首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 484 毫秒
1.
以硫铝酸盐水泥为基材,采用有机聚合物PVA,并且在MDF(Macro—Defect—Free)水泥中添加偶联剂KH,制备出抗折强度大于170MPa,抗压强度达240MPa的新型MDF水泥、同时,借助于X射线光电子能谱分析(XPS),红外光谱分析(IR)等测试手段研究了偶联剂KH和聚合物PVA在硫铝酸盐-MDF水泥中的作用机理  相似文献   

2.
确定聚合物共混的相容性最常用的方法是通过测定共混物的玻璃化转变温度(Tg),本文利用DSC-7(Epson)测定了不同共混比的PVA,CS共混物的玻璃化转变温度,结果表明PVA,CS之间有良好的相容性。本文利用扫描电子显微镜(SEM),红外光谱(IR)和X-射线衍射(XRD)等现代分析仪器,对研制的多元酸交联的PVA-CS/PSF膜结构进行了观察测试,探讨了膜结构与性之间的关系。  相似文献   

3.
理光XR-X3PF手动聚焦单反相机蒋宁在内置自动输片装置的手动聚焦35mmSLR中,功能较为齐全的有康泰克斯(CONTAX)167MT、佳能(CANON)T90、企能(CHNON)CP—7M、尼康(NIKON)F—601M、以及理光(RICOH)XR...  相似文献   

4.
用WAXD和FT-IR对高温超高压处理前后的HDPE进行了研究。发现经5.0GPa的高压处理或200℃下4.0GPa的高压同时处理后的HDPE分子链的化学结构未发生变化。HDPE晶体中(200)面与(110)面衍射峰的峰高比(γ)随着压力的升高而增大,表明HDPE分子链在超高压作用下发生了取向排列,且升高温度更有利于这种取向排列,但当压力增大至5.0GPa及温度升高至200℃时,γ反而大幅度下降。  相似文献   

5.
单酚脱盐法联苯聚醚酮的合成   总被引:2,自引:0,他引:2  
以Fries重排法合成新单体,用单酚脱盐法制备了含生链段的联苯聚醚酮。经DSC、IR和WAXD对聚合物的研究表明,联苯聚醚酮(DPEK)与聚醚醚酮(PEEK)均属正交晶系Pbcn空间群,而DPEK的玻璃化转变温度比PEEK高约40℃。  相似文献   

6.
高温超高压处理HDPE的WAXD及FT—IR研究   总被引:2,自引:1,他引:1  
用WAXD和FT-IR对高温超高压处理前后的HDPE进行了研究。发现经5.0GPa的高压处理或200℃下4.0GPa的高压同时处理后的HDPE分子链的化学结构未发生变化。HDPE晶体中(200)面与(110)面衍射峰的峰高比(γ)随着压力的升高而增大,表明HDPE分子链在超高压作用下发生了取向排列,且升高温度更有利于这种取向排列,且升高温度更有利于这种取向排列,但当压力增大至5.0GPa及温度升高  相似文献   

7.
研究了马来酸酐枝接聚丙烯(MAPP)对纸粉(PF)/聚丙烯(PP)复合材料性能的影响,并对其详机理进行了探讨,力学测试和扫描电镜(SEM)结果表明,MAPP是本体系有效的偶联剂,质量分析实验证明MAPP与纸粉发生了化学反应,同时差示扫描量热分析(DSC)和广角X射线衍射实验(WAXD)证明MAPP的PP链段可与PP基体形成共结晶。  相似文献   

8.
碳纤维表面涂碳及涂碳后纤维强度测定   总被引:1,自引:0,他引:1  
用4-甲氧基苯酚经醚化、氯甲基化、消除反应合成出不熔但可溶的聚(2-甲氧基-5-辛氧基)对亚苯基亚乙烯(PMOOOPV)。用PMOOOPV的CHCl3溶液浸涂碳纤维(CF),然后在773K碳化,得到亮黑色且分散性很好的涂碳CF。单纤维平均拉伸强度(σ)测定结果表明,与未涂碳的CF(σ=2977.8MPa)相比较,用0.1%PMOOOPV浸涂的CFσ=3908.2MPa,用0.2%PMOOOPV浸涂的CFσ=5031.2MPa,并浸涂后强度离散系数、平均矢径等有规律地变小。  相似文献   

