Lecture 21 - Rubber Flashcards
rubber scientific name
Hevea brasiliensis
origin of rubber
amazon basin, upper, orinoco, guyana’s
what did the mesoamericans use rubber for
footwear, bottles, torches, balls
how did rubber get its name
joseph Priestly discovered that it would rub out paper marks
who first suggests plantation growing of rubber
Hancock
who and when discovered vulcanization of rubber
Goodyear and Hancock in 1839
what is vulcanization
when rubber is heated with sulpher, it retains physical properties from 0-100C
who was responsible for sending rubber plants to brazil’s Kew garden
Sir Clements Markham of India Office
who developed the method for extracting latex
H.N. Ridley
what did Dunlop do for rubber
rediscovered pneumatic tires
where is most rubber produced
southeast asia, specfically Thailand
why is there little rubber production in south america
due to the South America Leaf Blight
what determines the Plasticity Retention Index
the amount of natural rubber. High in natural rubber means more stretchy because of cis configuration
ideal climate for rubber
slightly acidic and well draining soil
22-30C
1500-3000mm/year
reasons for defoliation in rubber trees
wintering at least once a year
drought
cold and short days
type of flowers in rubber plants
monoecious with female flowers on tips of branches and male flowers more numerous
cross pollinated
how many seeds does a rubber seed capsule have
3
how is rubber propagated
through seeds as rootstock. Plant is then budded. They sit in a nursery for 10-15 months until at 3 whorl stage and then are transplanted
how are rubber trees produced where South American Leaf Blight is a problem
use a 3 part tree with a seedling rootstock, a high yielding trunk, and a leaf blight resistant top
planting density of rubber trees
360-416plants/ha
when are rubber plants ready to be tapped
5-8 years. Need to be 50cm in circumference at 1m height. Trunk diameter of 7-8 inches
how long are rubber tree productive
production increases until 15 years old. Normally tap for 20-25 years and replace at 30yrs
what direction are rubber trees planted
N-S
t/f: legume cover crops are used in between rubber trees as N source and weed control
t
maintenance of rubber trees
remove all branches up to 2.5 m early on for smooth trunk for latex collection
what are latex vessels in rubber trees
modified sieve tubes of phloem that run counterclockwise 2.5 degrees to the vertical
laticiferous vessels
latex synthesis and transport
what direction are rubber trees tapped in
clockwise direction
excision method of tapping rubber trees
cut grove 30 degree angle mark 1-1.25m point, go 180 around tree, not too deep (dont reach cambium)
how many times is cutting repeated for rubber tapping
1-3 days
how much bark is consumed per year when rubber tapping
25 cm per year
latex composition
water, terpenes, sugars, enzymes, etc
rubber tapping intensity formula
S/2 d/2 = 100%
s=size of spiral (s2=half spiral)
d=frequency/day (d/2=every 2 days
rubber trees are usually tapped for __ months and rested for ___ months
6, 3
when does rubber cutting start in the day
early morning (6am) because latex flow is highest due to transpiration
how many rubber trees can one person cut in a morning
500
tapping schedule of rubber trees
first side tapped for 4-5 yrs
second tapped for 4-5 years
repeat cycle on original sides
3 types of latex
Liquid (highest quality)
Cup rubber (cut lump that sticks to cup)
Scrap rubber - strip of rubber from cut surface
how to coagulate rubber
10-25% ammonia (anticoagulent), 30-35% rubber, diluted with water
how is rubber processed
latex poured into moulds and then formic or acetic acid is added to coagulate the liquid latex
rollers make rubber sheets with curd
how much rubber does wild and modern clones yield
wild 300-450kg/ha
modern - 700-2000kg/ha
what is done with the rubber wood after cut down
high quality paper and hardwood floor
Major disease of rubber plants
South American Leaf Blight, Leaf Burning, Fusarium wilt, white root rot fungal disease, and bark disease
