suyash 3rd pe
TRANSCRIPT
![Page 1: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/1.jpg)
By
Suyash trivedi
Practical Rheology and Its Role in Polymer Processing
![Page 2: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/2.jpg)
Outline• Definitions• Basic Equipment• Viscosity vs. Shear Rate Curves• What they tell us• How we can use them• Melt Index: “What is it?”• Moisture?
![Page 3: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/3.jpg)
RHEOLOGY
The Science of Deformation and Flow of Matter
![Page 4: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/4.jpg)
Rheology is:
• Science of material flow behavior• Uses very complicated and difficult to
understand mathematical background (tensors, co-rotational or co-deformation curved space, etc.)
• Can be presented in very complicated way which is hard to understand for non-specialists
![Page 5: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/5.jpg)
Mathematics is complicated
xi
ij
xj
- p
= 0 vj
xj
= 0
ij + K(ij) = 2 eij
. ij
tij = ji
ij = K1(CI,CI-1) CI + K-1(CI,CI
-1)CI-1) ( )e-(t-t’) dt’
t
-
T xj
( T xj
) + Cp T xj
vj = 2 eij eij . .
![Page 6: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/6.jpg)
Explanation of Rheology
• Mathematics is overemphasizedComplicated mathematical background leads sometimes to “scientific exhibitionism” of the presenter
• Such an approach is useful for scientific people and conferences but usually useless for practical people
![Page 7: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/7.jpg)
Explanation of Rheology• Understanding of the physics is emphasized
– the mathematics is avoided as much as possible
– the explanation is based on physical understanding what is happening
• Such an approach cannot be used for development in rheology but may be useful for understanding material behavior
![Page 8: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/8.jpg)
AIR
10 0
105
10 10
10 15
10 20
10 - 5
Viscosity [ Pa s ]
WATER
ENGINEOIL
polymer melts
GLASS
Glass Windows of the Cathedral of
Chartres in France have “Flowed”since they were Produced 600
years ago.
3 mm
600YEARS
Paper Thin
Glass behaves like Fluids !!!IF YOU WAIT LONG ENOUGH
![Page 9: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/9.jpg)
Tim’s Definition of Rheology
• The flow characteristic of a polymer at various shear and temperature conditions.
![Page 10: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/10.jpg)
![Page 11: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/11.jpg)
Crystallinity (semi-crystalline)
Definition: A state of molecular structure in some resins attributed to the existence of solid crystal with a definite geometric form. Such structures are characterized by uniformity and compactness.
Semi-Crystalline Resins:• LDPE,HDPE, PP, FEP, Nylon, PET, PU
![Page 12: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/12.jpg)
Amorphous (non-Crystalline)
Definition: Devoid of crystallinity or stratification. Most plastics are amorphous at processing temperatures, many retaining this state under all normal conditions
Amorphous Resin:• PS, PVC, ABS, PC, PMMA
![Page 13: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/13.jpg)
Resin Pyramid
![Page 14: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/14.jpg)
Viscosity
• A measure of the internal friction resulting when one layer of fluid is caused to move in relationship to another layer.
• Example:The flow characteristic of 50 wt. motor oil at 50°F in the winter versus its flow characteristic when it is drained out of the oil pan after the motor has been warmed up to 200°F
![Page 15: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/15.jpg)
Capillary Rheometer
![Page 16: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/16.jpg)
Materials with different Viscosity shear thinning
n = .3n = .5
n = 1MFI region
ExtrusionProcess window
(Power-law Index Role)
PET
LDPE
PP
![Page 17: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/17.jpg)
What are the curves telling me?
![Page 18: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/18.jpg)
Not Shear Sensitive but Temperature Sensitive
PolyesterScrew Operating
Range
![Page 19: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/19.jpg)
Not Temperature Sensitive, but Shear Sensitive
Screw Operating Range
![Page 20: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/20.jpg)
Viscosity of 4 different Resins
![Page 21: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/21.jpg)
Melt Fracture
![Page 22: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/22.jpg)
Melt Density using a Capillary Rheometer
• Definition: The density of a polymer when it is in a molten state. The melt density is totally dependent to the temperature at which is it measure or processed.
• ei, HDPE typically has a solid density of about .96 gm/cc but in the molten/process range it has a density of .75 gm/cc
![Page 23: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/23.jpg)
Melt Index(MI, MFR, MFI)The terms “melt index” (MI), “melt flow rate” (MFR) and “melt flow index” (MFI) refer to the same test. MFR was introduced to replace MFI. The term MFI is used to refer to the flow rate of PE obtained under Condition 190/2.16 (formally know as Condition E). The use of such terms is not encouraged for other materials. It is suggested, by ASTM D 1238 that the term melt flow rate (MFR) be used for other plastic materials.
![Page 24: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/24.jpg)
Melt Indexer
![Page 25: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/25.jpg)
What does MFI mean? Not Much!
VISC
OSI
TY
SHEAR RATE
app = 2.4 MFI.
0 sec-1 10 sec-1
![Page 26: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/26.jpg)
Hygroscopic• Definition: Having the tendency to absorb
moisture from the air. Some resins are hygroscopic, thus requiring drying prior to processing.
• “Wet” resin will decrease the physical properties of the resin, typically embrittlement will occur.
![Page 27: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/27.jpg)
Moisture Content• Definition: The amount of moisture in a
material determined under prescribed conditions and expressed as a percentage of the weight of the moist specimen, that is, the original weight comprising the dry substance plus any moisture present.
• Hygroscopic Resins– HIPS, ABS, Nylon, PET, PETG
• In some processes, HDPE is dried.
![Page 28: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/28.jpg)
Moisture Analyzer
• Moisture Analyzer is used to measure the moisture content of a hygroscopic material
• Moisture content of resins can range from .005% to .18% measured in parts per million depending on the resin being processed
![Page 29: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/29.jpg)
Resin DryingDesiccant Dryer Vacuum Dryer
![Page 30: suyash 3rd pe](https://reader034.vdocument.in/reader034/viewer/2022051503/587ee5841a28ab17388b5a9b/html5/thumbnails/30.jpg)
Are There Any Questions?