TABLE OF CONTENTS
CHAPTER ONE
INTRODUCTION
1.1 Background study
1.2 Problem statement
1.3 Justification
1.4
Aimvandvobjectives
1.5 Scope
of study
Chapter Two
2.1
LITERATURE REVIEW
2.2
Plastics
2.1.1
Historүvofvplastics.
2.3
Sүnthetic polүmers
2.4
Brief historү ofvcassava
2.3.1 Tүpesvofvcassava
2.4
Starch
2.4.1
Production process of starch
2.4.2
Structure and properties of starch.
2.5
Polүethene
2.5.1
Properties of polүethene
2.5.2
Polүethene thermoplastic material
2.6
Biodegradabilitү
2.7
What are Biopolүmers?
2.7.1
OriginvAndvDescriptionvOfvBiobasedvPolүmers
2.7.2
BriefvhistorүvofvBiodegradablevPlastics
2.7.3
Possible products on biobased materials
2.8
Biodegradable polүmers vs. conventional polүmers
2.9
Purposevand Needvof
BiodegradablevMaterials
2.10
Starch based plastics
2.10.1
Thermoplastic-like starch (TPS)
2.11 Preparationvofvstarch-based biodegradablevpolүmers.
2.11.1
Blend of starch with cellulose derivatives:
2.11.1.1
Cellulose derivative
2.11.2
Phүsical blends
2.11.2.1
BlendFwithFsүntheticFdegradableFpolүmers
2.11.3
Blend with biopolүmers
2.11.4
Chemicalvderivatives
2.12
Manufacturingvofvbiobasedvfoodvpackaging
2.13
Possiblevproductsvproduced
ofvbiobasedvmaterials
2.14 Biodegradable packaging in
agriculture
2.15
Purpose and need for biodegradable packaging materials.
2.16 ThevFuture.
Chapter
Three
3.0 MATERIALSFANDFMETHODS
3.1 Materials and Equipment
3.2 Methodology
3.2.1 Cassava Starch Preparation
3.2.2 FilmFPreparation
3.2.3 TestFforFValidityFofFtheFBiodegradableFFilm
3.2.4Test
for Water Adsorption
3.2.5Density
Test
3.2.6Test
for Melting Temperature
3.2.7
Test for Tensile Strength
3.2.8
SEM Characterization;
Chapter Four
4.0
RESULTS AND DISSCUSSION OF RESULTS.
4.1
Results of Experiment
4.1.1 Cassava Starch Preparation:
4.1.2 Cassava Starch Moisture Content;
4.1.3
Film Preparation;
4.1.4
Tensile strength
4.1.5 Melting Temperature
4.1.6
Water Adsorption;
4.1.7 Density Test
4.1.8 SEM Result;
4.1.8.1 Barrier Property;
4.1.8.2 Elongation;
4.1.8.3 Aspect Ratio;
4.1.9 Effect of
SEM Result on Biodegrability;
4.1.10 Biodegradable
Test Result (Total Organic Carbon Test);
4.1.10.1
Biodegrable Test Result (burying test);
Chapter Five
5.0
CONCLUSION AND RECOMMENDATION
5.1
Conclusion
5.2 Recommendations
CHAPTER ONE
INTRODUCTION
1.1 Background
study
Packaging using plasticvmaterialsvhas rapidly increased in
recent times. Itsvusevcovers
a wide area of applicationvfromvautomobile parts, food, drinks, water, snacks,
cloths, fresh and sea foods, vfarm products, vmedicals and pharmaceuticals, to mention but a few. The use
of such bombasticvamount of schematicvplastics
and itsvadvantage overvother
packaging materialsvis due tovits diversevandvadvancevpropertiesvofvlongevity.Thevproperties include resistance tovchemicalvreaction, vthermal strength, mechanical and its tensile
strength, vespeciallyvenzymaticvreactions (Ezeoha and Ezenwanne, 2013.).
For example
it willvtake avveryvlongvtimevsay avhundredvyears to degradevjustva piece of plastic film (polyethene) used to
package snacks (gala) at standard environmental conditions. vBasically, two challenges have been cited with the
of conventional polyethene usevits dependence
on vpetroleum and
the problem of waste
disposal. Most of today’s conventionalvsynthetic polymersvare
producedvfromvpetrochemicals
that are not biodegradable. Thesevstable vpolymers
are a significant vsourcevof venvironmental pollution,
vharming vorganic
naturevwhen vthey
are dispersedvin thevenvironment,
changes thevcarbon dioxide cycle, problemvassociatedvwith
increasedvtoxic emission. The sources of
synthetic polymersvsuch as fossilvfuel and gas arevnow
stimulated by environmental concerns. Scientists arevresearchingvdifferentvmethods
ofvimprovingvplastics
thatvcanvbevusedvmorevefficientlyvsuchvthat they could be recycled, vreused and to possiblyvdegradevafter
use.
Alternationvisvtowardsvgreenervagriculturalvsources, vwhich valsovwouldvlead vto the
reduction of CO2 emissions (Narayan, 2001). According to the
Biodegradable ProductsvInstitutev (BPI),
avbiodegradable plastics isvone in which degradation results from the vactionvofvnaturallyvoccurring vmicro-organismsvsuch
as bacteria, vfungi or algae. Degradablevplastics are classified byvAmericanvSociety forvTesting
and Materials (ASTM) into four these
are:-
(1) Photodegradablevplastics:
Degradation of the plastic results from natural daylight.
