Cassava starch as an effective component
for Ideal Biodegradable Plastics
An Investigatory Project submitted to
the High School Department of
St. Paul College, Pasig
in partial fulfillment of the
requirements in Chemistry
Submitted by:
Group Number 9
Dianne Marie C. Roxas
Karla Angela P. Sese
Jannica Sibal
Mariel P. Sta. Ana
Teacher: Ms. Mendiola
Date of Submission: December 7, 2009
Abstract
The purpose of this experiment is to be able to help the society with its environmental issues by
creating a biodegradable plastic out of Cassava Starch. The researchers will use environment-friendly
materials which can be made into biodegradable plastics that will not harm the environment and will not
add to pollution problems. Cassava Tubers were ground and squeezed to extract its starch. Starch
obtained was weighed and divided into three equal parts; 80 grams in trial 1, trial 2 and trial 3. T1, T2 and
T3 also consisted of 60 ml Polyester resin and 50 grams of Polymer MEKP Hardener for T1, 75 grams for
T2 and 125 grams in T3. The components in every treatment or trial were mixed, stirred and then poured
in 3 different shirts with Petroleum Jelly and then sun-dried. Afterwards, different methods were used to
test the effectivity of the plastic. T1, T2 and T3 were sun-dried but they did not look like a plastic at all.
The researchers observed the product while waiting for it to dry but there were no signs of turning into a
plastic. The Cassava starch was too thick and the researchers realized that it would not turn into a plastic
because of its heavy weight and it would take more time before it would dry because of its thickness.
After letting T1, T2 and T3 dry under the sun, it became hard. Although the researchers had unexpected
results and the Cassava starch did not turn into plastic, studies have already proven that Cassava starch
could be used for making various types of packaging products. Cassava is a promising raw material for
the development of biodegradable plastics. The research activities have shown and proven that cassava
starch is effective in the development of biodegradable packaging materials such as plastics. Studies
determined the effectiveness of cassava starch as component of biodegradable plastic. Results confirmed
that cassava starch is ideal as tests proved its worth. Therefore, Cassava Starch is an effective component
for Biodegradable plastic.
Table of Contents
Introduction…………………………………………………………………………………………………1
Significance of the Study…………………………………………………………………………………...2
Review of Related Literature……………………………………………………………………………….3
Scope and Limitation……………………………………………………………………………………….5
Definition of Terms…………………………………………………………………………………………5
Methodology……………………………………………………………………………………………….7
Data and Results……………………………………………………………………………………………8
Discussion and Analysis…………………………………………………………………………………..12
Conclusion………………………………………………………………………………………………...13
Recommendations…………………………………………………………………………………………13
Bibliography………………………………………………………………………………………………14
Acknowledgment………………………………………………………………………………………….15
I. Introduction
Plastics are used because they are very useful, cheap, manageable and handy. Plastics have been
the fastest growing basic material because they are versatile, light weight, energy saving, durable and
recyclable. It has become a popular material used in a wide variety of ways. Plastics can last a long time
but unfortunately, this same useful quality can make plastic a huge pollution problem. Its long life means
it survives in the environment for long periods where it can do great harm. Non-biodegradable plastics are
durable but they degrade very slowly; molecular bonds that make plastic so durable make it equally
resistant to natural process of degradation. Plastic packaging provides excellent protection for the
product, it is cheap to manufacture and seems to last forever. Lasting forever, however, is proving to be a
major environmental problem. Plastics are also a huge problem in waste disposal and studies have been
made to find a substitute material which can be used in making biodegradable plastics. Because plastic
does not decompose, and requires high energy ultra-violet light to break down, the amount of plastic
waste in our oceans is steadily increasing. Studies that have been done locally show about 3, 500 particles
of plastic per square kilometer of sea off the southern African coast. The world production of plastic is
estimated to be more than 100 million tons per year. Plastics are indeed a threat to wild life. A great proof
for this is that plastics have been found in the stomachs of sea turtles, birds, and fish all over the world.
Tragically, millions of tons of plastic are poisoning our oceans. Plastic pollution harms people, animals,
and the environment because it is non-biodegradable. In the marine environment, plastic breaks down into
smaller and smaller particles that absorb toxic chemicals, are ingested by wildlife, and enter the food
chain that we depend on. People need alternative and effective components of plastic that is safe and
biodegradable which will not harm and pollute the earth.
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II. Problem
Could Cassava Starch be an effective component for ideal Biodegradable plastic?
III. Hypothesis
