Additives for extrusion

T able 5.4. Examples of additives for extrusion shaping (aqueous and non-aqueous systems)... 

The addition level for the different applications varies from 5-10 phr for moulded articles to 15-30 phr for extrusions. Roller coverings, dependant upon hardness, are often made using factices to facilitate grinding operations. Special products such as erasers use factice, usually white factice, at levels between 200-400 phr. 

As a melt viscosity and melt-strength-enhancing additive for modifying PET for film blowing and extrusion blow moulding applications... 

Control experiments establish that the initial process converting the dibromide 275 to 276 takes place in two steps with E1/2 for extrusion of the first and second axial ligands occurring at —0.36 and —1.08 V, respectively [75]. After reaction with the alkyl halide, the resulting octahedral complex 277 is further reduced in the range of -1.4 to -1.7 V to form a cobalt (II) complex which decays via the addition of an additional electron, cleavage of the C-Co and Co-Y bonds, and reaction with the Michael acceptor. 

Aqueous suspension polymerization requires the usual additives, such as free radical initiators, colloidal dispersants (not always), and chain transfer agents to control molecular weight. After the process is completed, the suspension contains spherical particles approximately 100 pm in diameter. Suspension polymers are available as free-flowing powder or in pellet form for extrusion or injection molding.58... 

Many of the comments in the previous chapter about the selection of grade, additives and mixing before moulding apply equally in preparation for extrusion. It is important of course that the material should be appropriate for the purpose, uniform, dry, and free from contamination. It should be tested for flow and while many tests have been devised for this it is convenient to classify them as either for low or high rates of shear. The main terms used in such testing ( viscosity , shear rate , shear strain , etc.) are defined in words and expressed as formulae in ISO 472, and it is not necessary to repeat them here. Viscosity may be regarded as the resistance to flow or the internal friction in a polymer melt and often will be measured by means of a capillary rheometer, in which shear flow occurs with flow of this type—one of the most important with polymer melts—when shearing force is applied one layer of melt flows over another in a sense that could be described as the relationship between two variables—shear rate and shear stress.1 In the capillary rheometer the relationship between the measurements is true only if certain assumptions are made, the most important of which are ... 

A typical masterbatch for extrusion, injection, or blow molding would consist of an appropriate carrier resin for the polymer being processed, a fluorescent pigment, and a wax additive. The following example illustrates a 25% color concentrate formula for injection molding which should be let down at 4% to yield a final color loading of 1% ... 

Journal of Vinyl and Additive Technology 4, No.l, March 1998, p.12-21 MATERIALS AND TESTING FOR EXTRUSION OF RPVC CONSTRUCTION PRODUCTS... 

The sohds remaining after fat removal are generally rich in protein and find a ready market in animal feeds. Some oilseed solids, especially soybean, go into human foods as flours, concentrates, textured particles, or protein isolates. Some oilseed sohds contain toxins or allergens that make them unfit for animal feeds tung nut and castor bean, for example. Unless treated, these solid residues go into fertilizers. Various processes have been developed to remove or chemically destroy undesirable compounds (10). One process developed at Texas A M University for UNIDO (11, 12) uses a chemical additive and extrusion to detoxify and deallergenate castor meal making it suitable for animal feed. 

Numerous aryl bromides, iodides [203], borates [204] and triflates [205, 206] have been successfully carbonylated. Triflates could serve as a route for the synthesis of arenecarboxylic acid derivatives from phenols. This carbonylation using dppf in a catalytic mixture generally shows higher efficiency than PPhj or P(o-Tol)3 [207]. Poor performance is also noted for PPhj in a Pd-catalyzed vinyl substitution of aryl bromides [208]. Side-reactions involving the formation of [PPhjAr]Br and ArH are responsible. A system which is catalyzed effectively by PdCljfdppf) under 10 atm CO is the desulfonylation of 1-naphthalenesulfonyl chloride 58 in the presence of Ti(OiPr)4. Formation of isopropyl 1-naphthoate 59 can be explained in a sequence of oxidative addition, SOj extrusion, carbonylation and reductive elimination (Fig. 1-27) [209]. A notable side-product is di-l-naphthyl disulfide. 

RE King, III, "Overview of Additives for Film Products", TAPPI Polymer Laminations and Coatings Extrusion Manual, T Butler (editor), TAPPI Press, September, 2000. 

The polymer is then collected, washed, dried, pelletized, and passed on for extrusion or other forming steps. Pyridine and solvents are recovered in additional operations. Chopey gives a detailed process diagram (2). 

Plastic, rubber, and non-iron metal processing (extrusion aid and release additive for plastics and rubber e.g., PUR, thermosets, casting resins, high melting point mold release agents and additives)... 

---