正丁酸封端的超支化聚酯改性环氧树脂的性能研究

设计并合成了一种以正丁酸为柔性链封端的超支化聚酯树脂(flexible chain blocking hyperbranched polyester,FCBHBP),并用其改性环氧酸酐树脂,结果表明,FCBHBP对环氧树脂具有增韧、降低介电常数和介电损耗的作用。通过核磁谱图(NMR)和傅里叶红外光谱图(FT-IR)表征FCBHBP分子的超支化结构;通过力学性能测试发现FCBHBP对环氧酸酐固化物有明显的增韧作用,当FCBHBP用量为环氧树脂的20%(质量分数)时,改性的环氧酸酐固化物的冲击和弯曲强度分别为未改性环氧酸酐固化物的160%和117%;通过介电性能测试发现,FCBHBP可以利用自由体积降低环氧树脂介电常数,同时可以利用柔性链与环氧树脂中极性官能团的相互作用在一定频率内降低介电损耗。     

液体聚硫聚脲增韧环氧树脂形态结构的研究

以液体聚硫聚脲齐聚物来增韧环氧-聚酰胺体系,用DMTA和SEM研究了固化后环氧树脂的形态结构、相分离程度和增韧效果．结果表明,液体聚硫聚脲齐聚物的用量、齐聚物中聚脲含量对固化后的环氧树脂玻璃化温度、模量及形态有较大影响。随增韧剂中聚脲含量的提高,固化物的玻璃化温度、相分离程度及模量增加,同时固化物韧性增加。     

TiO2紫外光固化新型涂料的研制

制备出双酚A类环氧丙烯酸酯齐聚物,并用马来酸酐进行改性,配制成紫外光固化新型涂料,考察了涂膜性能;研究了涂料成分中用TiO2作颜料,光敏剂二苯甲酮对紫外光固化树脂性能的影响.结果表明:马来酸酐改性的环氧丙烯酸酯树脂涂料对金属有较好的附着力,显示了较好的流平性;涂料中增加TiO2,其对金属的附着力有所增加;使用光敏剂增加了涂料的光洁度.     

环氧树脂增韧技术进展

环氧树脂是一种优良的基体材料,广泛用于低温工程、航空航天、绝缘材料等领域。但是环氧树脂固化后自身脆性大、韧性差,所以提高环氧的韧性是使其适用于工业的基本需求。笔者主要对环氧树脂几种常用的增韧方法,包括刚性粒子增韧、橡胶弹性体增韧、互穿网络增韧、热塑性树脂增韧等的研究进展进行评述,并对其研究应用前景进行了展望。     

高温固化树脂的增韧设计

本文综述了热塑性树脂对于环氧树脂、双马树脂和氰酸酯树脂等高温固化体系的增韧改性研究工作.热塑性树脂增韧设计的方法之一使用带反应性官能团的热塑性树脂,以期望热塑性增韧剂能够参与固化体系的反应.另一种增韧设计的方法是通过热塑性树脂在热固性树脂体系中以各种各样的分布方式来获得显著的增韧效果,例如“层间增韧”和“离位增韧”技术.对于这些增韧技术的不断探索与改进,有助于获得在高低温环境下都具有良好韧性的热固性材料.     

水分散型水性环氧涂料的制备

目前水性环氧涂料以亲水性的固化剂为主,它们与树脂之间的相溶性不好,直接影响了涂料的固化成膜和涂层性能.为此,制备了固化剂为水分散型的水性环氧涂料,研究了其固化机理,重点讨论了不同用量的水和成膜助剂对涂料性能的影响.结果表明:环氧-水分散型固化剂涂料中的加水量对体系的黏度影响不大,而环氧-亲水性固化剂涂料中的加水量对体系的黏度影响较大;成膜助剂2,2,4-三甲基戊二醇-1,3单异丁酸酯(TEXANOL)的加入可以显著降低乳液的最低成膜温度,并可取得较好的成膜效果.研制的水性环氧涂料具有较好的综合性能.     

