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

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

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

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.

Polypropylene Aging An Overview

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

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

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

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

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

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

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

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

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

Antioxidants: Primary AO’s Hydroxyphenylpropionates Active Site

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

Antioxidants: Secondary AO’s Thioethers Active Site

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

Antioxidants: Secondary AO’s Phosphites Active Site

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

Antioxidants With antioxidants: Color retained longer Physical properties maintained longer

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

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

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

Antioxidants: Measuring Effectiveness Color Index

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 http://www.hunterlab.com/pdf/Hunter-lab-vs-cie1976-lab.pdf

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

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

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

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

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

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

PLX 981 versus 1010/DSTDP

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!

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

PLX 981 versus 1010/TDBP LTHA

PLX 981 versus 1010/TDBP

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

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

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

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 http://www.patents.com/Stabilized-pigmented-polypropylene-fiber-resistant-gas-fade/US4929653/en-US/

PLX 981 Retards onset of Yellowing Unexpected reactions/interactions of phosphites within polyolefin stabilisation 2005, Svein H. Jamtvedt, Harry Øysæd. Addcon World 2005, Hamburg 21-22.09., 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: 1862-1868 (1995). Printed in Canada / Imprirnd au Canada BHT/1076 Yellowing

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)

PLX 981: an Antioxidant Stabilizer for Talc Filled Polypropylene

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 0.15-0.20 George Hawley, Peter Ciullo, Industrial Minerals and Their Use, Noyes Publications, Westwood, NJ, USA (1998) Polypropylene, $1.42/lb, Polypropylene Cost, accessed 1-05-09.

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.

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

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

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

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

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?

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

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

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

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”

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

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

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. 167-173 (2010).

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

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

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

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

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

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