膨胀单体改性环氧树脂粘合剂

采用膨胀单体与环氧树脂共聚的方法，可以对环氧树脂粘合剂进行改性，结果发现，膨胀单体的加入减少了固化过程中的体积收缩，有利于提高粘合剂的粘接强度，可制备高强度粘合剂，也可通过控制膨胀单体与环氧树脂的比例，制备有特殊用途的无体积收缩粘合剂。     

一种螺环原碳酸酯膨胀单体的合成及其与环氧树脂热固化

经两步法合成了一种螺环原碳酸酯类膨胀单体,该单体在固化剂三氟化硼乙胺催化作用下,能进行阳离子双开环聚合反应,并讨论了该单体聚合反应机理。采用差示扫描量热(DSC)跟踪环氧树脂及其被膨胀单体改性后的固化反应过程,发现纯环氧树脂存在2个固化反应放热峰,而改性树脂仅有一个反应放热峰。结果表明:膨胀单体和环氧树脂进行了开环共聚反应,膨胀单体的加入能提高环氧基团的转化率。     

一种制备硫化型吸水膨胀天然橡胶的方法

正由海南大学申请的专利(公开号CN104693458A,公开日期2015-06-10)"一种制备硫化型吸水膨胀天然橡胶的方法",涉及的硫化型吸水膨胀天然橡胶(NR)是通过由浓缩胶乳、稳定剂、异丙苯过氧化氢(CHP)/四乙烯五胺(TEPA)引发剂体系、丙烯酸钠的单体溶液、丙烯酰胺单体     

交联型吸水膨胀天然橡胶的吸水性能

以天然胶乳为原料,丙烯酰胺为吸水单体,通过接枝共聚反应制得吸水膨胀天然橡胶(WSNR)。分别以甲醛为单体交联剂,硫磺为天然橡胶交联剂,经过接枝共聚反应制备单体交联型吸水膨胀天然橡胶(WSNR-c)和橡胶硫化交联型吸水膨胀天然橡胶(WSNR-v)。研究了不同交联方式对吸水膨胀橡胶吸水倍率、重复吸水能力和弹性模量的影响,并对吸水膨胀天然橡胶中水的状态、热失重过程和微观形貌进行分析。结果表明：吸水膨胀天然橡胶的吸水倍率、重复吸水恢复率和储能模量随着吸水单体和天然橡胶交联程度的提高而降低;交联处理使吸水膨胀天然橡胶吸束缚水的能力减弱,失水稳定性降低;吸水膨胀天然橡胶经交联处理后体系网络结构致密,孔洞减少。     

膨胀单体研究进展

膨胀单体已成为研究非常活跃的功能高分子材料。介绍膨胀单体的类型、最新研究进展及今后研究方向。     

两种膨胀单体的合成及其对牙科修复树脂的改性

制备了两种螺环原碳酸酯类膨胀单体：3,9-二乙基-3,9-丙烯氧甲基-1,5,7,11-四氧螺杂[5,5]十一烷（BAOM）和3,9-二乙基-3,9-二羟甲基-1,5,7,11-四氧螺杂[5,5]十一烷（DHOM）。分别将其与环氧树脂单体3,4-环氧环己基甲基-3,4-环氧环己基甲酸酯（EE）、牙科树酯单体双酚A甲基丙烯酸缩水甘油酯（Bis-GMA）组成混杂树脂体系,可见光引发聚合固化,考察两种膨胀单体对于树脂聚合收缩、聚合程度及硬度的影响。结果表明经两种膨胀单体改性后,牙科修复树脂的聚合收缩均明显降低,自由基聚合程度较改性前也有明显提高,但改性后的树脂硬度略有下降。     

一种新型膨胀单体预聚物的制备及其改性BDM/DABPA共混体的研究

经两步法合成了螺环原碳酸酯膨胀单体3,9-二羟甲基-3,9-二乙基-1,5,7,11-四氧杂螺环[5.5]十一烷,用2,4-甲苯二异氰酸酯(TDI)与聚丙二醇(PPG)合成端异氰酸酯基的聚氨酯预聚物,并使二者共聚制备新型膨胀单体预聚物.采用红外光谱、核磁共振、元素分析对产物进行了表征.将该膨胀单体预聚物加入到N,N'-(4,4'-二苯甲烷)双马来酰亚胺(BDM)/3,3'-二烯丙基4,4'-二苯丙烷(DABPA)共混体系中,减少了BMI/DABPA体系固化过程中的体积收缩.     