芳香族聚醚型超支化环氧对双酚A型环氧的增韧研究

通过质子转移聚合,采用双酚A和三羟甲基丙烷三缩水合成了一种芳香族聚醚型超支化环氧(EHBP),将其添加到双酚A缩水甘油醚型环氧(DGEBA)中制备成杂化树脂进行增韧改性。采用酸酐固化后,利用差示扫描量热仪(DSC)和热重分析仪(TGA)对固化树脂的玻璃化转变温度和热稳定性进行了表征,并对其拉伸强度、弯曲强度和冲击强度进行了测试。结果表明向DGEBA中添加EHPE可以在不影响材料热性能和拉伸强度的情况下改善其韧性。在EHBP添加量为15%时,材料的冲击强度由纯DGEBA的19kJ/m2提高到28kJ/m2。扫描电子显微镜对材料冲击断面的形貌的表征表明,EHBP对环氧树脂的增韧机理为原位均相增韧。     

一种长侧链取代液晶环氧单体的酸酐固化与性能

采用非等温差示扫描量热法(DSC)研究了一种长侧链取代液晶环氧单体与甲基六氢苯酐的固化反应历程,考察了体系的固化反应动力学特征.并通过POM、WAXD、SEM、TGA和DMA 等对其等温固化产物的相结构、热性能和动态力学性能等进行表征和分析.结果表明,侧链的存在使其固化反应具有良好的可控性.固化反应活化能为77.8 kJ/mol,固化反应后期为扩散控制.液晶环氧单体经固化后呈向列相,其力学和耐热性能优良,韧性也得到明显改善.     

阳离子型水性丙烯酸涂料的耐腐蚀性能研究

为了解硅氧烷水解物固化阳离子型水性丙烯酸涂料的耐腐蚀性能,使用硅氧烷水解物WKHY-601固化含叔胺基的阳离子型水性羟基丙烯酸树脂分散体制得水性金属防腐涂料,采用DSC、TGA、FT-IR和CHI660E电化学工作站等手段研究了涂料的固化机理和影响其耐盐腐蚀性的主要因素.结果表明:涂料的固化由硅羟基和树脂中的醇羟基发生...     

聚乙二醇改性物对高交联度不饱和聚酯的增韧改性

合成了一种含有反应活性端基的聚乙二醇,并用之对高交联度不饱和聚酯进行增韧。结果表明,含有反应性马来酸酐端基的聚乙二醇参与了不饱和聚酯的固化反应,可在交联网络中构成不同长度的柔性链段,从而显著地提高了不饱和聚酯的韧性。将其应用于BMC材料的增韧也获得了满意的增韧效果。     

Impact of corrosion on low-cycle fatigue degradation of reinforcing bars with the effect of inelastic buckling

The combined effect of inelastic buckling and chloride induced corrosion damage on low-cycle high amplitude fatigue life of embedded reinforcing bars in concrete is investigated experimentally. A total of forty-eight low-cycle fatigue tests on corroded reinforcing bars varied in percentage mass loss, strain amplitudes and buckling lengths are conducted. The failure modes and crack propagation are investigated by fractography of fracture surfaces using scanning electron microscope. The results show that the inelastic buckling, percentage mass loss and nonuniform corrosion pattern are the main parameters affecting the low-cycle fatigue life of reinforcing bars. It was found that the fatigue life of corroded reinforcing bars combined with inelastic buckling has a significant path dependency. The results show that in some cases the number of cycles to failure of corroded bars under constant amplitude fatigue test is increased.     

Pullout tests of epoxy-coated reinforcement in concrete

The bond strength and slip of epoxy-coated reinforcing bars in concrete have been evaluated by carrying out single pullout and double pullout tests. In extended single pullout tests, slip measurements were made while tensile force was applied to reinforcing bars embedded in concrete. In double pullout tests, 20 cycles of load were applied at levels of steel stress between zero and 0·5 times characteristic steel strength. Strains were measured by electrical resistance strain gauges glued inside the bars. Both epoxy-coated and uncoated bars were used in the investigation, to obtain comparative results. The strain gradient along the bar was found to be less for the coated reinforcement. In general, the epoxy coating was found to increase slip in bond and thereby reduce the bond performance of coated bars.     

