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Effects of Ultraviolet Radiation,High Temperature and Alkaline Chemicals on Ageing of Silicone Sealants Used in Ballastless Track Expansion Joints

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Journal of Wuhan University of Technology(Materials Science) 2018年第5期33卷 1015-1021页

作者： LI Huajian YI Zhonglai cheng guanzhi WEN Hao XIE Yonjiang Institute of Railway Construction China Academy of Railway SciencesBeijing 100081China State key Laboratory of High Speed Railway Track Technology Beijing 100081China

Expansion joints silicone sealants used in high speed railway construction suffer from ultraviolet radiation（UV）, high temperature combined with the alkaline environment. To evaluate the durability and analyse the ageing mechanism, six one-component silicone sealants from different companies were selected and subjected to accelerated ageing tests including UV, thermal and alkali ageing treatments. The ageing effects on the performance of the sealants were evaluated via the appearance and the mechanical property changes. The changes in molecular structure were studied by means of Fourier transform infrared spectroscopy（FTIR）, differential scanning calorimetry（DSC） and thermogravimetry（TG）. This study revealed that different materials displayed different sensibilities to the ageing methods, in which 15 %-20 % decreases of mechanical properties could be observed under UV radiation test, owning the most significant effects. Structure analysis showed that the physical changes of aggregative states were the principal factors to the performance, along with the chemical slight changes. The glossiness dropped significantly in ageing test, which could be used as one of the effective evaluation parameters for ageing conditions in the field.

关键词： silicon sealant durability ageing expansion joints

Fabrication and Characterization of Sulfonate-containing Polystyrene/CaCO_(3) Core-shell Nanoparticles

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Chinese Journal of Chemistry 2014年第7期32卷 579-584页

作者： Yang Hu Jishuai Wang guanzhi cheng Jie Shen chengyou Kan Department of Chemical Engineering Laboratory of Advanced Materials of Ministry of EducationTsinghua UniversityBeijing 100084China

Polystyrene(PSt)seed latex was first prepared via soap-free emulsion polymerization in the presence of a small amount of methacrylic acid using ammonium persulfate as initiator,and then seeded emulsion polymerization of sodium 4-styrenesulfonate(NaSS)and St was carried out to synthesize P(St-NaSS)core latex using 2,2'-azobisisobutyronitrile as *** that,P(St-NaSS)/CaCO_(3) core-shell nanoparticles were fabricated by sequentially introducing Ca(OH)_(2) aqueous solution and CO_(2) gas into the core *** morphology of the core and core-shell nanoparticles was characterized by dynamic light scattering(DLS)and transmission electron microscopy(TEM),and the state of CaCO_(3) shell was confirmed with high-resolution scanning transmission electron microscope(HR-STEM)and selected area electron diffraction(SAED).Results showed that PNaSS chains were successfully grafted onto the PSt seed surface,and length of the PNaSS“hairs”could be modulated by adjusting NaSS *** groups of the PNaSS hairs served as additives in the formation and stabilization of amorphous CaCO_(3)(ACC)and prevented ACC from sequent transformation into crystalline *** amount of the anchored CaCO_(3) increased with the growth of PNaSS hair length,and reached 51 wt%(by thermalgravimetric analysis)under the optimal encapsulating temperature of 45℃.Moreover,the forming mechanism of P(St-NaSS)/CaCO_(3) coreshell nanoparticles was proposed.

关键词： core-shell nanoparticles sulfonate emulsion polymerization encapsulation amorphous calcium carbonate

制备参数对泡沫轻质土工作性能和力学性能的影响

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铁道建筑 2017年第1期57卷 56-60页

作者：程冠之中国铁道科学研究院铁道建筑研究所北京100081 高速铁路轨道技术国家重点实验室北京100081

分析不同制备参数对泡沫轻质土拌合物工作性能及其经时变化的影响,并对其硬化体力学性能进行了对比研究。结果表明:在水胶比为0.5且未掺加减水剂的情况下,泡沫轻质土拌合物流值随初始湿密度的增大而增大,不同初始湿密度的拌合物在60 mi... 详细信息

分析不同制备参数对泡沫轻质土拌合物工作性能及其经时变化的影响,并对其硬化体力学性能进行了对比研究。结果表明:在水胶比为0.5且未掺加减水剂的情况下,泡沫轻质土拌合物流值随初始湿密度的增大而增大,不同初始湿密度的拌合物在60 min内的湿密度增加率均在±5%以内;泡沫轻质土硬化体的抗压强度、劈裂抗拉强度均与拌合物初始湿密度呈良好的线性相关性,当拌合物湿密度为500 kg/m^3时,硬化体抗压强度已超过1 MPa;拌合物湿密度增加率随水胶比的变化有所波动,当水胶比为0.5~0.7时,硬化体力学性能基本稳定;减水剂会提高泡沫轻质土拌合物的流值,但对硬化体力学性能无明显影响。

