Pc

Beall, Rotational Molding Design, Materials, Tooling, and Processing, Hanser Publishers, Munich-Hanser Gardner Publications, Inc., Cincinnati, 1998. source Glenn L. Beall, Rotational Molding Design, Materials, Tooling, and Processing, Hanser Publishers, Munich-Hanser Gardner Publications, Inc., Cincinnati, 1998. undercut. If the undercut is too deep to be stripped, a side core which must be removed before demolding can be used. Holes can be molded-in rotational molded parts by...

196

*Heat-distortion temperature, C (stoichiometric amount of curing agent except BF3 MEA cured 15 h at 180 C). fNovolac resin, Dow Chemical Co. Epi-bis resin, Dow Chemical Co. The mixture reacts too quickly to permit proper mixing by hand. source Dow Epoxy Novolac Resins, Technical Bulletin, Dow Chemical Company. *Heat-distortion temperature, C (stoichiometric amount of curing agent except BF3 MEA cured 15 h at 180 C). fNovolac resin, Dow Chemical Co. Epi-bis resin, Dow Chemical Co. The mixture...

D

Crystallization is the competition between two processes nucleation and crystal growth. Nucleation is the formation of small sites (nuclei) from which crystallites can grow. Primary nucleation creates the initial nuclei. Crystallites develop around these nuclei. Then in secondary nucleation, the surfaces of the crystallites are nucleated. More polymer chains diffuse to the crystallite surfaces and growth continues. Crystallization is influenced by cooling rate, pressure, shear and orientation,...

Wz

CALIBRE* ZOO aerlea ses oai rel puifioae, l't listed PDascfectoritci teaiia ri> rouinrpii Tfl wmp'-y vifl arP f Mi T'A or.1 Bai dp pot Ei> gulaslc ifl goveEQi Ccod ecntaci111. lA-IEiRE DD series isain exh ali en excellent physical property balance c-C heat resistance., rcar-spicency ants 1143.51 t stcer-'Xth 'JLe LjU,ilU< - ' Oil series cai t- supplied vltfc t dcIO pmJsajje.- i IT steoi . . p .Jsay oc botju CALIBRE* ZOO aerlea ses oai rel puifioae, l't listed PDascfectoritci teaiia ri>...

175

Containing side branches of 1-butene most commonly, with 1-hexene or 1-octene also present. Density ranges of 0.915 to 0.940 g cm3 are polymerized with Ziegler catalysts which orient the polymer chain and govern the tacticity of the pendant side groups.222 High-density polyethylene (HDPE). HDPE is one of the highest-volume commodity chemicals produced in the world, in 1998 the worldwide demand was 1.8 X 1010 kg.223 The most common method of processing HDPE is blow molding, where resin is turned...

N H2C O CH2

Figure 1.4 Polymerization of formaldehyde to polyoxymethylene. above 270 C. It is important that processing temperatures remain below this temperature to avoid degradation of the polymer.5 Acetals are highly crystalline, typically 75 crystalline, with a melting point of 180 C.6 Compared to polyethylene (PE), the chains pack closer together because of the shorter C O bond. As a result, the polymer has a higher melting point. It is also harder than PE. The high degree of crystallinity imparts...

Info

Figure 6.15 Typical high-volume production mold and work-loading fixtures for encapsulating semiconductor integrated circuits by transfer molding. Figure 6.15 Typical high-volume production mold and work-loading fixtures for encapsulating semiconductor integrated circuits by transfer molding. Figure 6.16 Typical shot of encapsulated integrated circuits (dual in-line packages) as it is removed from transfer molding press. Figure 6.16 Typical shot of encapsulated integrated circuits (dual in-line...

Hdpe Lldpe

Weight Polyethylene PC Polycarbonate HDPE High Density Polyethylene Figure 8.2 Classification of thermoplastics. (Source Laura Pugliese, Defining Engineering Plastics, Plastics Machining and Fabrication, January-February, 1999, Courtesy DSM Engineering Plastic Products.) The next level are the Engineering plastics which can be used for applications ranging up to 250 F. ABS is often considered an engineering plastic for its other properties although it cannot withstand this temperature level....

1261 Bacterial polyesters

One of the early truly biodegradable polymers was polyhydroxybu-tyrate valerate (PHBV). This is a member of the polyester family which is produced by certain types of bacteria when they have a diet which is carbon-rich but poor in some essential nutrient. Under these conditions, they produce polyhydroxybutyrate (PHB) as a food store to be called upon when carbon sources are less available. With manipulation of the diet, the bacteria can be induced to form a copolymer, PHBV, which has more...

Temperature Zones

Figure 5.21 Barrel temperatures for selected materials.51 While most melting or plastication occurs in the transition zone, the polymer can melt in the feed zone and may not be fully molten until well into the metering zone. Although the heater bands and cooling fans maintain the barrel at a set temperature profile, conduction from the barrel walls provides only 0 to 30 percent56 of the energy required to melt the resin. The remainder of the energy is generated from the mechanical motion of the...