水性环氧聚氨酯富锌涂料的防腐蚀性能研究

为制得环保且防腐蚀性能优异的富锌涂料,引入环氧树脂来改性水性聚氨酯,以水性环氧聚氨酯为基料制备富锌涂料,通过对其腐蚀电位和电化学阻抗谱(EIS)的测试分析,研究了添加不同含量锌粉的富锌涂层在3%NaCl溶液中的腐蚀电化学行为,并与添加少量铝粉的富锌涂料及传统富锌涂料进行了对比.结果表明,水性环氧聚氨酯富锌涂料的防腐蚀能力比传统环氧富锌底漆强;锌粉的添加量对涂层的防腐蚀效果有一定的影响,添加少量铝粉能提高涂层的防腐蚀性能.     

聚邻氯苯胺-纳米SiC/环氧树脂复合材料的制备与防腐性能

导电聚合物在金属腐蚀领域存在着潜在的应用前景。为获得防腐性能良好的聚邻氯苯胺(POCl)-nano SiC/环氧树脂复合材料,利用原位聚合法制备了盐酸掺杂态POCl-nano SiC复合改性材料。通过FTIR、UV-vis、XRD、TGA、XPS和SEM等分析手段对其结构、组成和形貌进行了表征。以POCl-nano SiC复合改性材料为填料,环氧树脂为成膜物质,在碳钢表面制备了POCl-nano SiC含量为3wt%、5wt%和8wt%的POCl-nano SiC/环氧树脂复合涂层,并通过SEM对涂层的断面形貌进行了观察。利用Tafel极化曲线和电化学交流阻抗谱研究了涂层在3.5%NaCl溶液中的防腐性能。结果表明,POCl-nano SiC填充量为5wt%的POCl-nano SiC/环氧树脂复合涂层表现出较好的抗腐蚀性能,其腐蚀速率为2.78×10-3 mm/y,腐蚀保护效率高达90.45%。表明适量的POClnano SiC作为环氧树脂涂层的增强相,降低了涂层的孔隙缺陷,在腐蚀介质刺激下,能够在碳钢表面形成钝化保护层。Nano SiC粒子在涂层中充当着类似栅栏结构的屏障,从空间结构上阻止了气体分子和腐蚀溶液向金属基底的渗透。     

Bond fatigue of epoxy coated reinforcing bars

This paper reports the findings of a study concerning bond fatigue of epoxy coated reinforcing bars in comparison to that of normal mill scale bars and blast cleaned bars. There were two principle objectives of the series of fatigue tests. The first was to determine whether the bond-slip performance of epoxy coated reinforcement is significantly different from that of normal mill scale bars and blast cleaned bars when subjected to numerous cycles of loading in a working stress range. The second was to determine whether the static bond strength of epoxy coated reinforcement is significantly different from that of normal mill scale and blast cleaned bars after being subjected to numerous cycles of loading in a working stress range. The test results indicate no detrimental influence of the epoxy coating in relation to bond fatigue. The static bond strength of epoxy coated bars without cyclic loading was found to be slightly less than that of mill scale bars.

---

Résumé On décrit les résultats d'une étude sur l'adhérence en fatigue de fers d'armature revêtus de résine époxy en comparaison avec des fers calaminés et des fers décapés. Le premier objectif de ces séries d'essais de fatigue était de déterminer si la performance adhérence glissement des armatures revêtues d'époxy est notablement différente de celle des fers calaminés décapés soumis à un grand nombre de cycles de charge dans un domaine de contrainte utile. Le second objectif était de déterminer si l'adhérence statique des fers revêtus d'époxy est notablement différente de celle des fers normaux après avoir été soumis à un grand nombre de cycles de chargement dans un domaine de contrainte utile. Les résultats d'essai n'indiquent pas d'influence nuisible du revêtement époxy par rapport à l'adhérence en fatigue. On a établi que l'adhérence statique des fers revêtus d'époxy était légèrement moindre que celle des barres calaminées en l'absence de sollicitations cycliques.

