Extrusion repetition

Figure 4.12 Impact of extrusion repetition on expansion index of granulates from potato starch.

Figure 4.15 Impact of extrusion repetition on densities of potato starch granulates.

Research revealed an explicit influence of extrusion repetition on TPS density (Figure 4.15). Greater extrusion repetition induced an increase in granulate density irrespective of the material composition. This relationship was at its most pronounced in cases of extrusion of mixtures with 20% glycerol content A considerable density rise was observed on double repetition of the mixture extrusion. 

During the research it was found that storage modulus (E increases with extrusion repetition followed by a decrease in the potato granulate tan 6 value with 25% glycerol content (Figures 4.22 and 4.23). In the case of triple extrasion the increase in elasticity in the obtained material relative to the primary value was 30%. 

The specific mechanical energy also changes with repetition of extrusion. The higher the number of extrusion repetition cycles for the same material, the lower the SME recorded. 

The most probable mechanism for the reduction requires the initial nucleophilic attack by the hydridometal complex on the nitro group, followed by intramolecular cyclization and extrusion of carbon dioxide. Repetition of the cyclization and extrusion sequence, followed by proton transfer, leads to aniline (Scheme 11.6). 

The above methods of synthesis have already used existent ring systems like difunctionalized benzene or cyclohexadienes as starting compounds. In an alternative approach one can generate benzene rings as part of the polymerization reaction, for example, by repetitive Diels-Alder reactions [100] or by valence isomerization [101]. Typical examples of the former include the combination of bisdienes, such as 54 and bisdienophiles, such as 55, whereby the formation of the benzene ring proceeds by extrusion of carbon monoxide from the original Diels-Alder products (scheme 9). The reaction thereby produces a mixture of para- and meto-linked polyphenylenes. 

The mixture is then subjected to repetitive extrusion through Nuclepore polycarbonate (Sterlitech Corp., Kent, WA, USA or Sterico AG, Wangen, Switzerland) filters (400-, 200- and 100-nm pore size) using a Lipex Extruder (Northern Lipids, Inc.) (see Note 5). 

ST Injection molding, extrusion Super tough, high-viscosity resin, outstanding resistance against repetitive impact, even at very low temperature Fasteners and lock systems... 

Research has shown that repetition of extrusion influences the value of the Young modulus (Figure 4.21). Regardless of the glycerol content in a mixture, the Young modulus value rises - that is, the TPS elasticity increases - with repetition of extrusion. These results are in accordance with the findings made in investigations of the viscoelastic properties of thermoplastic starches. 

Figure 7.9 SME changes associated with repetition of potato TPS extrusion.

In injection molding, a reciprocating ram is used rather than a screw. Ram pressures up to 30,000 psi are developed in the chamber of the machine, which is heated to a range of 300-700°F. Injection molding is a repetitions process rather than a continuous process (like extrusion). Figure 10.7 shows an injection molding machine. There are three basic components that make up an injection mold the cavity, the core, and the... 

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