Modern Plastics And Charles A Harper

1.2 Polymer Categories 1.4 1.3 Comparative Properties of Thermoplastics 1.79 1.6 Polymer Blends 1.83 References 1.85 Chapter 2. Thermosets, Reinforced Plastics, and Composites 2.1 2.2 Thermosetting Resin Family 2.2 2.3 Resin Characteristics 2.10 2.5 Liquid Resin Processes 2.13 2.7 Molding Compounds 2.38 References 2.88 Chapter 3. Elastomeric Materials and Processes 3.1 3.2 Thermoplastic Elastomers (TPEs) 3.1 3.3 Melt Processing Rubbers (MPRs) 3.24 3.4 Thermoplastic Vulcanizates (TPVs) 3.26 3.5...

7252 Cooling analysis

The cooling of the mold is a key factor in efficient production and quality. Generally, cooling systems are given too little priority in the mold design process. This is unfortunate as careful attention to cooling system design can reduce cycle time and so increase the productivity of the mold machine combination. Injection-molding cooling systems can be analyzed quite readily today. Generally, two analyses are done. The first concerns the flow of the coolant in the cooling system the second...

125 Overview of Plastics Degradation

Until the early 1970s, attention to plastics degradation, including biodegradation, was focused primarily on ensuring that the plastic materials being used were resistant to such degradation so that they could maintain their usability. Biodegradation and other types of degradation, such as photodegradation, were not always clearly differentiated. Further, the extent of degradation was frequently measured based on loss of useful properties, such as tensile strength, rather than on chemical...

Ath

Martin Marietta Martinswerke (Lonza) Melamine Chemicals Mikuni Smelting & Refining Mines de la Lucette Mitsubishi Gas Chemicals Morton International Nabaltec Nihon Seiko Nippon Chemicals Nyacol Products Occidental Laurel Sherwin Williams Showa Denko Soci t Industrielle et Sumitomo Chemical Sumitomo Metal Mining Teijin Chemicals Tosoh U.S. Borax & Chemical United States Antiomy Sales Velsicol Witco gen-based products where it can. Look for some rapid growth in the other flame-retardant...

Time

Figure 2.21 Typical thermosetting curve. In all of the following flow tests, with the exception of the Brabender, three elements are always kept constant during the testing procedure Amount of compound. Charge weight Mold temperature. Usually 300 F Molding pressure. Usually 1000 lb in2 Cup closing (test and mold) (Fig. 2.22). With the mold set at 300 F (148 C) and a molding pressure of 1000 lb in,2 a room temperature charge of compound is placed in the lower half of the mold and the mold is...

O

And may have either aliphatic or aromatic hydrocarbon units. As an introduction, Table 1.4 offers some selected thermal and mechanical properties as a means of comparing polybutylene terephthalate (PBT), polycyclohexylenedimethylene terephthalate (PCT), and poly(ethylene terephthalate) (PET). Liquid Crystal Polymers (LCP). Liquid crystal polyesters, known as liquid crystal polymers, are aromatic copolyesters. The presence of phenyl rings in the backbone of the polymer gives the chain rigidity,...

974Fluorocarbons Ptfe Ctfe Fep etc

Because of the lower ductility of the fluorocarbon materials, snap-fit and press-fit joints are seldom used. Rivets or studs can be used in forming permanent mechanical joints. These can be provided with thermal techniques on the melt processable grades. Self-tapping screws and threaded inserts are used for many mechanical joining operations. In bolted connections some stress relaxation may occur the first day after installation. In such cases, mechanical fasteners should be tightened...

180

Phenolic molding compounds have found worldwide acceptance in such diverse market areas as. Automotive (as seen in Figs. 2.14a, b, and c) Cytec Fiberite Occidental Chemical Plastics Engineering Company Plaslok Corporation Rogers Corporation Cytec Fiberite Occidental Chemical Plastics Engineering Company Plaslok Corporation Rogers Corporation Figure 2.14 (a) Transmission stator and reactor. Figure 2.14 (a) Transmission stator and reactor. Figure 2.14 (Continued)...

122 Overview of Recycling

For plastics recycling (or recycling of other materials) to occur, three basic elements must be in place. First, there must be a system for collecting the targeted materials. Second, there must be a facility capable of processing the collected recyclables into a form which can be utilized by manufacturers to make a new product. Third, new products made in whole or part from the recycled material must be manufactured and sold. While the end uses differ substantially for different plastics, there...

1998

Alliance of Foam Packaging Recyclers, EPS Recycling What's Next, Molding the Future, October, 1998, p. 1. 91. Eastman Kodak Recycles 50 Million Cameras, Plastics News, August 14, 1995, p. 10. 92. Snapshot of Recycling, BioCycle, June 1996, p. 88. 93. Myers, S., Recyclers of Appliances, Durables Looking to Germany's Proposals, Modern Plastics, March 1995, pp. 14-15. 94. A Noncatalytic Process Reverts Polystyrene to Its Monomer, Chemical Engineering, February 1993, p. 19. 95. Battery Council...

Pot Type Transfer Moulding

Pot Type Transfer Moulding

Figure 6.5 Schematic showing four steps in the vacuum potting process. with matched molds (that is, with two mold halves closed after the reinforcing material has been impregnated with the liquid to produce a smooth uniform surface on both top and bottom of the part) and with conveyors, curing ovens, etc. Figure 6.6 Hand lay-up process for producing highly reinforced parts with fiber matting and polyester, epoxy, or other thermosetting liquid resin systems. Figure 6.6 Hand lay-up process for...

