Mod 7.6 - Polymers Flashcards

Question

What is the molecular weight relationship for a condensation copolymer?

Answer 1

MM (copolymer) = MM (Monomer 1) *n + MM (Monomer 2) * n - MM (By product) * (2n-1) where n is the number of repeating units in the polymer chain, and by product is a small molecule produced in condensation reaction like water

Answer 2

These contain repeating units joined by amide bonds (-CONH) (C double bonded to O and bonded to an NH) The amide link is formed fro a condensation reaction between carboxyl and amino (-NH2) groups

Answer 3

Nylon 6,6 (most commonly used nylon)

Answer 4

Condensation polymerisation of adipic acid (hexanoic acid) and hexamethylene diamine (1,6-diaminohexane) - will have to look at picture

Answer 5

Nylons are systematically named to reflect the monomers that compose the polymer chain. the numbers indicate the number of carbon atoms between each amide link Single digits indicate that the nylon is made from a single monomer (homopolymer), whereas two digits indicate that the nylon is made from two types of monomers (copolymer)

Answer 6

Mechanical performance, chemical resistance, electric insulation, biocompatability, appearance and opacity 9transparency) and texture Must also take into consideration; cost, complexity, availability and environmentla impact

Answer 7

Lightweight Durable Acid and base resistant Non conductive of electricity Flammable impermeable to water

Answer 8

These are intended as the ability of the material to withstand an applied force without breaking or permanent deformation. Polymers can exhibit tensile strength (resistant to pulling), flexural strength (resistant to bending) and toughness (resistance to impact)

Answer 9

They break with minimal deformation. They break before change of shape

Answer 10

When they deform extensively before breaking (in other words they can stretch)

Answer 11

When they resist breakdown. It is a measure of amount of energy a specimen can absorb before structure collapse

Answer 12

When they resist deformation and breakdown. They arent deformed during the test but can absorb high levels of energy before breaking

Answer 13

When they resist permanent changes under a compressive force. They can resit dents, scratches and abrasion

Answer 14

Crystallinity Chain length Bonds in polymer chain backbone Side groups Branching Cross linking Could also be influenced by manufacturing process and use of additives such as plasticisers

Answer 15

Refers to the degree of structural order in solid materials. It can be used to determine how rigid the material is. The extent and shape of crystalline regions have a strong impact on the properties of polymers Polymers can be regarded as crystalline, amorphous or semi crystalline

Answer 16

It is comprised of polymer chains that are packed very closely and orderly organised. However, as polymers are large covalent chains with complex structures, it is hard to achieve perfect crystallinity The regular arrangements brings the polymer chains closer together. The IMF between closely packed chains are stronger, and thus the presence of a crystalline polymer or crystalline regions strengthens the material overall Crystalline regions in a polymer prevents the transmission of light through the material, making it appear cloudy or opaque There re more crystalline regions in unbranched polymers

Answer 17

This is when polymer chains are randomly tangled and are unable to pack very closely These are comprised of polymer chains that are disordered. Most polymers have at least some part that isnt crystalline. The non crystalline parts of the polymer are called amorphous Also, these are more flexible and weaker and are often transparent

Answer 18

A polymer can contain both crystalline and amorphous regions (called domains). This is referred to as semi crystalline. Most polymers are semi crystalline, with the extent of crystalline domains depending on molecular properties and of the manufacturing methods

Answer 19

Low melting energy Soft Transparent Low chemical reisistance Low, even expansion when heated Permeable to gas

Answer 20

High melting energy Hard Opaque high chemical resistance High, uneven expansion when heated Low permeability to gas

Answer 21

Determined by the molecular structure of the material. the factors that favour high crystallinity are: Linear polymer chains Long polymer chains Rigid chain backbone Strong IMF These factors above allow for an ordered arrangement of the polymer chains --> increased crystallinity

Answer 22

Linear polymers have a higher degree of crystallinity, whereas branched polymers have a lower degree of crystallinity as they are more bulky and dont allow for the chains to pack densely

Answer 23

At low temps, an amorphous polymer is typically rigid and brittle Upon heating, atoms gain kinetic energy (vibrate) giving the molecules mobility and softening the polymer. Due to the disordered and tangled nature of amorphous polymers, some molecules will reuire relatively low energy to soften while other molecules will require more energy to soften Therefore the change in mechanical proeprties is gradual (no sharp melting point) as the energy required to mobilise varies between molecules

Answer 24

Highly crystalline polymers can preserve their solid properties at higher temps To mobilise molecules in crystalline polymers, relatively high energy is required The molecules in crystalline polymers require similar energy levels to mobilise. Once a certain temp is reached, all of the molecules gain mobility. At the macroscopic level, the polymer changes from solid to liquid (melting) Therefore, the melting happens over a small temp range. In other words, we observe a defined melting point

