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101.
102.
In this study, hot embossing by reusable Ni mold with features in the form of rectangular diffraction gratings of 4 μm period was successfully employed for surface texturing of polytetrafluoroethylene (PTFE) film above the glass transition temperature of PTFE amorphous phase with the aim to enhance surface hydrophobicity. Imprint pressure was set to 0.5 MPa and it was at least tenfold lower than reported by other authors using cold stamping. Embossed gratings were clearly seen on the surface of all imprinted samples even after the annealing at 140 °C and aging for 1 month at room temperature. The best results were achieved when imprint temperature was 150 °C. Measurements of the water contact angle on imprinted PTFE surfaces have showed that increase of the average contact angle for the current test setup was 8°. Using imprint stamp with the more favorable features may lead to somewhat higher hydrophobicity. 相似文献
103.
采用传统方法生产的NbTi/Cu多芯超导线在生产芯数较多的超导线时存在填充系数较大的问题,这直接影响了芯丝的整齐排布,所以组装完成后加入热等静压过程.研究了经过热等静压和未经过热等静压的NbTi/Cu多芯超导线的加工性能.经过试验证明,经过100~150MP,2小时热等静压处理的NbTi/Cu多芯超导线坯锭在加工过程中具有良好的加工性能,提高了超导线复合坯锭的成品率;而未经过热等静压处理的NbTi/Cu多芯超导线坯锭加工性能较差,坯锭内部缺陷较多. 相似文献
104.
105.
Guoxin Chen Huanming Lu Junfeng Cui Haitao Yu Bo Wang Yan Liu He Li Nan Jiang 《中国化学快报》2019,30(7):1401-1404
The real time analysis structure evolution of BNNT with compression showed that the formation of V-shape in the post-buckling before BNNT fracture was reversible. 相似文献
106.
Improved quantification limits in chiral capillary electrochromatography by peak compression effects
The peak compression effect has been applied to improve quantification limits in chiral capillary electrochromatography (CEC). A stationary phase based on the chiral selector vancomycin (Chirobiotic V) was used for separations of the enantiomers of mianserin. By adding solvents with a low dielectric constant, e.g. 2-propanol or tetrahydrofuran, to the sample solution, peak compression could be induced. The plate numbers for the minor enantiomer increased from approximately 100,000 to 1.4-1.6 million plates/m, when the composition of the mobile phase was adjusted so that the analyte eluted within either one of two system zones originating from the sample solution. A 10-fold improvement in the quantification limit for the minor enantiomer was obtained compared to elution under non-focused conditions. 相似文献
107.
Effects of graded porous structure on local strain distribution under compression in silicone rubber
Keijiro Yoshimura Kazunori Nakano Takeshi Nishiwaki Yuki Iwama Masanobu Murata 《Journal of Polymer Science.Polymer Physics》2019,57(16):1033-1042
Silicone rubber samples with gradually changing pore sizes within the range of 70–610 μm are produced using an improved spacer method. The samples are scanned using an X‐ray computed tomography to evaluate their graded structure as compared to uniform rubber. A compressive test reveals that graded porous silicone rubber has characteristic stress–strain curves whose slope changes within a specific strain range depending on the porous structure. Analysis results of local strain based on a digital image correlation of the graded porous silicone rubber under compression demonstrate that the characteristic stress–strain properties are caused by shifts in the main deformation region in the graded structure. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1033–1042 相似文献
108.
The determination of quercetin and rutin by flow injection analysis (FIA) and capillary electrophoresis (CE) using electrochemical detection was described. These flavonoids were determined at normal (unheated) and hot platinum microelectrodes using cyclic voltammetry. When quercetin or rutin is reaching the platinum electrode, a change of the current in the region of the platinum oxide formation is observed. Integration of the current changes in this in this region creates analytical signals in the form of peaks. An increase of temperature to about 76 ?C in a small zone adjacent to the microelectrode causes an increase of the analytical signal by more than 6 times under FIA conditions. This method enables the use of hot microelectrodes as detectors in HPLC or CE. In CE the improvement of the analytical signal at hot microelectrodes is smaller than in FIA and increase only 1.3–3.4 times. Heated microelectrodes were used for analysis of the flavonoids in natural samples of the plant (extract of sea buckthorn) and a pharmaceutical preparation (Cerutin). 相似文献
109.
