Extrusion technique

Both wet and dry extrusion techniques are available, and both are strongly influenced by the friclional properties of the particulate phase and wall. In the case of wet extrusion, rheological properties of the liquid phase are equally important. See Pietsch [Size Enlargement by Agglomeration, John Wiley Sons Ltd., Chichester, 346 (1992)] and Benbow et al. [Chem. Eng. Sci., 422,2151 (1987)] for a review of design procedures for dry and wet extrusion, respectively. 

Melt elasticity is of considerable importance in understanding much of the behaviour of polyethylene when processing by film extrusion techniques and when blow moulding. The complex relationships observed experimentally here have been summarised by the author elsewhere. ... 

Because of their low viscosity the liquid cyclic aliphatic resins find use in injection moulding and extrusion techniques, as used for glass-reinforced laminates. They are also very useful diluents for the standard glycidyl ether resins. 

VETs Vesicles by extrusion techniques homogeneous sized vesicles 8... 

Fig. 4. Configuration of a ceramic membrane reactor for partial oxidation of methane. The membrane tube, with an outside diameter of about 6.5 mm and a length of up to about 30 cm and a wall thickness of 0.25-1.20 mm, was prepared from an electronic/ionic conductor powder (Sr-Fe-Co-O) by a plastic extrusion technique. The quartz reactor supports the ceramic membrane tube through hot Pyrex seals. A Rh-containing reforming catalyst was located adjacent to the tube (57).

MJ Hope, R Nayar, LD Mayer, PR Cullis. Reduction of liposome size and preparation of unilamellar vesicles by extrusion techniques. In G Gregoriadis, ed. Liposome Technology. 2nd ed. Vol. I. Liposome Preparation and Related Techniques. Boca Raton, FL CRC Press, 1993, pp 123-139. 

Clear, water-soluble, oil-and grease-resistant films of moderate strength can be cast from hydroxyethylcellulose solutions. Flexible, nontacky, heat-sealable packaging films and sheets can be produced from hydroxypropylcellulose by conventional extrusion techniques. Both gums can be used in the formulation of coatings, and both can be used to form edible films and coatings. 

Ultem PEI resins are amber and amorphous, with heat-distortion temperatures similar to polyethersulfone resins. Ultem resins exhibit high modulus and are stiff yet ductile. Light transmission is low. In spite of the high use temperature, they are processible by injection molding, structural foam molding, or extrusion techniques at moderate pressures between 340 and 425°C. They are inherently flame retardant and generate little smoke dimensional stabilities are excellent. Large flat parts such as circuit boards or hard disks for computers can be injection-molded to maintain critical dimensions. 

Mixing and extrusion techniques are usually applied to elastomers for processing and improvement of physical properties. These mechanical processes normally lead to the occurrence of radical reactions such as chain scission, chain coupling, and crosslinking. The 13C-NMR analysis of EP showed that the shearing of polymer resulted in hydrogen abstraction. This was followed by disproportionation reaction to form olefins [75]. 

The principal solution to fabrication difficulties is copolymerization. Three types of comonomers are commercially important vinyl chloride acrylates, including alkyl acrylates and alkylmethacrylates and acrylonitrile. When extrusion is the method of fabrication, other solutions include formulation with plasticizers, stabilizers, and extmsion aids plus applying improved extrusion techniques. The literature on vinylidene chloride copolymers through 1972 has been reviewed (1). 

When the mol. percent of PHB in the copolymer exceeds about 30-40 percent, a liquid-crystalline melt is obtained. Up to about 60 mol. percent, order in the melt increases and melt viscosity decreases. Compositions containing about 60 mol. percent PHB can be melt-spun into fibers using standard extrusion techniques. It is the unusual combination of properties that makes this class of materials valuable for the formation of high-strength fibers and plastics. 

In the past with the development of single-screw extrusion techniques for newer TP materials, it was found that some plastics with or without additives required higher pressures (torque) and needed higher tempera-... 

A variation on the penetration method is the back extrusion technique, where the sample is contained in a cylinder and the penetrating body leaves only a small annular gap... 

The resin manufacturer and the specific resin product code should be established. Processors are very knowledgeable in molding and extrusion techniques but are not well versed in colorant use and resin compatibility. That is the job of the colorist. It may be helpful to contact the resin manufacturer directly for additional information regarding colorant and additive compatibility, especially when designing colorant systems for some of the more exotic engineering resins and alloys. The resin manufacturers may have done research or had experience that may help in selecting the colorant or avoiding certain problematic colorants or additives. 

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