Neoprene

1. Neoprene By Paul Morales

2. Neoprene Simple 4 carbon polymer with a single chlorine attached to the double bond.

3. Neoprene Also known as polychloroprene.

4. Neoprene Truths • Annual consumption of nearly 300 000 tons worldwide • Widely used due to its favorable combination of technical properties. • Mainly used in the rubber industry (61%) • also important as a raw material for adhesives (both solvent based and water based(33%) • has different latex applications such as dipped articles (e.g. gloves) and molded foam. (6%)

5. Interrogate #1 What property does chlorine give to the overall polymer? • Lower flammability!!!

6. Neoprene Truths cont. • The typical delivery form is “chips” • The polymer is not characterized by one outstanding property, but its balance of properties is unique among the synthetic elastomers. It has: • Good mechanical strength • High ozone and weather resistance • Good aging resistance • Low flammability • Good resistance toward chemicals • Moderate oil and fuel resistance

7. Neoprene Truths cont. • According to the IISRP, in 2000 the following production facilities and producers are shipping polychloroprene into the market place: • Additional capacities are located in Peoples Republic of China and Armenia.

8. Early History During the 1920s the increasing demand for natural rubber led to higher and higher prices, -There for sparking a search for an equivalent synthetic rubber. In1932, Wallace Carothers produced a rubber-like substance during a polymerization experiment using chloroprene. -A chemist in DuPont's fundamental research group.

9. History 1930s • The polymer was originally called Duprene and in 1937 DuPont discontinued the trade name • They changed it to "neoprene" • The name change was also used to signify that the material was an ingredient, not a finished consumer product. • It was also used in consumer goods like: • gloves • shoe soles • Although production was stepped up • it was all claimed by the military. • World War II removed neoprene from the commercial market. • Essentially unchanged since 1950, neoprene continues to be essential in the manufacture of • adhesives, • sealants, • power transmission belts, • hoses and tubes.

10. History 1950s • It wasn't until the 1950s that neoprene was first used in a wetsuit. • Hugh Bradner, • a University of California, Berkeley physicist is often considered the original inventor and "father of the modern wetsuit.” • Corporate legend Jack O'Neill from San Francisco was known for pioneering the application of neoprene wetsuits around 1955.

11. History 1960s-Present • During the 1960s a new type of neoprene was pioneered. • Up until this time, the process of manufacturing neoprene involved petroleum and petro-chemicals. • Petro based polymers use a polymerization process that heats oil to extremely high temperatures. • Yamamoto Corporation developed special technology to convert the calcium carbonate from limestone into chloroprene rubber chips and then further processing to achieve neoprene foam with a very high micro-cell structure. • This new process results in neoprene with very different characteristics to oil based neoprene. • Yamamoto has been marketing their Yamamoto limestone neoprene since this inception.

12. Types of neoprene • Normal linear grades (general-purpose grades): • General-purpose grades are mostly produced with n-dodecyl mercaptan as the chain transfer agent and occasionally with xanthogen disulfides. • Depending on the ingredients used the polymer can be more readily proccessible and give improved mechanical properties. • Precrosslinked grades: • Precrosslinked grades consist of a blend of soluble polychloroprene and crosslinked polychloroprene. • They show less swelling after extrusion (die swell) and better calenderability. • Precrosslinked grades are particularly suitable for the extrusion of profiled parts.

13. Interrogate #2 What is Vulcanization? • It is chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur.

14. Types of neoprene • Sulfur-modified grades: • Sulfur-modified grades are copolymers of chloroprene and elemental sulfur. • Sulfur-modified grades are used in particular for parts exposed to dynamic stress, such as driving belts, timing belts or conveyor belts because of their excellent mechanical properties. • But the polymers are less stable during storage and the vulcanizates less resistant to aging. • Slow crystallizing grades: • Slow crystallizing grades are polymerized with 2,3-dichloro-1,3-butadiene as a comonomer. • This comonomer reduces the degree of crystallization by introducing irregularities into the polymer chain. • Crystallization resistant grades are used to produce rubber articles, which have to retain their rubbery properties at very low temperatures.

15. Overall will focus on the one type of neoprene production: • Limestone based neoprene.

16. Limestone Neoprene • Limestone neoprene has a high micro-cell structure. • These are independent closed cells (bubbles basically) within the neoprene that are packed together at an extremely high density. • limestone neoprene has a 94% cell penetration. • less dense than oil-based neoprene. • Because of this micro-cell structure, limestone neoprene provides several serious distinct advantages to the functionality of wetsuits compared to the traditional oil-based neoprene: • It is more impermeable • It is lighter in weight • It is warmer • It is more durable • It is stretchy

17. Oil-Based Neoprene (comparison) • Low micro-cell structure. • Oil-based neoprene has a cell penetration of 60-70% • The amount of bubbles or pockets with in the polymer, oil based neoprene has low density closed cells. • Also denser than limestone neoprene. • Problems associated with inferior-quality neoprene: • Delamination: blisters between the nylon and rubber which deteriorates quickly • Compression: neoprene 'cave-ins', especially around the knee/elbow areas • No memory: does not return memory (hold its shape) and the fit gives out over time • Splits: neoprene splits unnecessarily within the nylon layers

18. The Makings!!! • Yamamoto uses acetylene derived from the calcium carbonate found in limestone. • Extracted limestone is fed into a furnace and heated at a temperature around one-tenth of that used for refining petroleum • Calcium carbide is produced by heating coke with calcium oxide (limestone) in an electrical furnace up to 2000 °C.

19. The Makings cont.!!! • Calcium carbide reacts with water, releasing acetylene, C2H2. • Dimerization of acetylene by passing it through an aqueous solution of Ammonium Chloride and Cuprous Chloride at 343K. • Vinylacetyleneperforms a Markonikov addition under acidic condition to produce Chloroprene CaC2(s) + 2 H2O(l)  C2H2 (g) + Ca(OH)2 (aq)

20. The Makings cont.!!! • The Chloroprene obtained undergoes Polymerization to give Neoprene. Though no specific catalysts are needed for this process but the polymerization becomes faster in the presence of Oxygen or peroxide. • The polychloroprene rubber chips are melted and mixed together with foaming agents and black carbon pigments, and then baked in an oven to make it expand. • It's during this process that Yamamoto's specialized technology combines with the calcium carbonate to create the micro-cell structure of limestone neoprene versus the regular oil-based neoprene.

21. Limestone Neoprene

22. Oil-Based Neoprene

23. Overall • Polychloroprene will continue to be one of the most important synthetic specialty elastomers because its balance of properties is unique.

24. Sources • Polychloroprene (CR), chloroprene rubber: http://www.iisrp.com/webpolymers/04finalpolychloropreneiisrp.pdf • NEOPRENE: THE INSIDE STORY: http://www.korduroy.tv/2012/neoprene-the-inside-story/ • How is Yamamoto limestone neoprene made: http://www.seventhwave.co.nz/wetsuits101/neoprene+info/How+is+Yamamoto+Limestone+neoprene+made.html • Pictures: https://www.wikipedia.org