9.
研究了马来酸酐接枝聚丙烯(MAPP)对纸粉(PF)/聚丙烯(PP)复合材料性能的影响,并对其偶联机理进行了探讨。力学测试和扫描电镜(SEM)结果表明,MAPP是本体系有效的偶联剂;质量分析实验证明MAPP与纸粉发生了化学反应,同时差示扫描量热分析(DSC)和广角X射线衍射实验(WAXD)证明MAPP的PP链段可与PP基体形成共结晶。  相似文献   

10.
采用乙烯-醋酸乙烯酯共聚物(EVA)作为聚氯乙烯(PVC)/高密度聚乙烯(HDPE)共混物的增容剂,通过冲击实验、拉伸实验、动态力学分析和扫描电镜(SEM),系统地研究了共混体系的性能与其形态结构之间的关系。结果表明,EVA是PVC/HDPE良好的增容剂,在一定范围内,EVA与PE对PVC有协同增韧效应  相似文献   

11.
Drug-loaded bone cement is used as an application method to prevent and treat prosthesis-related infection. Despite the commercial availability of drug-loaded bone cement, low release rate of drugs from drug-loaded bone cement may result in the emergence of drug-resistant coagulase-negative staphylococci in subsequent deep infection. This work presents a method to control and increase both the drug release rate and total release amounts of drugs for drug-loaded bone cement without losing the mechanical properties of cement. A novel drug-loaded bone cement is also developed by introducing cross-linked poly(methylmethacrylate-acrylic acid sodium salt) particles into bone cement. Capable of increasing the hydrophilicity of the cement and allowing fluids to pass into the cement, the bone cement developed here supplements both the drug release rate and total release amounts of drugs.  相似文献   

12.
施惠生  原峰  许碧莞 《材料导报》2007,21(12):87-91
阿利尼特水泥是一种节能水泥。介绍了阿利尼特矿物的组成、结构和固溶能力,总结了阿利尼特水泥的水化硬化性能、力学性能和节能特性,重点分析了氯掺加量和煅烧温度对阿利尼特水泥熟料烧成的影响,提出了利用固体废弃物制备阿利尼特水泥的资源化利用新思路,指出了阿利尼特水泥生产和使用过程中急需解决的技术难题。  相似文献   

13.
A successful total hip replacement has an expected service life of 10-20 years with over 75% of failures due to aseptic loosening which is directly related to cement mantle failure. The aim of the present study was to investigate the addition of nanoparticles of calcium carbonate to acrylic bone cement. It was anticipated that an improvement in mechanical performance of the resultant nanocomposite bone cement would be achieved. A design of experiment approach was adopted to maximise the mechanical properties of the bone cement containing nanoparticles of calcium carbonate and to determine the constituents and preparation methods for which these occur. The selected conditions provided improvements of 21% in energy to maximum load, 10% in elastic modulus, 7% in bending strength and 8% in bending modulus when compared with bone cement without nanoparticles. Although cement containing nanoCaCO(3) coated in sodium citrate also enhanced the energy to maximum load by 28% and the elastic modulus by 14% when compared with control cement, it is not recommended as a factor in the production of nanocomposite bone cement due to reduction in the bending properties of the final bone cement.  相似文献   

14.
Effect of superplasticizers on the rheological properties of cements   总被引:1,自引:0,他引:1  
In this paper, the rheological properties of cement pastes made with different types of cement and superplasticizers are discussed. As a tool for the discussion, experiments involving dispersion of cement particles, fluidity, viscosity, yield stress and zeta potential have been conducted. The results obtained show that the chemical compositions of the cements such as C3A and sulfate content, alkali and ground lime content are important features controlling the rheology of cement pastes. Three types of sulfonated superplasticizers (lignosulonate-based, melamine formaldehyde sulfonic acid, naphthalene formaldehyde sulfonic acid) and one type of polycarboxylic acid polymer were used. The results revealed that the mechanism by which these polymers disperse cement particles differs fundamentally. Sulfonated superplasticizers induced a negative charge on cement particles dispersing them by electrostatic repulsion, whereas with the polycarboxylate-based polymer the dispersion mechanism is mainly controlled by steric hindrance. A model for the adsorption of superplasticizer on a cement particle is proposed.  相似文献   

