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PLSC 333 > Lecture 21 - Rubber > Flashcards

Lecture 21 - Rubber Flashcards

1
Q

rubber scientific name

A

Hevea brasiliensis

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2
Q

origin of rubber

A

amazon basin, upper, orinoco, guyana’s

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3
Q

what did the mesoamericans use rubber for

A

footwear, bottles, torches, balls

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4
Q

how did rubber get its name

A

joseph Priestly discovered that it would rub out paper marks

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5
Q

who first suggests plantation growing of rubber

A

Hancock

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6
Q

who and when discovered vulcanization of rubber

A

Goodyear and Hancock in 1839

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7
Q

what is vulcanization

A

when rubber is heated with sulpher, it retains physical properties from 0-100C

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8
Q

who was responsible for sending rubber plants to brazil’s Kew garden

A

Sir Clements Markham of India Office

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9
Q

who developed the method for extracting latex

A

H.N. Ridley

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10
Q

what did Dunlop do for rubber

A

rediscovered pneumatic tires

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11
Q

where is most rubber produced

A

southeast asia, specfically Thailand

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12
Q

why is there little rubber production in south america

A

due to the South America Leaf Blight

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13
Q

what determines the Plasticity Retention Index

A

the amount of natural rubber. High in natural rubber means more stretchy because of cis configuration

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14
Q

ideal climate for rubber

A

slightly acidic and well draining soil
22-30C
1500-3000mm/year

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15
Q

reasons for defoliation in rubber trees

A

wintering at least once a year
drought
cold and short days

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16
Q

type of flowers in rubber plants

A

monoecious with female flowers on tips of branches and male flowers more numerous
cross pollinated

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17
Q

how many seeds does a rubber seed capsule have

A

3

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18
Q

how is rubber propagated

A

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

19
Q

how are rubber trees produced where South American Leaf Blight is a problem

A

use a 3 part tree with a seedling rootstock, a high yielding trunk, and a leaf blight resistant top

20
Q

planting density of rubber trees

A

360-416plants/ha

21
Q

when are rubber plants ready to be tapped

A

5-8 years. Need to be 50cm in circumference at 1m height. Trunk diameter of 7-8 inches

22
Q

how long are rubber tree productive

A

production increases until 15 years old. Normally tap for 20-25 years and replace at 30yrs

23
Q

what direction are rubber trees planted

A

N-S

24
Q

t/f: legume cover crops are used in between rubber trees as N source and weed control

A

t

25
Q

maintenance of rubber trees

A

remove all branches up to 2.5 m early on for smooth trunk for latex collection

26
Q

what are latex vessels in rubber trees

A

modified sieve tubes of phloem that run counterclockwise 2.5 degrees to the vertical

27
Q

laticiferous vessels

A

latex synthesis and transport

28
Q

what direction are rubber trees tapped in

A

clockwise direction

29
Q

excision method of tapping rubber trees

A

cut grove 30 degree angle mark 1-1.25m point, go 180 around tree, not too deep (dont reach cambium)

30
Q

how many times is cutting repeated for rubber tapping

A

1-3 days

31
Q

how much bark is consumed per year when rubber tapping

A

25 cm per year

32
Q

latex composition

A

water, terpenes, sugars, enzymes, etc

33
Q

rubber tapping intensity formula

A

S/2 d/2 = 100%
s=size of spiral (s2=half spiral)
d=frequency/day (d/2=every 2 days

34
Q

rubber trees are usually tapped for __ months and rested for ___ months

A

6, 3

35
Q

when does rubber cutting start in the day

A

early morning (6am) because latex flow is highest due to transpiration

36
Q

how many rubber trees can one person cut in a morning

A

500

37
Q

tapping schedule of rubber trees

A

first side tapped for 4-5 yrs
second tapped for 4-5 years
repeat cycle on original sides

38
Q

3 types of latex

A

Liquid (highest quality)
Cup rubber (cut lump that sticks to cup)
Scrap rubber - strip of rubber from cut surface

39
Q

how to coagulate rubber

A

10-25% ammonia (anticoagulent), 30-35% rubber, diluted with water

40
Q

how is rubber processed

A

latex poured into moulds and then formic or acetic acid is added to coagulate the liquid latex
rollers make rubber sheets with curd

41
Q

how much rubber does wild and modern clones yield

A

wild 300-450kg/ha
modern - 700-2000kg/ha

42
Q

what is done with the rubber wood after cut down

A

high quality paper and hardwood floor

43
Q

Major disease of rubber plants

A

South American Leaf Blight, Leaf Burning, Fusarium wilt, white root rot fungal disease, and bark disease

PLSC 333 (17 decks)

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