359Polychloroprene neoprene CR

Polychloroprene is produced by free-radical emulsion polymerization of primarily trans-2-chloro-2-butenylene moieties.23 Chloroprene rubber possesses moderate oil resistance, very good weather and oil resistance, and good resistance to oxidative chemicals.10 Performance properties depend on compound formulation, with the polymer providing fundamental properties. This is typical of any polymer and its compounds. Chloride imparts inherent self-extinguishing flame retardance. *Acron is a...

124 Recycling of Major Polymers

The amount of plastics entering the municipal solid waste stream in the United States in 1996 is estimated at 19.7 million tons. The amount which was recycled was 1.1 million tons, or 5.4 of plastics generation (see Figs. 12.5 and 12.6). The remaining 18.7 million tons amounted to 12.3 by weight of total MSW discards.2 Recycling rates are significantly higher for some plastic materials than for others, and for some types of plastic products, as will be discussed in more detail in the following...

1 1

Figure 5.77 Orientation developed during filling. (a) Across the cavity thickness (b) along the length of the cavity.175 the screw rotates and builds up a new shot. Cooling is usually the longest part of the molding cycle because the part is cooled until it can be ejected from the mold. The ejection temperature is estimated using the heat deflection temperature or Vicat softening temperature, but parts are ejected as soon as the ejection process does not damage the part. Parts ejected at high...

Sae

J 1686 Classification System for Automotive Polypropylene (PP) Plastics10 J 1687 Classification System for Automotive Thermoplastics Elastomeric Olefins (TEO)11 J 2250 Classification System for Automotive Poly(Methyl methacrylate) (PMMA) Plastics12 J 2273 Classification System for Automotive Polyester Plastics13 J 2274 Classification System for Automotive Acetal (POM) Plastics14 J 2323 Classification System for Automotive Polycarbonate Plastics15 J 2324 Classification System for Automotive...

961 Thermal welding

Welding by application of heat or thermal welding provides an advantageous method of joining many thermoplastics that do not degrade rapidly at their melt temperature. It is a method of providing fast, relatively easy, and economical bonds that are generally 80 to 100 the strength of the parent plastic. The thermal welding process can be of two kinds direct and indirect. With direct welding, the heat is applied directly to the substrate in the form of either a heated tool or hot gas. Indirect...

Adhesive Completely Fills Irregularities

Figure 9.15 Illustration of poor (top) and good (bottom) wetting by an adhesive spreading over a substrate surface. adherend. The diffusion theory is primarily applicable when both the adhesive and adherend are polymeric. For example, bonds formed by solvent or heat welding of thermoplastics result from the diffusion of molecules. Weak boundary layer theory. According to the weak boundary layer theory, when bond failure seems to be at the interface, usually a cohesive break of a weak boundary...

Ethylene Propylene Diene Monomer Impact Modifier Sippliers

*PVC Polyvinylchloride. **PE polyethylene. fPP polypropylene. PA polyamide. PET polyethylene terephthalate PBT polybutylene terephthalate. *PVC Polyvinylchloride. **PE polyethylene. fPP polypropylene. PA polyamide. PET polyethylene terephthalate PBT polybutylene terephthalate. Methacrylate-butadiene-styrene (MBS). Methacrylate-butadiene-styrene represents the highest volume of the styrenic type impact modifiers. This modifier is used in transparent packaging applications due to its clarity....

329

Figure 3.9 Dynamic mechanical properties for different hardness grades over a range of temperatures. (a) 55 Shore A grades (b) 50 Shore D grades. (Source Ref. 8, pp. 12-13.) Figure 3.9 Dynamic mechanical properties for different hardness grades over a range of temperatures. (a) 55 Shore A grades (b) 50 Shore D grades. (Source Ref. 8, pp. 12-13.) bags, pharmaceutical packaging, wound dressings (U.S. Pharmacopoeia Class VI rating for biocompatibility). Special-purpose Santoprene grades meet flame...

356 Ethylene propylene copolymer EPM and ethylene propylene diene terpolymer EPDM

EPM poly(ethylene-co-propylene) and EPDM can be metallocene catalyst polymerized. Metallocene catalyst technologies include (1) Insite, a constrained geometry group of catalysts used to produce Affinity polyolefin plastomers (POP), Elite * PE, Nordel f EPDM, and Engage polyolefin elastomers (POP) and (2) Exxpol ionic metal-locene catalyst compositions used to produce Exact plastomer octene copolymers.24 Insite technology produces EPDM-based Nordel IP with property consistency and...

983 Plating

Electroless, electrolytic plating, and vacuum metallizing are processes used to deposit metal surfaces on plastics materials. However, metal surfaces can also be provided by adhesives or hot-stamp methods. Some finished plastic parts must have shiny metallic surfaces. Besides providing a decorative finish, metal coatings may provide an electrical conducting surface, a wear- and corrosion-resistant surface, or added heat deflection. Many plated plastics have drastically altered physical...