关键词：泡沫轻质土经时损失流值湿密度抗压强度劈裂抗拉强度

种子乳胶粒表面修饰法制备核壳结构PSt/TiO_2复合微球

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高分子学报 2012年第2期22卷 111-116页

作者：程冠之邓伟胡杨阚成友清华大学化工系教育部先进材料重点实验室北京100084

首先采用无皂乳液聚合法合成了表面带负电荷、粒径为360 nm的单分散聚苯乙烯(PSt)乳液,并利用聚乙烯亚胺(PEI)在25℃下对PSt乳胶粒表面进行修饰,得到了表面带有正电荷的PSt种子乳液;然后以乙醇和水的混合物为反应介质,采用种子乳液加入... 详细信息

首先采用无皂乳液聚合法合成了表面带负电荷、粒径为360 nm的单分散聚苯乙烯(PSt)乳液,并利用聚乙烯亚胺(PEI)在25℃下对PSt乳胶粒表面进行修饰,得到了表面带有正电荷的PSt种子乳液;然后以乙醇和水的混合物为反应介质,采用种子乳液加入法,使钛酸正丁酯(TBT)在修饰后的乳胶粒表面进行水解与缩合,制备出了核壳结构PSt/TiO2复合微球,利用电镜对复合微球的结构形态进行了表征.结果表明,PSt乳液改性时体系的zeta电位随着PEI用量的增加而升高,当PEI用量为PSt聚合物重量的15%时,体系的zeta电位从原来的-40.3 mV升高到了38.3 mV,达到对PSt乳胶粒表面改性的最佳值;在制备PSt/TiO2复合微球时,TiO2包覆量随着反应时间的延长而增加,反应7 h时达到90.2%的最大值;随介质中水含量的增加,吸附到复合微球表面上的TiO2纳米颗粒逐渐减少,复合微球表面逐渐变得光滑,当EtOH/H2O质量比为100/6.0时,得到结构均一、壳层厚度为29 nm的核壳结构PSt/TiO2复合微球.

关键词：复合微球表面修饰 PSt/TiO2 Zeta电位形态

干燥条件对缓释型粉体聚羧酸减水剂性能的影响

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建筑材料学报 2023年第3期26卷 317-323页

作者：关文勋程冠之李旺栗少清谢永江中国铁道科学研究院集团有限公司铁道建筑研究所北京100081

对含有不同缓释功能基团的液体聚羧酸减水剂进行干燥处理,得到了相应的缓释型粉体聚羧酸减水剂,通过净浆流动度经时损失、红外光谱等方法研究了不同干燥条件对于缓释型粉体聚羧酸减水剂的性能影响规律及其作用机理.结果表明:干燥温度是... 详细信息

对含有不同缓释功能基团的液体聚羧酸减水剂进行干燥处理,得到了相应的缓释型粉体聚羧酸减水剂,通过净浆流动度经时损失、红外光谱等方法研究了不同干燥条件对于缓释型粉体聚羧酸减水剂的性能影响规律及其作用机理.结果表明:干燥温度是影响缓释型粉体聚羧酸减水剂产物性能的主要因素;由于不同缓释型聚羧酸减水剂含有的缓释功能基团的水解活性不同,其可耐受的最高干燥温度不同;高真空干燥条件及调节液体减水剂pH值至8.5以上均有利于改善干燥产物的性能.

关键词：聚羧酸减水剂缓释干燥条件水解

Triple reverse order law for the Drazin inverse

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 55-68页

作者： WANG Hua ZHONG cheng-cheng College of Sciences Inner Mongolia University of TechnologyHohhot 010051China College of Engineering University of Jinan Quancheng CollegeYantai 265600China

In this paper,we investigate the reverse order law for Drazin inverse of three bound-ed linear operators under some commutation ***,the Drazin invertibility of sum is also obtained for two bounded linear operators and... 详细信息

关键词： Drazin inverse reverse order law space decomposition

Statistical properties of ideal photons in a two-dimensional dye-filled spherical cap cavity

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Chinese Physics B 2024年第10期33卷 258-268页

作者： Ze cheng School of Physics Huazhong University of Science and TechnologyWuhan 430074China

