Porosity Characterization of Carbon Fiber/Epoxy Composite Using Hg Porosimetry and Other Techniques
POLYMER ENGINEERING AND SCIENCE
Authors: Monticeli, Francisco Maciel; Montoro, Sergio Roberto; Cornelis Voorwald, Herman Jacobus; Hilario Cioffi, Maria Odila
Abstract
In polymer composites, the porosity acts mainly as a stress concentrator, which has detrimental effects depending on the shape and position of the voids. Also, the presence of voids is detrimental to the mechanical properties, which results in the need for an accurate method for their characterization in terms of morphology, position, and volume fraction. The aim of this study was to establish an appropriate procedure for the measurement of voids in a polymer composite using the mercury porosimetry technique. Data were also collected using the Taguchi approach. Subsequently, the feasibility of applying the Hg porosimetry methodology was confirmed through a comparison with standard techniques. Statistical analysis was used to determine the best Hg porosimetry parameters and pressures between 203 and 231 MPa was found to generate reliable results for the maximum porosity measurement, with no dependence on other parameters. Since the Hg porosimetry, acid digestion, and optical microscopy methods provided porosity results with a statistically significant similarity, it can be concluded that all these methods are feasible for the analysis of voids. Finally, potential benefits of the proposed porosity analysis methodology were highlighted through the characterization of the void volume, position, and morphology. POLYM. ENG. SCI., 2020. (c) 2020 Society of Plastics Engineers
Experimental study on drop breakup time and breakup rate with drop swarms in a stirred tank
AICHE JOURNAL
Authors: Zhou, Han; Yu, Xiong; Wang, Bo; Jing, Shan; Lan, Wenjie; Li, Shaowei
Abstract
The direct experimental data for breakup parameters of drop breakup time, multiple breakage, and breakup rate are urgently required to understand drop breakup phenomena. In this regard, drop breakup experiments were carried out in a stirred tank using a high-speed online camera. The influences of the rotating speed, interfacial tension, and drop viscosity on the above breakup parameters were then quantitatively investigated. An mechanism correlation for the breakup time is proposed and is further verified by comparing with the results of Solsvik and Jakobsen (Chem Eng Sci, 2015;131:219-234). The percentage of multiple breakage comparing to binary breakup was statistically counted. The results indicated that the dimensionless drop diameter eta=d/d(max)can be adopted to characterize the proportion of binary breakup. Finally, the breakup rate was experimentally measured and the breakup probability was calculated using the inverse method.