Alternative to Some Plastics
University City High School
and Haas Company
Chemistry, Physics, Environmental Science, and Physical
This project provides students an understanding of how
the scientific method is applied
to the solution of a scientific problem.
This project gives students an opportunity to see that
some plastics [synthetic substances] can be replaced
by almost equally efficient biomasses [natural substances]
completion of these activities the student will be able
a controlled scientific experiment
the tensile strength of the fibers of biomass in comparison
to the tensile strengths of polypropylene and tuffal.
the degradability of the fibers of biomass.
a best method for preparing paper using biomass.
a Nitrocellulose using the chosen biomass.
following projects developed previously under Project
Labs will help students to understand the structure
and behavior of different types of plastics.
- 1990 (pages 27 to 28)
Recycling - 1990 (pages 17 to 20)
Bouncing Balls - 1991 (pages 97 to 99)
Plastics - 1994 (pages 149 to 168)
know the effects of plastics on the environment and
to recognize a need for finding an alternative to plastics,
it is helpful for students to examine the following
projects developed previously under Project Labs.
" How Degrading " by Marilyn Krupnick
" Biodegradability. The Elusive Disappearing Act "
by Sister John Anne Proach
6 Pack Loop Rings Photodegradable? " By Sister Francis
project serves as an extension of the solutions to the
scientific problem stated in the above projects.
of plastics began with a search for a satisfactorily
substitute for ivory. John Wesley Hyatt (1837-1920)
developed a method of pressure working Proxylin a cellulose
nitrate of low nitration, that has been plasticized
with camphor and alcohol solvent. Patented as celluloid
it achieved a notable commercial success. Other plastics
were developed gradually over a few decades.
strength to density ratios, excellent thermal and electrical
insulation properties, and good resistance to acids,
alkalies, and solvents characterize plastics. But the
major problem caused by plastics is their inability
to degrade. Some types of plastic materials, once produced,
will not start degrading for about 10,000 years.
above fact has led to the question addressed in this
project. Is there any substance which has similar
properties to plastics but can degrade easily in short
period of times?
is a substance obtained from a living organism. Since
biomasses are easily biodegradable, scientists are looking
for biomasses, which can compete with plastics. Some
possibilities are Kenny, Sisal, Henequen, Agave, Bagasse,
Jute, Swiss Grass and Sanseviera. But the most promising
one is Hemp due to its higher efficiency in converting
the sun's energy to biomass than any other plant. It
has a very high yield at the rate of ten tons per acre
in approximately four months.
is the common name for an Asian annual herb that is
often called True Hemp or Indian Hemp. Hemp stems are
hollow and have a fibrous inner bark. Strong course
fibers are obtained from mature plants while soft fibers
are obtained from Hemp harvested at the time of pollination.
A study of the chemical composition of hemp reveals
two parts called Bast and Core. The bast contains higher
percent of cellulose whereas the core contains higher
percent of hemicellulose, both having some lignin content.
and tow) are obtained from hemp bast and hemp hurd is
obtained from hemp core.
1: Literature search on the background of Hemp
the following questions with detailed information in
one or two paragraphs for each question.
its scientific classification of Class, Phylum, and
are the differences between Hemp and Marijuana?
What climate conditions are needed to grow Hemp?
is Hemp preferable than other fibrous plants such
as Kenaf, Jute, and Sisal?
Give a detailed explanation.
Environmentally, what are the advantages of growing
Hemp as compared to Cottonand
Where is Hemp grown at present?
What is the cost per acre for growing Hemp? How do
you compare this with the cost of raw materials used
for the production of plastics?
the cost of Hemp fibers, Hurds, and Tow per pound.
Name some things that are made of Hemp and are available
in the market.
Where is Hemp grown on the American Continent?
When was the growing of Hemp started in U.S.A. and
Is it legal to grow Hemp in the U.S.A.? Give a detailed
explanation for your answer.
you think Hemp will be grown in the future in U.S.A.?
Support your answer with
2: Tensile Strength
the fibers of Hemp plant as strong as the fibers of
fibers have strength comparable to polypropylene fibers
if not exactly equal.
G clamp (or Wooden clamp with support)
Hemp single fibers
Forty gallon bucket
or two-liter mug Electronic Balance (optional)
we have to determine the radius and area of cross section
of the fibers. This has to be done in an indirect method
because we cannot measure the radius accurately by using
a ruler. If you have an electronic balance use fibers
of about sixty to seventy centimeter long. If you use
a normal beam balance use about 10 pieces of hemp fibers,
hemp yarn and about five to six meters long polypropylene
the length of hemp fibers in centimeters. Measure the
mass in grams of each hemp fiber separately up to four
significant figures using the electronic balance. Using
the density of hemp, calculate the volume and then find
the area of the cross section of each fiber. If you
do not have an electronic balance you have to use very
long fibers and yarns to give considerable mass to measure.
Repeat the same for three pieces of hemp yarn.
the polypropylene yarn to make it into thinner strings.