a. If you’d use the starch of Cassava plant as a component of plastic, then the plastic will be
biodegradable.
b. If you’d use the starch of Cassava plant as a component of plastic, then the plastic will be nonbiodegradable.
IV. Significance of the Study
This study is important to be able to help Mother Earth in reducing its pollutants and toxic or
harmful wastes. Through this study, the researchers will be able to help other people, the animals and the
environment. The researchers would like to stop plastic pollution and be part of the solution. Plastic bags
and bottles, like all forms of plastic, create significant environmental and economic burdens. They
consume growing amounts of energy and other natural resources, degrading the environment in numerous
ways. In addition to using up fossil fuels and other resources, plastic products create litter, hurt marine
life, and threaten the basis of life on earth. There is over 45 million tons of plastics per year and nearly
every piece of plastic ever made still exists today because of its long-life properties. Biodegradable
plastics could be an effective solution to all of these problems. Biodegradable plastics are a much better
choice than non biodegradable plastics because they are friendlier to the earth and the environment.
Biodegradable plastics break down faster, can be recycled easier and are non-toxic. With these
characteristics of biodegradable plastics, we could help save lives and the environment as well and reduce
the threat plastics give to marine life. Plastic, the wonder material that we use for everything, is perhaps
the most harmful of this trash because it does not readily break down in nature but if it is biodegradable,
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these plastics break down faster so they have a much shorter effect on the earth, and they will degrade
completely. Normal plastics are manufactured using oil, and this process is very harmful to the
environment by polluting the air and environment, but this is not the case with green biodegradable
plastics. Using biodegradable plastics will minimize the effects that these products have on the earth, and
help eliminate their waste much faster.
V. Review of Related Literature
In the past few decades, there has been a marked advance in the development of biodegradable
plastics from renewable resources, especially for those derived from starch-based materials. The goal of
this development is to obtain biodegradable plastics that perform as well as traditional plastics when in
use and which completely biodegrade at disposal. Several starch-based plastics have been introduced into
the market, and are used in some applications now. Starch foam is one of the major starch-based
packaging materials. It is produced by extrusion or compression/explosion technology. This product has
been developed as a replacement for polystyrene which is used to produce loose-fillers and other
expanded items. Another type of starch-based plastics is produced by blending or mixing starch with
synthetic polyester. For this type of biodegradable plastics, granular starch can be directly blended with
polymer, or its granular structure can be destructurized before being incorporated into the polymer matrix.
The type of starch and synthetic polymer as well as their relative proportions in the blends influence the
properties of the resulting plastics. The last group of starch-based plastics is polyesters that are produced
from starch. The major starch-derived polyesters in the market now are polylactic acid and
polyhydroxyalkanoate. Experimental studies have demonstrated that cassava starch could be used for
making various types of packaging products. As a major source of starch in tropical and subtropical
regions, cassava is a promising raw material for the development of biodegradable plastics in these areas.
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Research has been done on biodegradable plastics that break down with exposure to sunlight
(e.g., ultra-violet radiation), water or dampness, bacteria, enzymes, wind abrasion and some instances
rodent pest or insect attack are also included as forms of biodegradation or environmental degradation. It
is clear some of these modes of degradation will only work if the plastic is exposed at the surface, while
other modes will only be effective if certain conditions exist in landfill or composting
systems. Starch powder has been mixed with plastic as a filler to allow it to degrade more easily, but it
still does not lead to complete breakdown of the plastic. Some researchers have actually genetically
engineered bacteria that synthesize a completely biodegradable plastic, but this material, such as Biopol,
is expensive at present.
The diversity and ubiquity of plastic products substantially testify to the versatility of the special
class of engineering materials known as polymers. However, the non-biodegradability of these
petrochemical-based materials has been a source of environmental concerns and hence, the driving force
in the search for ‘green’ alternatives for which starch remains the frontliner. Starch is a natural
biopolymer consisting predominantly of two polymer types of glucose namely amylose and amylopectin.
The advantages of starch for plastic production include its renewability, good oxygen barrier in the dry