一种新型膨胀单体预聚物的制备及其改性BMI/DABPA共混体的研究

经两步法合成了螺环原碳酸酯膨胀单体3,9-二羟甲基-3,9-二乙基-1,5,7,11-四氧杂螺环[5.5]十一烷,用2,4-甲苯二异氰酸酯(TDI)与聚丙二醇(PPG)合成端异氰酸酯基的聚氨酯预聚物,并使二者共聚制备新型膨胀单体预聚物。采用红外光谱、核磁共振、元素分析对产物进行了表征。将该膨胀单体预聚物加入到N,N’-(4,4’-二苯甲烷)双马来酰亚胺(BDM)/3,3’-二烯丙基-4,4’-二苯丙烷(DABPA)共混体系中,减少了BMI/DABPA体系固化过程中的体积收缩。     

改性吸水树脂的合成及相应吸水膨胀橡胶的性能研究

以丙烯酸（AA）为主要单体、过氧化氢 抗坏血酸为引发体系、甲基丙烯酸缩水甘油酯（GMA）为改性单体合成改性吸水树脂,考察GMA/AA摩尔比对改性吸水树脂及相应吸水膨胀橡胶性能的影响。结果表明：GMA改性对吸水树脂及相应吸水膨胀橡胶的吸水性能有较大影响;当GMA/AA摩尔比为0.02时,吸水膨胀橡胶综合性能最佳,且吸水膨胀过程中吸水树脂析出情况得到明显改善。     

利用疏水性单体对遇水膨胀橡胶进行改性的方法

利用疏水性单体对遇水膨胀橡胶进行改性的方法     

Molecular design of novel network polymers

Cationic, anionic, and radical ring-opening polymerization of spiro and bicyclic monomers, and their application to network polymers have been developed. Bicyclo orthoesters (BOEs), spiro orthoesters (SOEs), and spiro orthocarbonates (SOCs) were polymerized by cationic double ring-opening. Bicyclobis(γ-butyrolactone)s and spirobis(γ-butyrolactone)s were copolymerized with epoxides by anionic alternating ring-opening. Polymers from SOCs bearing exomethylene groups consisted of ring-opened and vinyl polymerized units. The degree of ring-opening of SOCs depended upon the number of rings and steric hindrance. The radical polymerization of vinylcyclopropanone cyclic acetals depended on the ring-size. With the monomers bearing 5- and 6-membered acetal rings, single ring-opened polymers were obtained. With the monomer bearing 7-membered acetal ring, the polymer mainly consisted of double ring-opened unit. These monomers could be crosslinked by bifunctionalization. Poly(cyclic orthoester)s linked by covalent bonds with dithiols to bifunctional SOEs were crosslinked by acid catalysts, and the reversible crosslinking-depolymerization system could be controlled by temperature.     

Preparation and Properties of Thermoplastic Expandable Microspheres With P(VDC-AN-MMA) Shell by Suspension Polymerization

Thermoplastic expandable microspheres (TEMs) having core/shell structure were prepared via suspension polymerization with vinylidene chloride (VDC), acrylonitrile (AN), and methyl methacrylate (MMA) as monomers and i-butane as blowing agent. TEMs were about 20 µm in diameter and had a hollow core containing i-butane. The influence of the monomer feed ratio and blowing agent content was researched. When the monomers composition of 58.4 wt% VDC, 28 wt% AN, 13.6 wt% MMA, and 32 wt% i-butane in oil phase, suspension polymerization could yield TEMs having good expansion properties. The maximum expansion volume was 25 times of original volume at about 111–120°C, the blowing agent content in microspheres was about 21.5 wt%. The T_m.e, T_o.e, and T_o.s. of the TEMs increased with the VDC content in the polymerizable monomers decreasing.     

Preparation of porous cordierite ceramic by gel-casting method

Porous cordierite ceramics were synthesised by gel-casting method, using talcum powder, kaolin and alumina as raw materials. Organic monomers and cross-linker were used as additives. The phase composition and microstructure were investigated by X-ray diffraction and scanning electron microscope. The open porosity, compressive strength and thermal expansion coefficient were tested by the Archimedes method, universal testing machine and thermal expansion instrument, respectively. The results indicate that sintering temperature and holding time have a great influence on the cordierite properties. We obtain the good performance of porous cordierite ceramic sintering at 1350°C for 3?h. The cordierite phase content in the sample is higher and the crystallinity is better. At this point, the porosity is 58.53%, the compressive strength is 22.44?MPa and thermal expansion coefficient reaches 1.69?×?10^?6?°C^?1.     

