含有机胶凝剂的Al_2O_3-SiO_2系泡沫料浆的流变性能与固化特性

采用泡沫法结合凝胶注模工艺制备莫来石多孔轻质材料,通过在Al_2O_3-SiO_2系泡沫料浆中分别引入三醋酸甘油酯、聚酰亚胺、羟丙基纤维素作为胶凝剂,研究胶凝剂的种类对泡沫料浆流变性能的影响及其与固化时间的关系规律。结果表明:3种胶凝剂对泡沫料浆的流变性能影响程度不同。流变性能直接影响泡沫料浆的固化时间,提高泡沫料浆的触变性、黏度增长速率以及扩大线性黏弹性区间是缩短泡沫料浆固化时间的有效途径。3种胶凝剂中,三醋酸甘油酯固化效果最佳,以其作为胶凝剂的泡沫料浆初凝时间和固化时间均最短。     

低温发泡制备酚醛泡沫材料及其表征

采用40℃低温发泡的方法制备酚醛泡沫,研究了发泡剂、表面活性剂和固化剂对泡沫的表观密度和压缩强度的影响,讨论了低温发泡对泡沫力学性能、导热性能、泡孔形态、阻燃性能、微观结构和热稳定性的影响。试验结果表明,40℃低温发泡对酚醛泡沫的阻燃性和热稳定性影响较小,泡沫的韧性和脆性得到了明显改善,泡孔孔径更小、分布更加均匀。     

Dimensional Changes in CFRP/PMI Foam Core Sandwich Structures

A sandwich structure was observed from the beginning of life—starting at the vacuum assisted manufacturing process up to several environmental in service conditions. Strain variations due to curing process at the manufacturing, well as thermal fluctuations and humidity environments in service were detected and reviewed by their influence on the overall dimensional stability. The CFRP/PMI foam core sandwich structure was checked for an application as a primary structure in commercial aviation with its specific environmental requirements.     

Amino surface functionalized microcapsules as curing agents for polyurethane foams

This work regards the manufacturing process and assessment of amino surface functionalized microcapsules (MCs) containing glycerol in their core, for application in one-component polyurethane (PU) foams to act as a sustainable curing catalyst. Microemulsion techniques combined with sol–gel processing, involving the development of specific steps during the synthesis, were found to enable this type of functional active microparticles. The MCs should only burst and release their content at the spraying stage, in order to assist and promote an accelerated curing of the foam. It has been found that the surface treatment employed in the last step of inorganic silica MCs synthesis procedure, using an amino silane, led to the best curing performance for PU foams. In fact, the amino functionalized MCs exhibited a more perfect spherical format and less aggregation than the inorganic MCs, did not exhibit significant leaching, and led to a significant increase in the curing rate of the PU foam. The study involved characterization techniques, such as scanning electron microscopy, Fourier transformed infrared spectroscopy, thermal gravimetric analyses, leaching, and curing speed evaluation.     

纳米纤维素凝胶微粒及其在Pickering泡沫中的应用

目的研究氧化纳米纤维素/乳酸链球菌素(TONCC/nisin)凝胶粒子的性质及其在环保抗菌泡沫中的应用。方法利用TONCC的表面羧基基团与nisin的表面阳离子的吸附耦合作用,制备TONCC/nisin水凝胶和微凝胶,以微凝胶作为稳定粒子,环氧大豆油丙烯酸酯(AESO)为油相,制备TONCC/nisin/AESO Pickering乳液,对水凝胶、微凝胶、乳液的稳定性进行研究;通过热固化乳液得到环保抗菌的泡沫材料,并对泡沫材料的结构和抗菌效果进行表征。结果水凝胶的结构随着在水中浸泡时长的增加而发生变化,宏观表现为坍塌变形,nisin逐渐析出,微凝胶随着静置时间的延长其粒径变化不大;以微凝胶作为界面稳定剂的AESO乳液的热稳定性较好,在90℃下加热30 min乳液液滴并未发生聚并现象,该乳液固化后形成的多孔泡沫材料对李斯特菌的抑制作用明显,当泡沫中nisin含量为2μg/g时,其抑菌率为43%。结论TONCC和nisin形成的微凝胶粒子在水中稳定性较好,可以用于乳化AESO制备Pickering泡沫,同时赋予泡沫多孔性和抗菌性,在制备环保抗菌泡沫方面有很大的应用潜力。     