state, abundance, low cost and biodegradability. The longstanding quest of developing starch-based
biodegradable plastics has witnessed the use of different starches in many forms such as native granular
starch, modified starch, plasticized starch and in blends with many synthetic polymers, both
biodegradable and non-biodegradable, for the purpose of achieving cost effectiveness and biodegradation
respectively. In this regard, starch has been used as fillers in starch-filled polymer blends, thermoplastic
starch (TPS) (produced from the combination of starch, plasticizer and thermomechanical energy), in the
production of foamed starch and biodegradable synthetic polymer like polylactic acid (PLA) with varying
results. However, most starch-based composites exhibit poor material properties such as tensile strength,
yield strength, stiffness and elongation at break, and also poor moisture stability. This therefore warranted
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scientific inquiries towards improving the properties of these promising starch-based
biocomposites through starch modification, use of compatibilizers and reinforcements (both organic and
inorganic), processing conditions, all in the hope of realizing renewable biodegradable substitutes for the
conventional plastics.
VI. Scope and Limitations
This experiment only covers plastic bags, not including other plastic materials such as plastic
containers, plastic cups, straws and other plastic utensils. The experiment can be done in a matter of 2
hours, excluding the sun-drying procedure. Most of the materials used in the experiment are accessible
and can be bought in supermarkets. However, there are a few which are not available in nearby stores.
Premix Polyester Resin and Polymer MEKP Hardener are manufactured by Polymer Products (Phil) Inc.
and can be bought in Bagong Ilog, Pasig City.
VII. Definition of Terms
Biodegradable - able to decompose naturally: made of substances that will decay relatively quickly as a
result of the action of bacteria and break down into elements such as carbon that are recycled naturally
Starch – a white, granular or powdery, odorless, tasteless and complex carbohydrate found chiefly in
seeds, fruits, tubers, roots and stem pith of plants, notably in corn, potatoes, wheat, and rice; an important
foodstuff and used otherwise especially in adhesives and as fillers and stiffeners for paper and textiles.
Plastics – the word plastic is derived from the words plasticus (Latin for “capable of molding”) and
plastikos (Greek “to mold,” or “fit for molding”). Plastics are polymeric, moldable and synthetic materials
which are derived from fossil fuels, such as oil, coal or natural gas. Plastics consist of organic (carboncontaining) long molecular chains that give them many of their unique properties. They can be made hard,
flexible, strong, transparent, light and elastic.
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Polymer – long-chain molecules that repeat their structures over and over
Polyethylene Bags - the bags that you will see commonly used, such as plastic grocery bags, are made
from petroleum byproducts, which is the root of most all of the environmental problems that they are the
source of. Not only do they take substantially longer to break down or degrade, but as they do they release
highly toxic chemicals.
Resin – It is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for
its chemical constituents and uses, such as varnishes and adhesives, as an important source of
raw materials for organic synthesis, or for incense and perfume.
Polymer Methyl Ethyl Ketone Peroxide (MEKP) - The most popular type of hardener because of
its economy and ease of use.
Polyester Resin - Polyester resins are the most commonly used matrix in the marine and
composite industry. These resins are styrene-based, flammable and catalyzed when combined
with Methyl Ethyl Ketone Peroxide(MEKP). Polyester resins are unsaturated resins formed by
the reaction of dibasic organic acids and polyhydric alcohols.
Premix Polyester Resin R10-60 – It is a fast gel premix polyester resin used for wood, kapiz, and
other lamination with cellophane, “Lumirror” or “Mylar” films. It is also used to make
decorative jewels and flowers from ceramic molds, to make small coatings from polyethylene &
silicone rubber molds, and to cast on intrinsic molds such as steel or bass frames.
Plastic Resin Glue – Plastic resins are made by heating hydrocarbons in what is known as the
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"cracking process." The goal here is to break down the larger molecules into ethylene, propylene,
and other types of hydrocarbons. The amount of ethylene produced depends on the cracking
temperature. Once the cracking process has been completed, the compounds are formed into
chains that are known as polymers. Different polymers are combined to make plastic resins that
have the characteristics needed for different applications. Once the plastic resins have been
formed, they are used to make many different kinds of products.
Catalyst - chemical that accelerates chemical reaction: a substance that increases the rate of a chemical
reaction without itself undergoing any change
VIII. Methodology
A. Materials