管壳式换热器中管子和管板的胀接

详细介绍管壳式换热器中管子和管板的各种胀接方法包括机械胀接、爆炸胀接、液压胀接和胀接等。     

Study on the volumetric expansion of benzoxazine curing with different catalysts

A systematic investigation on the volumetric expansion of four benzoxazine systems, which are benzoxazine, benzoxazine/tertiary amine, benzoxazine/organic acid, and benzoxazine/epoxy resin/tertiary amine, was done. By using gravitometric and dilatometric methods, etc., studies on volumetric shrinkage, isothermal cure shrinkage, and density versus cure time plots were done. The cure reactions of these benzoxazines were carried out at 140 and 160°C. The results show that all benzoxazine systems exhibit apparent volumetric expansion after polymerization, that is, the densities of monomers are larger than are those of polymers at room temperature. But, meanwhile, they exhibit volumetric shrinkage while curing isothermally. The results also show that the higher the cure temperature is, the larger the cure shrinkage of the benzoxazines will be and that the extent of the cure shrinkage of the benzoxazines with the aid of catalysts is larger than is that of thermal polymerization systems. The reason for this is that, accelerated by catalysts, the polymerization rate become faster and the extent of polymerizatiom becomes larger. It is obvious that catalysts can make a notable impact on the cure reaction of benzoxazines. Therefore, the dimension of the volumetric expansion of benzoxazine is associated with its polymerization mechanism, molecular structure, and extent of polymerization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1107–1113, 2002; DOI 10.1002/app.10267     

自然补偿器的设计和应用

文章主要介绍了自然补偿器的设计和应用。通过对配管设计等原则进行了分析和探讨,便于更好地掌握自然补偿的技术。     

膨胀剂对混凝土抗裂防渗的贡献

通过常规实验和基础实验，采用对比的方法，研究了膨胀剂的适宜掺量和对水泥砂浆强度的影响。结果表明，加入膨胀剂能补偿部分收缩，有效抑制或减少裂缝的产生，提高混凝土的耐久性；试验条件下试验所用膨胀剂的适宜掺量应小于6％：对补偿收缩混凝土，其限制膨胀率应作为第一性指标。     

Novel diol spiro orthocarbonates derived from glycerol as anti‐shrinkage additives for the cationic photopolymerization of epoxy monomers

Shrinkage that takes place during polymerizations induces internal stress in polymeric materials generating a series of problems like poor adhesion to substrates and delamination in coatings or microcracks and microvoids in composites. Some additives like spiro orthocarbonates can reduce or eliminate this shrinkage. This paper deals with the synthesis of novel diol spiro orthocarbonates (DIOL SOCs) and their effect as anti‐shrinkage additives in the photopolymerization of the monomer 3,4‐epoxycyclohexyl‐3′, 4′‐epoxycyclohexanecarboxylate. It was found that increasing the concentration of the DIOL SOCs resulted in higher conversion of the monomer due to the presence of hydroxyl groups. The viscoelastic properties of the polymer products were also measured. It was observed that at 5 mol% of the mixture of DIOL SOCs there was an increase in the storage modulus due to the crosslinking produced by the bifunctional SOCs. However, at higher concentrations, a decrease in the storage modulus was observed. The level of shrinkage using the DIOL SOCs at 20 mol% was reduced by 45% when compared to the case without any additive. DIOL SOCs can be easily prepared by reacting glycerol with tetraethylorthocarbonate. These additives reduced significantly the level of shrinkage of the polyether derived from the diepoxycyclohexane monomer. Copyright © 2010 Society of Chemical Industry     

换热器换热管与管板的胀管技术

介绍不同材料胀管连接使用的温度及压力范围，分析了影响胀接强度及密封性能的主要因素，对机械胀接法与液压胀接法中的特殊要求进行了说明。     

立式带膨胀节换热器轴向膨胀计算

利用静力学对带有膨胀节的立式换热器轴向膨胀计算方法进行了探讨，分别考虑热膨胀、内压等因素引起轴向伸长和重力导致的轴向变形。通过算例对各影响因素的作用效果进行比较。结果表明，热膨胀是主要因素，其他因素影响在总变形量的5％以内。