lec 23 Flashcards
what is latex?
a mixture of organic compounds produced by specialized lactifer cells
describe the two forms of lactifers
either individual latex producing cells, or connected lactifer cells that form columns/tubes
what is the role of a lactifer? what are some (two) examples of different latices than those that produce rubber?
produce latex, but also produce alkaloids (toxic compounds), proteins, sugars, etc in diff species
ex. papaya prod a latex that contains papain, an enzyme that breaks down proteins
ex. opium poppies contain a latex that contains morphine, codeine, and papaverine
what is the biological purpose of latex?
defense against biotic and abiotic stresses
on a molecular level, what is rubber?
rubber is a polymer made of interlinked 5-carbon isoprene units
what is the most important source of natural rubber?
the Brazilian Rubber Tree Hevea brasiliensis
i just planted a rubber tree. how long til i can start harvesting, and how much can i harvest once its mature?
they take 7-10 years to develop, at which point u can harvest until they’re 30ish
what is the best tie to tap a rubber tree?
in the morning, where its cool but still humid
tell me a quick story about why we went from natural rubber to synthetic rubber
in the early 19th century, tires had a problem: when roads got hot, the tires got sticky and popped
in 1830s, charles goodyear mixed sulfur and rubber and heated it, but found that instead of falling apart they actually got stronger –> we got a industry babey
marx revolutionizing industry etc etc now we have plantations
except uh oh! brazil plantations failed due to a leaf blight fungus pathogen!!
by WWII 90% world’s rubber came from rubber plants in asia
in WWII asia was a major player with respect to playing out proxy wars, and the result that NA was cut off
–> we need synthetic rubber babey
how does rubber processing into tires work?
solid rubber is macerated, and sulfur + pigments + etc are added in
liquid rubber is applied to a fabric such as rayon, and layered into plies
plies are stacked in 90 degree orientations, with the top layer having the tread pattern
finally its vulcanized by steam to harden it
which tires have more natural rubber: passenger tires, or trucking tires?
passenger tires have a natural:synth rubber ratio of about 19%:24%
trucking tires have a natural:synth rubber ratio of about 34%:11%
what are the benefits/problems of using guayule as opposed to hevea?
+ guayule is virtually identical to hevea rubber
+ shrubs can produce a shit ton of rubber (20% dry weight)
- plants must be 7 years old to harvest
- you need to harvest the whole thing, and can only harvest it once
how can u process guayule?
- shrubs are cut at base or uprooted
- dipped in hot water to coagulate rubber and remove leaves
- resins and latex rise to the surface and are skimmed off the top
- resin is separated from the latex
what is the problem associated with gutta-percha and chicle?
their isoprene links are trans configuration, meaning the links are all on the same side - less flexible
that being said they still have their uses
what are some traditional uses of gutta-percha rubber
fillings in golf balls and fillings in root canal surgeries
also was the first underwater transatlantic insulator (waterproof, insulating, biologically inert)
