Polymerer2

Question 1

Newtons law of viscosity, illustration and units

Answer 1

Lösblad

Question 2

Newtonian fluids

Answer 2

constant viscosity, ex:luft,vatten .

Question 2

Non-newtonian fluids. Vad är det och exempel

Answer 2

Förändrar viscosity beroende på flödeshastighet, ex:ketchup,blod

Question 3

Viscosity

Answer 3

Vätskans motstånd mot flöde. Hur seg vätskan är.

Question 4

Everything flows, Deborah

Answer 4

De=t deformation/ t återhämtning

Question 5

Fundamental concepts of polymer melt flow. Amourphous and semi-crystalline polymer structure in melt phase?

Answer 5

Disordered random molecular orientation. All polymers are amorphous in melten state.

Question 6

Fundamental concepts of polymer melt flow. Polymers are viscoelastic when deformed in the melt state, how different deformations? What is viscoelastic?

Answer 6

Small/slow deformation-> no change in orientation
Large/fast deformation->molecular orientation in the flow direction.

viscous part-molecular friction between molecules
elastic part-polymers förmåga att få tillbaka ursprunglig form

Question 7

What are the flow characteristics of polymers in the melt stage?

-Thermoplastic polymers, shear thinning, the viscosity function, what causes thinning?

Answer 7

the viscosity function=Låg skjuvning(långsamt flöde)=högre viscositet(mer strukt. molekyler som motverkar flödet.)
+tvärt om.
——
what causes shear thinning=molekulär orientering , molekylär friktion.(mindre friktion=>lägre viskositet)

Question 8

What are the flow characteristics of polymers in the melt stage?

-The melt flow index as measure of flowability how its measured

Answer 8

Sample heated in barrel, weight.
-The weight of the polymer in g extruded during 10 min test=MFI.
(Högt=mer lättflytande)