Natural and Synthetic Rubber
Polyisoprene from latex and synthetic analogs; vulcanization crosslinks chains with sulfur.
Polyisoprene from latex and synthetic analogs; vulcanization crosslinks chains with sulfur.
Natural rubber is cis-polyisoprene obtained from latex, and its chains are coiled and tangled, so it is soft and easily deformed. Vulcanization heats the rubber with sulfur, which forms crosslinks between the chains, making the material elastic, stronger and less sticky. Synthetic rubbers such as styrene-butadiene rubber, neoprene and butyl rubber were developed to provide specific properties, including resistance to oil, heat or gas permeation. The crosslinked network allows the material to stretch and then return to its original shape.
Key ideas: Natural rubber is cis-1,4-polyisoprene from latex; gutta-percha is the trans form and is hard. Vulcanisation heats rubber with sulfur (3 to 5 percent) to create disulfide cross-links, improving elasticity, strength and heat resistance. Synthetic rubbers: neoprene (chloroprene), Buna-S (butadiene plus styrene), Buna-N (butadiene plus acrylonitrile, oil resistant), butyl rubber. Over-vulcanising gives hard ebonite.
Common mistakes and connections: Students think vulcanisation makes rubber softer or that sulfur forms ring bonds; it makes cross-links. Another error is writing the double bonds as trans in natural rubber. Links to polymer structure, elastomers and polymerization of dienes with 1,4 addition.
Rubbers have glass transition temperatures far below room temperature, so their coiled chains stay flexible, unlike glassy polystyrene. The interactive lesson shows this as a live animation or chart.
Car tyres are made from vulcanized rubber reinforced with carbon black, which improves wear resistance.
Polyisoprene from latex and synthetic analogs; vulcanization crosslinks chains with sulfur.
Natural and Synthetic Rubber is a intermediate topic in Organic Chemistry. It builds on the vocabulary of beginner topics in this area.
Study these earlier topics in Organic Chemistry first: Polymers Overview, Addition Polymers, Condensation Polymers.
The next topics in Organic Chemistry are Biodegradable Polymers and Organic Reaction Mechanisms.
Yes. The interactive lesson includes a self-check question on Natural and Synthetic Rubber, and the Organic Chemistry quiz draws on every topic in this area.
Natural and Synthetic Rubber is topic 106 of 148 in Organic Chemistry.