Flashcards
Polymers
Flashcards do conjunto (87)
- 1What is the repeating unit of polyethylene?
- 2How to determine degree of polymerisation if given molecular weight of polymer?Molecular weight of polymer divided by the molecular weight of the repeating unit
- 3How would you figure out which is which if you know S2 has higher degree of polymerisation than S1?In general, an increase in molecular weight leads to an increase in the melting point. This is because longer polymer chains have more entanglements and interactions, requiring more energy to break these interactions during the melting process. As a result, polymers with higher degrees of polymerization typically require higher temperatures to transition from a solid to a molten state. So the one with the higher melting point is S2
- 4Chemical reaction showing the synthesis of a aromatic polyamide studied?
- 5Kevlar's three main applications1. Car and bicycle tyres
2. Bullet proof Vest
3. Cut resistant gloves - 6What are the main intermolecular interactions between Kevlar molecules?While van der Waals forces, including London dispersion forces and dipole-dipole interactions, contribute to the intermolecular interactions in Kevlar, the primary and most significant force is hydrogen bonding.
In the Kevlar polymer, hydrogen bonding occurs between the hydrogen atoms of the amide (CONH) groups and the oxygen atoms of the carbonyl (C=O) groups. This hydrogen bonding contributes to the overall strength, rigidity, and cohesion of the polymer chains. - 7What is the repeating unit of PVC?
- 8What is the repeating unit of PTFE?
- 9What is the repeating unit of polystyrene?
- 10What is the repeating unit of polypropene?
- 11Chemical reaction showing the synthesis of the polyamide nylon-6,10
- 12Chemical reaction showing the synthesis of the polyamide Nylon-6,6
- 13Chemical reaction showing the synthesis of a polyester
- 14Chemical reaction showing the synthesis of a polyurethane
- 15What are the main applications of polyethene?Plastic bags, bottles, plastic films, piping and toys
- 16What are the main applications of polypropene?Food containers, carpets and rugs, ropes, plastic furniture and piping
- 17What are the main applications of polystyrene?Plastic cutlery, CD cases, disposable razors in solid form. In foam form, packing materials, building insulation and foam containers for food and drink
- 18What are the main applications of polytetrafluoroethene?Non-stick coatings on cookware. Also used as a lubricant and as insulation for electric wires and cables
- 19What are the main applications of polyvinyl chloride?For window and door frames, piping and bank cards. Also more flexible forms used in electric cable insulation and as a rubber substitute
- 20What are the main applications of polyethylene terephthalate?Plastic drink bottles, clothing fibres, Meal packing and tapes
- 21What are the main applications of Nylon (polyamide)?Was intended as a synthetic silk replacement for military application such as parachutes. Today it is used in clothing, guitar strings and fishing lines
- 22What are the main applications of polyurethane?Foam seating, for both furniture and cars, non-latex condoms, shoe soles, football coatings, skateboard and roller-blade wheels, and some varnishes
- 23What is the repeating unit of Polyacrylonitrile?
- 24What are the main applications of polyacrylonitrile?hot gas filtration systems, outdoor awnings, sails for yachts, and even fiber reinforced concrete. But mostly copolymers containing polyacrylonitrile are used as fibers to make knitted clothing, like socks and sweaters, as well as outdoor products like tents
- 25What is the repeating unit of Poly(methyl methacrylate) Plexiglass?
- 26What are the main applications of Poly(methyl methacrylate)?bone cement, lenses, bone substitutes, and drug delivery systems. It is used to remove wrinkles and scars on skin tissue permanently. In dental implants, polymer material PMMA is substituted for missing dental roots.
- 27What is the repeating unit of Poly(vinyl acetate)?
- 28What are the main applications of poly(vinyl acetate)?shipping boxes and bags, food containers, envelopes, tapes, and as binders for paper, plastics, and foils.
- 29What is the repeating unit of Poly(Vinyl alcohol)?
- 30What are the main applications of Poly(vinyl alcohol)?PVA is mainly used to manufacture water-soluble films. Applications include water treatment chemicals, dyes, laundry detergents, agricultural chemicals, disinfectants, industrial cleaning chemicals
- 31What are the main applications of Polytetrafluoroethylene?cooking equipment to food coverings, conveyor belt rollers, temperature sensor casing and non-stick surface covers.
