Extrusion mixture, formulation

Extrusion mixtures are formulated to produce a cohesive plastic mass that remains homogeneous during extrusion. The mass must possess inherent fluidity, permitting flow during the process and self-lubricating... 

A gravity feed extruder with L/D = 2 recorded (28) higher forces, compared to power generated from a twin-screw extruder with L/D = 0.9, upon extrusion of mixtures of MCC with either lactose or DCP. The extrudate from the basket extruder was denser with a smoother surface than that from the screw extruder. Similarly, material extruded through a screen with L/D = 4 in a basket extruder was denser than that with L/D = 2 (37). However, a smaller L/D ratio is preferred in an axial extruder. An improper L/D ratio could result in a loosely bound extrudate with large surface defects (37), resulting in a formulation less amenable to pelletization, as seen from Figure 14. Since the mean diameter of the pellet often approximates the diameter of the die used in extrusion, choice of the latter is also dictated by desired pellet size. 

Type IV poly(ortho esters) are very similar in structure to type II poly(ortho esters), but they do not need to have excipients in the formulation due to the incorporation of no acidic moieties in the polymer backbone (Ng et al. 1997). Rods of poly(ortho ester) loaded with recombinant human-growth hormone and bovine serum albumin have been created. The rods are the products of polymer-protein mixture extrusion at a temperature between 50° and 70°C. Particles have also been produced from these rods (Heller et al. 2000). The size of these particles, >106 pm, was much larger than would be expected to be absorbed by the gastrointestinal lining (Florence 1997). If the particle size can be reduced, this type of polymer system may be made to be acceptable for oral administration. 

The matrix used for the encapsulation of juice solids was a mixture of low DE maltodextrin (DE 10) and lactose. A typical formulation prior to cooking would be 23% water, 26% lactose and 51% maltodextrin. This material was cooked to the desired temperature (ca. 110 C), mixed with 85 Brix juice solids and optionally, peel oil, extruded, washed and dried. The extrusion process is essentially the same as used by Swisher (3), A product containing up to 40% juice solids may be produced via this process. This loading of juice solids is substantially greater than the 10-15% juice solids loading claimed by Barnes and Steinke ( 5 ). 

Rambali, B., G. Verreck, L. Baert, and D. L. Massart. 2003. Itraconazole formulation studies of the melt extrusion process with mixture desidprug Dev Ind Pharrr 9 641-652. 

Vinylidene Chloride Copolymer Foams. Low density, fine-celled VDC copolymer foams can be made by extrusion of a mixture of vinylidene chloride copolymer and a blowing agent at 120—150°C (190). The formulation must contain beat stabilizers, and the extrusion equipment must be made of noncatalytic metals to prevent accelerated decomposition of the polymer. The low melt viscosity of the VDC copolymer formulation limits the size of the foam sheet that can be extruded. 

A variety of flaws can occur in the shaped article, and their elimination is a primary concern. Commonly, a practical approach involving modifications of the formulation of the powder mixture, the extrusion parameters and the die design is used to reduce the problems associated with the formation of flaws. 

For the preparation of -100 nm liposomes, the formulations are extruded through a 0.1pm polycarbonate membrane. Preheating of the extruder above the main phase transition of the lipid mixture (40°C) is essential to provide an effective liposome extrusion (see Note 4). The extrusion is conducted 21 times to each sample. The achieved liposomes have a diameter of 100-150 nm. If the initial size measurements verify larger diameters, the extrusion can be repeated 11 times more. 

Figure 2. X-ray diffractogram of lead formulation for insulating cables. (a) Dry blend, (b) the mixture after gelification, (c) the mixture after extrusion.

The 2 design - example of extrusion-spheronization Full factorial design for 3 factors (2 ) - formulation of an oral solution Full factorial design for 4 factors (2 ) - a mixture example Identifying active factors in saturated designs... 

Membranes used in microfiltration, reverse osmosis, dialysis, and gas separation are usually prepared by the wet-extrusion process, since it can be used to produce almost every membrane morphology. In the process, homogeneous solutions of the polymers are made in solvent and nonsolvent mixtures, while phase inversion is achieved by any of the several processes, such as solvent evaporation, exposure to excess nonsolvent, and thermal gelation. In most formulations, polymer solutions of 15-40 wt% concentration are cast or spun and subsequently coagulated in a bath containing a nonsolvent (usually water). 

Originally for the extrusion of ceramic bricks and tiles, clay and water were used to endow ceramic particle mixtures with sufficient plastic behavior to permit practical shaping of the ceratnic bodies. High performance ceramics, however, often require the elimination of clay from extrusion formulations because the chemistry of the clay is incompatible with that of the desired ceramic materials. Therefore organic materials are frequently used in ceramic extrusion to provide plastic flow. Not only plastic behavior is important for the extrusion of ceramic bodies. There are many other characteristics which can be tailored by the suitable addition of organics in a ceramic extrusion paste, or feedstock. 

Several approaches have been developed to prepare GRIN polymer fibers in our laboratories, e.g., initiator diffusion technique (70), interfacial-gel copolymerization (77), and extrusion technique (12,13). Our previous study successfully used a closed extrusion process to prepare GRIN polymer fibers (72,75). This new process has also overcomed several drawbacks in conventional extrusion processes, e.g., poor reproducibility and low production rate. The refractive index profiles of the GRIN polymer fibers prepared by the new process are affected by the following two factors (1) the formulation of the reactant mixtures, e.g., different types of monomer combination and variation of host polymers and (2)... 

Table I. The formulations of the reactant mixtures I-III and the An values of the resulting polymer fibers I-III from the extrusion process...

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