Interfacial testing system

The strength of adhesion between the fiber and matrix could also be expected to play a role in this change in failure mode. The interfacial testing system (ITS) provides comparative data on the interfacial shear strengths of the bare and sized E-glass fibers in real composites. A handbook value of 76 GPa [19] was used for the tensile modulus of E-glass fibers and the matrix shear modulus was previously determined as 1.10 GPa. Table 4 lists the mean interfacial shear strength, standard deviation (SD), and number of fiber ends tested for the two fiber types. 

ITS interfacial testing system KMC kneader molded compound... 

A biconical disk interfacial rheometer is available from Anton Paar, known as the Physica Interfacial Rheology System (IRS). A schematic of the rheometer tool is shown in Figure 4.22. Current specifications of the instrument include a torque range of 0.02 xNm to 150 mNm with temperature control from 5 to 70°C. All rheological test modes are available for the interfacial rheometer including oscillatory testing [59],... 

Carbon fibers in the cured epoxy was the composite system for the international round robin program on interfacial test method. The comparison of four test methods is given in Table 9.12. The results indicate that within each laboratory the reproducibility is good, with coefficient of variation (CV) less than 10%. However, the CV among the laboratories can be as high as 25%. The indentation method has the smallest percent of CV because two of the laboratories used the same commercial equipment. The sized fibers show 20 MPa higher IFSS than untreated fibers in pull-out, microbond, and fragmentation methods. The microindentation test method is insensitive to the surface treatment of the fiber. 

In a laboratory test system, the reactant gas is usually humidified by passing it through a water bath in a bubble humidifier that is controlled at a desired temperature. This process assumes that the dew point of the air is the same as the temperature of the bubble humidifier. This temperature can be controlled independently of the cell temperature to achieve the desired gas RH. Water vapor is absorbed by the gas, and water uptake is a function of the water-gas interfacial area. This is a conventional humidification method and is widely used in small-scale laboratory fuel cells due to its simphcity and low cost, but it is not very practical to be used in large-scale stacks. The main disadvantages of the method are its hmited water transfer capacity and slow response to the changes in the RH level. 

Figures 7-2 and 7-3 show the dispersed phase hold-up x as a function of the specific flow rate uc of the continuous phase, using various specific flow rates ud of the dispersed phase as a parameter. The experimental data shown in Fig. 7-2 is applicable to different random packing elements, such as metal Pall rings, Biatecki rings, Hiflow rings with a dimension of 25-38 mm, whereas the data shown in Fig. 7-3 is valid for 50 mm tube columns and other structured packings. The test system used for the experiments under normal conditions was toluol (D)/water, which has a high interfacial tension and is...

These relationships predict the binding Hquid content for wet agglomeration with an accuracy of only ca 30%. The Hquid content required to agglomerate a particular feed material depends, for example, on the interfacial properties of the system (45). Typical values of moisture content required for hailing a variety of materials are listed in Table 2. Very accurate information on the optimum Hquid content to agglomerate a particular feed material must be obtained from experimental tests. 

Fig. 2. Results of interfacial shear strength measurements of the same fiber/matrix systems using four different micro-mechanical tests during a round-robin program involving 12 different laboratories, (a) Results for untreated, unsized carbon fibers, (b) Results for carbon fibers with the standard level of surface treatment. Redrawn from ref. [13].

The sulfite oxidation is a recommended test reaction for determining the size of the specific interfacial area in gas/liquid systems, in particular as expressed by the a value [9, 10]. 

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