Within the framework of quantum statistical mechanics,we have proposed an exact analytical solution to the problemof Bose-Einstein condensation(BEC)of harmonically trapped two-dimensional(2D)ideal *** utilize this analyticalsolution to investigate the statistical properties of ideal photons in a 2D dye-filled spherical cap *** resultsof numerical calculation of the analytical solution agree completely with the foregoing experimental results in the BEC ofharmonically trapped 2D ideal *** analytical expressions of the critical temperature and the condensate fractionare derived in the thermodynamic *** is found that the 2D critical photon number is larger than the one-dimensional(1D)critical photon number by two orders of *** spectral radiance of a 2D spherical cap cavity has a sharppeak at the frequency of the cavity cutoff when the photon number exceeds the critical value determined by a temperature.

关键词： rigorous results in statistical mechanics Bose-Einstein condensation 2D photons

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聚氨酯泡沫体与道砟黏接性能的影响因素

建筑材料学报 2018年第6期21卷 926-932页

作者：李书明程冠之董全霄郑新国谢永江中国铁道科学研究院铁道建筑研究所北京100081 高速铁路轨道技术国家重点实验室北京100081

研究了原材料R值(双组分原材料间异氰酸酯基(—NCO)与羟基(—OH)的摩尔比)、外加水量(wwater)和环境湿度(RH)对固化道床用聚氨酯(PU)泡沫体与道砟界面黏接性能的影响,并采用傅里叶变换衰减全反射红外光谱(ATR-FTIR)和扫描电镜(SEM)对PU... 详细信息

研究了原材料R值(双组分原材料间异氰酸酯基(—NCO)与羟基(—OH)的摩尔比)、外加水量(wwater)和环境湿度(RH)对固化道床用聚氨酯(PU)泡沫体与道砟界面黏接性能的影响,并采用傅里叶变换衰减全反射红外光谱(ATR-FTIR)和扫描电镜(SEM)对PU泡沫体的组成和形态进行了表征.结果表明:随着原材料R值的增加,PU泡沫体与道砟之间的黏接强度逐渐增大,当原材料R值大于1.05时,试件黏接破坏形式为内聚破坏;外加水量越少,PU泡沫体密度越大,试件黏接性能越好,当外加水量小于0.45%时,试件的黏接破坏形式为内聚破坏;环境湿度会影响道砟表面干燥状态,进而影响试件黏接效果,当环境湿度不超过80%时,该值对试件黏接性能影响不明显.综合考虑PU泡沫体黏接性能和变形能力等因素,R值取1.05～1.20较合适,宜通过调整外加水量将PU泡沫体密度控制在160kg/m^3以上,实际施工环境湿度宜在80%以内.

关键词：高分子材料固化道床聚氨酯道砟黏接性能

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纳米氧化镁对聚碳酸酯阻燃性能的影响

塑料 2020年第4期49卷 78-81页

作者：曾志王希董全霄程冠之中国铁道科学研究院集团有限公司铁道建筑研究所北京100081

为研究碱土金属氧化物纳米材料对聚碳酸酯阻燃性能的影响,制备了聚碳酸酯/氧化镁(PC/MgO)纳米复合材料,并采用锥形量热测试、热失重分析等方法分析了纳米氧化镁(MgO)对聚碳酸酯(PC)阻燃性能和热稳定性的影响。锥形量热测试结果表明,与... 详细信息

为研究碱土金属氧化物纳米材料对聚碳酸酯阻燃性能的影响,制备了聚碳酸酯/氧化镁(PC/MgO)纳米复合材料,并采用锥形量热测试、热失重分析等方法分析了纳米氧化镁(MgO)对聚碳酸酯(PC)阻燃性能和热稳定性的影响。锥形量热测试结果表明,与纯PC相比,PC/MgO纳米复合材料的二次热释放速率的峰值显著下降;纯PC的总热释放量为53.5 MJ/m^2,而PC/MgO(1.0%)纳米复合材料的总热释放量为41.9 MJ/m^2,减少了21.7%。纯PC的比消光面积(SEA)为363 m^2/kg,而PC/MgO(4.0%)纳米复合材料可以达到487 m^2/kg,增加了34.1%。加入纳米MgO能促进PC基体提前分解成炭,在材料表面形成致密的连续炭层。对比受热生成的炭层照片可知,PC/MgO纳米复合材料在燃烧后能形成表面致密的膨胀炭层,具有较好的阻燃效果。

关键词：聚碳酸酯阻燃氧化镁燃烧性能机理