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Skincare > lesson 2 > Flashcards

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
Q

Particle size is influenced by

A
  • emulsifier choice
  • emulsifier placement
  • emulsifier concentration
  • processing time/temperature/order of addition
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26
Q

Two mechanisms of stabilization

A
  • 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
Q

Ways to retard coalescence AND creaming

A
  • Viscosity enhancement

- Protection of droplets through lamellar gel network phases and/or thickeners

28
Q

Type of surfactant association structure in which phases surround droplets to create a barrier to protect them from approaching closely

A

Lamellar liquid crystalline phase

29
Q

Type of surfactant association structure that forms a network to enhance viscosity to stabilize the droplets, making particles less likely to sink or collide

A

Gel phase network

30
Q

Emulsifying “wax” systems consist of

A

mixtures of hydrophilic and lipophilic emulsifiers

31
Q

3 Functions of emulsifiers

A
  • Reduce surface tension
  • form complex interfacial films on surface of emulsion droplets
  • form liquid crystalline structures which act as a barrier to coalescence
32
Q

Surfactants lower

A
  • surface tension of a liquid

- interfacial tension between two liquids

33
Q

Above CMC, surface tension ________

A

remains constant

34
Q

Which phase of an emulsion contains humectants and viscosity enhancers?

A

water

35
Q

Emulsifiers can be found in which phase of an emulsion?

A

Oil and water

36
Q

Emulsions take on the character of the _____ phase

A

external

37
Q

emulsion viscosity can be lowered by

A

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

38
Q

which type of emulsion has a stable pH

A

O/w

39
Q

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

A

phase volume

type of surfactant

40
Q

Bancrofts rule states that

A

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

41
Q

More than 74% internal phase leads to

A

close particle interaction and deformation

42
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
43
Q

Microemulsion droplet size

A

less than 100 nm

44
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

45
Q

Purpose of stabilizing emulsions

A

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

46
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

47
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

48
Q

Aggregation/floculation happens when

A

particles approach each other

this is reversible

49
Q

Coalescence happens when

A

particles approach each other and their films rupture

this is not reversible

50
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
51
Q

Causes of emulsion instability

A
  • Ostwald Ripening
  • Creaming/Sedimentation
  • Aggregation/flocculation
  • Coalescence
52
Q

Prevention of creaming

A
  • Thicken outer phase
  • Reduce particle size
  • Density effects
53
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

54
Q

Prevention of coalescence

A
  • Steric/electrostatic barriers to keep droplets apart through surfactant/polymer choice
  • Surfactants/emulsifiers to lower interfacial tension
55
Q

Ostwald ripening can be prevented by having

A

narrow range of particle sizes

56
Q

Particle size is influenced by

A
  • emulsifier choice
  • emulsifier placement
  • emulsifier concentration
  • processing time/temperature/order of addition
57
Q

Two mechanisms of stabilization

A
  • 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
Q

Ways to retard coalescence AND creaming

A
  • Viscosity enhancement

- Protection of droplets through lamellar gel network phases and/or thickeners

59
Q

Type of surfactant association structure in which phases surround droplets to create a barrier to protect them from approaching closely

A

Lamellar liquid crystalline phase

60
Q

Type of surfactant association structure that forms a network to enhance viscosity to stabilize the droplets, making particles less likely to sink or collide

A

Gel phase network

61
Q

Emulsifying “wax” systems consist of

A

mixtures of hydrophilic and lipophilic emulsifiers

62
Q

3 Functions of emulsifiers

A
  • Reduce surface tension
  • form complex interfacial films on surface of emulsion droplets
  • form liquid crystalline structures which act as a barrier to coalescence
63
Q

Surfactants lower

A
  • surface tension of a liquid

- interfacial tension between two liquids

64
Q

Above CMC, surface tension ________

A

remains constant

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