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 to achieve flowable melt viscosities, and shear force applied by the...
Spin Welding
Spin welding uses frictional forces to provide the heat of fusion at the interface. One substrate is rotated very rapidly while in touch with the other substrate, which is fixed in a stationary position. The surfaces melt by frictional heating without heating or otherwise damaging the areas outside of the joint. Sufficient pressure is applied during the process to force out a slight amount of resinous flash along with excess air bubbles. Once the rotation is stopped, position and pressure are...
Polymethylmethacrylate PMMA
Poly methylmethacrylate is a transparent thermoplastic material of moderate mechanical strength and outstanding outdoor weather resistance. It is available as sheet, tubes, and rods that can be machined, bonded, and formed into a variety of different parts, and in bead form, which can be conventionally processed via extrusion or injection molding. The sheet form material is polymerized in situ by casting a monomer that has been partly pre-polymerized by removing any inhibitor, heating, and...
Resistance Wire Welding
The resistance wire welding method of joining employs an electrical resistance heating element laid between mating substrates to generate the needed heat of fusion. Once the element is heated, the surrounding plastic melts and flows together. Heating elements can be anything that conducts current and can be heated through Joule heating. This includes nichrome wire, carbon fiber, woven graphite fabric, and stainless steel foil. Figure 8.4 shows an example of such a joint where a nichrome wire is...
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 no...
Branched copolymers of polyethylene Ethylene monomer can be co
polymerized with either alkenes of four to eight carbons or monomers containing polar functional groups like vinyl acetate, acrylic acid, and vinyl alcohol. Branched ethylene alkene copolymers are equivalent to LDPE, since, in commercial practice, a certain amount of propylene and hexene are always added to help control the average molecular weight. Inserting polar comonomers in branched ethylene copolymers increases their flexibility, widens the range of heat sealing temperatures, improves the...
Polystyrene
New copolymerization methods, additives, rubber modification, and blending have made of polystyrene polymer and copolymers versatile packaging materials. Developed in 1930 by BASF, polystyrene PS is commonly produced by the continuous bulk polymerization of styrene in the presence of ethylbezene that control product viscosity and heat transfer. PS is hydrophobic, nonhygroscopic, and easily processed by extrusion and thermoform-ing. Three types of PS are available general-purpose, impact PS, and...
Info Yzm
compression, shear, or flexure is not in a brittle manner and requires a relatively great deal of work. Aramid composites have relatively poor shear and compression properties careful design is required for their use in structural applications that involve bending. 4.2.1.4 PBO fibers. A new fiber, poly p-phenylene-2-6-benzobisoxazole PBO was introduced in the 1990s. It was developed by Dow Chemical Co. under U.S. Air Force funding and was tested in pressure vessels by Lincoln Composites. It has...
Info Vbk
Byrom, D., Miscellaneous biomaterials, in Biomaterials, D. Byrom, Ed., Stockton Press, New York, 1991, p. 338. Brydson, J.A., Plastics Materials, 6 e, Butterworth-Heinemann, Oxford, 1995, p. 860. Brydson, J.A., Plastics Materials, 6 e, Butterworth-Heinemann, Oxford, 1995, p. 862. McCarthy, S.P. Biodegradable Polymers for Packaging, in Biotechnological Polymers, C.G. Gebelein, Ed. Byrom, D., Miscellaneous biomaterials, in Biomaterials, D. Byrom, Ed., Stockton Press, New York, 1991, p. 351....
Packaging Plastics Polyethylene
Polyethylene PE is a group of polymers resulting from the polymerization of ethylene by chain reaction. Polyethylene can be either a homopolymer or a copolymer, and either linear or branched. Homopolymer PE is based mostly on ethylene monomer. In PE copoly-mers, on the other hand, ethylene can be copolymerized with short alkenes or with compounds having polar functional groups, such as vinyl acetate VA , acrylic acid AA , ethyl acrylate EA , methyl acrylate MA , or vinyl alcohol VOH see Fig....