Contributors

Anne-Marie Baker University of Massachusetts, Lowell, Mass. (chap. 1) Carol M. F. Barry University of Massachusetts, Lowell, Mass. (chap. 5) Allison A. Cacciatore TownsendTarnell, Inc., Mt. Olive, N.J. (chap. 4) Fred Gastrock TownsendTarnell, Inc., Mt. Olive, N.J. (chap. 4) John L. Hull Hall Finmac, Inc., Warminster, Pa. (chap. 6) Carl P. Izzo Consultant, Murrysville, Pa. (chap. 10) Louis N. Kattas TownsendTarnell, Inc., Mt. Olive, N.J. (chap. 4) Peter Kennedy Moldflow Corporation, Lexington,...

942 Mechanical fasteners

A large variety of mechanical fasteners can be used for joining plastic parts to themselves and to other materials. These include machine screws, self-tapping screws, rivets, spring clips, and nuts. In general, when repeated disassembly of the product is anticipated, mechanical fasteners are used. Metal fasteners of high strength can overstress plastic parts, so torque-controlled tightening or special design provisions are required. Where torque cannot be controlled, various types of washers...

1 2345

Spiral Flow Test

Figure 2.24 Disk flow test and mold (II). Figure 2.24 Disk flow test and mold (II). circles numbered 1 to 5. A disk matching the 1 circle on the target will be designated as 1S flow, whereas a disk matching the 5 circle will carry a 5S flow. The higher the number, the softer the flow. Orifice flow I (test and mold) (Fig. 2.25). This flow test involves the use of a mold with a lower plate containing a cavity into which a measured quantity of room temperature compound is placed. The upper plate...

60

Laminates using thermosetting resins are superior in stability, thermal resistance, and electrical properties, with dimensional stability the most important due to stresses incurred within the laminate during the molding and curing process. Laminate thickness is limited by the thermal conductivity of the polymerizing resin and the thermal conductivity of the cured laminate. The laminate derives its heat from the press platens to begin the curing action, and the resin, as...

98 Decorating Plastics

Several decorating processes can be accomplished with plastic parts either during processing of the part, directly afterward, or before final assembly and packaging. The most inexpensive method of providing decorative designs on plastics is to incorporate the design into the mold or to apply the decoration as part of the molding operation. However, often this is not possible either because of mold complexity, the need to apply decorations to customers' specifications, or other reasons. This...

325 Polyamides

Polyamide TPEs are usually either polyester-amides, polyetherester-amide block copolymers, or polyether block amides (PEBA) (see Fig. 3.7). PEBA block copolymer molecular architecture is similar to typical block copolymers.10 The polyamide is the hard (thermoplastic) segment, while the polyester, polyetherester, and polyether segments are the soft (elastomeric) segment.10 Polyamide TPEs can be produced by reacting a polyamide with a polyol such as polyoxyethylene glycol or polyoxypropylene...

822 Shrinkage and the use of draft in plastic parts

The shrink rate is the amount the part will reduce in size as it cools from processing temperature to room temperature. It is described in terms as the amount of shrinkage per inch of part size. Thus, a piece part 1 in long made of a material with a shrinkage rate of 0.005 in in will require a mold 1.005 in long if the final part is to wind up a true 1 in in length. Mold dimensions for other sizes would be determined by using 1.005 as a multiplier. Thus, the mold for a 1.500-in dimension would...

F

Suppliers need to be cautious regarding product claims to avoid misinformation. However, this increased awareness does appear to be a long-term trend and not solely a fad. 4.7 Chemical Blowing Agents 4.7.1 Description The term blowing agent in the broadest sense denotes an inorganic or organic substance used in polymeric materials to produce a foam structure. There are two major types of blowing agents physical and chemical. Physical blowing agents. Physical blowing agents are...

578 Chapter Five 536 Wire coating

Wire And Cable Coating Die

In wire coating (Fig. 5.51116), metal wire is covered with plastic insulation. This process requires a pay-off (input) drum, input capstan, preheater, extruder, cross-head or offset die, cooling trough, spark tester, diameter and eccentricity gauges, output capstan, and wind-up drum. The pay-off drum and input capstan unwind wire at high speeds and provide constant speed and tension. In the preheating station, a gas burner or electrical resistance heater preheats the wire to improve adhesion,...

Dehumidifier Dryer

Figure 7.26 High-temperature material drying system. Figure 7.27 Multimachine central dryer. 4 Figure 7.27 Multimachine central dryer. 4 applications such as molding PET bottle preforms may necessitate dewpoints as low as -50 or -60 F. 4. Residence time. Given proper airflow, temperature, and dewpoint, it still takes time for the moisture to be extracted from the resin, therefore, the drying vessel must have sufficient capacity to allow the material to be exposed to drying conditions for the...

0150 200

Figure 8.39 Difference in formed radius of pressure forming versus vacuum forming. (Source Designer's Guide to Pressure Forming, Arrem Plastics, Inc., 1981.) point. Pressure thermoforming can handle much tighter inside radii of 0.25 the starting gauge (Ti)(IR3 > 0.25Ti) at its thickest point increasing to 0.75T1 in its thinnest areas (IR4 > 0.75T1), the latter being ideal for pressure thermoforming. (For uncontrolled radii, such as IR2 and IR4 in Fig. 8.38, assume the wall thickness to be...

