SCI.POLYMERS FAQ

POLYMERS FAQ

Contents:

(1) Where to find this FAQ

a) The FAQ will be posted quarterly to the usenet newsgroup sci.polymers

b) The FAQ is archived at the following locations on the World Wide Web:

http://www.irc.leeds.ac.uk/irc/spfaq/

http://www.geocities.com/~spanoudi/poly-faq.html

http://www.polymers.com/poly-faq.html

(2) What is a "Polymer"

The word Polymer comes from the Greek "poly" meaning many, and "meros", parts or units. A polymer is a group of many units. You combine many "monomers" (individual units) to create a polymer.

Polymer is often used as a synonym for "plastic", but many biological and inorganic molecules are also polymeric. All plastics are polymers, but not all polymers are plastics. Plastic more commonly refers to the way a material behaves under applied forces, or behaves when it melts and flows.

Commercial polymers are formed through chemical reactions in large vessels under heat and pressure. Other ingredients are added to control how the polymer is formed and to produce the proper molecular length and desired properties. This chemical process is called "polymerization".

A "homopolymer" results from polymerizing only one kind of monomer. A "copolymer" results from using different monomers. Homopolymers have the same repeating unit while copolymers (which can be random, block, or graft) can vary have different numbers of repeating units. A "terpolymer" results from using three different monomers.

(3) Abbreviations for Common Polymers

Polymers are commonly refered to by both their names and abbreviations. Commercial polymers are also frequently refered to by the trade names of their manufacturer. Here are some abbreviations for common polymers:

ABS - acrylonitrile-butadiene-styrene terpolymer

BMC - thermoset polyester bulk molding compound

LCP - liquid crystal polymer

PA - polyamide, commonly called nylon

PAN - polyacrylonitrile

PAS - polyarylsulfone

PBT - polybuylene terephthalate

PC - polycarbonate

PE - polyethylene

HDPE - high density PE
LDPE - low density PE
LLDPE - linear low density PE
VLDPE - very low density PE
HMW-HDPE - high molecular weight HDPE
UHMWPE - ultrahigh-molecular-weight polyethylene

PEEK - polyetheretherketone

PEK - polyetherketone

PEI - polyetherimide

PES - polyethersulfone

PET - polyethylene terephthalate

PET-G - glycol modified PET

PI - polyimide

PK - polyketone

PMMA - polymethyl methacrylate, commonly called acrylic

PMP - polymethylpentene

POM - polyoxymethylene, commonly called acetal

PP - polypropylene, subdivided as:

homopolymer
random, impact and block copolymers

PPA - polyphthalamide

PPO/PPE - polyphenylene oxide, polyphenylene ether

PPS - polyphenylene sulfide

PS - polystyrene

EPS - expanded polystyrene
HIPS - high impact polystyrene

PSO,PSU - polysulfone

PTFE - polytetrefluoroethylene

PU,PUR - polyurethane

PVC - polyvinylchloride, commonly refered to as vinyl

RUBBER

EPR - ethylene propylene rubber
SBR - styrene butadiene rubber
EPDM - ethylene propylene diene monomer rubber

SAN - styrene acrylonitrile copolymer

SI - silicone

SMC - thermoset polyester sheet molding compound

TPE - thermoplastic elastomer

TPO - thermoplastic olefin
TPU - thermoplastic urethane

UF - urea formaldehyde

http://www.geocities.com/~spanoudi/abbrev.html has a more extensive list of polymer abbreviations

http://www.geocities.com/~spanoudi/tradname.html has a list of polymer tradenames

(4) Polymer Properties

Polymers are characterized in many ways - by chemical or physical structure, by strength or thermal performance, by optical or electrical properties, etc.

Most textbooks will give qualitative and some quantitative data on polymer properties. Properties can vary widely however, between manufacturers, for different performance grades, due to the presence of additives and reinforcements, or other reasons. For more precise data, contact a representative from a polymer producer, compounder, or distributor for a spec sheet on a particular material and grade. Often grades are offered to suit the needs of specific types of applications.