TABLE Mechanical Property Profile of Elastollan
Specific gravity, g cm3 1.11-1.21 Tensile strength, lb in2 MPa 4600-5800 31.7-40.0 Tensile strength, lb in2 MPa 100 elongation 770-1450 5.3-10.0 300 elongation 1300-1750 9.0-12.0 Tear strength, Die C pli 515-770 Abrasion-resistance, mg loss Tabor 25 Dow Plastics Pellethane TPU elastomers are based on both polyester and polyether soft segments.3 Five series indicate typical applications 1. Polyester polycaprolactones for injection-molded automotive panels, painted without primer with urethane...
Postmolding Operations
Most thermoset molding operations result in some excess material, called flash, at the parting line and on molded-in inserts. It is generally necessary to remove this flash, either for cosmetic reasons or, in the case of contacts and leads extending from an encapsulated electric or electronic device, to ensure good electrical contact to the leads. Robust parts may be tumbled randomly in a wire container to remove the flash. Slow rotation of the containers for 10-15 min, with parts gently...
Polyacrylonitrile
Polyacrylonitrile is prepared by the polymerization of acrylonitrile monomer using either free radical or anionic initiators. Bulk, emulsion, suspension, solution, or slurry methods may be used for the polymerization. The reaction is shown in Fig. 1.21. Polyacrylonitrile will decompose before reaching its melting point, making the materials difficult to form. The decomposition temperature is near 300 C.135 Suitable solvents, Figure 1.21 Preparation of polyacrylonitrile. Figure 1.21 Preparation...
ProcessRelated Design Considerations Flow
As thermoplastics cool and harden into solid shapes following amorphous flow, and as thermosetting materials polymerize, changing from a viscous liquid to a shaped solid, the plastics often carry some history of their flow conditions preceding hardening. This history often adversely affects mechanical and electrical properties, dimensions, cosmetic appearance, and even density of the finished parts. Flow inside a mold cavity in injection, compression, or transfer molding should ideally be such...
Polyamides 1
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, whereas 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 poly-oxyethylene glycol or polyoxypropylene glycol,...
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shows good resistance to chemicals, good moisture barrier properties, and good electrical insulation properties. Pipes prepared from polybutylene can be solvent welded, yet the polymer still exhibits good environmental stress cracking resistance.169 The chemical resistance is quite good below 90 C, but at elevated temperatures the polymer may dissolve in solvents such as toluene, decalin, chloroform, and strong oxidizing acids.170 Polybutylene is a crystalline polymer with three crystalline...
Polysulfide Rubber PSR
PSR is highly resistant to hydrocarbon solvents, aliphatic fluids, and aliphatic-aromatic blends.10a It is also resistant to conventional alcohols, ketones, and esters used in coatings and inks and to certain chlorinated solvents.10d With these attributes, PSR is extruded into hose to carry solvents and printing rolls, and, due to its good weather resistance, it is useful in exterior caulking compounds.10a Its limitations, compared with nitrile, are relatively poor tensile strength, rebound,...
Branched homopolymer polyethylene
Low-density polyethylene. Low-density polyethylene LDPE is a branched thermoplastic polyethylene with density values ranging from 0.915 to 0.942 g cm3, and melt flow index MFI between 0.2 and 20 g 10 min. Chain-branching yields desirable characteristics such as clarity, flexibility, sealability, and ease of processing. The actual values of these properties depend on the balance of the molecular weight, molecular weight distribution, and degree of branching. Due to its rheological...
Info Jwc
True properties are determined by the polymer and compound formulation and, for synthetic rubbers, additionally by type of curing agents such as sulfur or peroxides and the state of vulcanization. Typical properties for four polymers often used in automotive applications acetals, nylons, polycarbonates, and unsaturated polyester vinyl esters are shown in Tables 10.1 through 10.4. Typical property data is readily available from resin producers and compounders. Property data for elastomers is...
References 1
1. James M. Margolis, Elastomeric Polymers 2000 to 2010 Properties, Processes and Products Report, 2000. 2. KRATON Polymers and Compounds, Typical Properties Guide, Shell Chemical Company, Houston, Texas, 1997. 3. Products, Properties and Processing for PELLETHANE Thermoplastic Polyurethane Elastomers, Dow Plastics, The Dow Chemical Company Midland, Michigan, ca. 1997. 4. Modern Plastics Encyclopedia '99, McGraw-Hill, New York, 1999, pp. B-51, B-52. 5. Engage, A Product of DuPont Dow...