Answer 25

Chain length Bonds in polymer chain backbone Side groups Branching Cross linking

Answer 26

Generally, the longer the chains, the stronger the polymer is because longer chains can become more tangled and requires more energy to stretch and untangle Also, Because polymers are extremely large covalent molecules, the dominant intermolecular force is dispersion forces, which will increase as chain length increases--> higher crystallinity Thus, as chain length increases the MELTING POINT, RIGIDITY AND HARDNESS of a polymer increases

Answer 27

Chain flexibility depends on the types of bonds on the polymer backbone and the groups directly attached to it. Single covalent bonds such as C-C and C-O bonds make the polymer chains quite flexible. Thus, polymer chains can move easily, and the material is soft at relatively low temps Meanwhile, ringed groups result in rigidity to the chain, and makes the polymer stronger. Chains are stiffer and rigid even at higher temps

Answer 28

The side groups that give stronger attraction between polymer chains (e.g. intermolecular forces such as hydrogen bonding) make the polymer stronger. Side groups can be introduced to make a material more rigid and brittle --> harder polymer

Answer 29

Polymer chains that are close to each other can thus be held together by stronger interactions such as dispersion forces. Polymers are able to form branched and unbranched chains. Unbranched chains are able to pack more closely in an orderly fashion, forming a rigid crystalline solid Meanwhile, branched polymer chains are unable to align with each other, forming an amorphous solid that has weak IMF between the chain As a result, linear polymers can have higher density and crystallinity than their branched counterparts and are therefore stronger

Answer 30

Cross links join together polymer chains by covalent chemical bonds. Thus, they prevent the polymer chains from moving from each other. If cross linking is extensive, the polymer is harder and more difficult to melt This causes the polymer to be more rigid, hard and heat resistant. They also cant be remoulded Impacts thermosetting polymers

Answer 31

These are polymers with only intermolecular forces between their chains. They soften when heated as the IMF are relatively weak and easily broken to allow the chains to move between one another. This property allows polymers to be remoulded

Answer 32

Polymers with cross links are called thermosetting polymers. Since covalent bonds are very strong, cross links limit movement between polymer chains, making it more rigid, hard and heat resistant. These cant be remoulded

Answer 33

Identify the chemical structure of the polymer Determine the packing arrangement of the polymer Determine the strength of the IMF of the polymer Explain the properties and uses of polymer

Answer 34

Polyethylene (PE) Poly (vinyl chloride) (PVC) Polystyrene (PS) Polytetrafluoroethylene (PTFE)

Answer 35

Poly (ethylene terephthalate) - (PET) or poly (ethyl benzene-1,4-dicarboxylate) Nylon 6,6 or poly [imino (1,6-dioxohexamethylene)iminohexamethylene] They are common types of polyester and nylon (a type of polyamide) respectively

Answer 36

It is the most popular plastic in the world and has a very simple structure. Ethene is an unsaturated molecule because of the c=c bond. When ethene polymerases, the double bond breaks and new covalent bonds are formed between carbon atoms on nearby monomers. The polyethene formed does not contain any double bonds It typically manifests as low density polyethylene (LDPE) or High Density polyethylene (HDPE)

Answer 37

Mainly it is the extent of branching. HDPE is mostly linear: chains can be packed closely, whereas LDPE is branched: chains cannot pack closely together LDPE is produced under high temps and pressures --> formed too rapidly --> lots more branching whereas HDPE utilise catalysts to avoid need for higher pressure --> more mild conditions --> fewer branching

Answer 38

Reasons: no stiffening side groups, no cross linking, and has extensive chain branching Properties: Low MP, Low BP, flexible, soft, , lightweight, waterproof

Answer 39

Agricultural films, cling wrap, part of multilayer packaging, disposable shopping bags, flexible toys, milk bottles

Answer 40

Reasons: Virtually no chain branching --> molecules pack closely in orderly fashion, no cross linking Properties: Harder/more rigid than LDPE, strong, higher MP/BP than LDPE

Answer 41

Plastic containers Water pipes Toys Kitchen utensils 'Wheely' Bins

Answer 42

PVC is made out of vinyl chloride monomers which is chloroethene The polymer is given by [chlorethane]n PVC can be manufactured as flexible PVC (by adding plasticizers to the polymer) or there could be pure PVC

Answer 43

Thermoplastic, very hard, rigid, brittle. This is because it has chlorine side groups which introduce dipoles into long molecules --> increased IMF --> harder, rigid etc

Answer 44

pipes, credit cards

Answer 45

Flexible, flame retardant, resistant to chemical corrosion

Answer 46

Raincoats, shower curtains, electrical insulation on wires

Answer 47

It is the product of the addition polymerisation of styrene It involves a benzene ring which is covalently bonded on every second carbon in the polymer chain It is typically manufactured as a foam. Foamed polymers are formed by blowing a gas through melted polymer materials. This can drastically change the physical properties of a polymer material