2 Cassava Tubers

180 ml of Premix Polyester Resin

300 ml of Polymer MEKP Hardener

100 grams Petroleum Jelly

3 old shirts

Measuring cup

Grater

Plastic Spoon

Knife

3 Plastic Containers

Chopping board
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B. Procedure
1. Gather the Cassava Tubers. Ground and squeeze it to extract the starch.
2. Get hold of 240 grams of the starch and divide it into 3 equal parts: 80 grams in trial 1, trial 2 and
trial 3.
3. Place 60 ml of the plastic resin glue (Premix Polyester Resin) with 50 grams of flour catalyst for
T1, 75 grams for T2 and 125 grams in T3.
4. Mix and stir the components and pour it in the shirt with Petroleum Jelly and let it dry under the
sun.
5. To test its capacity to carry weight, use the plastic to carry objects.
6. For its ability to hold water, put water inside the plastic.
7. To test its tensile and bending properties, stretch the plastic as far as you can.
8. Repeat steps 5-7 using T2 and T3.
IX. Data and Results
Trial 1
Trial 2
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Trial 3
Materials
Sun – drying procedure
Amount of
Amount of
Amount of
Did the color
Cassava
Plastic Resin
Polymer
change?
Starch (g)
Glue (ml)
MEKP
Hardness
Can it be peeled
Texture of
from the shirt
the final
completely?
product
Hardener (g)
T1
80 g
60 ml
50 g
No
It hardened
It can be peeled
but did not
off the shirt
turn into
completely
Rough
plastic.
T2
80 g
60 ml
75 g
No
Hardened a
It can be peeled
Some parts
little but did
off the shirt but
are smooth
not turn into
not completely
but most of
plastic.
the parts
are rough.
T3
80 g
60 ml
125 g
Yes, it
Did not
It cannot be
Some parts
changed to
harden at all.
peeled off the
are rough
shirt at all
but most
color
Yellow.
parts are
smooth.
The researchers had unforeseen outcomes. The researchers had 3 trials: T1, T2 and T3. The three
trials contained 80 grams of cassava starch and 60 ml of plastic resin glue each. They also put 50 grams of
Polymer MEKP Hardener in T1, 75 grams in T2 and 125 grams in T3. The researchers used plastic resin
glue because plastic resins are made by heating hydrocarbons where larger molecules is breaking down
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into ethylene propylene. Once the process has been completed, the compounds are formed into chains that
are known as polymers. Polymers are combined to make plastic resins. Once the plastic resins have been
formed, they are used to make several varieties of products. Another reason on why the researchers used
plastic resin glue on their experiment because based on studies, plastic resin glue dries to a glass-hard
consistency depending on the ambient temperature. On the other hand, the researchers used Polymer
MEKP Hardener on their research because when it is mixed with the resin, the resulting chemical reaction
causes heat to build up and improve or harden the resin to make the product more effective. They used
different amounts of MEKP so that the researchers would know if what would work the best, the
container with more MEKP or the one with less. After mixing and stirring the treatments, it was
transferred on 3 separate shirts with Petroleum Jelly then sun-dried. After 4 hours of observing the
conducted experiment, their products hardened but did not look like it would turn into plastic like they
have been expecting. T1 is the hardest of them all hence, it can be peeled off the shirt and since T3 did not
harden, its texture is smooth and it cannot be peeled off the shirt in any way. T2 hardened a little but still
did not look like plastic. Some parts are smooth but most parts are rough. It can also be peeled off the
shirt but not completely. In order for us to test its capacity to carry weight, we used the plastic to
carry objects, we also tested its tensile and bending properties, T1 had the best result for both.
We also tested for its ability to hold water by putting water inside the three trials, none of our
trials worked. In view of the fact that the thickness of the cassava starch on the shirt is a factor why the
outcome didn’t work as expected. The cassava starch was not spread evenly making it so thick, thus, the
cassava starch being too thick means it would also be difficult for it to dry.
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X. Discussion and Analysis
The researchers have studied the final product of all three trials and have observed that: In the
first trial, the researchers have observed that among the three trials it was the most successful because of
the hard and sturdy layer it produced. It was strong enough to carry objects but it can also be bent without
breaking. Even when it was peeled from the white cloth it did not break down. The researchers believe
that trial one would be the most reasonable and efficient trial to use for a biodegradable plastic. In the
second trial, the researchers observed that the final product was somewhat not as whole as trial one. It
made a rather sticky substance that was very flimsy and fragile, especially when it was peeled off the
white cloth. In the third trial, the researchers have observed the looseness of the final product. Though it
has been sun dried, it kept its damp and very sticky attribute. It showed since of being very flimsy and
loose. When trial three was peeled of it easily broke down because of its very gooey feature. The
researchers believe that trial three would be the most inefficient trial to use for a biodegradable plastic
