱和聚酯的抗冲性。 相似文献
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以芝麻秸秆粉、水稻秸秆粉、玉米芯秆粉、菠萝叶粉、甘蔗渣粉五种不同植物纤维粉为填充体、不饱和聚酯树脂(UPR)为基体制作植物纤维粉/UPR复合材料,对比研究了秸秆种类对复合材料密度、力学性能及吸水性能的影响。结果表明,植物纤维粉粒径为100目、添加量为UPR用量的10%时,芝麻秸秆粉/UPR复合材料的综合力学性能最好,拉伸强度、弯曲强度和冲击强度分别为41.320 MPa、67.467 MPa和2.815 KJ/m^2,且每一浸泡阶段吸水率均最低。 相似文献
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Johannis Ch. Simitzis Loukas Th. Zoumpoulakis Spiridon K. Soulis Leonidas N. Mendrinos 《Mikrochimica acta》2001,136(3-4):171-174
Unsaturated polyesters are synthesized by means of polyesterification, often with catalysts like strong acids, metal oxides
and metal-organic salts. Most often, the catalysts used cannot be separated from the bulk of the polyester. Also, some organic
or inorganic additives – called fillers – which are used with the polyester in order to decrease cost, affect the curing of
the polyester. In this work the effect of residual catalyst on the curing of unsaturated polyester is studied. Unsaturated
polyesters were prepared using propylene glycol with a 10% molar excess over stoichiometry and a mixture of dicarboxylic acids,
namely maleic acid (unsaturated) adipic acid (saturated) and phthalic anhydride (saturated) at a molar ratio 1:2:2. Lead dioxide,
p-toluenesulfonic acid and zinc acetate were used as catalysts, at 0.1% w/w. After the polyesterification, the polymers were
diluted with styrene at a proportion of 100:30 w/w. The resins were cured by using MEKP (methylethylketone peroxide) as initiator
and CoNp (cobalt naphthenate) as accelerator. Catalysts affect the final color of the polyester. The kinetics of curing of
the resins was studied by DSC analysis based on the exothermic peak due to the double bonds breaking to give crosslinked macromolecules.
The heat released ΔH is decreased by the presence of catalyst, while activation energy, the frequency factor and the order of reaction are increased. 相似文献
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ZnO–glass fiber–unsaturated polyester composites have been prepared. On exposure to the metal halide lamp, their resistance to ultraviolet (UV) degradation is evaluated. Experimental results show that ZnO can reduce the UV degradation of the unsaturated polyester matrix. ZnO can significantly retard the UV degradation process of the matrix resin, and can also increase the impact strength of the composites under the experimental conditions. Differential scanning calorimetry (DSC) analyses also indicate that the addition of ZnO to unsaturated polyester may retard the crosslink process and catalyze the decomposition of the resin. However, after more than 40 hr of UV irradiation, it was crosslinked. SEM fracture morphology shows that nano ZnO could hinder crack growth and induce more cracks, and when the content of ZnO reaches 6 wt%, the impact fracture mechanism changes abruptly and plastic deformation appears, which indicates that 6 wt% for ZnO in unsaturated polyester could be considered as the critical content. Around the critical content, the particles are near enough to interact with each other and this results in the change of fracture mechanism. The results also indicate that the proper content of ZnO added into an unsaturated polyester could prolong the durability and lessen the reject rate of transparent glass fiber–polyester composites. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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将氟原子引入不饱和聚酯链中,合成了含氟不饱和聚酯,并探索了其合成条件;采用四球摩擦磨损试验机评价了含氟不饱和聚酯在液体石蜡中作为抗磨添加剂的摩擦学性能,并利用红外光谱仪、X射线光电子能谱仪和扫描电镜分析了摩擦表面膜的结构、形貌和化学状态.结果表明,氟原子的引入有利于降低聚酯的黏度,并改善聚酯在液体石蜡中的分散性;合成产物作为抗磨添加剂可以在钢球磨损表面形成聚合物膜,从而显著提高基础油的摩擦学性能. 相似文献
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Several structural series of unsaturated polyester networks which had different isophthalic acid–maleic anhydride ratios or different precentage rates of styrene incorporated in the network were studied by means of thermomechanical tests. It was demonstrated that the transition zone (α and β) did not correspond specifically to a polytyrene phase but could be linked to the presence of microdomains of different structures within the polyester network. It is the successive setting in motion of these microdomains, under the effect of a rise in temperature, which creates a broad transition zone. Structural chain formations based on the resin components (prepolymer and styrene) were proposed and linked to the transition temperatures detected. The improved knowledge of the structure and the various microdomains present within the networks will provide a better apprehension of the hydrolytic stability of unsaturated polyester materials. 相似文献