Properties of interest typically include:

Physical Properties

Specific Gravity
Mold Shrinkage (in flow, cross-flow, and thickness directions)

Mechanical Properties

Strength (Tensile and Flexural)
Modulus (Tensile and Flexural)
Elongation
Hardness
Impact Resistance

Thermal Properties

Heat Deflection Temperature
VICAT Softening Temperature
Glass Transition Temp
Heat Capacity
Thermal Conductivity
Thermal Expansion Coefficient

Processing Characteristics

Melt Flow Index
Melt Strength
Melting Point, No-flow Temp
Shear Rate/Viscosity Relation
Compressibility (Pressure/Volume/Temperature Relation)

Optical Properties

Light Transmission
Haze
Refractive Index

Electrical Properties

Surface and Volume Resistivity
Dielectric Constant
Dielectric Strength
Dissipation Factor
Breakdown Voltage

Environmental Properties

Chemical Resistance
UV Resistance
Flame Resistance (UL Rating)
Oxygen Index
Water Absorption

Morphology

Crystallinity
Orientation
Composition (Neat, Blended, Filled)

(http://www.lexmark.com/ptc/book6.html has a brief overview of properties for a number of commonly used polymers)

(5) Classificaton of Polymers

There are many ways in which polymer properties or behavior are classified to make general descriptions and understanding easier. Some common classificatons are:

Thermoplastic vs. Thermoset Polymers

"Thermoplastics" anre materials which can be heated and formed, then re-heated and re-formed repeatedly. The shape of the polymer molecules is generally linear, or slightly branched, allowing them to flow under pressure when heated above the effective melting point.

"Thermoset" materials undergo a chemical as well as a phase change when they are heated. Their molecules form a three-dimensional cross-linked network. Once they are heated and formed they can not be reprocessed - the three-dimensional molecules can not be made to flow under pressure when heated.

Amorphous vs Crystalline Polymers

Polymers with nearly linear structure, which have simple backbones, tend to be flexible and fold up to form very tightly packed and ordered "crystalline" areas. Levels of crystallinity can vary from zero to near 100%. Time and temperature during processing influence the degree of crystallinity. Crystalline polymers include: polyethylene, polypropylene, acetals, nylons, and most thermoplastic polyesters. Crystalline polymers have higher shrinkage, are generally opaque or translucent, with good to excellent chemical resistance, low surface friction, and good to excellent wear resistance.

Polymers with bulkier molecular chains or large branches or functional groups tend to be stiffer and will not fold up tight enough to form crystals. These materials are referred to as "amorphous" polymers. Common amorphous polymers include polystyrene, polycarbonate, acrylic, ABS, SAN, and polysulfone. Amorphous polymers have low shrinkage, good transparency, gradual softening when heated (no distinct melting point), average to poor chemical resistance, high surface friction, and average to low wear resistance.

Addition vs. Condensation Polymers

Polymers such as nylons, acetals, and polyesters are made by condensation or step-reaction polymerization, where small molecules (monomers) of two different chemicals combine to form chains of alternating chemical groups. The length of molecules is determined by the number of active chain ends available to react with more monomer or the active ends of other molecules.

Polymers such as polyethylene, polystyrene, acrylic, and polyvinyl chloride are made by addition or chain-reaction polymerization where only one monomer species is used. The reaction is begun by an initiator which activates monomer molecules by the breaking a double bond between atoms and creating two bonding sites. These sites quickly react with sites on other monomer or polymer molecules. The process continues until the initiator is used up and the reaction stops. The length of molecules is determined by the number of monomer molecules which can attach to a chain before the initiator is consumed and all molecules with initated bonding sites have reacted.

Commodity, Engineering, and Performance Polymers

Commodity polymers have relatively low physical properties. They are used for inexpensive or disposable consumer or industrial products or packaging. They have limited stress and low temperature resistance, but are well suited to high volume production. Polyethylene, polystyrene, and polypropylene are good examples. In recent years, material suppliers have achieved improved strength and thermal properties from some commodity materials, displacing low-end applications for engineering polymers.

Engineering polymers have higher strength and thermal resistance. Their price may range from two to ten times as much as a commodity polymer. They are used in enclosures, structural frames and and load bearing members, and applications requiring wear resistance, long life expectency, flame resistance, and the ability to endure cyclic stress loading. Good examples are polyesters, polycarbonates, ABS, and acetal.

