A. Polymer Basics
(1) Where to find this FAQ
(2) What is a "Polymer"
(3) Abbreviations for Common Polymers
(4) Polymer Properties
(5) Classification of Polymers
(6) Processing methods for Polymers
(7) Recycling of Polymers
B. References
Books on Polymers, Polymer Processing, Plastics Applications, and Plastics Design
Acknowledgements
(1) Where to find this FAQ
a) The FAQ will be posted quarterly to the use net newsgroup sci.polymers
b) The FAQ is archived at the following locations on the World Wide Web:
(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) Classification of Polymers
There are many ways in which polymer properties or behavior are classified to make general descriptions and understanding easier. Some common classifications are:
Thermoplastic vs. Thermoset Polymers
"Thermoplastics" are 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 shure 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
Polymer Science/Plastics Engineering
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
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)
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)
Acknowledgements
Jim Coffey, Dr. Ulrich Seitz, Ramesh Lakshmi Narayan, David O Hunt, Jeff Vavasour, George D Ryerson, Abe Verghis, Dave Ingram, Mike Greenfield, Sami Mohammed, Paul D. Whaley, Tom Brady, Bob Hutchins, Ed Stokes, Larry Dodd, Mike Stewart, Russell Schulz, David Bick, Tony Foiani, Mike Pollard, Steve Baxter, Tony Tweedale, Kevin Patterson, Thomas Pierce, Stephen DeFosse, Marc Lavine, Jim Ure, Bernhard Wessling, B. L. Dowler, Bernie Doeser, Kevin Byrne, Thomas Guery, Darren Schilberg, Pete Logan, Eric Amis