This article reports on mechanical properties of electron beam cured tripropylene glycol diacrylate (TPGDA) and propoxylated glycerol triacrylate (GPTA) films. This study has been motivated by the need to have direct access to those properties for analyzing the thermo‐mechanical behavior and electro‐optical properties of polymer dispersed liquid crystal systems in general, and systems made either of TPGDA or GPTA and low molecular weight liquid crystals in particular. Representative examples of these systems are considered in this work. The effects of the degree of crosslinking on the mechanical strength of the polymer network are analyzed by considering different doses of the electron beam irradiation. As the radiation dose increases, the mechanical strength of the film is enhanced. Addition of a small amount of liquid crystals leads to remarkable plasticizing effects.
Young modulus and rubbery state modulus as a function of EB dose for cured TPGDA films. The filled symbols represent the Young modulus and the open symbols represent the rubbery state modulus. Circles are for pure TPGDA and squares are for TPGDA/E7 mixture with 15 wt.‐% E7. 相似文献
Heat exchanger network (HEN) synthesis has been a well-studied subject over the past decades. Many studies and methodologies
were proposed to make possible the energy recovery, minimizing the utilities consumption and the number of heat transfer equipment. 相似文献
Poly(vinylidene fluoride), PVDF, samples containing exclusively the polar β phase were obtained by crystallization from N,N-dimethylformamide (DMF) solution at 60 °C and subsequent pressing. Some of these samples were uniaxially drawn at 120 °C
at draw ratio of 4, resulting in oriented films. Oriented and unoriented samples were characterized as to relative fraction
of β phase, degree of crystallinity and orientation by infrared spectroscopy (FTIR), differential scanning calorimetry (DSC),
and wide-angle X-ray diffraction (WAXD). The dependence on frequency of the real (
e\textr¢ \varepsilon_{\text{r}}^{\prime} ) and imaginary (
e\textr¢¢ \varepsilon_{\text{r}}^{\prime\prime} ) components of the relative permittivity of the samples was determined between 104 and 1.7 × 107 Hz. The coercive field and stable and metastable remanent ferroelectric polarization were determined from the hysteresis
loop obtained by the ramp voltage technique, described in detail in this work. The results allowed verification of the effect
of drawing on structure and of the resulting structure on the dielectric properties, remanent polarization, and coercive field
of β-PVDF. A possible effect of the crystal–amorphous interphase region on the metastable remanent polarization is suggested.
The results obtained with the oriented and unoriented samples were compared with those obtained for films commercialized by
Piezotech S.A. 相似文献
In this paper, a thermodynamic analysis was carried out to provide useful information about the operation of intermediate-temperature Solid Oxide Fuel Cells (IT-SOFCs) with direct internal reforming (DIR) fuelled by glycerol. A methodology, based on the principle of minimizing the Gibbs energy of a given system, using spreadsheets and the Microsoft Excel’s Solver function, was described for DIR operation of the SOFC with oxygen ion conducting electrolyte (SOFC-O2−) and proton conducting electrolyte (SOFC-H+). The effect of temperature, fuel utilization and type of electrolyte on the equilibrium composition of the anode gas mixture as well as on the boundary of carbon formation has been investigated in the temperature range of 773–1073 K. Based on the results of this thermodynamic study, glycerol can be considered an alternative fuel with suitable characteristics for electricity generation in IT-SOFCs. Operating at carbon-free conditions, between 773 and 1073 K, with a fuel utilization of 99.99% in the anode channel outlet, glycerol-fuelled IT-SOFCs systems attain high theoretical efficiencies in the range of 80.7–89.9% (SOFC-O2− case) and 90.3–96.7% (SOFC-H+ case). Regarding the maximum values of the average electromotive force (EMF) and efficiency, it was verified that glycerol exhibits very similar potential for power generation with ethanol. Although glycerol fed SOFC-H+ is superior to SOFC-O2− in terms of maximum theoretical efficiency, it should be taken into account that the SOFC-H+ shows a greater tendency for carbon deposition than does the SOFC-O2− during the operation. Besides, it was found that decreasing temperature increases the efficiency but also favors carbon formation, for both SOFC-O2− and SOFC-H+. When the system runs at 70% of its maximum power and the partial pressure of residual hydrogen in the anode outlet is kept equal to 0.1 atm, the highest efficiency (67%) is achieved by operating an SOFC-H+ at 823 K. 相似文献
The purpose of this study was to evaluate the detection limit of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for direct identification, without previous microbiological culture, of bovine mastitis-causing bacteria from milk samples. Milk samples (n = 15) were experimentally contaminated with Staphylococcus aureus, Streptococcus uberis, Streptococcus agalactiae, Streptococcus dysgalactiae, and Escherichia coli to have bacterial counts ranging from 103 to 109 cfu/mL. These contaminated milk samples were subjected to a preparation protocol for bacterial ribosomal protein extraction using the MALDI Sepsityper kit (Bruker Daltonik, Bremen, Germany), which allowed MALDI-TOF MS coupled with Biotyper software (Bruker Daltonik) to identify bacterial fingerprints based on intact ribosomal proteins. The ability of MALDI-TOF MS to correctly identify bacterial strains from experimentally contaminated milk (without previous microbiological culture) depended on the bacterial count of the samples and on the species of the bacteria evaluated. Adequate identification at the bacterial species level (score ≥2.0) directly from milk samples required bacterial counts in the following ranges: ≥106 cfu/mL of Staph. aureus, ≥107 cfu/mL of E. coli, and ≥108 cfu/mL of Strep. agalactiae, Strep. dysgalactiae, and Strep. uberis. We concluded that direct identification of mastitis-causing pathogens is possible for Staph. aureus, E. coli, Strep. agalactiae, Strep. dysgalactiae, and Strep. uberis, but correct identification depended on the bacterial count in the milk samples. 相似文献
The aim of this study was to identify the main amino acids responsible for the production of esters in ciders. The experiments were carried out in apple must and synthetic must. The amino acids were analysed by high‐performance liquid chromatography and the volatile compounds by gas chromatography. Aspartate, asparagine and glutamate positively influenced the production of esters in the cider models and were used in the experiments with mixtures. The response surface generated by the proposed model yielded two regions that maximized the production of esters. In addition, the combination of aspartate and glutamate predicted a higher production. The optimal suggested concentrations were 43.4% of aspartate and 56.6% of glutamate for 120 mg/L of total nitrogen. The apple must supplemented with these two amino acids resulted in four times more esters than in the same cider without supplementation, demonstrating the effectiveness of the proposed model. 相似文献