Penetrometer studies

Our own two studies on structure in amorphous polymers26.27 clearly missed the early papers of Ueberreiter. We have also checked the 1949 penetrometer study of Kargin and Sogolova on PIB. 0 This paper reports the first experimental observation by any method of a T>Tg phenomenon in any polymer. They designate their T>Tg event as but make no reference to Ueberreiter. 

From these results it is evident that there are two transitions which involve substantial changes in the heat capacity of the system and which possess the characteristics of a glass to rubber transformation. Penetrometer studies indicate that the "softening point of the sample is coincident with and this has been assigned as the main chain glass-rubber transition. At temperatures... 

De Man (1983) has reviewed this property of fats. Consistency is defined as (1) an ill-defined and subjectively assessable characteristic of a material that depends on the complex stress-flow relation or as (2) the property by which a material resists change of shape. Spreadabil-ity, a term used in relation to consistency, is the force required to spread the fat with a knife. The definition is similar to that for hardness the resistance of the surface of a body to deformation. The most widely used simple compression test in North America is the cone penetrometer method (AOCS Method Cc 16-60, 1960). More sophisticated rheological procedures are also available. Efforts have been made to calibrate instrumental tests with sensory response. With the cone penetrometer method, penetration depth is used as a measure of firmness. Hayakawa and De Man (1982) studied the hardness of fractions obtained by crystallization of milk fat. Hardness values obtained with a constant speed penetrometer reflected trends in their TG composition and solid fat content. 

Tanaka, M., deMan, J., and Voisey, P.W. 1971. Measurement of textural properties of foods with a constant speed cone penetrometer. J. Texture Studies 2 306-315. 

The time required to increase the batch temperature to 65°C was studied. Of the 20 batches, 18 required 35 min, while the other two batches attained the desired temperature in about 30 min. Such small differences were not thought important enough for further evaluation. The time required for the cooldown cycle was found to be 65 min for 16 batches, while four batches took 60 min. Final product characteristics, such as appearance and penetrometer readings, were compared for batches with cooling times of 60 and 65 min, and no difference was found in the end product. 

Figure 8-32 Mechanical Model for Foods as Viscoplastic Materials. Source From M. Tanaka, et al., Measurement of Textural Properties of Foods with a Constant Speed Cone Penetrometer, J. Texture Studies, Vol. 2, pp. 301-315, 1971.

Mobile or submersible seabed systems can be subdivided into unmanned and manned systems (Figure 4.11). These systems typically have very limited penetration capability because of the lack of reaction in the free-swimming submersible. Even with the vertical thrusters on full power, forcing the submersible down to complement whatever negative buoyancy that can be provided, penetration of the types of equipment shown in Figure 4.6 has been about 1 m in hard soils and about 3 m in soft soils (Richards, 1972). In special studies, such as for pipelines, a carrier tool and test rod-sensor has been deployed from both unmaimed and manned submersibles. A cone penetrometer and a temperature cone have been deployed from both types of submersibles (Kolk and Power, 1983 Geise and Kolk, 1983). 

Depth of cure in polyacid-modified composites has been studied and compared with that in conventional composites [12]. Two techniques were used to inspect the behaviour of the specimens that had been prepared in split metal mould and cured from one end for 40 s. Depth of cure was then measured either using a penetrometer or by scraping away the inadequately cured material from the end furthest away from the curing lamp using a plastic spatula. These two techniques gave very similar results for all materials. Overall the study showed that clinical materials are able to cure to a variety of depths, depending on the brand and the shade [12],... 

Measurement of C requires more sophisticated and expensive rheometers and more involved experimental procedures. It must be remembered that experiments have to he carried out below the critical strain value (see Sec II), or in [he region of linear viscoelastic behavior. This region is determined by measuring the complex modulus G as a function of the applied strain at a constant oscillation frequency (usually 1 Hz). Up to 7, G does not vary with the strain above Yr, G tends to drop. The evaluation of oscillatory parameters is more often restricted to product formulation studies and research. However, a controlled-fall penetrometer may be used to compare the degree of elasticity between different samples. Creep compliance and creep relaxation experiments may be obtained by means of this type of device. In fact, a penetrometer may be the only way to assess viscoeIa.sticity when the sample does not adhere to solid surfaces, or adheres too well, or cures to become a solid or semisolid. This is the case of many dental products such as fillings, impression putties, sealants, and cements. 

A variety of soil physical measurements can be used to evaluate the effectiveness of soil conditioners. These measurements include infiltration rate, air permeability, porosity, aggregate stability, penetration resistance, or bulk density. Reliable standardized procedures are needed to compare and/or evaluate the effect of soil conditioners on soil physical properties. For example, many companies rely on penetrometer measurements to evaluate their product, but do not standardize their measurements with respect to moisture content or bulk density. Such non-standardized observations may easily lead to erroneous claims about the product. Also, be cautious of studies relying on measurements that are not easily quantified such as soil tilth, stickiness, tightness, or hardness. 

Softening points or penetrometer measurements are frequendy used in studying the melting of polymers. Such values are listed as mdting points, but with the symbol s, and only if more rdiable values have not been reported. The polymer must first be demonstrated to be highly crystalline, and the softening must be abrupt, as expected for a solid-liquid transition. 

Obviously in each area, certain specific items of test equipment will be used, such as small extruders, paint rigs, Stevens texture testers and penetrometers, etc. However, here we are interested in those pieces of rheological equipment that we should also find. The following important features are generally measured in rheological studies for typical liquids listed above, with some specific examples ... 

Recently, a Raman probe has been designed for a cone penetrometer for studying underground storage tanks at the Department of Energy site in Hanford [143]. These tanks contain a mixture of chemicals and radioactive waste and, with in-tank characterization of such mixtures, significant reduction in personnel exposure, analysis time, and cost is achieved relative to laboratory analysis. RS has been shown to be well suited for detecting many of the chemicals contain within the tanks [43,144,145]. For example, Marston have detected and identified nitrite (NO2), nitrate (N03 ), sulfate (SO4 ), chromate (CrO ),... 

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