Injection-Molding Plasticators

Large quantities of secondary cellulose acetate are used worldwide in the manufacture of filter material for cigarettes. Because of its excellent clarity and ease of processing, cellulose acetate film is widely used in display packaging and extmded plastic film for decorative signs (see Packaging materials). Injection-molded plastics of cellulose acetate are used in toothbmsh handles, computer bmshes, and a large variety of other appHcations (7). 

Fig. 6-24 Example of effects of number of times in recycled injection molded plastics.

Contents Introduction to Materials. Manufacturing Considerations for Injection Molded Parts. The Design Process and Material Selection. Structural Design Considerations. Prototyping and Experimental Stress Analysis. Assembly of Injection Molded Plastic Parts. Conversion Constants. 

Pj hydraulic back pressure for an injection-molding plasticator (Eq. 10.22) maximum power rating for the motor in watts Pr pump ratio for a two-stage screw... 

Pf pressure at the tip of the screw for an injection-molding plasticator (Eq. 10.22) Q extrusion rate in kg/h O specific rate in kg/(h-rpm) for Eq. 10.21 R compression rate in the helical direction Pjs belt sheave reduction Rg speed reduction for the gearbox S support distance from the fixed end of the barrel shear strength of the material used for the screw t plasticating time in seconds (Eq. 10.21)... 

Potente, H., Effen, N., and Liu, ]., Throughput Calculation with Considerations of Leakage Flow on Injection Molding Plasticizing Units, Polym. Eng. ScL, 36, 1557 (1996)... 

For higher throughput applications, injection-molded plastic microtiter plates have served as the formats of choice for automated assay development. Thermoplastics such as polystyrene, polycarbonate, and polypropylene are used for a variety of purposes including storage and assay plates, lids, pipette tips, and Eppendorf PCR tubes. Polystyrene plates are used for cell culture and ELISAs. Polycarbonate reagent bottles are popular, while polypropylene storage plates and PCR tubes are standards. 

Cell Hardware. Cell jars are constructed almost exclusively of injection-molded plastics, which are resistant to the strong alkali electrolyte. 

McCormick, R.M., Nelson, R.J., Alonso-Amigo, M.G., Benvegnu, D.J., Hooper, H.H., MicroChannel electrophoretic separation of DNA in injection-molded plastic substrates. Anal. Chem. 1997, 69, 2626-2630. 

Hulme, J.P., Fielden, P.R., Goddard, N.J., Fabrication of a spectrophotometric absorbance flow cell using injection-molded plastic. Anal. Chem. 2004, 76, 238-243. 

MDI [4,4 -methylenebis (phenylisocyanate)] accounted for almost 85% of the worldwide demand for aniline in 2000. MDI is used primarily to make rigid polyurethane foam and polyurethane elastomers. MDI growth is expected to be 6% to 8% per year during the 2000 s as its use continues to increase in the construction industry (the largest user of rigid polyurethane foam) and the auto industry (the largest user of reaction-injection molding plastics). The aniline uses are shown in Table 20.3255. 

Injection Molding Plastic resin, in the form of pellets, is fed into a high temperature chamber where the resin is heated to the point that it becomes a fluid. This fluid is then fed into a mold. As it cools, the plastic takes the form of the mold to create a final shape. This is considered to be a relatively unsophisticated manufacturing process useful for such items as plastic toys and household items. 

In plate and frame modules, the membranes are placed (with or without spacers) between two plates. The packing density of this configuration varies between 100 and 400 m m, depending on the number of membranes or cassettes used. Andersson et al. [31] have used a plate and frame configuration for desalination purposes, where various cassettes were stacked together, each consisting of injection molded plastic frames of two membranes. Naveen et al. [92] used a plate and frame membrane... 

McCormick RM, Nelson RJ, Alonso-Amigo MG, Benvegnu DJ, Hooper HH. MicroChannel electrophoretic separations of DNA in injection-molded plastic substrates. Anal Chem 1997 69 2626-30. 

Ogura, M., Agata, Y., Watanabe, K., McCormick, R. M., Hamaguchi, Y, Aso, Y, and Mit-suhashi, M. RNA chip quality assessment of RNA by microchannel linear gel electrophoresis in injection-molded plastic chips. Clin. Chem. 44 2249-2255, 1998. 

Additives, nylon RIM (reaction injection molding), plasticizers. stabBiessu. 

Cell Hardware. Cell jars are constructed almost exclusively of injection-molded plastics, which are resistant to the strong alkali electrolyte. The most generally used materials are modified styrenes or copolymers of styrene and acrylonitrile (SAN). Another material that has been found to increase shock resistance of cells is ABS plastic (acrylonitrile—butadiene—styrene). All of these plastics can be injection-molded, are solvent-sealable and, in general, meet operating temperature ranges up to about 70°C. For applications that require greater resistance to temperature, some of the more recent plastics such as polysulfone and poly(phenylene oxide) (PPO) injection-moldable materials able to withstand operating temperatures up to 150°C are used. 

---