1. PLX 981: Long Term Heat Stabilizer for Polypropylene and Composites
Thermoplastic Concentrates
February 16-18, 2010
Presented by John M. DeMassa, Ph.D.

2. PLX 981: Long Term Heat Stabilizer for Polypropylene and Composites Overview
R.T. Vanderbilt, Inc.
Overview of Polypropylene Aging and Antioxidants
PLX 981: Antioxidant Stabilizer for Unfilled Polypropylene
PLX 981: Antioxidant Stabilizer for Talc Filled Polypropylene
Wrap-up
Acknowledgements
Questions

3. R.T. Vanderbilt, Inc. Rubber and Plastics Products
We sell Raw Materials:
Polymers, Fillers, Antioxidants, Accelerators, Peroxide Curatives
Neoprene W, VANOX® ZMTI, VANAX® DPG, VAROX® DCP
We sell to:
Custom Mixers – companies that sell mixed compounds (using our raw materials)
Molders – companies that mix and mold finished products (using our raw materials)
We do NOT sell finished goods or compounds
i.e. Viton o-ring, ready to mold Neoprene compound, 50 durometer EDPM

4. R.T. Vanderbilt, Inc. Plastic Department
Began in 1946 when Vanderbilt introduced its first vinyl heat stabilizer.
Over the years, expanded to include a wide range of antioxidants
Process Stabilizers
Long Term Heat Stabilizers
Polyurethane, polyethylene, and polypropylene industries.
Complete line of mineral fillers and reinforcing agents (Talc, Wollastonite, Kaolin Clay, Pyrophyllite)
Emphasis on new product development enables the Plastics Department to be responsive to the ever-changing needs of today’s plastics industry.

5. Polypropylene Aging
An Overview

6. heat, oxygen and mechanical stress degrade polypropylene
Polypropylene degrades upon exposure to heat, light, and/or mechanical stress.
heat, oxygen and mechanical stress degrade polypropylene

7. Signs of general polymer degradation
Color Change
Weakened Physical Properties
Oxygen makes rubber and plastic degrade

8. Polymer Degradation: A Chemical Explanation
Initiation
ENERGY .
- H
R-H . R O2
Chain Scission
+ RH .
Propagation RO . + .
ROO HO
+ RH
Crosslinking,
Embrittlement . R +
ROOH

9. Polyolefins degrade differently/ \ = C h a i n S c s o r l k g O P +
(PP)
(PE)
The answer lies in the fate of the free radicals.
Two free radicals can combine to terminate each other, which results in a new crosslink. A polymer with many double bonds will also provide many attachment sites for polymer radicals, again leading to more crosslinks. In this regard, oxidative aging is much like peroxide crosslinking. The peroxide generates free radicals that crosslink the polymer.
Some polymers can not be crosslinked by peroxides. These polymers tend to undergo reversion or chain scission during oxidative aging. Scission is favored in polymers that are branched or have many side groups.
Scission favored in polymers that are branched such as Polypropylene
Crosslinking favored in polymers lacking branches such as Polyethylene

10. How do we slow the process of plastic breakdown?
Antioxidants
How do we slow the process of plastic breakdown?

11. Antioxidants: Polymer Protection
Antioxidants interfere with various phases of the oxidation process
Primary AOs act as peroxy radical traps
Secondary AOs act as peroxide decomposers

12. Antioxidants: Polymer Protection
Selection of AO
Cost
Colorless
Low extractability
Good chemical resistance
Good stability with other components
Low odor
Low volatility
Low migration/blooming +
Good AO

13. Antioxidants: Types of AO’s
Primary: Hydroxyphenylpropionates
Secondary:
Thioester
Phosphite

14. Antioxidants: Primary AO’s Hydroxyphenylpropionates
Name 1
1076 4
1010
1076 = Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate
1010= Tetrakis [methylene 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] methane

15. Antioxidants: Primary AO’s Hydroxyphenylpropionates
Active Site

16. Antioxidants: Secondary AO’s Thioethers
Name
DLTDP
DSTDP
DLTDP = Dilauryl thiodipropionate
DSTDP = Distearyl thiodipropionate

17. Antioxidants: Secondary AO’s Thioethers
Active Site

18. Antioxidants: Secondary AO’s Phosphites
Name
Structure
1680
6260
1680 = TDBP Tris (2,4-di-tert-butylphenyl) phosphite
6260 = BDPP Bis (2,4-di-tert-butyl phenyl) pentaerythritol diphosphite

19. Antioxidants: Secondary AO’s Phosphites
Active Site

20. Antioxidants: Polymer Protection, A Chemical View
Initiation
ENERGY .
- H
R-H . R O2
Chain Scission
+ RH .
Propagation RO . + .
ROO HO
+ RH
Crosslinking,
Embrittlement . R +
PRIMARY AOs
Peroxy Radical
Scavenger
SECONDARY AOs
Peroxide Decomposers
Synergists
ROOH

