高邻位热塑性酚醛树脂的微波合成装置及实践

结合基础化学实验室的实际情况,以家用微波炉为基础,设计改装了一套能初步适用于高邻位热塑性酚醛树脂连续化试验的微波合成装置.利用此装置,合成出壳法用高邻位热塑性酚醛树脂.结果表明,与传统加热相比,采用微波合成其聚合及脱水时间分别缩短了95.5%和79.2%左右.     

微波辐射下壳法用高邻位酚醛树脂的合成

在传统加热合成高邻位壳法用酚醛树脂的基础上,就催化剂类型、微波功率及辐射时间等对微波辐射下树脂合成的影响进行了研究.结果表明:在微波辐射下,采用某类二价金属弱酸盐催化,可在相当短的时间内获得具有强烈邻位联接特征的壳法用高邻位酚醛树脂,与传统加热相比,微波辐射具有回流温度高,反应速度快,合成时间短的特点.     

铸造用热塑性酚醛树脂的研究进展

简述了铸造用热塑性酚醛树脂的的发展过程及研究现状.介绍了热塑性酚醛村脂的合成机理及不同催化剂对树脂合成的影响及高邻位热塑性酚醛树脂的特点.讨论了酚醛树脂的固化机理及不同固化促进剂对固化聚合速度的影响.概述了酚醛树脂用聚酰胺、橡胶、蒙脱土和环氧树脂的改性研究进展,并对热塑性酚醛树脂的发展方向进行了展望.     

专利摘要

正140801含有乌洛托品硬化剂的酚醛树脂覆膜砂的制备[欧洲]JP2011021093,2011.02.03,Ide Isamu.Lignyte Co.Ltd.[日本]酚醛树脂的价格较低,固化后的耐热性和力学性能都很好,在壳型铸造中得到了广泛的应用。但是,热塑性酚醛树脂加热时不会固化,只有加入乌洛托品才能固化。加入热乌洛托品能分解出醛和氨,污染作业环境,为了改善作业环境,必须降低树脂和乌洛托品的加入量。本专利提供一种将乌洛托品在树脂合成时加入树脂中,可免去在树脂覆膜时单独加乌洛托品的工序,从而缩短了树脂覆膜周期,提高了它的质量。具体办     

高性能壳法用酚醛树脂的微波合成

针对双酚A改性酚醛树脂固化速度慢的缺点,研究了复合催化和水杨酸改性对树脂微波合成的影响.结果表明,在微波作用下,先用某类二价金属弱酸盐A,再用草酸进一步催化,并结合双酚A及水杨酸改性,可得到高强度、低游离酚、快固化的高性能壳法用酚醛树脂.     

壳法用酚醛树脂粘连现象的研究

传统方法合成的壳法用热塑性酚醛树脂在高温高湿环境中存放，会出现粘连现象，其使用性能会受到不利影响。为此，利用红外光谱（IR）分析了壳法用热塑性酚醛树脂出现粘连现象的原因，证实在高温高湿的环境中，树脂中的活性点吸引空气中的水分到树脂体系中，使得树脂分子链之间的作用力减小，相互之间可以滑移，在宏观上表现为粘连。为降低热望性酚醛树脂的粘连倾向，尝试进行了用磷酸为树脂合成组分的试验，结果表明，磷酸不仅可以作催化剂以调整体系的pH值，同时还可以和树脂中的酚羟基发生反应，减少树脂中能够吸引水分的活性点，在磷酸用量适当的条件下，可获得分子量分布窄、抗粘连性能较好、强度足够的热塑性酚醛树脂，并且该树脂的粘连温度与其软化点无明显关系。     

双酚A改性热塑性酚醛树脂微波合成的研究

在微波合成的基础上，研究不同双酚A（BPA）加入量对热塑性酚醛树脂性能的影响，并对树脂的分子结构进行分析。结果表明：尽管双酚A的加入导致对位联结量增多而降低了树脂聚合速度，但在适当的加入量范围内，可使游离酚含量大幅度降低的基础上，树脂流动性、韧性以及覆膜砂强度等得到综合改善。     

耐温抗烧蚀酚醛树脂的合成及其性能研究

采用硼酸、有机硅预聚物对酚醛树脂进行化学改性,合成出具有较好耐温抗烧蚀性能的硼硅改性酚醛树脂。利用FT-IR对合成树脂的结构进行分析,结果表明,树脂分子链中含有硼氧基团和硅氧基团,具有明显的高邻位树脂结构。利用TGA和氧指数仪对树脂的耐热性和阻燃性进行分析,结果表明：合成的硼硅改性酚醛树脂具有优异的耐热性,固化后的改性酚醛树脂在800℃下的残重可达79％;同时,改性酚醛树脂具有良好的阻燃性,临界氧指数达46．8％,高于绝大部分热固性和热塑性树脂。     