Numerical prediction of the foam structure of polymeric materials by direct 3D simulation of their expansion by chemical reaction based on a multidomain method

The quality of thermosetting polymer foams (like polyurethane foam, used for example in automotive industry) mainly depends on the manufacturing process. At a mesoscopic scale, the foam can be modelled by the expansion of gas bubbles in a polymer matrix with evolutionary rheological behaviour. The initial bubbles correspond to germs, which are supposed quasi-homogeneously distributed in the polymer. An elementary foam volume (∼1 mm³) is phenomenologically modelled by a diphasic medium (polymer and immiscible gas bubbles). The evolution of each component is governed by equations resulting from thermodynamics of irreversible processes: the relevant state variables in gas, resulting from chemical reaction creating carbon dioxide (assimilated then to a perfect gas), are pressure, temperature and conversion rate of the reaction. The number of gas moles in each bubble depends on this conversion rate. The foam is considered as a shear-thinning viscous fluid, whose rheological parameters evolve with the curing reaction, depending on the process conditions (temperature, pressure). A mixed finite element method with multidomain approach is developed to simulate the average growth rate of the foam during its manufacture and to characterize the influence of the manufacturing conditions (or initial rheological behaviour of the components) on macroscopic parameters of the foam (cell size, heterogeneity of porosity, wall thickness).     

Simultaneous optimization of production planning and inventory management of polyurethane foam plant

In this work, the management of a polyurethane foam plant is tackled through a mixed integer linear programming model that simultaneously solves production and inventory planning problems. The production process considers the foaming stage where large polyurethane blocks are produced as well as the curing step where the blocks are dried. The proposed formulation takes into account several tradeoffs involved in the overall production process. The daily production planning is tightly related to production requirements, available space for the curing and stored elements. Moreover, the required time to dry blocks introduces a delay that must be appropriately considered in order to allow an adequate operation of downstream operations. Thus, an integrated approach where all these problems are jointly addressed is proposed using a mathematical programming model. Several study cases provided by a local company are tested to demonstrate the model performance.     

硅橡胶分子量对硅泡沫性能影响的研究

选用4种不同分子量的液体硅橡胶(107硅橡胶)作为生胶制备出了室温下固化的硅橡胶泡沫材料.探讨了生胶胶料黏度对固化速度的影响,以及分子量大小对硅泡沫的泡孔形貌、物理力学性能、热稳定性的影响.随着基础胶料黏度的增大,凝胶时间及其表干时间缩短,即固化速度加快;随着生胶分子量的增大,硅泡沫的泡孔变小,拉伸强度、压缩模量逐渐增...     

ZrSi_2/硼酚醛泡沫的制备及其裂解产物的增强机制

以ZrSi_2颗粒填充硼酚醛树脂制备了一种耐高温且裂解后结构较为完整的泡沫复合材料。研究了ZrSi_2颗粒质量分数对泡沫复合材料固化机制、高温裂解行为及裂解前后压缩性能的影响,并分析了ZrSi_2颗粒对泡沫复合材料裂解产物的增强机制。结果表明:添加的ZrSi_2颗粒虽未参与硼酚醛树脂的固化交联,但会和硼酚醛树脂裂解放出的气体挥发物发生化学反应,提高了裂解产物的残炭率和压缩比强度。当添加的ZrSi_2颗粒质量为硼酚醛树脂质量的10%时,裂解产物的残炭率和压缩比强度提高最为显著。ZrSi_2/硼酚醛泡沫经过裂解后,ZrSi_2颗粒作为第二相粒子钉扎在裂解产物的孔壁上,化学反应使得部分裂解气体挥发物被吸收并转化为固相产物,明显减少的缺陷提高了裂解产物的力学性能。     

