About crystallization of polyamide
Ted Brink
Page  2
Contents
• H-bonds in polyamide
• Thermal properties
• Crystallization
• Influence of moisture
• Crystal structur...
Page  3
Hydrogen bonds and interaction with water
water
Page  4
Consequences of H-bonds in polyamide
H-bonds influence:
• stiffness
• flexibility
• crystallinity
• glass transit...
Page  5
Thermal properties of PA6
1
0
50
100
150
200
250
300
1 2 3
processing range
crystal growth
melting point
glass tr...
Page  6
Crystallization of polyamide
• fast cooling prevents crystallization
• low cooling rate results in large crystals...
Page  7
Influence crystallinity on the density of PA6
1.23
1.084
1 1.1 1.2 1.3
crystalline
amorphous
density [kg/m3]
Page  8
Influence moisture on Tg of PA6
-20
0
20
40
60
0 2 4 6 8 10
Tg[°C]
moisture content [%]
Page  9
Influence temperature on modulus of PA6
0
1000
2000
3000
0 50 100 150 200 250
E-modulus[MPa]
temperature [°C]
Page  10
Moisture induced crystallization
Tg of PA6
• dry ~ 55 °C
• wet ~ -10 °C
Effects of moisture on PA6 film
• lower ...
Page  11
Polyamide crystal structures
Structure α phase β phase γ phase
Crystal
structure
Monoclinic Pseudo
hexagonal
Mon...
Page  12
Tensile behaviour crystal PA6 structures
0
20
40
60
80
0 1 2 3 4 5
Nominalstress[Mpa]
Extension ratio
Alpha
Beta...
Page  13 13
Transformations of the pure crystal phases
α β γ
αT αT γT
αλ αλαλ
Influence of temperature & stretching
on th...
Page  14
Conclusions
• PA6 crystallizes:
- from the melt at moderate cooling rate
- when Tg > ambient temperature
• α-pha...
Page  15
Contact
Ted Brink
Email: ted.brink@extrusionist.com
Internet: www.extrusionist.com
Tel.: +31 651109899
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Polyamide crystallization structures

Crystal structures of polyamide
Published on: Mar 4, 2016
Published in: Technology      
Source: www.slideshare.net


Transcripts - Polyamide crystallization structures

  • 1. About crystallization of polyamide Ted Brink
  • 2. Page  2 Contents • H-bonds in polyamide • Thermal properties • Crystallization • Influence of moisture • Crystal structures • Conclusions
  • 3. Page  3 Hydrogen bonds and interaction with water water
  • 4. Page  4 Consequences of H-bonds in polyamide H-bonds influence: • stiffness • flexibility • crystallinity • glass transition point • gas permeability
  • 5. Page  5 Thermal properties of PA6 1 0 50 100 150 200 250 300 1 2 3 processing range crystal growth melting point glass transition temperature temperature[°C]
  • 6. Page  6 Crystallization of polyamide • fast cooling prevents crystallization • low cooling rate results in large crystals • presence of nucleant results in small crystalls • moisture uptake results in decrease of Tg - when Tg below ambient conditions → crystallization
  • 7. Page  7 Influence crystallinity on the density of PA6 1.23 1.084 1 1.1 1.2 1.3 crystalline amorphous density [kg/m3]
  • 8. Page  8 Influence moisture on Tg of PA6 -20 0 20 40 60 0 2 4 6 8 10 Tg[°C] moisture content [%]
  • 9. Page  9 Influence temperature on modulus of PA6 0 1000 2000 3000 0 50 100 150 200 250 E-modulus[MPa] temperature [°C]
  • 10. Page  10 Moisture induced crystallization Tg of PA6 • dry ~ 55 °C • wet ~ -10 °C Effects of moisture on PA6 film • lower stiffness • increased flexibility • improved stretchability • easier thermoforming • lower O2 barrier at high RH When Tg drops below ambient conditions, crystallization will occur
  • 11. Page  11 Polyamide crystal structures Structure α phase β phase γ phase Crystal structure Monoclinic Pseudo hexagonal Monoclinic Melting point 220 °C 214 °C How created Slow cooling Quenching Specific nucleants
  • 12. Page  12 Tensile behaviour crystal PA6 structures 0 20 40 60 80 0 1 2 3 4 5 Nominalstress[Mpa] Extension ratio Alpha Beta Gamma
  • 13. Page  13 13 Transformations of the pure crystal phases α β γ αT αT γT αλ αλαλ Influence of temperature & stretching on the 3 crystal structures of PA6
  • 14. Page  14 Conclusions • PA6 crystallizes: - from the melt at moderate cooling rate - when Tg > ambient temperature • α-phase is most stable • β-phase is a mesomorphous state • γ-phase is optimal for stretching
  • 15. Page  15 Contact Ted Brink Email: ted.brink@extrusionist.com Internet: www.extrusionist.com Tel.: +31 651109899

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