Get two or three single fibers, measure the length and
mass of each fiber accurately. Using the density of
polypropylene determine the volume and the area of cross
section of each single fiber of polypropylene.
two or three pieces of polypropylene yarn of about the
same thickness as hemp yarn and repeat the same steps
to determine their area of cross section. Tabulate your
the mass of a forty-gallon bucket. Fix the G-clamp at
the end of a table of about 1.5 meters height. Take
one single fiber of Hemp; tie one end of this fiber
to the clamp screw using a suicide knot. If you are
using a board with support, tie one end of the fiber
to the screw attached to the board. At the bottom end
of the fiber tie the 40-gallon bucket using the same
kind of knot. A double knot will give a firm grip. Make
sure the bottom of the bucket is 6 to 7 inches above
a one-liter container and fill it with water. (You can
use a bottle, a beaker, or a can). Measure the volume
of water that filled the mug. Since the density of water
is close to 1.0 kg / L we can convert the volume to
water slowly and in small amounts into the forty-gallon
bucket. Keep track of the number of containers of water
being added. When you feel that you are close to the
breaking point, add smaller amounts of water. Keep adding
water till the fiber breaks and the bucket drops to
the volume of the left over water in the container at
the time of breaking. Repeat the above steps for each
fiber of hemp and each fiber of polypropylene separately.
the same for hemp and polypropylene yarn also. Tabulate
the readings. Measure the tensile strength in N/sq.
and in lb./sq.in . Compare the results with the tensile
strength of Tuffal as measured by Instron 1125 tensile
tester at Rohm and Haas.
3: Biodegradability of Hemp
Hemp be easily decomposed to simpler and safer substances
as compared to plastics?
Hemp is a biomass it decomposes easily to simple sugars.
Cardboard box with lid
a one- percent salt solution by adding ten grams of
NaCl to one liter of water.
the mass of each yarn separately. If you do not have
an accurate balance you might have to use four or five
yarns together instead of one to place in a beaker.
six beakers 1 through 6. Add 100 ml of distilled water
to each beaker. In beakers 1, 3, and 5 put Hemp yarn
of known mass. In the other three beakers labeled 2,
4, and 6 put polypropylene yarns of known mass.
beaker of polypropylene and one beaker of Hemp yarn
(beakers labeled 1 and 2) should be placed in normal
light (fluorescent light). Make sure the light is kept
on day and night, throughout your experiment.
the cardboard box and fix the UV lamp on its lid using
duct tape, so that when the lid is closed only UV light
will fall inside the box. Take the second polypropylene
beaker and the second Hemp beaker (beakers labeled 3
and 4) and put them inside the cardboard box with the
UV light on. The UV light should be kept on, day and
night, throughout your experiment.
third polypropylene beaker and the third Hemp yarn beaker
(beakers labeled 5 and 6) should be placed in a dark
corner with no light.
the other six beakers 7 through 12. Add 100 ml of 1%
salt solution to each beaker. In three beakers labeled
7, 9, and 11 put Hemp fibers of known mass. In the other
three beakers labeled 8, 10, and 12 put polypropylene
yarn of known mass.
beaker of polypropylene and one beaker of Hemp yarn
with salt water (beakers 7 and 8) should be placed in
second beaker of polypropylene and the second beaker
of Hemp (beakers 9 and 10) should be placed in the card
board box with UV light on.
third beaker of polypropylene and the third beaker of
hemp yarn (beakers 11, and 12) should be placed in the
dark corner of the room with no light.
or twice a week depending on the rate of evaporation
of water take the Hemp yarn out of the beaker and dry
it on a paper towel separately. When you take the yarn
out of salt water it is better to rinse it in fresh
water before drying, just to remove any salt sticking
to the fiber which could cause an error in the mass.
After all the water is absorbed by the paper towel put
the hemp yarn in a tray and place it in the oven for
10 minutes at 120 degrees Celsius to drive off any left
over moisture. Take it out and let it cool for about
10 minutes. Measure the mass of the yarn after cooling.
Add some water to the beaker to bring the level back
to 100 ml. Make sure not to add salt water into the
distilled water beaker or vice versa. Put the hemp yarn
back into the beaker and place it back in its appropriate
this process for all Hemp yarns (all odd numbered beakers)
one at a time. Make sure to put the yarn back into the
same beaker from which you took it; and to put the beakers
in the same place where they belong.
polypropylene yarn from its beaker and follow the same
steps as above to find it's mass. Add enough water to
bring the level back to 100 ml and place the yarn back
into the beaker. Put back the beaker in its position.
Repeat for all even numbered beakers.
the date and the time on the clock while measuring the
mass of each yarn.
the whole process for about 10-15 weeks or longer, until
considerable changes in the masses are noticed. Tabulate
the results with mass versus time and find the equation
of the best-fit curve. (Try exponential, quadratic,
logarithmic and linear functions.) If this is a linear
regression find the slope and explain the significance
of slope for this experiment.
the total time needed to completely decompose the hemp
yarns by extrapolating the graph and also by using the
equation. (TI-83 graphing calculator will be helpful
in processing this data.)
your conclusions address the following questions:
the 12 beakers of your experiment, which conditions
showed the greatest change in the mass of the yarn?
you notice considerable difference in the change of
the mass for those placed in UV light versus those
placed in the normal light?
you think salt water acted different than the distilled
water? Support your answer with a proper explanation.
is the cause for the change in the mass of the yarns?