1273 Other polyesters

DuPont has created a family of synthetic polyesters which are degraded by a combination of hydrolysis and microbial action. These materials, sold under the Biomax name, are similar to polyethylene terephthalate, but incorporate as many as three different proprietary aliphatic monomers into the structure. The monomers create weak spots which are susceptible to hydrolysis. The much smaller molecules which result are biodegradable. DuPont claims that in composting operations the materials are...

543 Injection molding process

An injection molding cycle has a number of steps, including mold close, injection, packing, holding, cooling, plastication, mold open, and part ejection. Injection molding machines are operated in three modes manual, semiautomatic (single cycle), and automatic (continuous). With manual control, all steps of the molding cycle are performed manually that is, the operator activates each part of the cycle with separate controls. Manual control is used for purging, machine and mold setup, and...

T

Blown Film Die

Thus, film tends to be thicker on one side of the die. In addition, gauge control is poor, and so the die is seldom used in production lines. With a spider-arm die (Fig. 5.39b86), polymer melt is fed through the bottom of the die while air is introduced through three or more spider arms that extend from the sides of the die to support the mandrel. This creates a relatively low pressure drop, and allows the die to be used with high-viscosity materials. The weld lines are stronger than the...

541 Injectionmolding machines

Injection-molding machines have three components the injection unit, the clamping unit, and the control system. The injection unit plasti-cates and injects the polymer melt while the clamping unit supports the mold, opens and closes the mold, and contains the part ejection system. Typically different injection units can be assembled with the same clamping unit. The injection unit brings the nozzle into contact with the sprue bushing of the mold, generates contact pressure between the nozzle and...

Heplon Injection

But Cargill and Dow expected it to fall to about 500 lb by 2001, with increases in production.235237 Polylactic acid has Generally Regarded As Safe (GRAS) status for food packaging.234 Potential applications for PLA include cast, blown, and oriented films rigid containers and coating for paperboard. A major application is compost bags. PLA resins were also being used for consumer packaging in Japan, and injection molding applications in both Japan and Europe. Other PLA manufacturers include...

Pcabs

E., Polymer Chemistry, An Introduction, 4th ed., Marcel Dekker, Inc., New York, 1996, p. 238. 2. Brydson, J. A., Plastics Materials, 6th ed., Butterworth-Heinemann, Oxford, 1995, p. 516. 3. Kroschwitz, J. I., Concise Encyclopedia of Polymer Science and Engineering, John Wiley and Sons, New York, 1990, p. 4. 4. Brydson, Plastics Materials, 6th ed., p. 517. 6. Billmeyer, F. W., Jr., Textbook of Polymer Science, 2d ed., John Wiley and Sons, Inc., New York, 1962, p. 439. 7. Brydson,...

References on Cad Cam Cae

Tucker III, ed., Computer Modeling for Polymer Processing, Hanser, New York, 1989. 2. J. N. Reddy, An Introduction to the Finite Element Method, McGraw-Hill, New York, 1993. 3. Z. Tadmor and I. Klein, Engineering Principles of Plasticating Extrusion, Van Nostrand Reinhold Company, New York, 1970. 4. D. H. Sebastian and R. Rakos, Extrusion Process Analysis with PASS, in K. T. O'Brien, ed., Computer Modeling for Extrusion and Other Continuous Polymer Processes, Hanser, New York, 1992. 5. N....

Hlf

Drying Hopper

Figure 7.41 Typical insulated drying hoppers. The two hoppers on the right are stainless-steel construction. The hopper on the left is painted carbon steel. Figure 7.41 Typical insulated drying hoppers. The two hoppers on the right are stainless-steel construction. The hopper on the left is painted carbon steel. is a critical component of a dehumidifying drying system, and a poorly designed and manufactured drying hopper can spell disaster in a critical drying application. More often than not,...

33 Melt Processable Rubber MPR

MPRs are amorphous polymers, with no sharp melt point,1 which can be processed in both resin melt and rubber processing machines, injection molded, extruded, blow molded, calendered, and compression molded.1 Flow properties are more similar to rubber than to thermoplastics.1 The polymer does not melt by externally applied heat alone, but becomes a high-viscosity, intractable semifluid. It must be subjected to shear in order to achieve flowable melt viscosities, and shear force applied by the...

542 Injection molds

Diaphragm Runner Disc Gate Model

Injection molds distribute the melt, give final shape to the part, cool the material, and eject the final part. They also must withstand the forces of injection and ejection, transfer motion, such as ejector platen (machine) to the ejector plate (mold), and guide the moving parts of the mold. A standard two-plate mold (Fig. 5.66153) has two halves an A side and a B side. The division between these halves is called the parting line. The A side, or cavity half of the mold, contains the top clamp...

43Antiblock and Slip Agents 431 Description

Antiblocking agents function by roughening the surface of film to give a spacing effect. The inherent tack of linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE) is a detriment when used in film where self-adhesion is undesirable. An antiblock additive is incorporated by the compounder to cause a slight surface roughness which prevents the film from sticking to itself. Years ago, efforts were made to prevent this by dusting the surface with corn...