Performance polymers are at the highest end of the spectrum, with very high strength and thermal resistance. They tend to be very expensive, priced two to five times above most engineering polymers. They are used in high temperature, high stress applications, in harsh environments, and in generally low to medium volume production. Examples include PEEK, polyetherimides, and LCP's.

(6) Processing Methods for Polymers

There are many processing methods for polymers. Commercial processing equipment can range from a few thousand dollars to many millions of dollars. In addition to the equipment itself, tooling is generally required to make a particular shape. Most processes involve melting or softening the material and then forcing it into the desired shape. Other processes force a monomer or pre-polymer mixture into the right shape, then polymerize it in-place.

Molding

Compression Molding

Transfer Molding

Injection Molding

Gas Assisted Injection Molding (GAIN)
Reaction Injection Molding (RIM/SRIM)
Injection/Compression Molding
Structural Web Molding

Blow Molding

Extrusion Blow Molding
Injection Blow Molding
Injection Stretch Blow Molding

Rotational Molding

Extrusion

Rod, Pipe, Sheet, Profile Extrusion

Coextrusion

Extruded/Blown Film

Extruded/Blown Foam

Pultrusion

Casting

Cast Film

Cast Shape

Vacuum Casting

Forming

Vacuforming

Thermoforming

Pressure Forming

Calendering

Roller Mill

Web Processing

Coating

Powder Coating

Dispersion Coating

Extrusion Coating and Laminating

Spray Coating

Dip Coating

Spinning

Lay-up

Filament Winding

Melt Blown Fiber

Many processing methods have their own Special Interest Group as a subdivision of the SPE.

(A good textbook for understanding different processing methods is the Plastic Engineering Handbook by SPI, Michael L. Berrins, Ed. (Van Nostrand Reinhold, pub, c 1991, 845p.) ISBN 0-442-31799-9, LCCCN 90-22784)

(7) Recycling

Most thermoplastic polymers can be recycled - that is converted from their initial use as a consumer, business, or industrial product, back into a raw material from which some other product can be manufactured. Recycled materials are often classified as Post-Industrial and Post-Consumer.

Post-Industrial includes such things as manufacturing scrap, containers and industrial packaging. Post-Consumer is basically any product, container, packaging, etc. that has passed through the hands of a consumer, e.g. plastics bags, beverage containers, carpeting, home appliances, toys, etc.

Thermoset polymers can only be recycled for use as an inert filler (something to take up space) in another material.

The keys to effective recycling are:

an efficient infrastructure for collecting used materials
ease of separation and low levels of contamination
an established market for reprocessing/reusing the materials

There are many arguments whether there is not enough of a market for recycled materials to create the proper recycling infrastructure, or not a consistent supply of recycled material to encourage the growth of a market. In the case of the US paper industry, decreasing availability of virgin wood pulp rapidly created a profitable market for recycled paper.

The contamination issue is very important for plastics. While oil, grease, paper labels, glue, etc. will burn off when glass or metals are recycled, they become contaminants and degrade thermoplastics during reprocessing.

There are several versions of the recycling logo. The original one was three arrows chasing each other in the shape of a triangle, the second was just a triangle, and the current one is a pair of angle brackets.

< 1 >

The number inside the triangle or brackets indicates the material used in the part. There are six specific numbered categories, and a generic seventh for "other". In the case of "other" it is good form to put the material name under the recycling logo.

SYMBOL              MATERIAL

  1             PET (polyethylene terphthalate)
                - beverage containers (2-liter soda bottles), boil-in
                   food pouches, processed meat packages, etc.