铸造用酚醛树脂聚合速度的影响因素研究

探讨了酚醛摩尔比、固化温度、固化剂加入量、酚含量以及促进剂加入量对酚醛树脂的聚合速度的影响。结果表明:酚醛摩尔比在可以合成热塑性酚醛树脂的前提下,随着树脂酚醛摩尔比的增大聚合速度加快,最佳酚醛摩尔比为0.73;固化温度升高可以提高聚合速度,最佳固化温度为150℃;固化剂加入量增大也可以加快酚醛树脂的聚合速度,最佳加入量为10%;酚含量在2.5%时聚合速度最快;四种促进剂均可以不同程度地加快酚醛树脂的聚合速度,其中二甲基咪唑对树脂的促进作用最好。     

以累托石/酚醛树脂纳米复合物制备β-Sialon粉末

采用熔融插层的方法将热塑性酚醛树脂插入累托石的层间形成累托石/酚醛树脂纳米复合物,以其为前驱体,在流动的氮气中加热,利用酚醛树脂在累托石层间热解所得的炭作为反应的还原剂,以制备β-Sialon粉末.研究了合成温度、前驱体中酚醛树脂的含量对合成产物的影响,结果表明以累托石/酚醛树脂纳米复合物为前驱体能制备出几乎不含氧化物杂质的β-Sialon粉末.     

微波辐射时间对木质陶瓷导电性能影响的研究

以烟杆和酚醛树脂为原料,采用微波辐射制备了高导电性能的烟杆基木质陶瓷。同时,研究了微波辐射时间对木质陶瓷体积电阻率的影响,并采用X射线衍射技术、激光喇曼光谱和扫描电镜对其微观结构进行了研究。实验结果表明:与常规加热制备木质陶瓷相比,采用微波辐射的方法可将制备时间缩短99.4%。当微波辐射时间为80s时,木质陶瓷的体积电阻率仅为0.97Ω·cm。通过样品XRD谱图和激光喇曼谱图的分析,随着微波辐射时间的延长,样品有序化程度的提高,根据Tuinstra-Koening经验公式计算所得的石墨微晶面网直径La与通过XRD图谱计算得到的值相近。通过SEM观察可知,当微波辐射时间达到80s时,样品中由酚醛树脂形成的玻璃炭与由烟杆炭形成的无定形炭已融合为一个整体,呈多孔状。     

Preparation of montmorillonite modified phenolic resin for shell process

The development of montmodllonite modified phenolic resin under microwave irradiation heating was investigated. The effect of montmorillonite content and stirring time on the structure and morphology of synthetic resin was analyzed. The optimum processing procedure was found to be 45 rain stirring time with 5.4% montmorillonite addition. Further, the platelet spacing increases with stirring time till montmorillonite exfoliated to nanoscales platelet. When montmorillonite is exfoliated, layered structure at nanoscale can be uniformly distributed in the resin. The overall performance of montmorillonite modified phenolic resin is improved remarkably, such as flow ability, tensile strength and toughness property of resin coated sand. However, the gelation speed decreased slightly by adding montmorillonite.     

Influence of microwave irradiation on the preparation of novolacs for the shell process

1. IntroductionThe shell process is unique in its ability to makeexcellent reproducible castings with better surface finishand dimensional accuracy than castings made of othersand processes. It is also simpler to operate than many ofother casting processes [1-3]. Therefore, it has been widelyused in the foundry industry and presents a promisingfuture. In recent years the application of shell process inChina has been greatly increased and novolacs consumedin this process are up to tens of thou…     

Research on Properties of Carbon Fiber/Epoxy Resin Composite Material by Microwave Curing

Microwave irradiation was used to reduce the curing time of carbon fiber/epoxy resin composite material.The properties of carbon fiber/epoxy resin composite material under microwave curing were investigated by thermogravimetry(TG),dynamic mechanical analysis(DMA),impact strength test and scanning electron microscope(SEM).The results show that composite materials patch have high thermal stability after microwave curing.The initial degradation temperature is 330.9℃,the maximum thermal decomposition rate is at 368.1℃.When the layer of composite materials patchis 4 layers,the dynamic mechanical properties are the best after microwave curing.The initial storage modulus is 43.2 GPa,increased 28.3 GPa and 27.1 GPa than 3 layers and 5 layers,the glass transition temperature(Tg)is 67.48℃,increased about 12 ℃than 3 layers and 5 layers.Microwave curing can significantly improve the infiltration capacity of epoxy resin,enhance interfacial bonding,and increase the impact strength of composite patch.Under microwave curing,the impact strength of 3,4,5-layers composite material patches increases 35.9%,6.4% and 15.1%,respectively than heating curing.The SEM analysis of impact fracture surface shows that microwave curing can improve the interface of carbon fiber and epoxy resin.     