821 Cooling effects and the need for uniform wall thicknesses

Most of the processes require the plastic to be heated to elevated temperatures. When the part cools, it shrinks away from the cavity and onto the core, if there is one. Clearly, the thicker the nominal wall of the plastic part, the longer it will take to cool. When the thickness of the wall varies within the part, the thinner portion of the moldment solidifies before the thicker segment. Nonuniform cooling leads to problems of voids, warpage, and sink, as illustrated in Fig. 8.10. The extent...

Images Of T Joints In Civil Engineering

Adhesive shear strength is directly proportional to the width of the joint. Strength can sometimes be increased by increasing the overlap depth, but the relationship is not linear. Since the ends of the bonded joint carry a higher proportion of the load than the interior area, the most efficient way of increasing joint strength is by increasing the width of the bonded area. In a shear joint made from thin, relatively flexible adherends, there is a tendency for the...

600750

Trademark of General Electric Company. Trademark of General Electric Company. Hot-gas welding. An electrically or gas-heated welding gun with an orifice temperature of 425 to 700 F can be used to bond many thermoplastic materials. The pieces to be bonded are beveled and positioned to form a V-shaped joint as shown in Fig. 9.29. A welding rod, made of the same plastic that is being bonded is laid into the joint, and the heat from the gun is directed at the interface of the substrates and the...

827 Holes and Bosses

For those processes in which the plastic fills out a mold (cold press, compression, injection, reaction injection, resin transfer, structural foam, and transfer molding), openings in the part can be molded into the part through the use of cores. Holes in plastic parts are normally cut with a router (or drilled if round) for the remaining processes (although large openings can be molded into parts to be rotational or blow molded in some cases). When holes are created with cores, there will...

357 Fluoroelastomers FKM

Fluoroelastomers can be polymerized with copolymers and terpoly-mers of tetrafluoroethylene, hexafluoroethylene, and vinylidene fluoride. The fluorine content largely determines chemical resistance and Tg, which increases with increasing fluorine content. Low-temperature flexibility decreases with increasing fluorine content.1 The fluorine content is typically 57 wt.11 TFE propylene copolymers can be represented by Aflas * TFE, produced by Asahi Glass. They are copolymers of tetrafluoroethylene...

Vacuum Line

Figure 7.12 Combination vacuum-pressure system (one pump). Figure 7.12 Combination vacuum-pressure system (one pump). VACUUM PUMP VACUUM FILTER PRESSURE BLOWER Figure 7.13 Combination vacuum-pressure system (two pump). Bulk shipment of resin is accomplished either by special bulk trucks or railcars dedicated to that service. As explained earlier, all that is necessary to receive material by bulk truck is a storage vessel large enough to hold the quantity delivered and a fill line for the truck...

Non Intermeshing Screw Extruders

Ram Extruder Diagram

Figure 5.29 Pressure profile associated with a vented barrel extruder.63 the bulk properties (coefficient of friction, particle size, and particle-size distribution). In contrast, the design, principles of operation, and applications of twin-screw extruders vary widely. While the two screws are usually arranged side by side, the introduction of two screws produces different conveyance mechanisms, varied degrees of mixing, and controllable shear. The low head pressure generated by twin-screw...

Moldflow Polyflow Cadmould

The specific material properties employed in the computation of each design parameter involved in these analyses are summarized in Table 11.10. Similar to design calculations in the case of structural analyses, the modulus type suitable for these calculations is determined by the applied stress type and duration. It is worth noting that, although the exhaustive compilation of data identified here will suffice in most cases, commercial CAE tools often insist on a significantly large volume of...

35 Synthetic Rubbers

A second major group of elastomers is that group known as synthetic rubbers. Elastomers in this group, discussed in detail in this section, are Acrylonitrile butadiene copolymers (NBR) Butadiene rubber (BR) Butyl rubber (IIR) Ethylene propylene diene monomer (EPDM) Worldwide consumption of synthetic rubber can be expected to be about 11 million metric tons in 2000 and about 12 million metric tons in 2003, based on earlier reporting (1999) by the International Institute of Synthetic Rubber...

Molding In Civil Engg

Concrete Foaming Chemical Formula

Convert the low molecular weight resins into three-dimensional ther-moset structures exhibiting valuable properties. The standard epoxy resins used in molding compounds meeting Mil-M-24325 (ships) are based on bisphenol A and epichlorohydrin as raw materials with anhydride catalysts, as illustrated in Fig. 2.4. The low-pressure encapsulation compounds consist of an epoxy-novolac resin system using amine catalysts. 2.2.5 Phenolics Resoles and novolacs Chemical characteristics.5 Phenol and...

532 Flat film and sheet extrusion

Another process for producing plastic films is flat, or cast, film extrusion. In this process the extruder pumps molten resin through a flat film or sheet die. The melt leaves the die in the form of a wide film, or sheet. This is typically fed into a chill-roll assembly which stretches and cools the film. After the film passes through the rolls, the film is wound up on a roll. A film or sheet extrusion line consists of an extruder, film or sheet die, cooling system, take-off system, wind-up...

1272 Polycaprolactone

Polycaprolactone is a member of the polyester family which has been used in relatively small quantities for a long time. The most well-known supplier is Union Carbide of Danbury, Conn., which sells polycaprolactone resins under the brand name Tone. These polymers are compostable but not water soluble.216 A primary application is for compostable bags for yard waste or other organics collection. They can be utilized as homopolymers, copolymers, or in blends. For example, R. Narayan, of Michigan...