21. Antioxidants With antioxidants: Color retained longer
Physical properties maintained longer

22. How can we measure antioxidant effectiveness?
Antioxidants
How can we measure antioxidant effectiveness?
in the lab

23. Antioxidants: Measuring Effectiveness
Process Stabilizers
Multi-pass
Melt Flow Index (MFI)
Torque response
Prolonged dwell in hot injection molding cylinder
Physical Property Change
Tensile
Flexural
Impact

24. Antioxidants: Measuring Effectiveness
Long Term Heat Stabilizers
Assess quality of specimen subjected to elevated temperature over time
Color or appearance change
Physical Property Change
Tensile
Flexural
Impact
Infra Red Spectroscopy
Melt Flow Index (MFI)
Present study

25. Antioxidants: Measuring Effectiveness
Color Index

26. Color Index: The L, a, b Color Space
ΔΕ = √(L1 – L2)2 + (a1 – a2)2 + (b1 – b2)2
Generally:
L “lightness” index
B “yellow-blue” index
A “red-green” index

27. The Original Study PLX 981: an Antioxidant Stabilizer for Unfilled Polypropylene

28. Antioxidants: Measuring Effectiveness
General Method
Comparative study of selected AO’s at equal weight loading in Polypropylene
Heat age plaques in oven until scorching or yellowing
Collect Delta E values throughout run

29. PLX 981 PLX 981 is a powder blend suitable for easy compounding
PLX 981 delays thermal degradation of polypropylene at elevated temperatures better than conventional blends
PLX 981 retards discoloration of polypropylene at elevated temperatures better than conventional blends.
PLX 981 is a patented product
Product samples available

30. The Study: Sample Preparation
Extrusion
1,000 Gram Batches (0.4% AO + Polypropylene + stabilizers)
210oC-220oC-220oC-200oC Extruder Zone Temperatures
60 RPM
¼ inch round Die
Pellitized
Pressing
20 grams of pelletized material of each compound
350oF
3 minutes, warm up, 0 pressure
2 minutes, 30 Tons pressure
7 ½ minutes Cooling, maintaining pressure
0.6 mm plaques

31. The Study: Sample Preparation
Oven Aging Test Specimens (LTHA)
150oC Convection Oven
From each pressed plaque die cut (18) ¾ x 1 ¼ inch pieces
Place 16 pieces of each compound specimens sampled periodically.
Remove 2 specimens for each compound when any one or more fail, or at regular intervals, weekly, bi-weekly.
Staple each specimen to test card and record elapsed time, in hours, on the card/s
Color Determination using Colorimeter

32. Unfilled Compounds Component 1 2 3 Profax 6301 100 AO 1680 0.2 AO 1010
AO DSTDP
PLX-981
0.4

33. PLX 981 versus 1010/DSTDP

34. PLX 981 versus 1010/DSTDP LTHA Less discolored over time! PLX 981
Time (hrs)
1010:
DSTDP
1700 hrs
PLX 981
2000 hrs
Less discolored over time!

35. PLX 981 versus 1010/DSTDP LTHA
PLX 981 delays polypropylene degradation 20% longer than DSTDP/1010 control
PLX 981 gives less color drift than DSTDP/1010 control

36. PLX 981 versus 1010/TDBP LTHA

37. PLX 981 versus 1010/TDBP

38. PLX 981 versus 1010/TDBP LTHA Less discolored over time! Time (hrs)

39. PLX 981 versus 1010/TDBP LTHA
PLX 981 delays polypropylene degradation 80% longer than TDBP/1010 control
PLX 981 gives less color drift than TDBP/1010

40. PLX 981 vs DSTDP/1010 and TDBP/1010
Why does PLX 981 discolor polypropylene less than controls?

41. PLX 981: Polymer Protection A Chemical View
Initiation
ENERGY .
- H
R-H . R O2
Chain Scission
+ RH .
Propagation RO . + .
ROO HO
+ RH
Crosslinking,
Embrittlement . R +
PRIMARY AOs
Peroxy Radical
Scavenger
ROOH
SECONDARY AOs
Peroxide Decomposers
Synergists
Yellow

42. PLX 981 Retards onset of Yellowing
Unexpected reactions/interactions of phosphites within polyolefin stabilisation
2005, Svein H. Jamtvedt, Harry Øysæd. Addcon World 2005, Hamburg , 2005
Phenolic Yellowing
The effect of transformation products of the antioxidant BHT on the initial stages
of thermo- and photo-oxidation of LDPE J. Kovaiova, J. Rotschova, 0. Brede, and M. Burgers
Can. J. Chern. 73: (1995). Printed in Canada / Imprirnd au Canada
BHT/1076 Yellowing

43. Long-Term Heat Aging Conclusions for Unfilled PP
PLX 981 delays thermal degradation in thin film polypropylene longer than controls (1010/DSTDP, 1010/1680)
PLX 981 provides longer color retention than controls (1010/DSTDP, 1010/1680)