Kübra Yumakgil Argun Talat Gökçeören Candan Erbil 《Journal of Polymer Science.Polymer Physics》2010,48(12):1256-1264
N‐isopropyl acrylamide (NIPAAm) hydrogels are known as thermosensitive crosslinked polymer networks. In this work, the network parameters of their composites, i.e., NIPAAm/sodium montmorillonite (NIPAAm/Na+MMT) hydrogels synthesized by free radical solution polymerization in the presence of two different types of accelerator (tetramethyl ethylenediamine (TEMED) and ethylenediamine tetraacetic acid (EDTA)) and initiator (potassium persulphate (K2S2O8) and cerium ammonium nitrate ((NH4)2Ce(NO3)6), Ce(IV)) using five different clay content (in the range of 1.0–5.0 wt % of total monomer concentration) at 25 °C were presented and discussed. FTIR spectra, XRD patterns, SEM photographs, and network parameters of the samples indicated that the presence of COOH groups on EDTA molecules was resulted in the formation of exfoliated structures and the activity of EDTA/KPS redox pair was higher than those of TEMED/KPS and EDTA/Ce (IV) pairs. The compression moduli (G) of the hydrogels initiated with EDTA/Ce(IV) redox pair showed smooth and continual changings with increase in Na+MMT content (for swelling equilibrium at 25 °C) on the contrary of EDTA/KPS and TEMED/KPS pairs. It might be related to low initiator efficiency of cerium ammonium nitrate than KPS molecules, having higher effective crosslinking density with increasing clay content. On the other hand, the G moduli of NIPAAm/Na+MMT hydrogels (above their phase transition temperature) initiated with TEMED/KPS redox pair were higher than the others because of the more hydrophobic nature of TEMED molecules. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1256–1264, 2010 相似文献
110.
Several methods of extraction were optimized to extract polycyclic aromatic hydrocarbons (PAHs), their nitrated derivatives and heavy n-alkanes from a highly adsorptive particulate matter resulting from the combustion of diesel fuel in a diesel engine. This particular carbonaceous particulate matter, collected at high temperatures in cordierite diesel particulate filters (DPF), which are optimized for removing diesel particles from diesel engine exhaust emissions, appeared extremely refractory to extractions using the classical extracting conditions for these pollutants. In particular, the method of accelerated solvent extraction (ASE) is described in detail here. Optimization was performed through experimental design to understand the impact of each factor studied and the factors’ possible interactions on the recovery yields. The conventional extraction technique, i.e., Soxhlet extraction, was also carried out, but the lack of quantitative extractions led us to use a more effective approach: hot Soxhlet. It appeared that the extraction of the heaviest PAHs and nitroPAHs by either the optimized ASE or hot Soxhlet processes was far from complete. To enhance recovery yields, we tested original solvent mixtures of aromatic and heteroaromatic solvents. Thereafter, these two extraction techniques were compared to microwave-assisted extraction (MAE) and supercritical fluid extraction (SFE). In every case, the only solvent mixture that permitted quantitative extraction of the heaviest PAHs from the diesel soot was composed of pyridine and diethylamine, which has a strong electron-donor character. Conversely, the extraction of the nitrated PAHs was significantly improved by the use of an electron-acceptor solvent or by introducing a small amount of acetic acid into the pyridine. It was demonstrated that, for many desirable features, no single extraction technique stound out as the best: ASE, MAE or SFE could all challenge hot Soxhlet for favourable extractions. Consequently, the four optimized extraction techniques were performed to extract the naturally polluted diesel soot collected inside the DPF. Comparisons with the NIST standard reference material SRM 1650b showed that the soot collected from the DPF contained 50% fewer n-alkanes, and also markedly lower levels of PAHs (44 less concentrated) than SRM 1650b, and that the ratio of nitroPAHs to PAHs was increased. These results were attributed to the high temperatures reached inside the particulate filter during sampling runs and to the contribution of the catalytic DPF to aromatic and aliphatic hydrocarbons abatement. 相似文献