Test
DF 34 - 35 Rheology
Este test tiene tipos de pregunta que se abren en el reproductor de siempre.
Preguntas del test (12)
1We can classify flow properties of materials as Newtonian, meaning flow properties [blank_start]obey[blank_end] Newton’s law of flow, or non-Newtonian (flow properties [blank_start]do not obey[blank_end] Newton’s law of flow). Emulsions, suspensions, creams, ointments, gels have [blank_start]non-Newtonian[blank_end] flow properties. New's law of flow is that shear [blank_start]stress[blank_end] is proportional to shear [blank_start]rate of flow[blank_end], ie the more [blank_start]force[blank_end] that is applied the [blank_start]faster[blank_end] a fluid flows.
- Aobey
- Bdo not obey
- Cnon-Newtonian
- DNewtonian
- Estress
- Frate of flow
- Gforce
- Hfaster
2A flow curve/rheogram plots [blank_start]shear rate over shear stress[blank_end],
A viscogram plots [blank_start]viscosity over shear stress[blank_end], or sometimes shear rate.- Ashear rate over shear stress
- Bviscosity over shear stress
3For non-Newtonian materials viscosity is independent of shear stress, and can be represented by a single value known as "absolute viscosity".
- AVerdadero
- BFalso
4A Newtonian fluid will have low viscosity.
- AVerdadero
- BFalso
5For Newtonian materials, viscosity depends on the [blank_start]magnitude[blank_end] of applied [blank_start]shear stress[blank_end]. Viscosity cannot be represented by a single ([blank_start]absolute[blank_end]) value and is expressed as an “[blank_start]apparent[blank_end] viscosity” at a particular rate of shear.
- Amagnitude
- Bshear stress
- Capparent
- Dabsolute
6Classification of Non-Newtonian materials
1. Plastic:
Materials that [blank_start]do not flow[blank_end] at low shear stresses, but flow [blank_start]like Newtonian-liquids[blank_end] above their yield value.
2. Pseudoplastic flow:
Materials whose [blank_start]viscosity decreases[blank_end] with an increasing rate of shear stress
3. Dilatant flow:
Materials whose [blank_start]viscosity increases[blank_end] with an increasing rate of shear stress.
4. Thixotropic flow:
Materials whose [blank_start]viscosity depends on[blank_end] the [blank_start]duration and the rate[blank_end] of shear stress.- Ado not flow
- Blike Newtonian-liquids
- Cviscosity decreases
- Dviscosity increases
- Eviscosity depends on
- Fduration and the rate
7Plastic flow is caused by [blank_start]concentrated[blank_end] suspensions associated with the presence of [blank_start]flocculated[blank_end] particles; [blank_start]floccules[blank_end] at rest have a high frictional
force holding them [blank_start]together[blank_end] that can be overcome by shear stress (at the [blank_start]yield value[blank_end]). Individual particles mean there is [blank_start]no frictional force[blank_end].- Aconcentrated
- Bflocculated
- Cfloccules
- Dtogether
- Eyield value
- Fno frictional force
8Pseudoplastic materials exhibit shear thickening and dilatant materials exhibit shear thinning.
- AVerdadero
- BFalso
9Pseudoplastic properties are typically displayed by natural and synthetic polymers in solution. Which of these would not cause pseudplastic flow?
- ATragacanth
- BMethycellulose
- CAlginates
- DSodium lauryl sulfate
10Pseudoplastic flow is caused by:
- AHigh frictional forces being lowered as particles deflocculate.
- BHigh viscosity globular polymer chains aligning in the direction of applied shear stress which reduces internal resistance to flow.
- CVolume increasing as shear is applied due to high fraction of dispersed solids.
11[blank_start]Hysteresis loop[blank_end]: the curve obtained on increase of shear stress is [blank_start]not superimposable[blank_end] with that obtained on decrease of shear stress = the system is [blank_start]thixotropic[blank_end].
- Anot superimposable
- BHysteresis loop
- Cthixotropic
12Thixotropy is useful for intramuscular depot injections.
- AVerdadero
- BFalso
Información
- Descripción
- (Formulation) PHCY211 Test sobre DF 34 - 35 Rheology, creado por Mer Scott el 06/05/2018.
- Autor
- Mer Scott
- Idioma
- English
- Visitas
- 11
- Etiquetas
- Valoración
- Aún sin valoraciones Valora este test