- 32What are some examples of Natural polymers?DNA, Carbs, protein, cotton, silk from silkworms, wood and natural rubber
- 33What effect do secondary intermolecular forces have on polymers?Affect orientation/properties of the polymers
- 34Describe how condensation polymerisation occurs
- 35Describe how addition polymerisation occurs
- 36What is an example of radical initiators?Azobisisobutyronitrile, text-butyl peroxide
Each initiator forms radicals at different temperature. The radicals attack the weak bond in the double bond of monomers - 37What are the two possibilities in termination?
- 38What effect does chemical structure of repeating unit have on polymers?Different intermolecular interactions so different physical properties. E.g. polyethylene can be modded into a wide variety of shapes as it only has singled bonds and is flexible. Kevlar can be spun into strong fibers and cannot be melted as it has rigid phenyl groups on backbone
- 39What does high polydispersity mean?This means the polymer chains have high heterogeneity in terms of chain length
- 40What type of polydispersity is in free radical polymerisation?Broad molecular weight
distribution in free radical
polymerization. High polydispersity - 41What type of polydispersity is in other types of addition polymerisation?Narrow molecular weight
distribution in other type of
addition polymerizations. Low polydispersity - 42Are polymer chains stretched or not stretched?Not stretched
- 43Are Short/Low molecular weight chains entangled or have no entanglements?No entanglements
- 44Are Long/High molecular weight chains entangled?Yes they are
- 45What are the effects of increased chain length?1. Entanglements causes free movement of chains to be hindered
2. London dispersion forces→
Secondary bonds→ similar
to lower MW alkanes
With the increase in size
these intermolecular forces
increase in magnitude and therefore have higher melting points - 46What do Secondary bonds do in polymers?In linear and branched polymers they keep the polymer chains together
These interactions are eliminated when Temperature↑ - 47What is hydrogen bonding?The forces of attraction between
the lone pair of electrons in an
electronegative atom in one
molecule and a hydrogen atom
that is covalently attached to
either nitrogen, fluorine, or
oxygen in another molecule. - 48What are dipole-dipole forces?These interactions are formed due
to uneven distribution of
electrons in a molecule. This
gives rise to a partial positive (δ+)
and a partial negative (δ-) charge
in a molecule that, as a whole, is
neutral - 49What are London Dispersion forces?This kind of force arises due to the
instantaneous dipoles that may be
created in the atoms of molecules
due to the movement of electrons.
✓ As the electrons in atoms are in
continuous motion, there might be
an instance when most of the
electrons have shifted to one side
of the electron cloud causing a
momentary dipole to be created.
✓ When two such instantaneous
dipoles come close together, there
is attraction between the molecules - 50What happens as number of carbons in chain increase?Gas --> liquid ---> solid
- 51What state is formed in a 1-4 carbon chain?Simple gas
- 52What state is formed in a 5-25 carbon chain?liquids
- 53What state is formed in a 25-5000 carbon chain?Solids
- 54What state is formed in a 3-6x10^5 carbon chain?Fibres
- 55What are the different polymer architectures?1. Linear
2. Branched- star, dendrimer, comb like
3. Cross-linked network - 56What happens from linear to branched to crosslinked?Chain mobility restricted
- 57What are the properties of High Density Polyethylene (HDPE) which is linear?Linear chains → dense arrangement
Highly crystalline (>90%)
More crystalline →less transparent
Melting point →135 C
More crystalline→ More rigid
Chemically inert - 58What are the properties of Low Density Polyethylene (LDPE) which is branched?Branched chains → loose arrangement
Low crystallinity (>50-60%)
More amorphous →good transparency
Melting point →115 C
Less crystalline→ More flexible
Chemically inert - 59What are some applications of HDPE?Plastic bottles, plastic bags, toys, hula hoops, plastic furniture
- 60What are some applications of LDPE?Plastic wrap, tubbing, air tight plastic bags and plastic water bottles
- 61What are some properties of linear rubber before vulcanization?Amorphous linear polymer chains
Increased chain mobility
Lacks structural integrity (soft)
Decreased mechanical strength
Very weak/soft when is heated