  2             HDPE (high density polyethylene)
                - milk bottles, detergent bottles, oil bottles, toys,
                   plastic bags

  3             PVC (polyvinyl chloride)
                - food wrap, vegetable oil bottles, blister packaging

  4             LDPE (low density polyethylene)
                - shrink-wrap, plastic bags, garment bags

  5             PP (polypropylene)
                - margarine and yogurt containers, grocery bags,
                caps for containers, carpet fiber, food wrap,

  6             PS (polystyrene)
                - plastic utensils, clothes hangars, foam cups and plates

  7             Other (all other polymers and polymer blends) including
                polycarbonate, ABS, PPO/PPE

(8) Polymer Resources on the Net - Selected World Wide Web Sites

(make sure you use upper and lower case letters as shown below - most web sites run under UNIX or Windows NT based operating systems and are case sensitive)

http://www.asresin.com/: Allied Signal Plastics
http://www.PlasticsResource.com/: American Plastics Council - Plastics / Environment Page
http://cps-www.bu.edu/: Boston University Center for Polymer Studies
http://www.polymer-age.co.uk/: British Plastics & Rubber
http://k2.scl.cwru.edu/cse/emac/: Case Western Reserve University - Polymer Science
http://www.cmold.com/: C-Mold (formerly A.C. Technologies)
http://xenoy.mae.cornell.edu/: Cornell University Injection Molding Program
http://www.cpt.stm.tudelft.nl/index.html: Delft University Materials Science
http://www.dow.com/cgi-bin/frameup.cgi?/plastics: Dow Plastics
http://www.eastman.com/ppbo/: Eastman Performance Plastics Home Page
http://www.ferro.com/: Ferro Corporation
http://www.ge.com/plastics/index.htm: General Electric Plastics Home Page
http://www.ashchem.com/DivisionPages/DIV3.html: General Polymers
http://www.idesinc.com/: IDES Materials Database
http://www.industrylink.com/cgi-bin/auto_01.asp?Industry=plas: Industrylink - Plastics and Polymers page
http://www.plasticsnet.com/live/imm/index.cfm: Injection Molding Magazine Online
http://www.mahanna.com/: M.A. Hanna Company
http://www.matweb.com/: Matweb - Materials Database
http://www.moldflow.com/: Moldflow Home Page
http://www.worldserver.pipex.com/moldflow/usergroup/na_mfug.html: North American Moldflow Users Group home page
http://eetsg22.bd.psu.edu: Penn State University - Erie
http://www.plasticsnet.com/: The Plastics Network
http://www.plasticsnews.com: Plastics News Magazine
http://www.lexmark.com/ptc/ptc.html: Plastics Technology Center / Lexmark Electronics
http://www.polymers.com/: Polymers Dot Com - Online Magazine and Polylinks
http://www.polymerland.com/: Polymerland
http://www.polysort.com/: Polysort Network
http://www.rtpcompany.com/: RTP Company
http://www.sme.org/: Society of Manufacturing Engineers
http://www.4spe.org/: Society of Plastics Engineers (slow web site)
http://www.idesinc.com/pd3/: SPE Product Design and Development Division PD3 Home Page at IDES
www.thomasregister.com: Thomas Register online
http://www.umr.edu/~wlf/: University of Missouri at Rolla - Polymer Chemistry Page
http://www.psrc.usm.edu/index.html: The University of Southern Mississippi, Department of Polymer Science

(9) Calendar

Major events in the Polymer/Plastics Industry:

ANTEC - Annual Technical Conference of the SPE: Held in May each year
RETEC - Regional Technical Conference: Frequently held throughout the year in different locations; generally focused on a special interest topic
K-Show - Kunststoffe und Kautschuk - the largest plastics trade show and conference in the world: Held in October/November every three years in Dusseldorf, Germany; Next show is in 1998, contact 312-781-5180 for more information
NPE -National Plastics Exposition - the largest US plastics trade show and conference, sponsored by SPI: Held in June every three years in Chicago; Next show is in 2000
Plastics USA - Interim Show sponsored by SPI: Held in September in Chicago in the years between NPE shows
NDES -National Design Engineering Show, sponsored by NAM: Held annually in Chicago in March during National manufacturing Week

