Inflation methods

Schematic of the apparatus used for planar elongation tests, in which a tubelike sample is extended and inflated. From Laun and Schuch (1989). 

Transient planar viscosities (open symbols) compared to uniaxial ( ) and shear (0)— all at constant extension or shear rate of 0,05 s —for a low density polyethylene at 125°C. The solid line is the linear viscoeslastic limit. Ticks denote a repeat test (at half the sample length, 

Inflation of a sheet clamped over a circular hole suffers the same difficulty. More work has been done with this method (see Dealy, 1982). Inflation has been done with both liquid and gas. The stress and deformation equations are treated in Chapter 1, Exercise 1.10.8, andby Dealy (1982). The results can give the biaxial viscosity function and e up to 2 has been achieved (Rhi-Sausi and Dealy, 1981 Yang and Dealy, 1987). But results so far have been limited to relatively low extension rates. The method requires photography and a somewhat complex apparatus. Inflation tests, however, are similar to the vacuum forming process for making shaped plastic items (Schmidt and Carley, 1975 DeVries and Bonnebat, 1976). Thus there is motivation to continue this work. 

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For the inflation method the test piece is held with a circular clamp and pressurized through a central hole. The biaxial strain state holds near the apex and optical methods can be used to find the radius of curvature and the extension of a grid drawn on the test piece. The nominal stress is then ... 

Various biaxial straining devices have been constructed, as for example those described in references 91 - 96. References 92 and 96 cover the inflation method and reference 95 describes a device that will give unequal biaxial and sequential biaxial straining. 

O Connell, P. A., and McKenna, G. B., Novel nanobnbble inflation method for determining the viscoelastic properties of ultrathin polymer films. Rev. Sci. Instrum., 78, 013901-1 to 013901-12(2007). 

These results suggest that the bubble inflation method for measuring the properties of ultrathin polymer films has a broader range of applicability than originally foreseen. 

Blown Film. The blown or tubular film process provides a low cost method for production of thin films (Fig. 3). In this process, the hot melt is extmded through an aimular circular die either upward or downward and, less frequently, horizontally. The tube is inflated with air to a diameter... 

Inflated Diaphragm Method (ASTM D3886). This method is appHcable both to woven and knitted fabrics. The specimen is abraded by mbbing either unidirectionally or multidirectionally against an abradant having specified surface characteristics. The specimen is supported by an inflated mbber diaphragm under a constant pressure. Evaluation of abrasion resistance can be either by determination of the number of cycles required to wear through the center of the fabric completely or by visual examination of the specimens after a specified number of cycles. 

The effect upon total taxes paid, when they are corrected to their purchasing power in Year 0, is shown in Fig. 9-36. Differential inflation not only decreases the profitability of the project to its owner but also decreases the revenue received by the taxing authority. The method of calculation is identical to that of the earlier example. 

Method of forming plastic articles by inflating masses of plastic material with compressed gas. 

Although plastic sheet and film may be produced using a slit die, by far the most common method nowadays is the film blowing process illustrated in Fig. 4.20. The molten plastic from the extruder passes through an annular die and emerges as a thin tube. A supply of air to the inside of the tube prevents it from collapsing and indeed may be used to inflate it to a larger diameter. 

The convention extrusion blow moulding process may be continuous or intermittent. In the former method the extruder continuously supplies molten polymer through the annular die. In most cases the mould assembly moves relative to the die. When the mould has closed around the parison, a hot knife separates the latter from the extruder and the mould moves away for inflation, cooling and ejection of the moulding. Meanwhile the next parison will have been produced and this mould may move back to collect it or, in multi-mould systems, this would have been picked up by another mould. Alternatively in some machines the mould assembly is fixed and the required length of parison is cut off and transported to the mould by a robot arm. 

In this method each year s savings need to take account of the fact that, as the equipment gets older, the cost of maintenance and repairs is likely to increase. The effect of inflation can also be allowed for in assuming the annual cash flows through the life of the equipment. 

To reduce deviations in blood pressure measurement in the clinic, the patient and clinician should not talk during blood pressure readings. The measurement arm is supported and positioned at heart level with the blood pressure cuff encircling at least 80% of arm circumference. If a mercury or aneroid device is used, then the palpatory method must be used first to estimate the systolic blood pressure.18 If an automated device is used, this is not necessary. After the patient s cuff is inflated above the systolic pressure, the mercury column should drop at a rate of 2 to 3 mm per second. A stethoscope placed over the brachial artery in the antecubital fossa identifies the first and last audible Korotkoff sounds, which should be taken as systolic and diastolic pressure, respectively. A minimum of two readings at least 1 minute apart are then averaged. If measurements... 

Balloon tamponade involves the application of direct pressure to the area of bleeding with an inflatable balloon attached to a nasogastric tube. It is an option for patients in whom drug therapy and band ligation fail to stop variceal bleeding. Balloon tamponade is used only when other methods have failed. Once the direct pressure of the balloon is removed, rebleeding often occurs, so balloon tamponade is only a temporary measure prior to more definitive treatment such as shunting.11... 

The cost of materials and labour has been subject to inflation since Elizabethan times. All cost-estimating methods use historical data, and are themselves forecasts of future costs. Some method has to be used to update old cost data for use in estimating at the design stage, and to forecast the future construction cost of the plant. 

Widely different from that estimated by method 1. This is not surprising as inflation in the UK has been very much greater than that in the US over this period. 

In order to show the inflation of q2, which results from the use of improper statistical methods, we have performed comparative studies involving stepwise regression and RR [68,70]. In these studies, comparative models were developed for the prediction of rat fat air and human blood air partitioning of chemicals. For the former, proper statistical methods yielded a model with a q2 value of 0.841, while the stepwise approach was associated with an inflated q2 of 0.934. Likewise, the rat fat air model derived using proper methods had a q2 value of 0.854, while the stepwise approach yielded a model with an inflated q2 of 0.955. 

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