Microencapsulation of oil soluble polyaspartic acid ester and isophorone diisocyanate and their application in self-healing anticorrosive epoxy resin

Isocyanate and amine solution are microencapsulated, respectively, via in situ polymerization to realize the self-healing function in epoxy matrix. First, the isophorone diisocyanate (IPDI) microcapsules prepared with different core/shell ratios, emulsifier dosages and emulsification rates are characterized by field emission scanning electron microscope (FE-SEM). They exhibit integral spherical shape when the core/shell ratio is 3:1 and emulsifier concentration is 2.52 wt %, and the diameter of IPDI microcapsules ranged from 2.66 μm to 11.25 μm is manufactured by adjusting emulsification rate over the range of 3000–9000 rpm. Besides, during the microencapsulation of polyaspartic acid ester (PAE), urea, tung oil, as well as aqueous isocyanate are proposed to improve the stability of PAE emulsion. SEM and FTIR results reveal that aqueous isocyanate can react with partial PAE and form polyurea (PU) layer to take protection effectively. Further, IPDI-PAE dual microcapsules are incorporated into epoxy coatings, the self-healing and anticorrosion performance of coatings with various amounts of microcapsules are investigated systematically. It was found that the degree of repair and anticorrosion are increased with increasing microcapsules loading, and the appropriate amount of microcapsules addition is 15 wt %, which corresponding to 93% repair efficiency. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48478.     

型钢半悬挑外脚手架悬挑梁计算实例

结合某型钢半悬挑外脚手架工程的设计参数,从荷载取值、强度、挠度等方面,对主梁进行了验算,并分析了悬挑主梁的整体稳定性,为实际工程的施工设计提供了参考依据。     

1-十六醇接枝聚乙烯醇共聚物的合成及性能研究

利用接枝共聚法将具有储热功能的1-十六醇(C<,16>OH)与异氰酸酯(TDI)反应,再与聚乙烯醇反应制备1-十六醇接枝聚乙烯醇共聚物(PVA-g-C<,16>OH).通过傅立叶变换红外光谱分析(FT-IR)、差示扫描量热分析(DSC)、热重分析(TG)和X射线衍射分析(XRD)对共聚物结构、相转变行为、热稳定性和结晶...     

某建筑群基础注浆加固试验与实践

南通市某4幢2层框架建筑群外立面增加了仿古木建筑屋顶,上部荷载的增加将导致结构承载力不足和较大的沉降变形。为有效解决上述问题,对原结构的部分基础和屋面梁进行加固处理。对施工中提出的基础植筋加固方法进行了分析;通过模拟试验验证基础注浆加固的可行性,总结了注浆加固在该建筑群实施的经验。     

Microencapsulated <Emphasis Type="Italic">n</Emphasis>-Octadecane with styrene-divinybenzene co-polymer shells

Microcapsules containing n-Octadecane using styrene (St)-divinybenzene (DVB) co-polymer shells were synthesized by suspension-like polymerization. The effects of stirring rates and monomers/n-Octadecane mass ratios on the average diameter and phase change properties of microencapsulated n-Octadecane (MicroC18) were investigated. The surface morphology, diameters, phase change properties and thermal decomposition temperature of MicroC18 were investigated by using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electronic Microscope (SEM), Differential Scanning Calorimeter (DSC), and Thermogravimetric Analysis (TGA). The average diameters of MicroC18 decreased with an increase of stirring rate. When the monomers/n-Octadecane mass ratio of 1:1 is used, the enthalpy of MicroC18 reaches the highest-126 J/g. Surfaces of majority of MicroC18 show large concaves because of the production of reserved expansion space in the process of micro-encapsulation. The thermal decomposition temperature of MicroC18 is about 230 °C which is higher than that of MicroC18 using melamine-formaldehyde shell.     

三聚氰胺氰尿酸盐对锦纶6的抗滴落阻燃改性研究

通过在聚己内酰胺(PA6)切片中加入不同比例的三聚氰胺氰尿酸盐(MCA)或三聚氰胺多聚磷酸盐(MPP)-MCA共混纺丝,改善锦纶6的抗滴落阻燃性.研究发现,加入30%(wt)MCA的PA6仍具有可纺性,且随MCA添加量的增加,极限氧指数(LOI)增加,纤维的物理力学性能下降,阻燃剂的加入使聚合物的热稳定性变差,含有MCA-MPP共混物的纤维阻燃性及物理力学性能均好于单纯含有MCA的纤维.     

高温除尘技术综述

介绍了高温除尘技术的特点,综述了国内外高温除尘设备的现状、水平以及发展趋势,并对该技术在各行业中的应用前景进行了展望。     

Chain packing and phase transition of N-hexacosylated polyethyleneimine comb-like polymer: A combined investigation by synchrotron X-ray scattering and FTIR spectroscopy

In this paper, the chain packing and phase transition of comb-like polymer has been deeply analyzed with N-hexacosylated polyethyleneimine (PEI26C) as a template, fabricated through the reaction between n-hexacosyl bromide and PEI in a homogenous solution. The effect of long alkyl groups on the chain packing and phase transition of PEI26C was systematically investigated by synchrotron X-ray scattering and variable-temperature FTIR spectroscopy. PEI26C comb-like polymer exhibited an interesting structure-evolution process, and phase transformation from orthorhombic (β_O), monoclinic (β_M), to hexagonal (α_H) phase, and finally to amorphous state was demonstrated, indicating that large alkyl domains induced the complicated structures. Size-depended phase transition behavior provides an insight into the formation of metastable structure during the early stage of polymer crystallization.