(10) Professional and Industry Organizations

SPE - Society of Plastics Engineers: 14 Fairfield Drive, Brookfield, CT 06804; Phone 203-775-0471 Fax 203-775-8490
SPI - Society of the Plastics Industry: 1275 K Street NW, Suite 400; Washington D.C. 20005; Phone 202-371-5200 Fax 202-371-1022
ACS - American Chemical Society: Division of Polymer Chemistry or; Division of Polymer Materials Science and Engineering
APC - American Plastics Council: 1275 K Street NW; Washington, DC 20005; Phone 1-800-243-5790; BPF - British Plastics Federation; 6 Bath Place, Rivington Street; LONDON EC2A 3JE, England; Phone 00 44 +171 457 5000; Fax 00 44 +171 457 5045; email: bpf@dial.pipex.com
PINZ - Plastics Institute of New Zealand: P.O.Box 76378, Manakau City, Auckland, New Zealand.; Phone +64 9 262 3773
CANZ - Composites Association of New Zealand: 5 Balmacewen Road, Dunedin, New Zealand.; Phone +64 3 467 2514.
PIA - Plastics Industry Association [Australia]: 41-43 Exhibition Street, Melbourne Vic 3000 AUSTRALIA; Phone +61-3-654-2199 Fax +61-3-654-2384

(11) Universities with Degree Programs in Polymers

Undergraduate Programs:

Case Western Reserve University
UMass at Lowell
U of Southern Mississippi
Virginia Polytech

Graduate Programs:

University of Akron: Akron, OH 44325-0001; Department of Polymer Engineering; Dr. James White, Department Head
Case Western Reserve University: 10900 Euclid Avenue, Cleveland, OH 44106; Department of Molecular Science; Dr. John Blackwell, Department Chair, Phone 216-368-4450
Georgia Institute of Technology: Atlanta, GA 30332; School of Chemical Engineering; Dr. A.S.Abhiraman, Program in Polymers Coordinator
LeHigh University: 111 Research Dr, Bethlehem, PA 18015; Center for Polymer Science and Engineering; Dr. Mohamed S. El-Aaser, Director
University of Massachusettes at Amherst: Amgerst, MA 01003; Department of Polymer Science
University of Massachusettes at Lowell: 1 University Avenue, Lowell, MA 01854; Department of Plastics Engineering; Dr. Rudolph Deanin 508-934-3420 Graduate Coordinator for M.S.; Dr. Ross Stacer 508-924-2420 for PhD; Dr. Robert Nunn 508-934-3420 (chair) for Undergrad; Prof. Stephen Driscoll 508-934-3420 for night school Undergrad; Dr. Stanley Israel 508-934-3650 (chair) for Joing PhD in
McGill University / Institut Francais du Petrole: Montreal, Quebec, Canada / Paris France; Collaborative Graduate Program; Advanced Technology in Petrochemicals, Polymers, and Plastics
University of Michigan: Ann Arbor, MI 48109; Macromolecular Science and Engineering Program; Dr. Frank Filisko, Graduate Committee Chair
North Carolina State University: Raleigh, NC 27695-7905; Department of Chemical Engineering; Department Head: Ruben Carbonell; Graduate Coordinator: Carol Hall; contact: Chris McDowell, (919)515-4701; e-mail: mcdowell@che.ncsu.edu
Polytechnic University of Brooklyn: Six Metrotech Center, Brooklyn, New York 11201; Prof Eli Pearce or Allan S. Myerson, Phone 718-260-3620; E-mail amyerson@robling.poly.edeu
San Jose State University: San Jose, CA 95192; Department of Chemistry; Dr. Gerald Selter, Graduate Advisor
Univ. of Southern Mississippi: Hattiesburg, MS 39406; Department of Polymer Science, College of Science & Technology; Dr. Robert Lochhead, Department Head, Phone 601-266-4868
University of Tennessee: Knoxville, TN 37996; Departmen of Materials Science & Engineering; Dr. J.E. Spruiell, Department Head
Virginia Polytechnic and State University (also VPI or Virginia Tech): Blacksburg, VA 24061; Dr. Garth Wilkes, Chairman, 120 Patton Hall

(12) Publications of Interest on Polymers

All publications are monthly unless noted otherwise.

