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89 Cards in this Set
- Front
- Back
Why is the solvent resistance of PPS special?
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No known solvent at temperatures under 400F
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What is the processing temperature of PPS?
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600-650F
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What year did PPS become available on the market?
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1968
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T/F
PPS is self lubricated. |
True
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PPS is crystalline or amorphous?
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Highly crystalline
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PPS does what when it degrades?
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Cross links
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Cost of PPS high or low?
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High $5-6/lb glass filled
Up to $70+/lb carbon fiber fill |
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PPS requires what for good impact strength?
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Fillers (30-40% common)
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PPS competitors
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PPO
PC High temperature eng. plastics @ room temp - comparable to Nylon |
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PPS Applications
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Automotive
Electrical Metal/Ceramic Replacement Coating Applications |
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PPS Trade Names and Suppliers
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Suppliers:
Chevron Phillips Ryton Xtel Trade Names: Ticona Celstran Celstran S. Fortron Ryton |
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PPS is primarily used when ______ is anticipated.
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High service temperatures.
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How does PPS react with moisture?
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PPS has exceptional moisture resistance.
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PPS is subject to ____ and _____.
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Warping and brittleness
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PPS has _____ flammibility resistance.
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High
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What is a Mesogen?
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Molecules with rod like shapes that have strong dipoles and/or easily polarized substituents.At least one aromatic ring.
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Why are LCP's so easily injection molded?
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Very low viscosity, nearly perfectly align.
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Why are LCPs known as self reinforcing materials?
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Individual chains become so stiff with the addition of the meosgens.
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What are the two types of LCPs?
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Main Chain LCPs
Side Chain LCPs |
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What is the processing temp for LCPs?
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540-850F
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Do LCPs require oil mold heaters?
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Yes
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What are the two melt phases of LCPs?
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Soild to liquid crystal
Liquid crystal to amorphous liquid. |
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LCPs are good for what injection molding applications.
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Thin walled parts
Reinforements |
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LCPs show potential in what field and what is the current problem?
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Optical displays, molecules align too slow.
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What are three good properties of LCPs?
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Low stretch/elongation
Resistance to cutting Chem/solvent resistance Excellent thermal properties High strength Low weight High impact resistance |
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Applications of LCPs?
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Sub hulls
Bulletproof vests Helicopter blades Rocet engine castings |
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LCP trade names
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Vectra
Zydar |
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LCP comparable to:
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Fiber reinforced polymers
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How do you lower the Tg of LCPs?
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Introduce multiple mesogens and orient as random copolymer iwth spacers
Add kinks to the spacers in the Main Chain LCPs. |
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Why are LCPs difficult to cut?
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Becuase of the director axis which acts like wood grain.
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Why is suspension polymerization good for producing fluoropolymers?
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Creates a powder, good for sinter molding, a common form of processing fluoropolymers.
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Why is PTFE so difficult to process?
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The melting temperature is slightly below the decomposition temperature.
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What does decomposition of PTFE produce?
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Toxic fluorine gas.
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What are alternatives to PTFE?
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PEEK
Nylon |
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Applications of PTFE
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Gortex
Industrial Rollers Process Dies Kitchen Utensils Tank/Pipe Linings Wire Coverings Gaskets Medical Applications |
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PTFE accounts for ____% of fluoropolymer sales.
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90%
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What is the benefit of fluoroelastomers?
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Remain elastic at high temperatures, won't break down like natural elastomers.
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Making fluoropolymers is a endo/exothermic process.
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Exothermic
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How does Teflon stick to the pan?
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Sand blast the pan first.
Lay a primer layer Add Teflon, then apply pressure. |
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Fluorine is the most ____ element on the periodic table.
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Electronegative
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Fluoropolymers have _____ coefficient of friction and ____ high lubricity.
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Low coefficient of friction
High lubricity |
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Fluoropolymers have a ____ resistance to solvents.
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High
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Two main kinds of acetals.
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Homopolymer
Copolymer |
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Acetal trade names.
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Delrin
Celcon Hostaform |
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How does acetal degrade?
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Similiar to PVC by unzipping.
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Competing materials with acetal.
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Nylon
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Acetal applications.
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Moving mechanical parts
Snap fits Hose fittings Wiperblade fittings Chain linkages |
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Acetal is or is not self lubricating.
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Is self lubricating
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Acetal is crystalline or amorphous?
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Very crystalline
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T/F
Acetal is thermally stable. |
False
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Acetal has a high or low UV resistance.
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Low UV resistance.
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Copolymer acetal is the copolymerization of what two things?
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Formaldehyde with ethylene oxide.
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Homopolymer acetal is created by what two things?
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Formaldehyde and acetic anhydride.
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What happens when acetal degrades?
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Gives off toxic fumes.
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What is really important when processing acetal?
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Uniform mold heating to insure uniform crystallinity.
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What is PBIs trade name?
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Celazole
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What are the advantages of PBI?
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Excellent thermal properties
Low CTE High ionic purity |
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What are the disadvantages of PBI?
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PRICE
Difficult to process Water absorption |
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Competitors to PBI
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Polyimides
Ceramics Metals Polyamidimides |
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PBI applications.
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Figherfighter turnout coats
Astronaut space suits High temperature gloves Welder's apparel Racecar driver suits |
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PBI comes in what forms?
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Powder
Pellet Filament Solutions |
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Why can't you injection mold pure PBI?
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No melting point, very high processing temperatures.
Commonly blended with PEEK. |
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Glass transistion of PBI?
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800F
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PBI is manufactured using what technique?
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Step growth polymerization
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What was PBI first used for?
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NASA applications
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T/F
PBI does not have good creep resistance. |
False.
PBI has excellent creep resistance. |
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PBIs compressive strength is _____.
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Very high. Highest compressive strength of any unfilled plastic (56000 psi)
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What unique thing will not stick to PBI?
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Other plastics will not stick to PBI.
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When being manufactured, PBI undergoes a ____ process.
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Dry spinning.
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What contributes to PBIs flame retardedness?
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LOTS of benzene rings.
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What are the three properties that make polycarbonate very vulnerable if they are not treated?
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Poor weather resistance
Poor abrasion resistance Poor chemical resistance |
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What property gives polycarbonate such high impact strength?
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Rotation of the oxygen bonds
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What are the three properties of PC considered the most important?
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Clarity
Impact strength High thermal stability |
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How is PC produced?
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Through a condenstation reaction
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What happens when PC absorbs water?
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Causes drool
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PC trade names:
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GE - Lexan
Dow - Calibre Bayer - Makrolon |
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Competitive Materials for PC
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Acrylic
ABS |
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PC applications
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Safety equipment
Power tools Electronics CD/DVDs Food safe Automotive |
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How do you overcome the drawbacks of PC?
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Hard coats and primers are used.
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PC has up to ___% clarity.
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90% clarity
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When was PC first introduced.
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1953
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What is PC alloyed with?
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ABS
PET PBT P'sulfone Styrenics Acrylics |
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What is PC blended with?
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P'esters
P'urethans PBT PET |
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What happens when PC is weathered?
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Yellows in weather
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PC
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Polycarbonate
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PBI
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Polybenimidazole
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PTFE
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Polytetrafluoroethylene
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LCPs
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Liquid Crystal Polymers
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PPS
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Polyphenylene Sulfide
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