44. PLX 981: an Antioxidant Stabilizer for Talc Filled Polypropylene

45. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
Talc is a widely used filler in Polypropylene Composites
Economic advantages
Performance advantages
Filler
Wire and Cable
Non-Structural Automotive Parts
Outdoor Furniture
Cost ($/lb)
Talc (functional)
Electrical Resistance
Mech. Strength
UV Resistance
Temp Resistance
George Hawley, Peter Ciullo, Industrial Minerals and Their Use, Noyes Publications, Westwood, NJ, USA (1998)
Polypropylene, $1.42/lb, Polypropylene Cost, accessed

46. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
Mechanical Properties of 40% Talc-Filled Polypropylene
Filler
None
Talc
Tensile Str.a
4.7
4.3
Flexural Str.a
4.5
6.4
Flex. Modulusa
180
680
Impact Resist.b
Notched
0.45
Unnotched
No brk.
Heat Distortionc 56 78
Mold Shrinkaged
0.02
0.012
aKpsi bIzod; ft.lb./in c264 psi, °C din./in.

47. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
The Study
Component/ Compound 1 2 3 4
Unstabilized PP 60
Vantalc 6HII 40
Calcium stearate
0.05
Epon 1002
0.25
AO 1010
0.1
AO DSTDP
AO 1680
PLX-981
0.2

48. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
Extrusion
1,000 Gram Batches (60% Polypropylene + 40% Talc + 0.2% AO + stabilizers)
210oC-220oC-220oC-200oC Extruder Zone Temperatures
60 RPM
¼ inch round Die
Pellitized
Injection Molding

49. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
Oven Aging Test Specimens (LTHA)
150oC Convection Oven
Observed injection molded discs (1mm)
Generally catastrophic failure noted

50. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
LTHA Results
Still Going!
HOURS

51. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
What active species in talc is responsible for degrading polypropylene so quickly?
Why is PLX 981 proportionately stabilizing the filled system better than the unfilled system?
Why is PLX 981 so much better?

52. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
A brief review of talc…

53. Typical Chemical Analysis of Vantalc 6HII (calculated as oxides)
% by weight
Magnesium Oxide (MgO)
31.5
Silicon Dioxide (SiO2)
61.4
Aluminum Oxide (Al2O3)
0.6
Calcium Oxide (CaO)
0.2
Ferric Oxide (Fe2O3)
1.1
Sodium Oxide (Na2O)
<0.1
Loss on Ignition (1000°C)
5.2

54. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
General Structure of Talc
0.96-nm thick tri-layers, Si8Mg6O20(OH)4
Top and bottom layers: Tetrahedral Silica Network
Middle layer: Octahedral Magnesia Network
Lattice bound Si4+
Some lattice bound Al3+
Lattice bound Mg2+
some lattice bound Fe3+ and/or Fe2+
Hasmukh A. Patel, Sumeet K. Sharma, Raksh V. Jasra, Journal of Molecular Catalysis A: Chemical 286 (2008) 31-40

55. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
Talc presents a highly oxidizing environment towards polypropylene.
Theories of degradation.
Aluminum Catalyzed “Top Face” Model
Iron Catalyzed
“Edge Model”
“Iron Oxide Grain Model”

56. Aluminum Catalyzed Polypropylene Thermal Degradation
“Top face” Al3+ R

57. Iron Catalyzed Polypropylene Thermal Degradation “Edge Model”
Edge of Talc Fe 2+ Fe3+
Personal Communication Peter Ciullo

58. Iron Catalyzed Polypropylene Thermal Degradation “Iron Oxide Grain Model” H. Nakatani
Fe2O3
Nakatani et al. attribute degradation of polypropylene to iron oxide impurities.
Nakatani Hisayuki et al., Journal of Applied Polymer Science, Vol. 115, no1, pp.  (2010).

59. Iron Catalyzed Polypropylene Thermal Degradation “Iron Oxide Grain Model” H. Nakatani
Fe2O3

60. A proposed mechanism for talc filled polypropylene thermal degradation and PLX 981 stabilization
The PLX 981 difference
Free Radical Trap?
Peroxide Scavenger?
Resists Talc Adsorption?
Oxidation Site Blocking?
Al2O3
Fe2O3 R

61. PLX 981 Stabilizes Talc Filled Polypropylene Compounds
Conclusions
PLX 981 stabilizes talc filled polypropylene compounds much better than conventional phenolic/phosphite or phenolic/thioester antioxidant systems.
Mechanism of action uncertain

62. PLX 981: Long Term Heat Stabilizer for Polypropylene and Composites Wrap-up
PLX 981 provides improved long term heat stability (20-80%) over conventional stabilizer blends.
PLX 981 provides much improved long term heat stability (328%) over conventional stabilizer blends.
Samples available upon request

63. Acknowledgements Carrie Burr Kevin Chase, Ph.D. Peter Ciullo
Jennifer Forgue
Bruce Garney

64. PLX 981: Long Term Heat Stabilizer for Polypropylene and Composites
Questions