William R Lukaszyk

North Plainfield, New Jersey Correct selection of auxiliary equipment and utilization of efficient material handling systems can make the difference between a marginal plastic processing operation and a successful one. Introduction of a well thought out system, whether it is done all at once or in phases as capital budgets allow, results in savings and improvements in many areas including 1. Direct reduction in material cost. When material is purchased in bulk and...

Epdm

Table 4.9 presents a list of selected suppliers of coupling agents. The two leading suppliers in North America are Witco and Dow Corning. Worldwide, Witco is the leading supplier with a strong presence in Europe, in Asia Pacific (through a distribution agreement), as well as in North America. The coupling agent market follows the growth of its three major uses fiberglass reinforced plastics, plastics compounding, and mineral filler pretreatment. The latter two markets, although smaller than the...

Processing of Thermosets

President, Hull Corporation Warminster, Pennsylvania Because thermoset plastics undergo an irreversible chemical reaction (cross-linking or polymerization) involving a time-temperature exposure, processing of such materials consists of (1) getting the resin formulation to a liquid state, (2) causing the liquid to flow into a cavity of the desired configuration, (3) heating the liquid sufficiently to cause the chemical reaction to advance to the point where the plastic is essentially rigid...

9715Polysulfone

Polysulfone parts can be joined with all the processes described in this chapter. Because of their inherent dimensional stability and creep resistance, polysulfone parts can be press fitted with ease. Generally, the amount of interference will be less than that required for other thermoplastics. Self-tapping screws and threaded inserts have also been used. Urethane and epoxy adhesives are recommended for bonding polysulfone substrates. No special surface treatment is necessary. Polysulfones can...

Cj1

Since the pressure is greatest just before the die, this head pressure creates two other flows, pressure flow QP and leakage flow Ql. In pressure flow, the head pressure forces the melt to rotate in the channels of the extruder screw. Leakage flow occurs when the head pressure forces melt back over the flights of the screw. Since they both counter the forward motion of the melt, pressure and leakage flow are often lumped together as back flow. As depicted in Fig. 5.25,...

References

Shaffer, What Does the Property Datasheet Really Tell You ASTM Symposium on Limitations of Test Methods for Plastics, Norfolk, Virginia, November 1, 1998. 2. D. Rackowitz, Beyond the Datasheet A Designers Guide to the Interpretation of Datasheet Properties, Challenging the Status Quo in Design, '94 Design RETEC Proceedings, March 1994, pp. 28-31. 3. D. Rackowitz, Looking Beyond the Material Datasheet Understanding Plastic Material Properties, SAE Tech. Paper...

322 Olefenics and TPO elastomers

Thermoplastic polyolefin (TPO) elastomers are typically composed of ethylene propylene rubber (EPR) or ethylene propylene diene M (EPDM) as the elastomeric segment and polypropylene thermoplastic segment.18 LDPE, HDPE, and LLDPE copolymers ethylene vinyl acetate (EVA), ethylene ethylacrylate (EEA), ethylene, methyl-acry-late (EMA) and polybutene-1 can be used in TPOs.18 Hydrogenation of polyisoprene can yield ethylene propylene copolymers, and hydrogenation of 1,4- and 1,2-stereoisomers of...

Dr Ranganath Shastri

The Dow Chemical Company Midland, Michigan Although the terms testing and characterization are used interchangeably to describe evaluation of various properties of plastics, there is a subtle difference between the two terms. Characterization often refers to evaluation of the molecular or structural characteristics of plastics while testing is used to refer to evaluation of behavior of plastics in response to the applied external loads, environment, etc. The testing is not limited to plastics...

155

In view of the enormous cost associated with material data measurement, a pragmatic approach for resin suppliers is to measure only the data which is really necessary and useful to the design engineers. For example, 1. Make core sets of material data that essentially constitute the minimum data required for carrying out the engineering analyses available for key products in their portfolio, since not all commercial grades are intended for large-volume applications involving complex molded...

Ch 265001e1197x

Figure 11.1 Example of a typical technical datasheet available from resin suppliers. misconceptions about which properties are essential for the design process. (See also Chap. 7, Sec. 3.) Whether the CAE tools are used or not, the data required for product design go beyond the single-point data. To effectively design with plastics, more comprehensive data, such as the following, are essential Isothermal stress-strain curves at temperatures and strain rates reflective of service conditions...

12411 Commingled plastics and plastic lumber

In some cases, separation of collected plastics by resin type is either not feasible with current technology or is economically unattractive. For such streams, use of the plastics in a commingled form may be preferable. A number of applications have been developed for commingled plastics. Many fall in the general category of plastic lumber, while others are replacements for concrete or other materials. Some of these processes are also able to handle substantial concentrations of nonplastic...

Ap

Where the die constant K varies with geometry. Selected constants are given in Table 5.8.61 When drag flow dominates, extruder output increases linearly with screw speed, and larger screws and deeper channels carry more melt. However, head pressure also rises with screw speed. Although this increases pressure flow, the actual effect depends heavily on melt viscosity. With high-viscosity melts, pressure flow may be minimal and have little effect on extruder output. In contrast, low-viscosity...

