Extrudate diameter

The first scale-up method was developed by Carley and McKelvey [1] in 1953. In this original work, the rate and power consumption at a fixed speed and for a geometrically similar extruder was simply a ratio of the extruder diameters as follows ... 

Most high polymers exhibit die swell on extrusion. Thermotropic polymers do not, and indeed values of the ratio of extrudate diameter to capillary diameter as low as 0.9 have been observed 104). Since die swell is associated with viscoelasticity in the melt, it is interesting to note that even in the isotropic phase little or no elastic behaviour is observed in a thermotropic polymer 105),... 

Newtonian and Power Law Fluids Extrudates A Newtonian and a Power Law model fluid are extruded from a long horizontal pipe of diameter Dq. Show that in the absence of gravity, the ratio of the extrudate diameter D to the tube diameter is given by 0.87 and [(2n+ l)/(3w+ 1)]1,/2 for the Newtonian and Power Law model, respectively. 

As an example, a process with 1000 1/h (equal to approximately 1 metric ton per hour) and a speed of 400/min would result in a minimum extruder diameter of 60 mm. 

Five profiles of this type arc usually recorded along five different sphere (or extrudate) diameters in order to be able to judge how representative the analysis is and/or how frequent the sphere-to-sphere heterogeneity actually is in the catalyst batch. 

Deactivation measurements were made using three catalysts. The two alumina catalysts were identical except that their extrudate diameters were 3.2 and 1.6 mm respectively, and thereby provided different diffusion path lengths. Descriptions of the catalysts and the bitumen (ref. 3) from which... 

Figure 18.1. Extrudate diameter swell vs. distance from die exit. [Adapted, by permission, from Chang Ho Suh, White J L, Polym. Engng. Sei., 36, No.l 1, 1996, 1521-30.]...

Extruder Diameter, mm Length to Diameter Ratio (L/D) Compression Ratio Polymer Film Thickness, fxm... 

Experimentally obtained data on concentration dependences of B B = De/Dq, where De and Dq are, respectively, extrudate diameter and capillary diameter) and Om values for binary and ternary blends of PA are given in Fig. 18.6. 

This general relation is based on an analytical solution of unsteady heat conduction in an infinite cylinder with constant Ihermophysical properties. A similar relationship is applicable to a rectangular profile where the extrudate diameter is replaced by the half-sheet thickness. 

While the upper collimated light serves as the measuring beam, the lower portion impacts on the second photodetector and acts as the reference beam. Thus, the temperature and age affected by drift which occurs on all semiconductor elements is negated. In some applications such as hose and tubing manufacturing, it is important to know both the extrudate diameter and cross-section. The device described can provide two diameter measurements, which will give an out-of-round indication (eccentricity). 

Capillary and extrudate diameter, respectively Droplet deformability in extensional flow Rotational Brownian diffusion coefficient Steady-state tensile compliance Volume-to-surface average particle diameter Elasticity of the interphase Interaction energy Tensile, or Young s, modulus Electron... 

The basic assumption of classical rheological theories is that the liquid structure is either stable (Newtonian behavior) or its changes are well defined (non-Newtonian behavior). This is rarely the case for flow of multiphase systems. For example, orientation of sheared layers may be responsible for either dilatant or pseudoplastic behavior, while strong interparticle interactions may lead to yield stress or transient properties. Liquids with yield stress show a plug flow. As a result, these liquids have drastically reduced extrudate swell. Be s d/do (d is extrudate diameter, do that of the die) [7]. Since there is no deformation within the plug volume, the molecular theories of elasticity are not applicable. 

Extruder diameter, mm Blown film die diameter, mm Cast film die width, mm Extrusion coating die width, mm... 

The components of a pipe extrusion line include an extruder, annual die, calibration system, cooling system, puller, wind-up unit or stacker, and auxiliary equipment. The extruder typically has anL/D of 24 1 or greater and the screw design depends on the material. Conical twin-screw extruders are often used for poly(vinyl chloride). The diameter of the annular dies is 25 to 100 percent of the extruder diameter. However, the output of a pipe extrusion line is limited by the ability of the downstream equipment to cool the product and hold tolerances. Since extruder capacity is often underutilized, the same die may be used for a range of pipes of differing diameter and wall thickness. IVpically, a number of adapters and replaceable components are used with the same rear section of die. Dies with multiple outlets are employed when large-diameter extruders are used for small-diameter pipe. 

Drawing of the extrudate (diameter range, usually 18-20 mils) is accomplished by first passing it through rollers at an input speed of four feet per minute and into a heated draw bath of glycerine. The temperature of the draw bath can vary from 25 to 90°C, but is typically between 49 and 60 C. The draw ratio in this first stage of drawing can vary from 3x to 7x. 

Consider a cylindrical tower filled with a solid-supported catalyst. The feed is liquid and flows upward through the reactor. The reactor operates adiabatically. The geometric variables are reactor diameter D [L] reactor length L [L], which is the height of the catalyst mass and solid-supported catalyst pellet or extrudate diameter Jp [L]. The material variables are fluid viscosity /x [L MT ], fluid density p [L M], fluid—solid heat capacity Cp [L MT 0 ], fluid—solid heat conductivity k [LMT 0 ], and molecular diffusivity Z>Difr [L T ]. The process variables are... 

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