Very brittle when is cold - 62What are some properties of crosslinked rubber after vulcanization?Cross-linked polymer chains/Rubber shrinks
Decreased mobility
Improved structural integrity (harder)
Improved mechanical strength
Elasticity/rigidity depends on the number of
cross-link points (Cross-link density) - 63Define HomopolymerConsist of identical
(one type) monomers - 64Define CopolymerMixture of more than
one type of monomer - 65What are the 4 types of CopolymerRandom-> Random monomer arrangement
A-ran-B
Alternating-> Monomers in alternating sequence
A-alt-B
Block-> Monomers cluster together and form 'blocks'
A-b-B
Graft-> Backbone with A, branches with B
A-g-B - 66What is an example of a copolymer?Poly(Acrylonitrile, Butadiene, Styrene) (ABS)
- 67What are ABS properties?• High rigidity
• Good impact resistance, even at low temperatures
• Good insulating properties
• Good abrasion and strain resistance
• Mechanical strength and stability over time - 68What were the properties of the single monomers in ABS?Butadiene → toughness & impact strength
Acrylonitrile → chemical resistance and heat stability
Styrene → rigidity and processability - 69What are primary bonds?Covalent bonds that join together the monomer units to form the backbone
- 70What are secondary bondsWeaker interactions/attractions either between functional groups in
different chains (intermolecular) or different units of the same chain (intramolecular) and affect
the shape of the polymer - 71What are the effects of intermolecular interactions – Hydrogen bonds?Forms strong fibers which do not stretch, high tensile strength, elongation, and tear resistance.
Hydrogen bonding occurs very regularly to form a very strong lattice, similar to that formed in crystals. The fibres consequently have very few flaws and they are very difficult to break up. High tensile strength and melting point.
E.g. Nylon 6,6, Polyurethane, Kevlar - 72What are the effects of intermolecular interactions- Dipole-dipole interactions?Make fairly strong
material. Weaker than hydrogen bonded ones but stronger than London dispersion forces.
E.g. Poly(vinyl chloride), Polyacrylonitrile, Poly(ethylene terephthalate) - 73What are the effects of intermolecular interactions- London dispersion interactions?London dispersion forces similar to lower MW alkanes→ effects on melting point
E.g. polyethylene - 74Define TacticityTacticity is simply the way the side groups are arranged along the backbone chain of a polymer
- 75What is isotactic?Side groups are lined up on the same side of the backbone plane
- 76What is syndiotactic?Alternating placement of the side groups
- 77What is Atactic?Random arrangement of the side groups lack of regularity
- 78Why are thermal transitions in Polymers are more complex compared to small moleculars?Due to large size, polymers do not exist in the gaseous state- decompose before boiling.
They compose of a mixture of different molecules (copolymers)
Both crystalline and amorphous domains exist in the same polymer sample - 79Define thermoplasticsUpon heating soften and upon cooling they regain solid/rubbery nature
- 80Define ElastomersThey can be either thermoplastics or thermosets
- 81Define thermosetsUpon heating soften but degrade before they melt
Upon cooling they do not regain their initial properties - 82What are the properties of thermoplastics?No cross-links between chains
Weak attractive forces between chains
are eliminated by warming
Change shape – can be remoulded
Weak forces reform in new shape
when cold - 83What are the properties of thermosets?Extensive cross-linking formed by covalent bonds
Bonds prevent chains moving relative to
each other
Once formed they are intractable and
degrade rather than becoming fluid upon
heating - 84What are some examples of amorphous thermoplastics?PMMA, PS, Polycarbonate, PVC, ABS
- 85What are some examples of semi-crystalline thermoplastics?PE, PP (isotactic),
PET, Nylon - 86What is the most commonly used method of 3D printing?The most widely used process is known as Fused Deposition Modeling (FDM).
FDM printers use a thermoplastic filament, which is heated to its melting point and then
extruded, layer by layer, to create a three-dimensional object - 87What are examples of thermoplastics used in 3D printing?ABS, Nylon,
Polycarbonate, Polylactic acid, PET, PVA,
PP
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- University Molecular World (Polymers + Electrochemical cell) FlashCards sobre Polymers , criado por Adrianna Bialecka em 04-12-2023.
- Criado por
- Adrianna Bialecka
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