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The preparation and characterization of polymer blends with structured natural rubber (NR)-based latex particles are presented. By a semicontinuous emulsion polymerization process, a natural rubber latex (prevulcanized or not) was coated with a shell of crosslinked polymethylmethacrylate (PMMA) or polystyrene (PS). Furthermore, core–shell latexes based on a natural rubber/crosslinked PS latex semi-interpenetrating network were synthesized in a batch process. These structured particles were incorporated as impact modifiers into a brittle polymer matrix using a Werner & Pfleiderer twin screw extruder. The mechanical properties of PS and PMMA blends with a series of the prepared latexes were investigated. In the case of PMMA blends, relatively simple core (NR)–shell (crosslinked PMMA) particles improved the mechanical properties of PMMA most effectively. An intermediate PS layer between the core and the shell or a natural rubber core with PS subinclusions allowed the E-modulus to be adjusted. The situation was different with the PS blends. Only core–shell particles based on NR-crosslinked PS latex semi-interpenetrating networks could effectively toughen PS. It appears that microdomains in the rubber phase allowed a modification of the crazing behavior. These inclusions were observed inside the NR particles by transmission electron microscopy. Transmission electron photomicrographs of PS and PMMA blends also revealed intact and well-dispersed particles. Scanning electron microscopy of fracture surfaces allowed us to distinguish PS blends reinforced with latex semi-interpenetrating network-based particles from blends with all other types of particles. 相似文献
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Epoxy resins toughened with carboxyl-terminated butadieneacrylonitrile copolymers (CTBN) are two-phase thermosets. The network of the in situ formed rubber particles depends upon the curing mechanism of the resin. When a primary polyamine such as triethylene tetramine was used as curing agent, the network of the rubber phase was quite incomplete, whereas a perfect rubber network was formed with 2-ethyl-4-methyl imidazole as the curing agent. 相似文献
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Zulhelmi Alif Abdul Halim Muhamad Azizi Mat Yajid Mohd Hasbullah Idris Halimaton Hamdan 《Journal of Dispersion Science and Technology》2018,39(8):1093-1101
The thermal-mechanical properties of unsaturated polyester (UP) composite were enhanced by the dispersion of silica aerogel (SA) with preserved pores. Low-cost SA was prepared from rice husk via the sol-gel process and ambient pressure drying. A new method was proposed to encapsulate the hydrophobic aerogel surface pores with hydrophilic polyvinyl alcohol (PVA) film using the fluidized-bed coating process. The dispersion of PVA-coated aerogel with preserved pores in the polyester matrix resulted in an increase of specific compressive strength (44.1?MPa?·?cm3?g?1), thermal insulation (0.23?W?m?1?K?1), and thermal stability (Tonset?=?310°C), but decreased the glass transition temperature (Tg?=?260°C). 相似文献
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K. De La Caba P. Guerrero J. Gavald I. Mondragon 《Journal of Polymer Science.Polymer Physics》1999,37(14):1677-1685
An unsaturated polyester (UP) resin modified with a liquid polymer, polyoxypropylenetriamine (POPTA), at a concentration of 10 wt% has been precured at several temperatures. Phase separation takes place before gelation at all precure temperatures used. The glass‐transition region has been analyzed by dynamic mechanical analysis. Mechanical properties have been related to microstructural features. With a precure temperature fixed, the unsaturated polyester (UP) resin has also been modified with different contents of POPTA. Fracture toughness of the mixtures has also been analyzed and results are compared to those for the unmodified mixture. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1677–1685, 1999 相似文献
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聚酯薄膜与紫外光(UV)固化光油之间的附着力极差,用胶带拉脱时完全脱落.为此,分别采用AF-201磺化聚酯、YF-40聚丙烯酸树脂、PR-32聚氨酯、EX-40F丙烯酸改性聚氨酯和PX-1010丙烯酸改性聚酯等表面处理剂对聚酯薄膜表面进行涂覆处理,以改善聚酯薄膜的表面性能,提高其与UV光油之间的附着力.附着力测定结果表明,PX-1010丙烯酸改性聚酯可明显提高聚酯薄膜与UV光油的附着力. 相似文献
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Young-Min Yun Seung-Jong Lee Ki-Jun Lee Young-Kwan Lee Jae-Do Nam 《Journal of Polymer Science.Polymer Physics》1997,35(15):2447-2456
Curing kinetics of unsaturated polyester resin system exhibiting apparent induction periods was investigated by modeling free radical initiation and propagation processes. The isothermal curing induction time as well as the maximum-rate time provided the same activation energy in the Arrhenius relation, and therefore, the isothermal curing master curve was constructed by using the reduced time method. Two model elementary rate equations for radical and monomer were proposed to describe the free radical polymerization of unsaturated polyester resin systems. The power law was adopted to express the conversion dependence function of the initiation efficiency and the monomer reaction rate. Demonstrating the capability of the developed model, the agreement between experimental and predicted data was excellent in both isothermal and dynamic-heating conditions, even with the same model parameters in different thermal conditions. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 2447–2456, 1997 相似文献