What is meant by coextrusion?
[ koh-ik-stroo-zhuhn ] SHOW IPA. / ˌkoʊ ɪkˈstru ʒən / PHONETIC RESPELLING. noun Engineering. simultaneous extrusion of two or more different yet compatible metals or plastics through the same die.
What is a Feedblock?
The purpose of the feedblock is to shape and combine the multiple polymers entering from the adapter into a well-defined stack of polymers for delivery to the flat die.
What is co extruded composite pipe?
The pipe is produced in Schedule 40 IPS sizes by a co extrusion die system, in which the concentric layers are formed and combined before exiting the die. Coextruded composite drain, waste, and vent pipe, DWV, by definition, is permitted to be produced with two or more layers. The outer layer shall be ABS.
What is co extruded PVC pipe?
PVC products have suffered in the last years from attack by environmental activists. The coextruded pipe, up to 4500 mm,has the external compact layers in virgin PVC material whilst the intermediate layer consists of scrap material regenerated from the collected waste.
What are the advantages of coextrusion?
The advantage of coextrusion is that each material used imparts a desired characteristic such as stiffness, heat-seal-ability, impermeability, or resistance to a particular environment.
What is extrusion co-extrusion and film extrusion?
Co-extrusion is an extrusion process used to obtain a product that combines two textures : one material is extruded and continuously filled with another to form a single product. For example, a crispy cereals outer envelope can be co-extruded with a sweet or savory filling basis.
What role does feed section play in extrusion process?
The feed attains fine structure that is convenient for digestion. During the expansion at the outlet of the extruder, inner structure of the material is disrupted, which increases its surface area and aids transport of nutrition in the digestive system.
What is co extruded film?
Co-extrusion is the process of forming a single filmic structure from more than one type of thermoplastic resin. The intention is to produce a mono filmic structure where each layer contributes a key property that improves the films overall performance.
What is a co-extrusion in terms of packaging materials?
Coextrusion is the process of forming an extrudate composed of more than one thermoplastic melt stream. The process came about because some service demands, particularly from the packaging industry, could not be satisfied by a single polymer although they could be met by a combination of polymers.
What is multilayer extrusion?
Coextruded multi-layer film is produced by a compound molding technique that simultaneously extrudes thermoplastic resin with multiple extruders and passes that through a single die to build up layers of melted resin both on the inside and outside of a film.
How does blown film extrusion work?
Blown film is another extrusion processes used to fabricate film products. In this case the extrusion die is shaped as a circle and air pressure is used to further expand the film. After it is expanded to the desired dimensions it is cooled to solidify the polymer.
What is coextrusion?
Coextrusion is the process of forming an extrudate composed of more than one thermoplastic melt stream. The process came about because some service demands, particularly from the packaging industry, could not be satisfied by a single polymer although they could be met by a combination of polymers.
Is polymer extrusion monolithic or coextruded?
While a large majority of polymer extrusion is done in monolithic form, the world of coextruding polymers has been growing now for half a century. The whole concept of polymer extrusion grew from the already existing technology for extrusion of processed foods, ranging from cereals to meats.
What is a coextruded film?
Coextruded films may be very complex structures composed of many different functional layers, including tie layers whose purpose is to bond neighboring layers of limited compatibility. Five layers is not uncommon. However, side-by-side coextrusion is also possible. Separate extruders are required for each distinct material in the coextrusion.
How does feed block coextrusion work?
In feed block coextrusion, the streams are merged into a single laminar melt flow in a feedblock ( Fig. 6.18) which is positioned immediately upstream of the extrusion die. The process depends on the high viscosity of plastics melts to prevent intermingling of the layers as they pass through the extrusion die.