Extrusion measurement

Table 10.6 Extrusion Measurements for Barrel Temperatures of 200, 220, and 240 °C for Zones 1, 2, and 3, Respectively...

Table 10.7 Extrusion Measurements for a Screw Speed of 60 rpm and Different Barrel Temperatures...

Figure 20.1 Capacitance probe high-pressure cavity and seals for continuous intrusion-extrusion measurements. 

Van den Bergh, B.A., et al. 2001. Elasticity of vesicles assessed by electron spin resonance, electron microscopy and extrusion measurements. Int J Pharm 217 13. 

In this review article, primary attention will be given to the results of hydrostatic extrusion measurements on polymers by the author and his colles es at Leeds University. This work will be described in the context of major developments which have taken place on both hydrostatic extrusion and ram extrusion by other groups, notably Takayanagi and his colleagues in Japan, Porter and his colleagues in... 

For determination of the overall porosity, pycnometric methods are recommended that use imbibition of the material in a light inert gas and mercury. Mercury porosimetry is the method of choice for assessing macro- and meso-pores. The use of intrusion and extrusion measurements is necessary to understand more complex pore structures. 

The pore size distributions obtained by the mercury intrusion and liquid extrusion techniques are expected to be different. Mercury intrusion allows access to the pores from both sides of the mat and the entire pore volume is likely to be sampled. For pores that have large surface openings, the liquid extrusion generally tends to imderestimate the pore volumes relative to those measured by intrusion porosimetry. Liquid extrusion measurements yield the pressure needed to push the liquid past the most constricted part (or the throat ) of the pore. The pore volume of the channel is estimated based on the throat diameter. This also introduces directionality to the liquid extrusion measurement For a sample where porosity includes converging or diverging channels, the pore volumes (and pore dimensions) obtained from the liquid extrusion method will depend on the direction of the gas flow into the membrane. However, this is not expected to be a serious source of error in routinely characterizing nanofiber mats. 

Nakajima et al. [101] studied the viscoelastic behavior of butadiene-acrylonitrile copol)rmer filled with carbon black. Capillary extrusion measurements with an Instron and dynamic oscillatory measurements with a Rheovibron suggested the occurrence of strain hardening in filled elastomer due to tensile extension causing structural changes in the carbon black filled elastomer. It is possible fliat the structure built by the carbon black in the elastomer increasingly jams against... 

The physico-mechanical properties of films at a stretching (extrusion) measured in a direction by means of universal tensile machine EZ-40 (Germany) in accordance with Russian State Standard GOST-14236-71. Tests are spent on rectangular samples in width of 10 mm, and a working site of 50 mm. The speed of movement of a clip was 240 mm/min. The five parallel samples were tested. 

Mercury intrusion-extrusion measurements were made with a Carlo-Erba 225 pressure porosimeter. 

A method for calculating the dimensions of the cavities and narrow necks from the intrusion-extrusion curves has been proposed by Reverberi." " The method is essentially as follows the ascending curve (penetration) branch is measured in the usual way, but the descending curve is mapped out from a series of steps each step commences at the same maximum pressure, proceeds to a pre-determined minimum pressure which is different for... 

Piston Cylinder (Extrusion). Pressure-driven piston cylinder capillary viscometers, ie, extmsion rheometers (Fig. 25), are used primarily to measure the melt viscosity of polymers and other viscous materials (21,47,49,50). A reservoir is connected to a capillary tube, and molten polymer or another material is extmded through the capillary by means of a piston to which a constant force is appHed. Viscosity can be determined from the volumetric flow rate and the pressure drop along the capillary. The basic method and test conditions for a number of thermoplastics are described in ASTM D1238. Melt viscoelasticity can influence the results (160). 

Tableting, pressing, mol ding, and extrusion operations are commonly used to produce agglomerates of well-defined shape, dimensions, and uniformity in which the properties of each item are important and output is measured in pieces per hour (see Ceramics, ceramics processing Pharmaceuticals Metallurgy, powderp tallurgy Plastics processing).

Figure 13.6 shows the influence of temperature on specific volume (reciprocal specific gravity). The exaet form of the eurve is somewhat dependent on the crystallinity and the rate of temperature change. A small transition is observed at about 19°C and a first order transition (melting) at about 327°C. Above this temperature the material does not exhibit true flow but is rubbery. A melt viseosity of 10 -10 poises has been measured at about 350°C. A slow rate of decomposition may be detected at the melting point and this increases with a further inerease in temperature. Processing temperatures, exeept possibly in the case of extrusion, are, however, rarely above 380°C. 

The Ml test equipment is easy to operate, provides repeatable results, and low cost to operate. It is widely used for quality control and for distinguishing between members of a single family of plastics. Specifically, this MI makes a single-point test that provides information on resistance to flow at only a single shear rate. Because variations in branching or MWD can alter the shape of the viscosity curve, the MI may give a false ranking of plastics in terms of their shear rate resistance to flow. To overcome this problem, extrusion rates are sometimes measured for two loads, or other modifications are made. 

Mooney Viscometer studies at 100°C and 120°C show lower viscosity of the Al-hlled gums. Lower viscosity compounds require less energy input for extrusion. Comparative results on the dynamic mechanical properties, measured using a rubber process analyzer (RPA), show that at the... 

Table 3.10 shows the recovery from PP of Irgafos 168 and its oxidised and hydrolysed by-products by various extraction procedures. As may be observed, One-Step Microwave-Assisted Extraction (OSM) and US lead both to negligible hydrolytic additive degradation. The measured additive decay (by oxidation) is essentially due to the antioxidant activity during the processing (extrusion) step of the polymer and not to the US or microwave heating treatment. 

Processes such as film extrusion, fiber spinning, injection molding, and drawing tend to impart orientation to products made from semicrystalline polymers. Mechanical, dielectric, and optical properties, to mention only three, are often strongly influenced by orientation. X-ray diffraction offers a direct approach to studying crystallite orientation because the Intensity that is diffracted into a detector placed at an appropriate position is directly proportional to the number of crystal lattice planes that are in the correct orientation for diffraction. The principles of such measurements are well described in textbooks 0,2). 

Empty space in which there are no atoms or molecules. A perfect vacuum cannot be attained in practice and the term denotes a space containing air or other gas at a very low pressure. In industry vacuum is measured in inches of mercury (in Hg) ranging from 0 in at atmospheric pressure to around 30 in at zero absolute pressure. Vacuum Extrusion... 

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