because its lack in plastic features.
The physical properties of plastic include transparency, flexibility, elasticity, permeability,
ductility, electrical resistance and its ability to hold water. The researchers observed that the final
products lack plastic properties. None of the 3 trials were transparent and for its flexibility, it was only T1
that can be bent without getting destroyed. Though T1, T2 and T3 lack those properties, it can still be
considered as an effective component for biodegradable plastics because they are biodegradable.
Studies have already proven that cassava starch is an effective component of biodegradable
plastics. However, the end product of the experiment did not look like a plastic at all. The researchers had
altered the suggested procedure found on the internet. The procedure was not also vey precise and
specific. A factor that might have affected the results was the use of chemicals. The shirts, petroleum
jelly, Polymer MEKP Hardener were only used as substitutes for the actual materials. The shirt was used
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to replace silk screen and Petroleum Jelly was used instead of oil. Polymer MEKP Hardener was used a
substitute for the flour catalyst. Also, the appropriate type of Plastic Resin must be selected to make the
particular type of product needed but in the procedure, no type was specified so the researchers used
Premix Polyester Resin. There were lots of flaws in the experiment which probably was the reason why
the researchers failed in the experiment. The cassava starch was not also ground and it was the reason
why it was thick and it was not also spread thoroughly. The weather was also a factor because sunlight
and heat was really needed for the cassava starch to dry but then, it was not too sunny.
XI. Conclusion
Even though the researchers had unanticipated outcome, they still conclude that Cassava starch
can be used as a biodegradable polymer to replace plastics in packaging materials. Cassava starch can be
applied for the production of biodegradable plastics. Starch can be incorporated into plastics to improve
the biodegradability of the plastic and finished product. According to different studies and research,
cassava starch could be used for making a range of types of plastics and is now being used in the market.
Cassava has a promising raw material and its starch have the characteristic of being able to absorb
humidity, just like normal plastics. It’s also has a low bulk density and only a little modification is needed
to increase its moisture content which is needed in producing plastics. Since starch is a natural polymer
and is biodegradable, it can play as an important role in the biodegradable plastic manufacturing.
Therefore, Cassava starch is an effective component in biodegradable plastics.
XII. Recommendations
Although the researchers were not successful in this experiment and had unexpected results, they
still recommend this topic which can be used in Investigatory Projects. For those who are interested in
this topic and would like to perform this experiment in the future, the researchers are suggesting that you
should follow the right procedure and be accurate with your measurements. People should have sufficient
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background information about the chemicals that they will be using and they make sure that they areusing
the right materials or chemicals. Remember that little factors might affect the outcome so you should be
careful in performing the different steps. Future experimenters should clarify the procedure and make sure
that the ingredients that you will be using as substitutes will be effective in this project.
XIII. Bibliography
Jodee Redmond. (2003) What is Plastic Resin? Retrieved December 2009, from
http://www.wisegeek.com/what-is-plastic-resin.htm
Australian Academy of Science (2002) Making packaging greener – biodegradable plastics Retrieved
December 2009 http://www.science.org.au/nova/061/061key.htm
Cassava and Starch Technology Research Unit (1998) Biodegradable and Physical Properties of
Cassava
Starch/Polycaprolactone
Blend.
Retrieved
September
2009
from
http://www.cassava.org/Pub/1998/1998_04.htm
(2007) Cassava starch as an effective component for Ideal Biodegradable Plastic Retrieved September
2009 from
http://www.investigatoryprojectexample.com/biochemistry/cassava-starch-as-biodegradable-plastic.html
Jaarsma, Frank. (2000) Physical And Mechanical Properties of Plastics. Retrieved December 2009 from
http://www.thefreelibrary.com/Physical+And+Mechanical+Properties+of+Plastics.-a067717233
Biodegradable plastic. In Wikipedia. Retrieved September 2009, from
http://en.wikipedia.org/wiki/Biodegradable_plastic#Advantages_and_disadvantages
http://sundoc.bibliothek.uni-halle.de/diss-online/02/02H017/t7.pdf
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http://www.ciat.cgiar.org/asia_cassava/pdf/proceedings_workshop_00/538.pdf
Japan Echo Inc. (2005) Plastic from plants Retrieved December 2009 from,
http://web-japan.org/trends/business/bus050107.html
Biodegradable Plastic. Retrieved December 2009 from,
http://www.mindfully.org/Plastic/Biodegradable-Plastic.htm
XIV. Acknowledgement
The researchers would like to acknowledge Dianne Roxas’ parents for allowing them to work on
the experiment in their house.
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