Plastics

Question 1

what are polymers from and what are they made of

Answer 1

petrochemicals
C, H, O and Cl, F, Si, N, P, S
a plastic = synthetic polymer + additives

Question 2

size and melting point properties

Answer 2

as chain increase size increase and so is melting point increasing
increase of melting point = increase in tensile strength, hardness, stiffness, barrier and decrease the solubility

Question 3

properties of polyethylene
poly(vinyl alcohol)
ethylene vinyl alcohol

Answer 3

polyethylene = poor O2 barrier, excellent moisture barrier
poly vinyl = superior O2 barrier and poor moisture barrier and soluble in water
ethylene vinyl =- excellent O2 barrier and reduced water solubility

Question 4

which plastic is polar/non polar

Answer 4

polar = water, polyester, polyamide, polyvinyl chloride

non polar = CO2, polyethylene, polypropylene, polystyrene

Question 5

are plastics permeable?

Answer 5

yes

only glass and metals are complete barriers

Question 6

shapes of molecules and crystallinity

Answer 6

shape determines fit
regular = regular fit = orderly packing = crystalline
irregular = random = amorphous

Question 7

difference amorphous and crystalline

Answer 7

all poly are amorphous when melted
amorphous = rapid cooling, clear, low mp, poor barrier, less stiff
crystalline = slow cooling, hazy, high mp, better barrier, more stiff

Question 8

orientation

Answer 8

align = more crystalline and less amorphous 
uniaxial = 1 direction 
biaxial = 2 direction

Question 9

memory plastic

Answer 9

cooled slowly = heat stable

cooled quickly = given memory when heat again and melt it shrinks

Question 10

thermoplastics properties

Answer 10

soften when heated
 solidify when cooled
can be remelted 
viscoelastic 
like PE, Polypropylene, polystyrene

Question 11

thermo set plastics

Answer 11

once set it cannot be remelted or reformed because polymers are cross linked
ex: urethane, bakelite, melmac

Question 12

additives

Answer 12

plasticizer = increase flexibility and decrease flow temperature and hardness of polymer
stabilizer = UV, heat, oxygen like carbon dioxide, titanium oxide, antioxidants
flame retardants = Al (OH)3, polybrominated diphenyl ether
antistatic
slip agents
foaming agents
pigments
fillers

Question 13

PET polyethylene terephthalate

Answer 13

group 1
acid TPA and Alcohol EG by condensation
aromatic and 2 oxygen each side

Question 14

polyethylene family

Answer 14

LDPE and HDPE

LDPE = longer chain, smaller density, smaller tensile strength, higher elongation and lower softening point than HDPE

Question 15

branching number consequences

Answer 15

as branching increase clarity increase, crystallinity, moisture and gas barrier decreases

Question 16

HDPE

Answer 16

group 2

Question 17

poly vinyl chloride

Answer 17

group 3
additive = plasticizer and heat stabilizer
Cl

Question 18

LDPE

Answer 18

group 4

Question 19

polypropylene

Answer 19

group 5

CH3

Question 20

polystyrene

Answer 20

group 6
aromatic ring
HIPS = high impact = rubber increase impact strength but not tensile strength
EPS = extended = foaming with hexane and N2 initiator increases insulation but not gas barrier properties

Question 21

polyamide (nylon)

Answer 21

group 7

form acid and amide by low pressure condensation to high

Question 22

polyvinylidene chloride

Answer 22

group 7
2 Cl
copolymer of PVC (high Cl)

Question 23

Ionomers

Answer 23

group 7

made form EMAA with H on the carboxyl group replaced with Na+ or Zn2+ = charged ionic areas