Answer 48

Reasons: Because of benzene rings covalently bonded in the polymer chain --> increases rigidity and causes it to be hard but quite brittle plastic with a low density. Also because of minimal chain branching, it is therefore very crystalline Properties: As a result, polystyrene is a hard but quite brittle plastic with a low density. Can form clear objects, It is also quite rigid because of the reasons listed above. It is sensitive to high temps

Answer 49

Foam drinking cups Bean bag fillers Foam packing material CD cases

Answer 50

In this case, the monomer is tetrafluoroethene (C=C, with 2 F bonds on each C). It is formed when all hydrogen atoms in ethene is replaced by highly electronegative F atoms These fluorine side groups repel each other. PTFE chains assume an elongated configuration because of the repulsion. PTFE is linear and can form crystalline structures

Answer 51

Reasons: Electronegative fluorine atoms reduce strength of IMF with other substances --> non stick PTFE is linear and can form crystalline structures --> contributes to it being hard and rigid Properties: Hard, rigid, high MP, high chemical resistance, low coefficient of friction, flame resistant, heat resistant, strong anti adhesion properties, flexible

Answer 52

Non stick coating for cooking pans, anti corrosion container, pipes, medical equipment coatings, medical implants, gears, clothing, Teflon, It is a cost-effective solution for industries ranging from oil and gas, chemical processing, industrial to electrical/electronic and construction sector as an insulator for electrical wiring

Answer 53

It is a type of polyester formed through the process of condensation polymerisation. PET is synthesised by reacting benzene-1,4-dioic acid monomers with ethane-1,2-diol monomers

Answer 54

Reasons: The benzene ring from the terephthalic acid monomer unit in PET causes it to make chains rigid and gives the polymer its stiffness Ester groups in the structure can be hydrolysed upon heating by water, acids or bases. Properties: High strength Resistant to impact PET fabrics are wrinkle resistant Amorphous forms are transparent, lightweight and less rigid Low chemical resistance Semi-rigid to rigid (depending on degree of crystallinity) Thermoplastic

Answer 55

In textiles as heat insulation layers, sportswear, workwear, automotive upholstery, plastic bottles, component in multilayer packaging It is used in everyday items, especially in packaging, owing to its lightweight and good resistance to impact. Most common applications include rigid and flexible packaging as it is very lightweight

Answer 56

Polyester fabrics and fibers are extremely strong. Polyester is very durable: resistant to most chemicals, stretching and shrinking, wrinkle resistant, mildew and abrasion resistant. Polyester is hydrophobic in nature and quick drying. It can be used for insulation by manufacturing hollow fibres. Polyester retains its shape and hence is good for making outdoor clothing for harsh climates. It is easily washed and dried.

Answer 57

Polyester is used in the manufacturing of all kinds of clothes and home furnishings like bedspreads, sheets, pillows, furniture, carpets and even curtains HYDROPHOBIC NATURE - High tenacity and good durability makes polyester the choice of fabric for high stress outdoors use. Polyester is also a strong fiber that is hydrophobic in nature. It is thus ideal for clothing to be used in wet and damp environments. The fabric is also coated with a water-resistant finish and further intensifies the hydrophobic nature. CREATING INSULATION - By creating hollow fibers it is also possible to build insulation into the polyester fiber. Air is trapped inside the fiber, which is then warmed by the heat of the body. This keeps the body warm in cold weather. WRINKLE RESISTANT - It assists in resisting formation of wrinkles

Answer 58

While clothing used to be the most popular use of polyester and which made it a household name worldwide, there are many other uses polyester is put to. PET − The most common use of polyester today is to make the plastic bottles that store our much beloved beverages. Shatterproof and cheap these bottles are an absolute boon to the beverages industry. Mylar − An unusual and little known use of polyester is in the manufacturing of balloons. Not the rubber kind that you use for water balloons but the really pretty decorated ones that are gifted on special occasions. Polyester is also used to manufacture high strength ropes, thread, hoses, sails, power belting and much more in industries. Polyester is hydrophobic in nature and quick drying. It can be used for insulation by manufacturing hollow fibres.

Answer 59

A nylon is a type of polyamide with linear carbon chains. The most commonly used nylon is Nylon 6,6 which is manufactured by the polymerisation of adipic acid and hexamethylene diamine

Answer 60

Reasons: Strong attractive forces (hydrogen bonds) established between polymer chains --> high crystallinity and thus greater strength Properties: Thermoplastic Strong Abrasion resistant High thermal stability Spun into fibres High tensile strength (ability to stretch)

Answer 61

Mechanical parts for vehicles and machinery (e.g. screws, gears) Seat belts Rope Fishing line Guitar strings Fire hoses Parachute material Clothing (socks, stockings)

Answer 62

Nylon fiber is produced in two general product types: the regular type for textile use and the high-strength type for industrial uses. Therefore it is often used for the manufacture of: * Carpets * Tire cords * Apparel * Hosiery * Upholstery * Seat belts * Parachutes * Ropes * Industrial cords * Guitar strings