Give a proper scientific reason.
the change in mass violate the law of conservation
of mass? Explain.
4: Preparation of Nitrocellulose
we prepare nitrocellulose using Hemp?
Acid (fuming or > 50 % concentration)
Beakers of 50 ml
3 Beakers of 25 ml
the Hemp tow at 100�C till all the moisture evaporates.
Allow it to cool in the dessicator. Weight three samples
of about 0.25g of Hemp. Take one beaker, add 15g of
water to the beaker and place one sample of 0.25g of
hemp into the water. Mix well; label the beaker A.
the second beaker and label it B. Add 10g of water.
Then put the beaker under a ventilated hood and slowly
add 5g of sulfuric acid. (Remember always that the acid
should be added to the water and not the water to the
acid.) Mix it. Place the second sample of 0.25g of Hemp
tow in beaker B. Mix it well and put it aside.
the third beaker and label it C. Add 1.5g of water.
Place the beaker under a hood and then add 3g of nitric
acid slowly (Remember always that the acid should be
added to the water and not the water to the acid.) Then
add 9g of concentrated sulfuric acid to beaker C. This
is called the nitrating mixture. Now add the third sample
of 0.25g of Hemp Tow to this nitrating mixture. Mix
it well and put it aside.
the beakers in a very safe place under a ventilated
hood for 24 hrs. The next day take the Hemp tow from
beaker A and squeeze the water out. Place it in a dessicator
the Hemp tow from beaker B containing sulfuric acid,
wash it well in cold water and then in hot water several
times until all the acid is removed. Then wipe any left
over water by squeezing in paper towels. Place this
Hemp tow in another dessicator.
the Hemp tow from beaker C and wash it in cold water
well and then in hot water several times until all the
acid leaves the tow. Free it from all water and put
it in a third dessicator. After several hours when the
hemp tow is perfectly dry, measure the masses of each
sample separately and very accurately. Observe any changes
in the color, and texture. Record your observations
in a table.
5: Preparation of Paper
is the best technique to prepare paper using hemp hurds?
be formulated by students with the help from teacher.
seeds (Indian Spice called Methi)
cooker (or Pot with lid)
Sponge (8" by 11")
Cheesecloth (12" by 15")
one cup of hemp hurds and soak them in three cups of
water for several hours. (Test what time will give the
best results) Soak one tablespoon of Fenugrick seeds
in a cup of water for several hours.
the hurds and water in a pressure cooker and cook them
for 30 minutes. Shut off the pressure cooker and wait
till it cools. If you do not have pressure cooker use
a pot with a lid. Add more water and cook for a longer
the hemp hurds from the cooker and put them in a blender
with just enough water (1 cup). You can use the water
that is left in the pressure cooker. Blend the hurds
for five minutes.
add the soaked Fenugrick seeds and continue blending
until you see a fine paste. This is called pulp slurry.
the cheesecloth and place it on the piece of sponge
(8" by 11"). Pour the pulp slurry onto the
cheesecloth and press lightly to remove excess water.
Squeeze the sponge A couple of times to keep it dry
and to be able to absorb water from the pulp slurry.
place the cheesecloth containing the pulp between two
pieces of felt. Gently roll out pulp to a thickness
of 2 millimeters. Wring out excess liquid from felt.
the cheesecloth containing the paper from the felt cloth.
Set the cheesecloth with the paper out to dry overnight.
Stacking layers together will help to keep paper flat.
Gently remove the paper from cheesecloth the next day
while it is damp to prevent it from sticking to the
Repeat the process using cornstarch instead of Fenugrick
Take one tablespoon of all-purpose flour and add it
to one cup of water. Add this solution to the hemp hurds
while cooking them in water. Then blend them in the
blender without adding Fenugrick seeds and follow the
same steps given in procedure (A) after preparing the
Repeat the same process in C and use Fenugrick
seeds while blending the mixture in the blender. Follow
the rest of the procedure as in (A).
Repeat the same process as in (A), but add
3% sodium hydroxide solution to the pulp slurry.
conclusions should address the following:
your hemp papers made through processes A to E to
decide their quality. What tests do you plan to perform
one do you feel is the best process? Give all possible
reasons to support your answer.
the hemp paper you made with that made by paper wasps.
Give the similarities and differences.
to recycle the Hemp paper you made. Write your observations
while recycling your paper.
a brief procedure you followed to recycle your Hemp
What are the ecological implications of using Hemp
instead of wood for making paper?
What are the economical implications using Hemp instead
of wood for making paper?
(Questions 6 and 7 need some research on how normal
paper is made and the effects of the process.)
what way can you link this activity of making Hemp
paper, to the main goal of finding an alternative
This experiment is courtesy of