15.
A preliminary study has been done to examine the sorption, diffusion and degradation of mustard (HD) in cement. The sample of dried cement paste is a meso-porous adsorbant with a BET surface area around 40.8 m2/g, which is able to adsorb vapor of HD at room temperature and to result in a multiple-layer isotherm of II type. The molecule of HD seemed to chemically adsorb onto cement surface. Droplet of HD contaminating cement was able to be degraded into less toxic products, but in a very low rate of k = 4.8 x 10(-5) min(-1) and t(1/2) = 16 x 10(4) min at room temperature. Droplet of HD is able to penetrate through the layer of cement, but a cement plate of 8mm can protect against HD droplets over 48 h. A decrease of thickness for cement layer or addition of sand in cement would lead to lower the protection time against HD droplets. The diffusion coefficient of HD molecule in cement was determined, about 1.3 x 10(-4) cm2/min and of a typical diffusion in solid.  相似文献   

16.
水泥水化过程的细观力学模型与性能演化   总被引:2,自引:1,他引:1       下载免费PDF全文
基于水泥水化过程的实验测量数据, 建立了一个研究水泥水化过程的细观结构和有效性能演化的细观力学模型。该模型由未水化的水泥颗粒、水泥凝胶和孔洞三相介质组成, 并假设细观结构呈周期性均匀分布。随着水化过程的进行, 模型中的组份是连续变化的, 并与实验测量的组份含量完全一致。利用本文中模型和均匀化方法(直接平均法和二尺度展开法) 计算了水泥浆体在各瞬时的杨氏模量和泊松比。研究表明, 在水泥的水化过程中, 水泥浆体的弹性性能随水化度而变化, 其变化规律和精度与现有的实验数据符合很好。该方法可容易地推广到三维情况和其他水化介质。   相似文献   

17.
Sialite technology—sustainable alternative to portland cement   总被引:1,自引:1,他引:0  
The objective of this article is to describe the current state of the cement industry, its sustainability, and how it compares to alternative cement technologies—specifically Sialite technology. The process for creating the most widely used cement, portland cement, is an energy intensive process, which consumes considerable natural resources, such as limestone. In addition, portland cement production releases harmful air pollutants, detrimental to human respiratory health, and also emits significant quantities of carbon dioxide. The cement industry will not be sustainable in its current state. A new process for creating cement is necessary, which requires less energy, less use of natural sources, and emits less air pollution. Sialite technology is a new technology based on earth science that simulates natural rock formation. Sialite may lead to a more sustainable cement industry as it requires less energy to produce, has an abundant source of natural resources, and emits less to almost no pollution compared to portland cement. In addition, other technologies are presented for cement industry sustainability.  相似文献   

18.
Cement and asphalt mortar (CA mortar) is the key component in the structure of Shinkansen slab track and serves as the elastic shock-absorber. A new method was put forward to evaluate the setting process of cement and asphalt emulsion (CAE) in CA mortar. It was noted that the setting process was governed by several factors such as cement types, cement/asphalt emulsion ratios (C/AE ratio). Results also indicated that the setting process of CAE was faster, the higher proportion of cement content was; the early age strength and the separation rate of CA mortar could be improved by using cement of high early age strength and rapid hydration rate, or a blended cement with ordinary Portland cement partially replaced by sulfoaluminate cement, or by increasing C/AE ratio. Nevertheless, the replacement ratio of ordinary Portland cement by sulfoaluminate cement should not exceed 15% and C/AE ratio should be not less than 0.8.  相似文献   

19.
水泥材料成型过程对硬化体结构与性能的影响   总被引:2,自引:1,他引:1  
沈业青  翟超  孙成玉 《材料导报》2016,30(15):100-103
新拌水泥混凝土浆体常被抽象为含水的颗粒悬浮结构,这种抽象将复杂的成型过程过于简化,存在许多难以预知和不可量化的因素,给水泥基材料科学体系的架构造成技术障碍。分别综述了混凝土成型、水泥净浆成型共同存在的组分材料离析、泌水和夹杂气泡等缺陷,分析了组分分散效果对水泥水化硬化体结构与性能的影响。将水泥颗粒堆积体与其水化硬化体制备结合起来,通过压制绝干水泥颗粒堆积结构,再毛细吸水成型水泥水化硬化体,可以最大程度避免微观层面的离析、泌水及夹杂气泡等不易量化的因素对成型的影响,有利于模型化研究非均质、多层次复杂结构的演变与性能调控。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号