British Plastics & Rubber (MCM Publishing Ltd): 37 Nelson Road, Caterham, Surrey CR3 5PP England; Phone +44 1883 347059 Fax +44 1883 341350
Injection Molding Magazine(Abbey Communications): 3400 East Bayaud Avenue, Suite 230, Denver, CO 80209; Phone 303-321-2322 Fax 303-321-3552; Editorial Contact Online I.D.: immck@aol.com or immmm@aol.com; ISSN 1071-362X
Journal of Polymer Science - Polymer Physics Edition (John Wiley & Sons)
Journal of Polymer Science - Polymer Chemistry Edition (John Wiley & Sons)
Makromoleculare Chemie
Macromolecules(ACS Journal)
Modern Plastics(McGraw-Hill): 1221 6th Avenue, New York, NY 10020; Phone 212-512-6242 Fax 212-512-6111; Editorial Comment Online I.D.: modplas@ios.com
Modern Plastics International(McGraw-Hill)
Plastics Compounding(Advanstar): (no longer being published ? May return)
Plastics Engineering(SPE Publication): 14 Fairfield Drive, Brookfield, CT 06804-0403; Phone 203-775-0471 Fax 203-775-8490; ISSN 0091-9578; (Note: Regional SPE Chapters and SPE Special Interest Divisions tend to have quarterly publications of their own)
Plastics News(Crain Communications): 1725 Merriman Road, Akron, OH 44313-5251; Phone 216-836-9180 Fax 216-836-2322; ISSN 1042-802X
Plastics Technology(Bill Communications): 355 Park Avenue South, New York, NY 10010; Phone 212-592-6570 Fax 212-592-6579; Editorial Comment Phone: 212-592-6573; ISSN 0032-1257
Plastics World (PTN Publishing): Phone 516-845-2700 Fax 516-845-7109; 445 Broad Hollow Road, Melville NY 11747; ISSN 0032-1273
Polymer (a research Journal)
Polymer Composites (SPE Publication)
Polymer Engineering and Science (SPE Publication)
Polymer Processing and Rheology (SPE Publication)

Other publications with frequent Plastics/Polymers articles:

Appliance (Dana Chase): 1110 Jorie Boulevard, CS 9019, Oak Brook, IL 60522-9019; Phone 708-990-3484 Fax 708-990-0078; Editorial I.D.: scot@appliance.com or tim@appliance.com; ISSN 0003-6781
Design News(Cahners): 275 Washington Strees, Newton, MA 02158; Phone 617-964-3030 Fax 617-558-4402; Editorial Comment Online I.D.: DN@cahners
Machine Design(Penton Publishing): 1100 Superior Avenue, Cleveland, OH 44114-2543; Phone 216-696-7000 Fax 216-621-8469; ISSN 0024-9114

(Polylinks has a more extensive catalog of plastics publications at http://www.polymers.com/polylink/subs/polpub.html)

(13) Commercial Polymer Producers, Compounders, and Distributors

Due to the size of this listing, it is maintained as a separate appendix listing companies by name with telephone contact numbers: Appendix A.

(14) Books on Polymers and Polymer Processing

This is a very brief sampling of some texts on polymer science, processing, properties and applications. SPE, McGraw Hill, Van Nostrand Reinhold, and John Wiley and Sons all have catalogs of available books on these subjects).

Plastic Engineering Handbook of the Society of the Plastics Industry, Michael L. Berrins, Ed. (Van Nostran Reinhold, pub, c 1991, 845p.) ISBN 0-442-31799-9, LCCCN 90-22784

Polymeric Materials and Processing, Jean-Michael Charrier, (SPE, pub, c 1990, 650p.) ISBN 0-19-520854-4

Plastics: How Structure Determines Properties, Geza Gruenwald (SPE , pub, c 1992, 352p.) ISBM 3-446-16520-7

Principals of Polymer Systems, Rodriguez (McGraw Hill, pub)

Fundamental Principles of Polymer Materials, Rosen (John Wiley and Sons, pub) ISBN 0-471-08704-1

Plastic Part Design for Injection Molding - An Introduction, Robert A. Malloy (SPE, pub, c. 1994, 460p.) ISBN 1-56990-129-5

Designing with Plastics and Composites, a Handbook, D.V. Rosato and D.P. DiMattia (SPE, pub, c. 1991, 977p.) ISBN 0-442-00133-9

Plastics Polymer Science and Technology, Mahendra D. Baijal, Ed. (John Wiley & Sons, pub, c. 1982, 945p.) ISBN 0-471-04044-4

A catalog with many good text on various polymer/plastics subjects is available from SPE, in the US: Phone 203-775-0471 (Brookfield, CT), in Europe: Phone 32-0-2-774-9630 (Brussels, Belgium)