Coextruded

A typical coextruded sheet has a total thickness of 1270 p.m (50 mil). After the container is formed by one of several methods, the sheet might then yield a wall thickness of 510 p.m. The barrier layer in the container is typically in the range of 25 to 75 p.m. 

Thermoformed chassis and body panels are featured on the car. The products were made initially in the USA for assembly in China. The car will weigh less than 2000 lb (900 kg). Automotive Design Composites, Inc of San Antonio, TX, designed the vehicle to have body panels and trunk formed from coextruded sheet of ABS with an ASA cap layer that will hang on a pultruded composite frame. Ceramic tooling is used to thermoform plastic products. 

A similar problem is presented by vehicle tires and certain blow molded bottles, which must be virtually impermeable to air and other gases. An example of the use of a very impermeable elastomers is butyl rubber. Because of its impermeability to gases, butyl rubber is used as a roof coating. With plastic bottles, different layers of both coinjected and coextruded plastics (Chapter 8) can be used to fabricate the bottle to make it impermeable to different vapors and gases depending on the barrier plastic included. 

Table 8-19 General comparison of metalized coextruded polyethylene and aluminum foil...

A number of techniques are available for coextrusion, some of them patented and available only under license. Basically, three types exist feedblock, multiple manifolds, and a combination of these two (Table 9-18). Productions of coextruded products are able to meet product requirements that range from flat to complex profiles. Figure 8-35 (a) shows a typical 3-layer coextrusion die and (b) examples of rather complex profiles that are routinely extruded. 

Also popular is the use of thermoforming coextruded sheets or films (Figs. 8-51 and 52). 

Fig. 8-51 Bonding two coextruded thermofor-med parts to produce a gasoline fuel tank.

Fig. 8-52 The addition of an extruded single plastic clamping strip at each side of a coextruded sheet permits scrap reclaim of the trim waste.

The recycled plastic will also have a degree of different contaminants that would eliminate its use in certain devices or products, such as in medicine, electronics, and food packaging. However, within these market applications there are acceptable designs with three-layer coextruded, coinjected, or laminated structures having the contaminated plastic as the center layer, isolated by clean plastics around it and no migration occurring. 

Another product, defatted com germ flour was coextruded at 150 or 170 °C with 5% milk protein to produce a puffed nutrient snack (Peri et al., 1983). The addition of fhe milk profein af fhe lower temperature improved the organoleptic characteristics of fhe exfrudafes but adversely affected the product expansion and consistency of fhe samples at the higher temperature. 

Membrane banners are applied to the exterior of the foundation and also beneath the floor slab during construction. Materials used for the membrane barriers range from coextruded poly olefin to polyvinyl chloride to foil sheets with many other materials in between. All membrane barriers must have the edges sealed to prevent radon from migrating around the edges and back into the building. 

Coenzyme A (CoA), 20 249—250. See also Ace to acetyl- Co A in citric acid cycle, 6 633 Coenzyme Q10, 17 673 Coercivity, ofM-type ferrites, 11 70 Coextruded food packaging, 18 44, 45 Coextrusion techniques, for gelatin capsule preparation, 11 549 Cofactors, 10 253 11 4 folic acid, 25 801-802 for enzymes, 3 672-673 protein, 20 828-829 vitamin B12, 25 804 vitamins as, 25 781 Coffea arabica, 7 250 Cojfea Canephora, 7 250 Coffea liberica, 7 250 Coffee, 2 108 6 366 7 250-271 biotechnology, 7 265-267 decaffeinated, 7 263 economic aspects, 7 263-264 estimated maximum oxygen tolerance, 3 381t... 

The EVOH-COOH compatibilizer use determines the increasing of the blend film oxygen permeability that becomes two orders of magnitude higher than that of a coextruded film with the same percentage of EVOH [298], That means that EVOH-COOH acts that an interfacial agent. 

Company Technology This is about whether the product utilizes the company s multilayer technology. It has a weighting of 0.15. The optical polymer should have a high score because the coextruded film does not require much knowledge of other technologies such as adhesives, etc. 

Beagan, C.M., McNally, G.M., and Murphy, W. R., Metallocene Catalysed Polyethylene in Blown Film Applications-A Comparison Between Monoextruded Blended Films and Coextruded Films, SPEANTEC Tech. Papers, 44, 128 (1998)... 

It is briefly reported that PP foam sheet from Convenience Food Systems in thickness from 500 to 1800 micron is thermoformable into chilled food packaging trays. Trays made in TiroPak XPP, which is coextruded with an EVOH barrier layer, can be taken from the freezer and heated to 90C in a microwave oven without loss of shape or properties. 

GE introduced, in 2000, a new polyester carbonate based on resorcinol arylates called W-4. It is now marketed as Sollx. Sollx does not need to be painted, it offers good weather, chip, scratch, and chemical resistance and is being used as the fenders for the new Segway Human Transporter. It is also aimed at automotive uses including body panels. Sollx is coextruded into two layers clear and colored, to simulate automotive paint. It is then thermoformed and molded into the finished product. 

Attempts to substitute PVC containers have shown, however, that non-PVC containers may also contain plasticizer components resulting in the release of some DEFIP into the preparation. A study conducted by Sautou-Miranda and co-workers showed that [65] leaches rapidly from coextruded and triple-layered IV tubing into etoposide infusion solution (see details of the results under Section 9.1.3.3). 

Sautou-Miranda et al. [77] showed that DEHP is rapidly leached from PVC, coextruded, and also triple-layered IV tubing by action of an etoposide infusion... 

The wire coating material can be coated on a conductor by coextruding the conductor and the molten material in an extrusion molding machine. The compound is provided in the form of pellets. 

Phase contrast-Thin sections (100-200 nm) in thickness (and having refractive indices which differ by approximately. 005) are supported on glass slides and examined "as is" or with oil to remove microtoming artifacts, e.g., determination of the number of layers in coextruded films, dispersion of fillers, and polymer domain size. (Figures 2 and 3)... 

Viscoelastic flow effects in polymer coextrusion. In this example we will present work done by Dooley [7, 8] on the viscoelastic flow in multilayer polymer extrusion. Dooley performed extensive experimental work where he coextruded multilayer systems through various non-circular dies such as the teardrop channel presented in Fig. 9.39. For the specific example shown, 165 layers were coextruded through a feedblock to form a single multiple-layer structure inside the channel. 

As mentioned previously, the see-through clarity of the coextruded films deteriorates with the presence and extent of the wavelike interfacial instability. Quantitative... 

Fig. 12.40 Narrow angle scattering measurements of the coextruded films. [Reprinted by permission from H. Mavridis and R. N. Shroff, Multilayer Extrusion Experiments and Computer Simulation, Polym. Eng. Sci., 34, 559 (1994).]...

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