37

Epon 828 diethylenetriamine A 4 B + 66 by weight tabular alumina 18.0 B + 64 by volume tabular alumina 50.0 Polyurethane (highly filled) 8-11 Emerson & Cuming, 2651 ft Wakefield Engineering Company International Electronic Research Company TABLE 10.20 Thermal Conductivities of Coatings (Continued) Material ( C cm) X 104 Source of information Other materials used in electronic assemblies Alumina ceramic Aluminum oxide (alumina), 96 Beryllium oxide, 99 Copper Glass (Borosill, 7052) Glass...

34 Thermoplastic Vulcanizate TPV

TPVs are composed of a vulcanized rubber component, such as EPDM, nitrile rubber, and butyl rubber, in a thermoplastic olefinic matrix. TPVs have a continuous thermoplastic phase and a discontinuous vulcanized rubber phase. TPVs are dynamically vulcanized during a melt-mixing process in which vulcanization of the rubber polymer takes place under conditions of high temperatures and high shear. Static vulcanization of thermoset rubber involves heating a compounded rubber stock under zero shear...

Coat Hanger

Figure 5.42 Manifold designs (a) T manifold and (b) coat-hanger manifold.99 Figure 5.42 Manifold designs (a) T manifold and (b) coat-hanger manifold.99 Three mechanisms produce the fine adjustment for flow through the die. In a flex lip die, a metal bar with a flexible hinge is machined into the upper part of the die. Bolts at an angle to the die lip adjust the die gap. For thin films < 0.25 mm (0.010 in) , the bolts only push the die lips together the natural spring of the metal and the melt...

823 Stress concentrations in inside corners

Radius Stress Concentration

Plastics are particularly vulnerable to the concentration of stresses on inside corners as most of them tend to be notch sensitive. The graph in Figure 8.13 Relationship of inside corner radius to the stress concentration factor. (Source Jordan I. Rotheiser, Joining of Plastics Handbook for Designers and Engineers, Hanser Publishers, Munich-Hanser Gardner Publications, Inc., Cincinnati, 1999.) Figure 8.13 Relationship of inside corner radius to the stress concentration factor. (Source Jordan I....

825 Gas traps

The interior of a closed mold is not empty before it is filled with plastic. The space is occupied by a gas, air to be precise. The plastic displaces the gas, chasing the gas before it as it fills the mold. Certain design configurations, such as the free-standing rib shown in Fig. 8.17, create a trap with nowhere for the gas to escape. Such a design detail is referred to as a gas trap and the compression of the gas into it causes the gas to burn. The moldmaker can place very small vents on the...

D3

Berins, ed., Plastics Engineering Handbook, 5th ed., The Society of the Plastics Industry, Chapman amp Hall, New York, 1991. source M. L. Berins, ed., Plastics Engineering Handbook, 5th ed., The Society of the Plastics Industry, Chapman amp Hall, New York, 1991. Tolerance notation. Dimensional control and tolerances have been extensively discussed in Secs. 8.2.8 Dimensional Control and Establishing Tolerances. For noncritical tolerances, a general tolerance notation, or a tolerance...

Extrusion Screw Nomenclature

Nomenclature Screw

Where Lflight is the length of the flighted section, with or without the feed pocket. Screw features, such as the flights and channel nomenclature are shown in Fig. 5.16.43 Pitch t is the axial distance from center of one flight to the center of the next flight, whereas lead is the axial distance the screw moves in one full rotation. Since most extruders use square-pitched metering screws, both the pitch and lead equal the diameter, and the helix angle is 17.7 . The helix angle can also be...

Fep Ctfe

Solvents poor Alkalies poor Dilute acids poor to fair Solvents good Alkalies good Acids good excellent Alkalies good Dilute acids fair Solvents good Alkalies Dilute acids Solvents fair Alkalies good Dilute acids poor Solvents excellent Alkalies fair Dilute acids good Solvents excellent Alkalies good Dilute acids excellent Excellent resistance to UVand weather Good to excellent Solvents good to excellent Alkalies poor Dilute acids good to excellent Coatings for circuit boards. Quick dry...

Polymethylpentene Radical Polymerisation

Figure 1.32 Routes for PEK synthesis. Figure 1.32 Routes for PEK synthesis. injection molding. The sheet form material is polymerized in situ by casting a monomer which has been partly prepolymerized by removing any inhibitor, heating, and adding an agent to initiate the free-radical polymerization. This agent is typically a peroxide. This mixture of polymer and monomer is then poured into the sheet mold and the plates are brought together and reinforced to prevent bowing to ensure the final...

12 Polymer Categories 121 Acetal POM

Atactic Syndiotactic

Acetal polymers are formed from the polymerization of formaldehyde. They are also known by the name polyoxymethylenes POM . Polymers prepared from formaldehyde were studied by Staudinger in the 1920s, but thermally stable materials were not introduced until the 1950s when DuPont developed Delrin.1 Homopolymers are prepared from very pure formaldehyde by anionic polymerization, as shown in Fig. 1.4. Amines and the soluble salts of alkali metals catalyze the reaction.2 The polymer formed is...