This document discusses using polyfunctional chain extenders to improve the properties of recycled polyamides from post-consumer carpet. It finds that low molecular weight anhydride functional additives, like styrene maleic anhydride copolymers, can significantly improve the mechanical and thermal properties of recycled polyamide to levels approaching virgin polyamide. The increased mobility of lower molecular weight additives makes them more effective than higher molecular weight alternatives at restoring properties through chain extension reactions in the melt.

1. ADDING VALUE TO RECYCLED POLYAMIDES
WITH POLYFUNCTIONAL CHAIN EXTENDERS
Cray Valley USA, LLC
Exton, PA

2. Overview
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3. Environmental Motivation
“Developing market-based solutions for the recycling and reuse of
post-consumer carpet”
• Carpet America Recovery Effort slogan
Voluntary initiative by industry/government to prevent burdening landfills
Plan to achieve 40% landfill diversion by 2012
• 2002 diversion goal, 178 million pounds (3.8%)
• 1.3 billion pounds diverted since 2002, 92% of which has gone into other value
added products
• Estimated 5 billion pounds landfilled annually
• 5 billion pounds can support the NA injection molding market
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4. Material Availability
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5. A Value Added Process
Limited opportunities Used residential and
due to poor properties industrial carpets
Pile fiber heat
compacted into
useful form
• Nylon 6
• Nylon 66
• PET
• PP, etc.
Patented process to
separate nylon fiber
from backing
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6. Improved ‘Green’ Materials
Position recycled carpet Degradation Adding Value
fiber to injection with additive
molding market
Recycled Virgin Fiber Injection
Specifications Nylon Grade Molding
Step - 1 Start Step - 2
Mechanical Low Med High
Properties
Molecular Low Med High
Weight
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7. Technical Objectives
Improve the mechanical properties of reprocessed recycled nylon
derived from carpet using a functional additive to:
• Direct recycled content to injection molded applications
• Impart value added properties to recycled nylon that stay within a low cost model
Expand the application space of virgin grade nylon using the same
chain extension mechanism
• Improve melt strength for blow molding
• Enhance thermal and mechanical properties beyond convention
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8. Theory
5. Chain Extended
F
F F
F F
F
1. Dry Blending A
A
A A A
A
(polymer + additive)
F
F
A
A 4. Reaction
F
F
F
F A
A
A
A
3. Homogenizing
2. Melt Processing
Low Mw and/or Degraded High Mw and/or Branched
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9. Materials
Material Anhydride Molecular
Structure
Class Range Weight
Styrene Maleic
Anhydride 8 to 42% by
5k to 225k
Copolymers weight
(SMA)
Liquid
Functional 3 to 17% by
5k to 6k
Polybutadiene weight
(LPBD)
Yan et al. documented the importance of diffusion of reactive species
Hargreaves et al. described the reaction between amino group and
anhydride
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10. Materials
Functionality Anhydride Molecular
Label
Class Level Weight
SMA® EF-80P In chain anhydride 10.5% 14,000
Dylark® 232 In chain anhydride 8% 225,000
Ricon® 131MA5 HS* Grafted anhydride 5% 5,000
Model Formulation
98% to 99% by weight r-PA6/6 (>95% purity)
1 to 2% by weight chain extender
*Ricon 131MA5 was prepared on a porous silica at 70% active
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11. Results
Induction Time
Ricon® 131MA5 HS
SMA® EF-80P
Dylark® 232
Equivalency
Grafted MA yielded more efficient chain extension reaction
Mobility of low Mw SMA® led to shorter induction times
Bulky high Mw Dylark® underwent slower chain extension
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12. Results
Low frequency spread
Increased shear thinning
Low shear viscosity attributed to increased branched
Increased long chain branching or MWD
Reactivity of graft versus in-chain anhydride
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13. Results
SMA® improved mechanical properties more than Ricon®
Homogenization an important factor in additive selection
Chain extended r-PA has properties encroaching on virgin PA
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14. Results
Thermal characteristic improved with low/high Tg additive
Extent of branching suggested by improvement in HDT
SMA® more efficient at restoring properties of r-PA
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15. Conclusions & Recommendations
Significant improvements in r-PA using low molecular weight
anhydride functional additives
Anhydride grafted Ricon® 131MA5 HS gave the greatest extent of
reaction as shown by increased melt characteristics
Low molecular weight additives were deemed more beneficial than
bulky high Mw chemistry due to increased mobility in the melt
Homogenizing the melt involved balance of reactivity and mobility as
provided by SMA® EF-80P
• More recent work shows SMA® 3000P to be even more effective in r-PA
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16. Cray Valley HSC
 Leading global supplier of hydrocarbon resins, diene-based resins,
and specialty monomers
- Wingtack® and Norsolene® (C5 & C9 tackifiers)
- Poly bd®, KrasolTM and Ricon® (low molecular weight
liquid polybutadiene resins)
- SMA® (styrene-maleic anhydride copolymer resins)
- DymalinkTM (metal centered monomers)
 Annual sales over $350 million and has more than 340 employees
worldwide
 Company’s more than 250 products are manufactured at 9 sites in 4
countries
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17. Cray Valley HSC
A Division of Total SA
Upstream Downstream Chemicals
Oil & gas exploration Trading & shipping Base chemicals
Production Refining & marketing Industrial & consumer
Focus market specialty chemicals
Gas & power Commodity & specialty
Alternative energy fluids
Sales
$24.6 $163.4 $23.2
(billion)
Employees 17,192 32,631 41,658
Total, a partner in your challenges
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18. Cray Valley HSC
Focus Markets
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19. Cray Valley HSC
Global Presence
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20. The End
Thank You!
Contact Information:
Cray Valley HSC
www.crayvalley.com
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