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Flashcards in Plastics Deck (23):
1

what are polymers from and what are they made of

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

2

size and melting point properties

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

3

properties of polyethylene
poly(vinyl alcohol)
ethylene vinyl alcohol

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

4

which plastic is polar/non polar

polar = water, polyester, polyamide, polyvinyl chloride
non polar = CO2, polyethylene, polypropylene, polystyrene

5

are plastics permeable?

yes
only glass and metals are complete barriers

6

shapes of molecules and crystallinity

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

7

difference amorphous and crystalline

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

8

orientation

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

9

memory plastic

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

10

thermoplastics properties

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

11

thermo set plastics

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

12

additives

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

13

PET polyethylene terephthalate

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

14

polyethylene family

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

15

branching number consequences

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

16

HDPE

group 2

17

poly vinyl chloride

group 3
additive = plasticizer and heat stabilizer
Cl

18

LDPE

group 4

19

polypropylene

group 5
CH3

20

polystyrene

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

21

polyamide (nylon)

group 7
form acid and amide by low pressure condensation to high

22

polyvinylidene chloride

group 7
2 Cl
copolymer of PVC (high Cl)

23

Ionomers

group 7
made form EMAA with H on the carboxyl group replaced with Na+ or Zn2+ = charged ionic areas