Mechanical Strength Analysis

The tensile test was carried out with rectangular specimens (width =10 mm and thickness = 5 mm) using a universal tensile machine (UTM 3366, Instron) according to ASTM D 638. A crosshead speed of 1 mm/min was applied. All tests were conducted under ambient conditions. The data reported were averages of at least six measurements. For cured ENR (The results are reported in Table 16.2) and its composites, six measurements were executed with each sample. The tensile properties of both of these coir and luffa fibers were determined using the same tensile machine at a strain rate of 1 mm/min and a gripping length of 50 mm at 23°C 1°C and 58% relative humidity (The results are reported in Table 16.1). 

The impact strength of the pure ENR and its hybrid composites was measured with a standard Izod impact testing machine (model IT 1.4, Fuel Research Instruments, Maharashtra, India) according to ASTM D 256. The measurements were done on unnotched samples (70x10x4 mm) with an impact speed of 1 m/s and energy of 1.4 joules. For each specimen, six measurements were recorded. 

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A laminate can be subjected to thermal, moisture, and mechanical loads with the objective of surviving those loads. A method of strength analysis is required to determine either (1) the maximum loads a given laminate can withstand or (2) the laminate characteristics necessary to withstand a given load. The maximum loads problem is, of course, an analysis situation, and the laminate characteristics problem is a design situation that will be discussed in Chapter 7. 

This second group of tests is designed to measure the mechanical response of a substance to applied vibrational loads or strains. Both temperature and frequency can be varied, and thus contribute to the information that these tests can provide. There are a number of such tests, of which the major ones are probably the torsion pendulum and dynamic mechanical thermal analysis (DMTA). The underlying principles of these dynamic tests have been covered earlier. Such tests are used as relatively rapid methods of characterisation and evaluation of viscoelastic polymers, including the measurement of T, the study of the curing characteristics of thermosets, and the study of polymer blends and their compatibility. They can be used in essentially non-destructive modes and, unlike the majority of measurements made in non-dynamic tests, they yield data on continuous properties of polymeric materials, rather than discontinuous ones, as are any of the types of strength which are measured routinely. 

Komrska Satava (1970) showed that these accounts apply only to the reaction between pure zinc oxide and phosphoric acid. They found that the setting reaction was profoundly modified by the presence of aluminium ions. Crystallite formation was inhibited and the cement set to an amorphous mass. Only later (7 to 14 days) did XRD analysis reveal that the mass had crystallized directly to hopeite. Servais Cartz (1971) and Cartz, Servais Rossi (1972) confirmed the importance of aluminium. In its absence they found that the reaction produced a mass of hopeite crystallites with little mechanical strength. In its presence an amorphous matrix was formed. The amorphous matrix was stable, it did not crystallize in the bulk and hopeite crystals only grew from its surface under moist conditions. Thus, the picture grew of a surface matrix with some tendency for surface crystallization. 

Beilken et al. [ 12] have applied a number of instrumental measuring methods to assess the mechanical strength of 12 different meat patties. In all, 20 different physical/chemical properties were measured. The products were tasted twice by 12 panellists divided over 4 sessions in which 6 products were evaluated for 9 textural attributes (rubberiness, chewiness, juiciness, etc.). Beilken etal. [12] subjected the two sets of data, viz. the instrumental data and the sensory data, to separate principal component analyses. The relation between the two data sets, mechanical measurements versus sensory attributes, was studied by their intercorrelations. Although useful information can be derived from such bivariate indicators, a truly multivariate regression analysis may give a simpler overall picture of the relation. 

This limitation is offset by the high efficiencies and rapid analysis times of high-performance SEC. It should be evident that as support pore diameter and pore volume increase, the amount of solid material in the particle will be reduced, compromising the mechanical strength of the support matrix. 

Thin membranes have the advantage of low area specific conductivities and more favorable back diffusion of water in comparison with thicker membranes. In the former case, this means that membranes with lower conductivity values could be tolerated. Analysis of voltage loss versus membrane thickness and specific conductivity has revealed that, if a membrane voltage loss of 25 mV at a current density 1 A cm can be tolerated, then existing materials with conductivity values similar to Nation (0.1 S cm i) could be prepared as 20-30 pm thick membranes. However, thinner membranes also typically exhibit lower mechanical strength than their thicker counterparts and can therefore fail earlier. Therefore, future materials might be suitable with just half the specific conductivity if they can be prepared into membranes of half the thickness and still possess sufficient mechanical strength. ... 

Polymer films of approximately 1000 microns wet film thickness were laid down with a bar applicator on PTFE coated glass panels and the solvent allowed to evaporate at ambient temperature for a standard period of seven days. A typical plot of solvent weight loss with time is shown in Figure 2. The thickness of the wet film was dictated by the need to have adequate mechanical strength in the dry films in order that they might be suitable for subsequent mechanical test procedures. Dry film thicknesses were approximately 300 microns as measured by micrometer. The dried polymer films were examined by dynamic mechanical thermal analysis (DMTA) (Polymer Laboratories Ltd.). Typical DMTA data for a polymer and paint are... 

In this section, various issues concerning solid particles are presented. The analysis covers the most important particle properties (surface area, particle shape and size distribution, mechanical strength, and density) as well as the behavior of a single particle in suspension (terminal velocity) and of a number of particles in fluidization state. Finally, the diffusion of molecules in a porous particle (diffusion coefficients) is also discussed. 

White Highly inert surface useful for biomedical and pesticide analysis mechanical strength similar to Chromosorb G... 

The mechanical strength of extrudates was measured with an standardized apparatus according to ASTM D-4179 and the crush strength was obtained as the average of 20 measurements. A scanning electron microscope (SEM) ISI DS-130 coupled to a Kevex Si/Li detector and a Sun SparcStation 5 for energy dispersive X-ray (EDX) analysis was used to... 

Characterization of the keratinized cells by classical histological and biochemical approaches has been difficult because of the intractable nature of the tissue. Yet it is precisely these properties of mechanical strength, insolubility, macromolecular character, and lack of metabolic activity along with its ease of isolation which makes stratum corneum amenable to analysis by physical methods. The extreme complexity of composition, molecular structure, and organization of stratum corneum make interpretation of these macroscopic properties in terms of molecular structure and events dependent heavily on analogous studies of model synthetic polymer systems and the more thoroughly characterized, keratin-containing wool. 

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