Term
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Definition
| Large molecule comprised of repeating monomer (small atoms) units. |
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Term
| Single Chain Polymer Conformation |
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Definition
| Path of single macro molecule in solution "random walk" |
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Term
| In tructure formation of polymers, what basic properties change? |
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Definition
Dissordered, non-crystalline - Highly oriented/partially crystalline.
Low strength-much higher strength
Isotropic-Anisotropic (same/not same properties regarless of direction |
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Term
| Physical properties of Polymers depend on? |
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Definition
-MW and MW distribution
-Degree of crystallinity
-Crystallinte size, shape, defects, connetivity
-Arrangement of crystal and non crystal regions |
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Term
| What does Polymer really mean? |
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Definition
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Term
| What does plastic mean in terms of composites? |
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Definition
| material property: whether it is moldable (easy to form out of) |
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Term
| What are natural polymers? |
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Definition
-Proteins: (wool, silk, hair, skin, human tissue
-Nucleic Acid: DNA, RNA
-Sugars: Cellulose, Chitin, Starch
-Isoterpene: natural rubber |
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Term
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Definition
| Hydrocarbon and silicon based: Polyesters, Polyethylene |
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Term
| Condensation polymers vs addition polymers? What is the difference? |
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Definition
Condensation: two molecules form single molecule by loosing a small one
Addition polymers: moleules bond without loosing any molecules (byproducts) |
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Term
| Step growth polymerization? |
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Definition
| monomers-dimers/trimer/tetramers etc-long high mw polymers |
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Term
| Chain Growth polymerization? |
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Definition
| initiator (catalyst) reacts with monomers to add to a chain |
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Term
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Definition
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Term
| Type of Polymer topology? |
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Definition
Linear
Crosslinked
Branched (Hyper and Star Branched) |
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Term
| Thermosplastic vs Thermosetting polymer? |
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Definition
Thermoplastic: Linear or branched, NOT crosslinked
Thermosetting: Heavily cross-linked producing 3d network |
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Term
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Definition
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Term
| Homopolymers vs copolymers? Type of copolymers? |
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Definition
Homo: Single, repeating unit
Co: Alternating, block, random, graft |
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Term
| What promotes crystallinity? |
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Definition
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Term
| Why are polymers never totally crystalline? |
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Definition
| They are long, are entangled, and have little mobility |
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Term
| Crystallinity increases an decreases what? |
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Definition
increases: modulus and strength
decreases: extensibillity |
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Term
| What are the two stages crystallinzation go through? |
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Definition
Nucleation: close packing of molecules to form cylindrical embryo until energy balances
Crystal Growth: linear growth |
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Term
| What are the First order phase transitions? |
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Definition
Crystallization: Liquid to solid
Melting: solid to liquid |
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Term
| What are the second order transitions? |
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Definition
Glass transition: polymer changes from glassy state to rubbery with temp increasing
-Crystal-crystal and B transitions |
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Term
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Definition
| Study of deformation and flow of matter |
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Term
| What is special about polymers in both solid and liquid phase in terms of Rheology? |
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Definition
| deformation properties are viscoelastic. Do not obey Newtonian viscocity or pure elastic behavior. |
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Term
| What are experimental obesrvation of polymer materials? |
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Definition
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Term
| Describe glass transition |
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Definition
| Polymer changes from glassy state to rubbery state as temperature increases |
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Term
| Describe the processing of thermoset polymers (stages). |
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Definition
-Starts with "prepolymer".
-Flows into mold and corsslinking starts trhough heat/chem reactand/UV
-Stage A: Soluble
-Stage B: barely soluble
-Stage C: High;y crosslinked |
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Term
| Describe process stages of thermoplastic polymers |
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Definition
Starts with solid matter that can be melted/remolded
-Can be heat softened, re-shaped, then cooled again |
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Term
| What is the structure of thermoplastic polymer? |
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Definition
| amorphous (random distribution) |
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Term
| What are properties of Thermoplastics vs Thermosettings? |
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Definition
Thermoplastic: higher viscocity in melt phase, strength depend of mw, topology and process conditions, high toughness. Polyamides
Thermosettings: High strength/desinity depending on crosslinking, high resistance to temperature, low toughness. epoxy |
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Term
| What is the general polymer processing steps? |
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Definition
Synthesis: chemically careating polymers in batch or reactor
Compounding: Addition to polymers (additives, primers)
Fomring/molding: engineering and shaping of product |
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Term
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Definition
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Term
| Why does Tensile strength increase with MW to assymptotic value? |
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Definition
| Number of chain ends decrease |
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Term
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Definition
| Have elastic deformation greater than 2X (200%)Lightly crossed thermosets/copolymer thermoplastics |
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Term
| What is Mc and what happens here? |
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Definition
| Critical molecular weight for polymer. Properties are poor below this. arround 600 atoms |
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