纳米银对环氧树脂的增韧改性及其微波固化行为

在80℃双酚A型环氧树脂E-51中,通过还原原位构筑了超分散稳定纳米银(n-Ag);用冷冻蚀刻电镜、离心实验对其进行表征和分散稳定性评价;用间歇微波对分散系中n-Ag的微波吸收特性和环氧树脂的微波固化行为进行研究;通过拉伸试验和冲击试验考察n-Ag对环氧树脂的增韧改性行为。结果表明:银为30nm的粒状颗粒,大小均匀,有理想的分散稳定性;n-Ag对环氧树脂有显著地增韧作用,当其含量为2.0%～2.5%(质量分数)时,增韧改性效果最佳,复合材料的断裂伸长率可提高l10%～130%;原位合成n-Ag有良好的微波吸收特性,它的存在能明显减少环氧树脂的微波固化时间,当n-Ag含量超过2.5%时,微波固化时间可缩短38%;微波固化环氧树脂速度比传统加热固化速度快数倍,其抗拉伸强度和抗冲击强度也好于热固化,但拉伸断裂伸长率比热固化的小。     

超声辐照对碳纳米管增强环氧树脂黏度和力学性能的影响

采用超声辐照处理多壁碳纳米管增强环氧树脂复合材料,分析了超声辐照条件对复合材料的黏度、力学性能及拉伸断口显微形貌的影响。结果表明:温度一定时,多壁碳纳米管增强环氧树脂体系的黏度随超声辐照时间的延长而逐渐降低;超声辐照时间为5min时,环氧树脂的拉伸强度、弯曲强度、拉伸剪切强度达到最大值,较处理前分别提高了37%,167%和86%;经超声辐照后,拉伸断口形貌显示出更多的韧性断裂特征。     

Kinetics of the reactions of carbon containing zinc oxide composites under microwave irradiation

As a fundamental study for the recycling of EAF dust using microwave heating, the reduction rate of a zinc oxide composite by solid carbon under microwave irradiation was investigated. It was found that the reduction of zinc oxide by solid carbon under microwave irradiation was much faster than the conventional method, and the activation energy for the reaction under microwave irradiation was estimated to be 335 kJ/mol.     

纳米复合材料Ag/TiO2微波辅助合成与光催化性能

采用EO20PO70EO20(P123)作为模板剂,通过溶胶-凝胶-程序升温溶剂热一步法并经不同时间微波辐射处理,制备了一系列纳米复合材料Ag/TiO2。采用XRD、XPS、TEM、N2吸附-脱附测定和SEM-EDS等测试手段对其组成、结构及形貌等进行表征。结果显示,微波辐射5min制备的Ag/TiO2晶型结构最佳,该产物中Ag以单质形式存在,其比表面积可达100.64m2·g-1,平均孔径约为6.9nm。与未经微波辐射样品相比,其颗粒细小、结构规则、分布均匀、无明显团聚现象。以甲基橙为模型分子,考察经不同时间微波辐射处理的纳米复合材料Ag/TiO2的紫外光催化活性。结果表明,在微波功率为200W,微波时间为5min时获得的Ag/TiO2的催化活性最高,循环使用3次后降解率仍能达到80%以上。     

Fiber Reinforced Polyester Resins Polymerized by Microwave Source

Polyester resin based composite materials are widely used in the manufacture of fiberglass boats. Production time of fiberglass laminate components could be strongly reduced by using an intense energy source as well as microwaves. In this work a polyester resin was used with 2% by weight of catalyst and reinforced with chopped or woven glass fabric. Pure resin and composite samples were cured by microwaves exposition for different radiation times. A three point bending test was performed on all the cured samples by using an universal testing machine and the resulting fracture surfaces were observed by means of scanning electron microscopy (SEM). The results of mechanical and microscopy analyses evidenced that microwave activation lowers curing time of the composite while good mechanical properties were retained. Microwaves exposition time is crucial for mechanical performance of the composite. It was evidenced that short exposition times suffice for resin activation while long exposure times cause fast cross linking and premature matrix fracture. Furthermore high-radiation times induce bubbles growth or defects nucleation within the sample, decreasing composite performance. On the basis of such results microwave curing activation of polyester resin based composites could be proposed as a valid alternative method for faster processing of laminated materials employed for large-scale applications.