     

涂料盐雾试样的勘误方法研究

在盐雾试验的基础上,对涂料试样提出了2种拓展考察的方法:残余附着力测试和划"×"处金属腐蚀状态勘验。在高氯化底漆+高氯化面漆、环氧底漆+高氯化面漆、环氧底漆+工程面漆和高氯化底漆+工程面漆等不同的涂料体系,通过试验得出了高氯化涂料具有突出的封闭阻挡性能,但涂层发脆。工程面漆与底漆粘附力较差,环氧底漆具有突出的基体附着力,与高氯化面漆配合,是性能优良的防腐涂料体系。     

Efficiency of coatings applied on rebars in concrete

The performance of three reinforcing steel bars (rebars) coatings is analyzed by means of electrochemical methods. The coatings are representative of those commonly used during the repair of concrete structures affected by corrosion in the coastal regions of Argentina: an epoxy rust conversion coating, a zinc-rich epoxy, and a sprayed zinc coating. Two exposure conditions were investigated: immersed in a saline solution (wet) and exposed to an indoors atmosphere (dry). The rebar corrosion potential (E_corr), the corrosion rate (CR) and the electrical resistance (R) between bars were measured during approximately 800 days. In the dry condition the three coatings presented a satisfactory performance characterized by passive E_corr values and CR values lower than 1 m/year. On the other hand, the performance of the coatings in the wet condition depended on their formulations. The rust conversion coating showed active E_corr values and CR values higher than those measured on the uncoated bars. The zinc-rich epoxy and the sprayed zinc coatings presented E_corr values typical of active zinc. This indicates a certain degree of cathodic protection provided to the reinforcing steel. Besides, R values showed that in this condition, coatings do not provide a barrier type of protection.     

一种可剥性气相防锈涂料的研制

一般的可剥性涂料成膜后所形成的涂层较脆,不能够大面积剥离,在金属防锈方面比较差,更不具有对金属气相防锈的功能.研制了一种能在常温下快速成膜的可剥性气相防锈涂料,所形成的涂层具有优良的柔韧性和耐冲击强度,能够大面积地进行剥离.提出了涂料的最佳配方为:乙烯基高分子树脂100.0 g,复合型油溶性气相缓蚀剂13.3 g,环氧树脂6101 10.0 g,增韧剂(邻苯二甲酸二丁酯)25 mL,稳定剂(二月桂酸二丁基锡)0.5 g,抗氧剂B215 0.5 g,润滑油2 mL,混合溶剂700 mL.结果表明,这种涂料对金属具有一定的防锈性能和浸泡性能,喷涂于金属表面可有效地提高金属产品的防锈性能.     

锈蚀RC桥梁弯曲抗力时变概率模型与试验研究

在退化RC结构的时变性能评估、剩余寿命预测以及维修加固决策分析中,其抗力模型的建立至关重要。钢筋锈蚀导致钢筋的屈服强度降低、改变钢筋力学行为和影响钢筋与混凝土之间的粘结行为。钢筋腐蚀损失量影响钢筋的失效模式,即从延性破坏到脆性破坏变化。该文发展了退化RC 桥梁的概率抗力时变模型,可以定量考虑腐蚀对钢筋力学行为、倒塌机理和粘结性能的影响。建立退化结构的抗力概率模型可以抓住退化结构的退化机理、点蚀分布、结构尺寸参数、粘结行为、腐蚀扩展、钢筋失效模式和计算模型的随机性和变异性。RC 梁的加速腐蚀试验和旧桥的破坏性试验验证了该文模型的正确性和可靠性。     

Evaluation of the Mechanical Properties of Reinforcing Steel Bars from Collapsed Building Sites

Mechanical properties of reinforcing steel bars obtained from three different collapsed building sites in Lagos, Nigeria were examined. An optical emission spectrometer was used for chemical composition analysis while the tensile test was carried out using a Universal Testing Machine. The yield strength of the steel bars was found to be higher than BS4449 (GRADE 460B), Nst.65-Mn, and ASTM A706 standards, while their percentage elongations were lower than most of the standards. The steel bars used at the Sango collapse site have higher UTS compared with the standards, while those used at Ilesanmi and Ewuntun collapse sites have UTS values that are in close range with the standards. The reinforcing bar obtained from Ilesanmi collapsed site has higher percentage elongation than ASTM A706 standard but lower than Nst.65-Mn and BS4449 (GRADE 460B) standards. The bars obtained from Sango and Ewuntun collapse sites displayed lower percentage elongation compared with that from Ilesanmi site. All the investigated reinforcing bars possessed reasonably high strength with low ductility. Thus, these bars are susceptible to brittle fracture, which might have contributed to the collapse of the building structures.