The Thermal Degradation of Poly(dimethyl Itaconate-co-4-vinylpyridine)

Copolymers of dimethyl itaconate (DMI) and 4-vinylpyridine (4VP) were synthetized in toluene at 60°C with0.26 mol% of AIBN as initiator. Their compositions were determined by differential refractometry and by differential scanning calorimetry. The 4VP contents of the copolymer samples ranged between 7 and 75 mol%. The reactivity ratios calculated via the Fineman-Ross method were r ₁=0.24 (DMI) and r ₂=0.57 (4VP). The thermal degradations of these copolymers were studied. The results of thermogravimetric measurements indicated that the copolymers degrade at lower temperatures than those of their parent homopolymers. A possible explanation of this anomalous behaviour is the formation of thermally unstable structures during the copolymerisation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Influence of the Degree of Dehydroxylation of Kaolinite on the Properties of Aluminosilicate Glasses

The degree of dehydroxylation of kaolinite, D_TG and D_IR, respectively, is characterized by thermogravimetric analysis (TG) and Fourier transform infrared spectroscopy (FTIR). The relation between DTG and DIR based on the infrared absorptions at 3600–3700, 915, 810, and 540 cm⁻¹ is established. Three regions can clearly be distinguished: the dehydroxylation region (D_TG<0.9), the metakaolinite region (0.9<D_TG<1) and the ‘spinel’ region(D_TG=1). The effect of the degree of dehydroxylation of kaolinite on the amount of reactive material is measured by the reaction enthalpy, ΔH, of the low-temperature reaction of the dehydroxylated kaolinite with a potassium silicate solution using differential scanning calorimetry (DSC). |ΔH| increases almost linearly with DTG in the dehydroxylation region. In the metakaolinite region, ΔH and thus the amount of reactive material, becomes constant. |ΔH| is sharply decreasing when metakaolinite transforms into other phases in the ‘spinel’ region. No significant differences in the reactivity of the dehydroxylates is detected with DSC. According to FTIR, the use of partially dehydroxylated kaolinite is not influencing the molecular structure of the low-temperature synthesized aluminosilicates, but residual kaolinite is retrieved as an additive. This revised version was published online in August 2006 with corrections to the Cover Date.     

Energy Dispersive X-Ray Fluorescence Analysis and X-Ray Microanalysis of Medieval Silver Coins

 Austrian medieval silver/copper coins were investigated at their surfaces by energy dispersive X-ray fluorescence analysis (EDXRF) and at the cross-sections by X-ray microanalysis in the scanning electron microscope (SEM/EDX) in order to estimate the error occurring when corroded objects of art and archaeology are analyzed on the surface by non-destructive methods. Additionally, Ag/Cu-standards were treated in diluted sulphuric acid and the depletion of copper on the surface was measured by EDXRF. By calculating the ratio of the Ag-K/Ag-L intensity the process of blanching could be studied.     

激光隧道断面放样方法研究

隧道开挖技术中的放样工序目前主要用手工操作,难度大精度低成本高,需要发展激光隧道断面放样技术。本文提出的激光隧道断面放样方法,包括平移物镜扫描,光束发散我遥压缩,扫描光点的计算机数字控制（ＣＮＣ）,光电零位恢复装置,及仪器精确定信方法。理论分析和样机的试用这一放样方法是成功的。     

扫描探针显微镜的最新技术进展及应用

本文在讨论SPM基本原理和应用的基础上,详细介绍了近期SPM的最新技术进展和成像模式以及拓展的应用领域,使我们能对SPM有一个全新的认识和了解,以便把它们更好地应用到研究领域中。     

一种新型激光扫描式大工件孔-孔同轴度测量仪

介绍了一种新型的基于激光扫描原理的大尺寸工件孔—孔同轴度测量原理和测量仪器。由于采用了反馈系统自动调节补偿光束漂移、大气扰动的误差 ,使精度有了较大提高。在3 0 m测量范围内相对误差可达 2× 1 0 -6。可应用于大型工件设备的制造和装配过程中的检测。     

远端光纤监测系统

介绍 HP公司推出的一种远端光纤监测系统 HP8170 0 2 0 0系列和该系统的软硬件构成、功能、报警管理。针对铁路光缆线路的特点 ,描述了铁路光缆线路地标图。这种系统对提高光纤网的维护效率、预知光纤故障、缩短排除故障时间将会有很大作用。     

频扫天线慢波线的幅相误差对天线方向图影响的分析

从理论上分析计算了频扫阵列天线慢波线的幅相分布误差对天线方向图的影响 ,给出了几组误差分布条件下频扫天线扫描波束指向偏离和副瓣电平变坏的结果 ,与试验小阵的测试数据比较 ,两者吻合较好 ,这对频扫天线慢波线的工程设计具有重要的指导作用。本文的分析方法也同样可用于相扫、频相扫以及相控阵天线的工程设计     

Kinetics of Temperature-induced and Reaction-induced Phase Separation Studied by Modulated Temperature DSC

Temperature-induced phase separation of P(EO75-ran-PO25)/PES and reaction-induced phase separation of DGEBA/MDA modified with PVME are studied using MTDSC as an in-situ tool. Phase separation can be probed by the onset of an ‘excess’ contribution in the MTDSC heat capacity signal, in good correspondence with the cloud point temperature. This feature enables the complete construction of the state diagram of P(EO75-ran-PO25)/PES. The detection of phase separation-induced partial vitrification of the high-T_g phase (PES-rich phase) enables to sub-divide the LCST-type heterogeneous region in a zone 1 (no interference of partial vitrification) and a zone 2 (interference of partial vitrification of the PES-rich phase). This sub-division of the heterogeneous region has drastic implications on the remixing behavior of demixed blends. In DGEBA/MDA modified with PVME, reaction-induced phase separation accompanied by an increase in reaction rate, followed by a vitrification step of the epoxy-amine phase can be detected in-situ. In non-isothermal conditions, a diffusion-controlled reaction after vitrification and a final devitrification of the system is also observed.     

Influence of the Curing Temperature in the Mechanical and Thermal Properties of Nanosilica Filled Epoxy Resin Coating

0.5–3 wt% nanosilica was added to an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) and cured at 25, 40 or 60 °C using isophoronediamine (IPDA) as hardener. Aggregates of nanosilica were properly dispersed into the DGEBA-IPDA resin and agglomerates formation was avoided. Addition of nanosilica increased the storage modulus E′ and the area and height of the tan δ curve of DGEBA-IPDA resin cured at 25 °C, but no significant differences were found by curing at higher temperature. Gel time measurements and the results obtained by applying the Kamal model to isotherm DSC curing of DGEBA-IPDA-nanosilica revealed that nanosilica catalysed the curing reaction between DGEBA and IPDA, in less extent by increasing the curing temperature.