Effect of extrusion conditions

Journal of Vinyl and Additive Technology 3, No.3, Sept. 1997, p.210-5 EFFECT OF EXTRUSION CONDITIONS ON RIGID PVC FOAM... 

Results are presented of an investigation of the effect of extrusion conditions, such as melt temp., screw speed and draw-down, on process morphology of rigid PVC foams and the properties of the extruded profile, including density, cell structure and surface appearance. The optimum conditions for the best quality profile found in this study were 190 to 196C melt temp, and no greater than 20 rpm screw speed on a 63.5 mm single screw. 15 refs. 

Edi-Soetaredjo, F., Nashed, G., Rutgers, R.P.G., and Torley, P.J. (2003). Numerical analysis on the effect of extrusion conditions on flow in slit die rheometer. Srdint. Conf. On CFD in Minerals and Processing Ind., CSIRO, Melbourne, Australia, pp. 300-302. 

Liang, J. Z. (2008) Effects of extrusion conditions on die-swell behavior of polypropylene/diatomite composite melts. Polym. Test, 17, 936-940. 

The effects of extrusion-cooking mainly on citrus fibres will be now detailed on samples which have been, unless otherwise stated, extruded in the same average conditions (SME 250kWh/t). 

Patil, R.T. D.S. Singh R.E. Tribelhorn. Effect of processing conditions on extrusion cooking of soy-rice blend with a dry extrusion cooker. /. Food Sci. Technol. India 1990, 27, 376—378. 

In Chapter 8, a new section on efUcient extrusion of medical devices has been added. It covers good manufacturing practices in medical extrusion and automation. The effect of processing conditions and screw design on molecular degradation is covered in detail. Screws designs that minimize molecular degradation are discussed and explained. 

Qin Y, Brydon DL, Mather RR, Wardman RH (1993) Fibers fi-om polypropylene and liquid crystal polymer blends 2. Effect of extrusion and drawing conditions. Polymer 34 1202 Seo Y, Hwang SS, Hong SM, Park TS, Kim KU (1995) Effect of die geometry on the structural development of a thermotropic liquid crystalline polymer in a thermoplastic elastomer matrix. Polym Eng Sci 35 1621... 

Han, C.D., and Segai, L., A Study of Fiber Extrusion in Wet Spinning. II. Effects of Spinning Conditions on Fiber Formation , Journal of Applied Polymer Science, 14, 2999-3019, 1970. 

Ilo, S., Tomschik, U., Berghofer, E. Mundigler, N. (1996). The effect of extrusion operating conditions on the apparent viscosity and properties of extrudates in twin-screw extrusion cooking of maize grits. Lebensm Wiss. Technol, 29, 593-598. 

Lo, T. E., Moreira, R. G. Castell-Perez, M. E. (1998). Effect of operating conditions on melt rheological characteristics during twin-screw food extrusion. Transactions of ASAE, 41, 1721-1728. 

Han, C. D., and L. Segal, A Study of Fiber Extrusion in Wet Spinning n. Effects of Spirming Conditions on Fiber Formation, J. Appl. Polym. Sci., 14, 2999-3019,1970. Tsay, C. S., and A. J. McHugh, Mass Transfer Modeling of Asymmetric Membrane Formation by Phase Inversion, J. Polym. Sci. Polym. Phys., 28, 1327-1365, 1990. Davankov, V A., and M. P. Tsyutupa, Structure and Properties of Hypercrosslinked Polystyrene—The First Representative of a New Class of Polymer Networks, React. Polym., 13, 27-42, 1990. 

EFFECTS OF PROCESSING CONDITIONS ON THE FOAMING PERFORMANCES IN THE POLYOLEFIN INSULATED COAXIAL CABLE EXTRUSION... 

The designer should be aware of the fact that this is to be considered in designing with extruded products. The designer can exercise little control over this pull back condition except to be guided by the experience of the extrusion processor to indicate which materials are particularly susceptible to this problem and what the recommended wall thicknesses are to minimize the effect. In general, one of the best ways to improve the condition is to slow down the rate of extrusion. As a result, products have a tendency to pull back. They also will be more costly to produce. 

Distortion Another problem with extrusions is caused by distortion of the section by the effect of heat and other environmental conditions such as exposure to water or chemical agents that tend to soften the plastic. These distortions are generally reversals of the profile back to the shape that it had exiting in the die. This action indicates that the post die forming operations were done at a lower than desirable temperature which results in a molded-in stress. When the stress is relieved the product distorts. In some instances these stresses cannot be eliminated by process changes so that the product is inherently deficient in performance. 

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