聚甲基丙烯酰亚胺泡沫夹层结构全生命周期的关键技术研究进展

聚甲基丙烯酰亚胺(Polymethylimide,PMI)泡沫夹层结构特有的性能优势使其广泛应用于航空航天领域。为推动PMI泡沫夹层结构的稳定化、系列化和高性能化,本文系统地综述了面向全生命周期的PMI泡沫夹层结构设计与制造技术的研究现状与发展趋势。首先,总结了PMI泡沫及其夹层结构的性能和应用现状,分析了PMI泡沫夹层结构的市场需求。然后,概述了面向全生命周期的PMI泡沫夹层结构关键技术现状,包括PMI泡沫研发、结构设计与分析、结构固化成型、维修及维护。最后,展望了PMI泡沫夹层结构的发展趋势,以期为该领域后续的研究工作提供参考。      

纳米片层石墨填充聚氨酯泡沫塑料的制备和电学性能EI

Using polyester polyol and diphenylmethane diisocyanate(MDI)as basic component,and using graphite as conduct.ive filler,polyurethane/graphite nanosheet foam plastics is produced by filling mould curing reaction.Also the electrical properties of the foam plastics are studied.     

纳米片层石墨填充聚氨酯泡沫塑料的制备和电学性能

Using polyester polyol and diphenylmethane diisocyanate(MDI)as basic component,and using graphite as conduct.ive filler,polyurethane/graphite nanosheet foam plastics is produced by filling mould curing reaction.Also the electrical properties of the foam plastics are studied.     

Low-energy electron beam cured tape placement for out-of-autoclave fabrication of advanced polymer composites

The autoclave curing process for advanced polymer composites is labor and capital intensive, with the curing cost increasing dramatically by the growth in part size. In order to develop an out-of-autoclave (OOA) fabrication process for advanced polymer composites, a new process integrating automated tape placement with low-energy electron beam radiation curing was explored, by which in situ layer-wise curing of advanced composites can be achieved with the tape placement process. The irradiation process was optimized to get a homogenous curing, by tuning the electron beam dose-depth distribution in the prepreg material. Besides, the curing characteristics of the prepreg material by the low-energy electron beam irradiation was investigated and effect of exposure dose and post curing on curing degree, glass transition temperature (Tg) and interlaminar shear strength (ILSS) were characterized experimentally.     

聚氨酯/纳米石墨微片复合泡沫塑料的制备及导电性能研究

以聚酯多元醇及二苯甲烷二异氰酸酯为基体,以二月桂酸二丁基锡为催化剂,以纳米石墨微片为导电填料,经过灌模固化反应合成了聚氨酯/纳米石墨微片复合泡沫塑料.并观察了其微观结构,分析了其导电性能,在纳米石墨微片的质量分数为14%时出现了渗滤效应.     

基于因次分析方法的树脂基复合材料等温固化均匀性分析

在复合材料固化过程中,固化度场的非均匀性是引起残余热应力和固化收缩应力的重要因素。为了探讨树脂基复合材料结构件固化成型过程中的工艺参数对固化均匀性的影响,首先针对Epon862/W环氧树脂体系建立了复合材料固化仿真模型,并对模型进行了验证;然后,通过因次分析得出了树脂基复合材料结构件的热传递方程和固化动力学方程的无因次形式;最后,通过数值模拟定量分析了固化工艺温度、对流换热系数和结构件厚度对复合材料固化均匀性的影响规律。结果表明:在等温固化条件下,对流换热系数对复合材料固化均匀性的影响很小,无因次式特征时间t_c/树脂固化反应特征时间t_R与固化度差值间存在拟合函数关系,该函数可以方便地用于工程计算。      

