Latex Flashcards
What is latex? Where is it produced
- Milky emulsion, secondary metabolites
- Produced by laticifers, special secretory cells
- Has very different compositions
Where are laticifers found?
- Sporadically in flowering plants
- Mostly dicots, approx. 20 families
- Many in Euphorbiaceae, spurge family (poinsettias)
Where does latex form in plant
- Vessels and networks
- Bark/stem (lettuce)
- Fruit (fig, papaya)
- Seed capsule (poppy)
What is the function of latex for the plant?
- Defensive
- Contain numerous different compounds
Rubber
- Latexes w/ elastic properties
- Long unbranched terpene polymer chain gives flexibility
- Up to 6000 isoprene units
Where does the name ‘rubber’ come from?
- Discovered that latex, when rubbed on paper, removes pencil marks
Rubber containing plants, where from
- Mostly tropical, over 2000 species
- First used in tropical america, seen by Spanish in 1500’s
What where some of the first human uses of rubber?
- Bouncing ball for Aztec games (Castilla elastic, Moraceae, fig family)
- Amazonians used for rubber shoes, smoking feet dipped in sap (coagulation by heat made coating waterproof)
- ‘Rubberizing’ as waterproof coating by Charles Macintosh
‘Rubberizing’
- 1823, Charles Macintosh
- Dissolve rubber in solvent
- Water proof coating, called the Macintosh
- But coating cracked in cold, became sticky in heat
What fixed the problem of ‘Rubberizing’?
- Vulcanization
- Discovered by Charles Goodyear in 1839
- Add sulfur w/ heating
- Adds cross-links to isoprene chain
- Improved elasticity too
What are the uses of rubber?
- Boots, gloves, electric wire coating, hose, drive belt, tires, etc.
Why is rubber so useful?
- Elastic and waterproof
How much rubber is used for tire manufacturing?
- About 2/3 of total produced rubber
- Not just car tires
When was rubber no longer harvested from the wild?
- 1880
Where does natural rubber mostly come from?
- 98% harvested from Hevea brasiliensis, Euphorbiaceae, spurge family
- Tree native to Amazonian basin
- Abundant laticifers in inner bark, high rubber content in latex
- Tapped from spiral cuts into bark, drip into cup
What did British explorer Wickam do?
- Worked for Kew Gardens
- Took rubber tree seeds out of Brazil
- Plantations then established in British, French, and Dutch colonies in SE Asia in late 1800’s
- 50 million trees by 1910
Where is the most modern natural rubber produced?
- SW China and SE Asia
What happened to Amazonian plantations of Rubber trees?
- Destroyed by fungal blight
What did Henry Ford try to do?
- Massive rubber plantation in Brazil in 1930’s
- Failed because didn’t use local Brazilian knowledge to grow
- Succumbed to fungal blight
Synthetic Rubber
- Polymers of units similar to isoprene
- Not the same, natural is stronger and more flexible
What led to development of synthetic rubber?
- Rubber supply to US cut off in WWII
‘High Performance’ use calls for what kind of rubber?
- Natural
What percentage of rubber used is from trees?
- 40%
How long does it take to get enough latex to make one tire?
- One months drip of latex from 4 trees
Possible alternate sources of rubber?
- Guyule, Parthenium argentatum, sunflower family, Asteraceae
Guyule plant and how used
- Shrub grows in arid areas
- Plant that makes Rubber alternative
- Latex not in laticifers
- Plant can be mechanically harvested and crushed
- Latex extracted with solvent
- Hypo-allergenic
What led to the US sanctioned import of rubber to China?
- Korean war 1950-53
China’s expansion of rubber growth
- Selected varieties to grow in cooler climes
- Established state-run plantations
- plantations bring wealth to people but are environmentally dangerous
What is the environmental result of China’s rubber production?
- Expanding into ecologically vulnerable/valuable areas
- Rubber trees consume large amounts of water
- Clearing forest for growing rubber increasing in Laos, Myanmar, Cambodia, Vietnam, Thailand, Malaysia, Indonesia
Nootkatone
- Fragrant
- 1st found in Alaska cedar
- Scent may win fight against ticks, natural insect repellant
Ambergris
- Whale vomit, sperm whales
- used to put scents on body b/c allows scent to stick to body longer
Why does the skin often feel ‘cool’ when applying scents?
- Because perfumes/aftershaves are often having scent suspended in alcohol
What is used to remove ski wax?
- Limonene