Polyurethane PUR
Polyurethanes are very versatile polymers. They are used as flexible and rigid foams, elastomers, and coatings. Polyurethanes are available as both thermosets and thermoplastics, in addition, their hardnesses span the range from rigid material to elastomer. Thermoplastic polyurethanes will be the focus of this section. The term polyurethane is used to cover materials formed from the reaction of isocyanates and polyols. The general reaction for a polyurethane produced through the reaction of a...
Fluoropolymers
Fluoropolymers are noted for their heat resistance properties. This is due to the strength and stability of the carbon-fluorine bond.58 The first patent was awarded in 1934 to IG Farben for a fluorine containing polymer, polychlorotrifluoroethylene PCTFE . This polymer had limited application, and fluoropolymers did not have wide application until the discovery of polytetrafluoroethylene PTFE in 193 8.59 In addition to their high-temperature properties, fluoropolymers are known for their...
Peekk
Figure 1.39 Structures of PEK, PEEK, and PEEKK. thermal properties due to the aromaticity of their backbones and are readily processed via injection molding and extrusion, although their melt temperatures are very high 370 C for unfilled PEEK and 390 C for filled PEEK and both unfilled and filled PEK. Mold temperatures as high as 165 C are also used.273 Their toughness surprisingly high for such high-heat-resistant materials , high dynamic cycles and fatigue resistance capabilities, low...
TABLE Typical InjectionMolding Settings for Pellethane TPU
Temperature, F C Shore A 80 Shore D 55 Melt temperature max Cylinder zone Rear feed Middle transition Front metering Nozzle 350-370 177-188 360-380 183-193 370-390 188-199 390-410 199-210 80-140 360-380 183-193 370-390 188-198 390-410 204-210 400-410 204-210 27-60 Typical temperature and pressure settings are based on Ref. 3. Settings are based on studies using a reciprocating screw, general-purpose crew, clamp capacity of 175 tons, and rated shot capacity of 10oz 280 g . Molded specimen...
Epichlorohydrin ECH ECO
ECH and ECO polyethers are homo- and copolymers, respectively chloromethyloxirane homopolymer and chloromethyloxirane copolymer with oxirane.23 Chloromethyl side chains provide sites for cross-linking curing and vulcanizing . These chlorohydrins are Hypalon is a registered trademark of DuPont Dow Elastomers LLC. chemically 1-chloro-2,3-epoxypropane. They have excellent resistance to swelling when exposed to oils and fuels good resistance to acids, alkalis, water, and ozone and good aging...
TABLE Typical Temperature Pressure Settings for Pellethane TPU
First stage 8000-15,000 55.0-103 Second stage 5000-10,000 34.5-69.60 Cycle time, s injection, relatively slow to avoid flash, etc. 3-10 Typical temperature and pressure settings are based on Ref. 3. Settings are based on studies using a reciprocating screw, general-purpose screw, clamp capcity of 175 tons, and rated shot capacity of 10 oz 280 g . Molded speciment thickness ranged from 0.065 to 0.125 in 1.7- to 3.2-mm . fU.S. units refer to line pressures metric units are based on the pressure...
Polyacrylate Acrylic Rubber ACM
Acrylic rubber can be emulsion- and suspension-polymerized from acrylic esters such as ethyl, butyl, and or methoxyethyl acetate to produce polymers of ethyl acetate and copoly-mers of ethyl, butyl, and methoxyl acetate. Polyacrylate rubber, such as Acron from Cancarb Ltd., Alberta, Canada, possesses heat resistance and oil resistance between nitrile and silicone rubbers23 Acrylic rubbers retain properties in the presence of hot oils and other automotive fluids, and they resist softening or...
Polyetherimide PEI
Polyetherimides PEIs are a newer class of amorphous thermoplastics with high temperature resistance, impact strength, creep resistance, and rigidity. They are transparent with an amber color.218 The polymer is sold under the trade name of Ultem General Electric and has the structure shown in Fig. 1.31. It is prepared from the condensation polymerization of diamines and dianhydrides.219 Figure 1.31 General structure of polyetherimide. Figure 1.31 General structure of polyetherimide. The material...