内加热固化环氧玻璃钢管制造系统

为提高环氧玻璃钢管生产的效率和质量,研制了仅用一台机床就能完成管道缠绕、固化和脱膜三道工序的集成制造系统.介绍了制造系统机床结构和工作原理,建立了缠绕运动控制和管道固化过程的数学模型.缠绕部分采用嵌入式多任务运动控制器实现主轴和小车的同步运动控制和缠绕逻辑控制.固化部分采用内加热固化工艺,由嵌入式工控机和PLC实现固化控制.利用有限元软件对管道固化过程的温度和固化度分布进行了数值模拟以优化固化工艺参数,并对该系统生产的管道进行了性能检测试验.实践应用表明采用内加热固化工艺可实现环氧玻璃钢管高效工业化制造.     

Co-cure bonding method for foam core composite sandwich manufacturing

The conventional manufacturing of composite sandwich structures is completed by adhesive joining separately prepared composite faces to cores. The joining process during sandwich fabrication is most difficult process, which requires strict quality control. The joining process can be eliminated when the sandwich structures are manufactured by co-cure method inside a mold using the large coefficient of thermal expansion (CTE) of foam cores.

In this work, the foam core composite sandwich beams were manufactured inside a mold using the pressure generated due to the difference of CTEs between the mold and the foam. Considering the non-linear thermal expansion properties of foam during co-cure manufacturing, the pressure generated inside the mold was analyzed and calculated. In addition, the calculated pre-compression strain was given to the foam core sandwich beams for enough consolidation of the composite faces.     

羧基碳纳米管增强酚醛泡沫的压缩性能及热性能

研究了羧基碳纳米管(CNT-COOH)增强酚醛泡沫复合材料的制备工艺、微观结构、压缩性能和热性能,并结合红外光谱和泡沫在不同压缩应变下的变形破坏形貌,探讨了CNT-COOH对酚醛泡沫的增强机制。结果表明,CNT-COOH作为异相成核剂,使酚醛泡沫泡孔的平均尺寸减小,泡孔密度增大; 随着酚醛泡沫中CNT-COOH含量增加,CNT-COOH/酚醛泡沫复合材料的压缩模量和压缩强度提高。红外分析表明,CNT-COOH可能未与酚醛泡沫发生固化反应。CNT-COOH/酚醛泡沫复合材料在不同压缩应变下的SEM分析表明,CNT-COOH位于泡孔的孔壁上,并通过CNT-COOH/酚醛泡沫的界面传载作用承受了一定载荷,增强了泡沫的力学性能。热重分析和垂直燃烧试验表明,CNT-COOH作为稳定剂,降低了泡沫的热降解速率,使其热稳定性和阻燃性能均略有提高。     

基于多场耦合方法的厚截面复合材料固化过程的多目标优化

针对厚截面复合材料固化过程温度峰值过大所引起的材料力学性能降低及残余应力过大等问题,建立了基于多场耦合方法的复合材料固化过程多目标优化模型,用以降低固化温度峰值和缩短固化时间.首先建立包含热化学子模型、树脂黏度子模型和流动压实子模型的固化温度多场耦合模型,用以准确描述固化过程复合材料内部温度及构件厚度的演化规律.通过与...     

非等温DSC法研究高温固化胶膜的固化动力学

采用非等温DSC法对高温固化胶膜(METLBOND 1515-4)的固化反应热行为以及固化动力学进行了研究,分别利用Kissinger和Ozawa动力学模型计算得到各体系固化反应的表观活化能,分别为90.2kJ/mol、92.7kJ/mol。通过Crane模型计算出固化反应级数,得出了适于该树脂体系固化反应过程的动力学方程。结果表明,体系中只有一种反应,该胶膜的反应级数为0.95。此外,基于得到的动力学参数,结合体系固化反应特点,预测了其固化时间,从而确定了胶膜固化工艺。本文为该环氧胶膜的固化、性能测试和应用提供了理论依据。