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lesson 2 Flashcards

1
Q

Which phase of an emulsion contains emollients and fragrance?

A

oil

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2
Q

Which phase of an emulsion contains emollients and fragrance?

A

oil

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3
Q

Which phase of an emulsion contains humectants and viscosity enhancers?

A

water

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4
Q

Emulsifiers can be found in which phase of an emulsion?

A

Oil and water

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5
Q

Emulsions take on the character of the _____ phase

A

external

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6
Q

emulsion viscosity can be lowered by

A

diluting with water (o/w) or diluting with oil (w/o)

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7
Q

which type of emulsion has a stable pH

A

O/w

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8
Q

The type of emulsion is somewhat governed by _________, but mostly depends on _________

A

phase volume

type of surfactant

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9
Q

Bancrofts rule states that

A

the continuous phase will be whichever phase the surfactant is most soluble in

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10
Q

More than 74% internal phase leads to

A

close particle interaction and deformation

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11
Q

Explain the 3 phase-system theory of emulsions

A
  • emulsifier forms a gel network of liquid crystalline and lamellar structures in water
  • oil phase is dispersed in between gel network
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12
Q

Microemulsion droplet size

A
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13
Q

Less traditional method of producing an emulsion that allows the emulsifier the optimal opportunity to adsorb at the interface

A

Make an emulsion concentrate and then dilute it with the external phase

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14
Q

Purpose of stabilizing emulsions

A

delay the day when the instability will arrive, since all are inherently unstable

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15
Q

Shelf life requirements

A

Product is safe, stable, and usable for some specified time during normal storage and handling, under extraordinary warehouse and shipping conditions and even when mishandled by consumers

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16
Q

van’t hoff’s rule says

A

rate of biochemical reactions doubles for every 10 degree celsius increase in temperature up to the point that proteins break down

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17
Q

Aggregation/floculation happens when

A

particles approach each other

this is reversible

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18
Q

Coalescence happens when

A

particles approach each other and their films rupture

this is not reversible

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19
Q

Phase inversion happens when

A
  • HLB of nonionics decreases as temperature increases
  • At a specific temperature (PIT) hydrophilic and lipophilic characteristics will be equal relative to required HLB of oil phase
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20
Q

Causes of emulsion instability

A
  • Ostwald Ripening
  • Creaming/Sedimentation
  • Aggregation/flocculation
  • Coalescence
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21
Q

Prevention of creaming

A
  • Thicken outer phase
  • Reduce particle size
  • Density effects
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22
Q

The Gibbs-Marangoni effect describes the incorporation of movable elastic surfactant film at the oil-water interface to prevent coalescence by

A

creating interfacial tension gradient to stabilize droplets in close proximity

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23
Q

Prevention of coalescence

A
  • Steric/electrostatic barriers to keep droplets apart through surfactant/polymer choice
  • Surfactants/emulsifiers to lower interfacial tension
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24
Q

Ostwald ripening can be prevented by having

A

narrow range of particle sizes

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25
Particle size is influenced by
- emulsifier choice - emulsifier placement - emulsifier concentration - processing time/temperature/order of addition
26
Two mechanisms of stabilization
- Barrier forms around droplets to strengthen o/w interface - Gel network is formed which extends from the droplet surface out into bulk of external phase to increase viscosity and impede droplet movement
27
Ways to retard coalescence AND creaming
- Viscosity enhancement | - Protection of droplets through lamellar gel network phases and/or thickeners
28
Type of surfactant association structure in which phases surround droplets to create a barrier to protect them from approaching closely
Lamellar liquid crystalline phase
29
Type of surfactant association structure that forms a network to enhance viscosity to stabilize the droplets, making particles less likely to sink or collide
Gel phase network
30
Emulsifying "wax" systems consist of
mixtures of hydrophilic and lipophilic emulsifiers
31
3 Functions of emulsifiers
- Reduce surface tension - form complex interfacial films on surface of emulsion droplets - form liquid crystalline structures which act as a barrier to coalescence
32
Surfactants lower
- surface tension of a liquid | - interfacial tension between two liquids
33
Above CMC, surface tension ________
remains constant
34
Which phase of an emulsion contains humectants and viscosity enhancers?
water
35
Emulsifiers can be found in which phase of an emulsion?
Oil and water
36
Emulsions take on the character of the _____ phase
external
37
emulsion viscosity can be lowered by
diluting with water (o/w) or diluting with oil (w/o)
38
which type of emulsion has a stable pH
O/w
39
The type of emulsion is somewhat governed by _________, but mostly depends on _________
phase volume | type of surfactant
40
Bancrofts rule states that
the continuous phase will be whichever phase the surfactant is most soluble in
41
More than 74% internal phase leads to
close particle interaction and deformation
42
Explain the 3 phase-system theory of emulsions
- emulsifier forms a gel network of liquid crystalline and lamellar structures in water - oil phase is dispersed in between gel network
43
Microemulsion droplet size
less than 100 nm
44
Less traditional method of producing an emulsion that allows the emulsifier the optimal opportunity to adsorb at the interface
Make an emulsion concentrate and then dilute it with the external phase
45
Purpose of stabilizing emulsions
delay the day when the instability will arrive, since all are inherently unstable
46
Shelf life requirements
Product is safe, stable, and usable for some specified time during normal storage and handling, under extraordinary warehouse and shipping conditions and even when mishandled by consumers
47
van't hoff's rule says
rate of biochemical reactions doubles for every 10 degree celsius increase in temperature up to the point that proteins break down
48
Aggregation/floculation happens when
particles approach each other | this is reversible
49
Coalescence happens when
particles approach each other and their films rupture | this is not reversible
50
Phase inversion happens when
- HLB of nonionics decreases as temperature increases - At a specific temperature (PIT) hydrophilic and lipophilic characteristics will be equal relative to required HLB of oil phase
51
Causes of emulsion instability
- Ostwald Ripening - Creaming/Sedimentation - Aggregation/flocculation - Coalescence
52
Prevention of creaming
- Thicken outer phase - Reduce particle size - Density effects
53
The Gibbs-Marangoni effect describes the incorporation of movable elastic surfactant film at the oil-water interface to prevent coalescence by
creating interfacial tension gradient to stabilize droplets in close proximity
54
Prevention of coalescence
- Steric/electrostatic barriers to keep droplets apart through surfactant/polymer choice - Surfactants/emulsifiers to lower interfacial tension
55
Ostwald ripening can be prevented by having
narrow range of particle sizes
56
Particle size is influenced by
- emulsifier choice - emulsifier placement - emulsifier concentration - processing time/temperature/order of addition
57
Two mechanisms of stabilization
- Barrier forms around droplets to strengthen o/w interface - Gel network is formed which extends from the droplet surface out into bulk of external phase to increase viscosity and impede droplet movement
58
Ways to retard coalescence AND creaming
- Viscosity enhancement | - Protection of droplets through lamellar gel network phases and/or thickeners
59
Type of surfactant association structure in which phases surround droplets to create a barrier to protect them from approaching closely
Lamellar liquid crystalline phase
60
Type of surfactant association structure that forms a network to enhance viscosity to stabilize the droplets, making particles less likely to sink or collide
Gel phase network
61
Emulsifying "wax" systems consist of
mixtures of hydrophilic and lipophilic emulsifiers
62
3 Functions of emulsifiers
- Reduce surface tension - form complex interfacial films on surface of emulsion droplets - form liquid crystalline structures which act as a barrier to coalescence
63
Surfactants lower
- surface tension of a liquid | - interfacial tension between two liquids
64
Above CMC, surface tension ________
remains constant

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