1. Not All Nylons are Created Equal A look at the range of nylon fibers used for making brushes Bob Dill-Monahan Filaments

2. Hair – a Nylon Like Polymer

3. Another Early Source of Bristles

4. The Beginning Wallace Carothers: Nylon 6.6 -1935 –Dupont Paul Schlack: Nylon 6 - 1938 –I.G. Farben

5. Nylon Types Used for Brush Making Nylon 6 Nylon 6.6 Nylon 610 Nylon 612 Type 11 Nylon 12

6. Nylon Naming Nylon 6.10 –Hexamethylene diamine has 6 carbon atoms –Sebacic acid has 10 carbon atoms –The connection between the two monomers is an amide group. Nylon 6 –Caprolactam reacts with itself and has 6 carbon atoms

7. Why types are different Water absorbed by the amide groups connecting the monomer molecules. Water reduces the stiffness of the nylon More amide groups per unit of molecular length means more stiffness loss when wet Water absorption: – Type 6: 9% vs Type 612: 3%

8. Why types are different Long carbon chain monomers (Type 12 for example) start to be more polyethylene like. Properties suffer as the chain length gets longer than roughly 12.

9. So what is so great about nylon? Excellent bend recovery Good set resistance Excellent abrasion resistance High melting point (420-495 deg F) Very good flex fatigue resistance Modest price

10. What is not so great? Wet stiffness Attack by strong acids High temperature oxidation resistance

11. High Temperature Properties Melting Point (420-495 deg F) Heat Stability (oxidation resistance)-300 deg  One Day w/o HS  Many weeks w/ HS Stiffness and bend recovery at elevated temperatures

12. Other things nylon is good for Abrasive nylons Antimicrobial Wear Indicator Dyed paintbrush fiber 610 is about 2/3 plant derived (castor oil)

13. Alternatives to Nylon PBT polyester: better wet stiffness –Toothbrushes –Scrubs –Many industrial brushes –Price/brush approximately equal to 6.6 Polypropylene: better for strong acids

14. Simple Fiber ID Sharp bend test: Nylon>90 deg –PET, PS, PVC < 45 deg –PP: 45-90 deg Nylon vs PBT: Density (1.14 vs 1.32) Nylon vs PP: Density (1.05 vs 0.9) T66 and 6 vs 612: Density (1.14 vs 1.05) T66 vs T6: Melting point (495 vs 430)

15. Questions

16. Making Salt Solutions Use canning salt: Table salt has anti-caking agents that make cloudy solutions Make a saturated solution: put a bit over a pound of salt in a quart of water and stir or shake the mixture several times to be sure it is fully saturated. Let the undissolved salt settle and pour off the saturated solution. This has a density of about 1.25 g/cc and is suitable for separating nylon from PBT. Mix some of the solution with an equal volume of water and it will be a suitable density for separating T6 and 66 from 612. Test it with known samples and adjust as needed. Tap water used to separate PP from other fiber should either be heated to near boiling and cooled or let stand for a day to allow the dissolved air that is in all tap water to escape. A drop of detergent to reduce surface tension and labels or a little food coloring for identification are helpful. A more detailed Fiber ID description can be obtained from Ray Mainer rmainer@monahanfilaments.com or 802-388-4956 ex 1349 rmainer@monahanfilaments.com