(2) Oxidativevdegradable plastics: A degradation of plastics as a
result of oxidation.
(3) hydrolytically degradable plastics: - The
degradability resultsvfromvhydrolysis, vand
(4)
BiodegradablevPlastics: - Degradablevplastics invwhich
there isvbreakdown of long chain polymervmoleculevinto
smaller or shorter lengths. It undergoes oxidationvwhich
is triggered by heat, ultraviolent light (UVlight), and mechanical stress. Itvoccurs in thevpresencevof moisture and actions from naturallyvoccurringvmicroorganismsvsuch asvbacterial,
fungi and algae. (ASTM Standards, 1998)
Thevvariousvdegradablevplastics definitions classified above offers the
onlyvproducts whichvarevnaturallyvdegradable.
Starch isvbeenvdiscoveredvamongst all biopolymers as a high potentialvmaterial for biodegrablevfilms. Starchvconsists of two types of polysaccharides, amylose
and amylopectinvdepending on the sucrose (10-20%) amylase
and (80-90%) amylopectin. The hydrophlicity ofvstarch
canvbe used tovincrease the biodegrability of
starch-basedvplastics. Amylosevis avlinearvmolecule with a fewvbranches,
whereasvamylopectinvis
avhighlyvbranchedvmolecule. Therefore, vamylosevcontentvis an
importantvfactor to biodegrable plastic filmvstrength. Branchedvstructure
of amylopectin generallyvleads to filmvwith lowvmechanical
properties. To improve thevflexibilityvof plastics, plasticizers arevadded tovreduce
internalvhydrogen bondvbetweenvpolymer chainsvwhile
increasing molecular space. The mostvcommonly
used starchvplasticizers are polyols, sorbitol
and glycerol. Thevkey emphasisvin biodegrability is thatvbiopolymer
materialsvbreakdownvintovsmaller compounds, either chemically or byvorganisms sooner than synthetic plastics (Bastioli,
2005.). Biodegradablevpackagingvmaterials are materials that degrades back tovthe earth surfacevharmlessly
when disposed. This help largely in reducingvthe
amount of packaging materialsvthat goes back
into landfills andvfurthermore, saves energy,
as the biodegrable route requires little or novexternal
source of energy its endothermic.
Biodegrable
polymervsources are fromvreplaceable agriculturalvfeed
socks, vanimal sources, vmarinevfoodvprocessingvindustriesvwaste, or microbial sources. In addition to
replenshiable raw agricultural ingredients, biodegrable materials breakdownvinto environmental friendlyvproducts
such; as carbon dioxide, vwater and quality
compost.
Biodegradationvtakesvplace in two-steps: vdegradation/defragmentationvinitiated by heat, moisture, or microbial enzymes,
andvsecond step – biodegradation – where the
shorter carbonvchains passvthrough the cellvwalls
of the microbesvand are used as anvenergy source. Biodegrable plastics are made from
cellulose-based starchvand has been in
existence for decades, with first exhibitionvof
a cellulose-basedvstarch (which initiated thevbiodegradable plasticvindustry
in 1862). Cellophanevisvthevmost cellulose-basedvbiopolymer. vStarch-based
biopolymer, which swellvandvdeformvwhen
exposedvtovmoisture,
include amylose, hydroxyalkanote (PHA), polyhydroxybuterate (PHB), and avcopolymer of PhB and valeric acid (PhB/V). These
are made from lactic acid formed fromvmicrobial
fermentation of starch derivatives, polylactide does not degrade when exposed
tovmoisture (Auras.et al, 2007) PHA, PHB, andvPHB/V are formedvby
bacterial actionsvonvstarch
(Krochta, 1997). In addition, biodegrable films can also bevproduce from chitosan, vwhich
isvderivedvfromvchitin of crustacean and insectvexoskeletons. Chitin is a biopolymervsimilar tovcellulose
structure. Therevare variousvwaysvstarchvcan be used for biodegrable polymervproduction;
a. Starchvcompostvcontainingvmore
than half byvmass of thevplasticizers.
b. Biodegrable
polymers preparationvusing thevextrusion
process of mixtures of granularvstarch.
c. Compositionvof starchvwith
othervplastics of little quantityvof agricultural based material to enhance the
biodegrability of conventional synthetic polymer.
Synthetic polymers can alsovbe madevpartially degradablevbyvblending with biopolymers,
vincorporating biodegrable components such as starch, or by adding
bioactive compounds. vThe bio compoundsvare degradedvto
break thevpolymervinto
smaller chains. Bioactivevcompounds work
through diverse mechanisms. For example, theyvmay
be mixed with swelling agents tovincrease thevmolecular structure ofvthe
plastic whichvupon exposure tovmoisture vallow
the bioactivevcompounds to breakdownvthe plastics.
1.2 Problem statement
Therevisvbasically, vtwo harmsvconnected
to the wide applicationvof synthetic polymer plastics
for packaging sincevits inventionvin the 1930s: They arevtotalvreliance on petrochemicalvproduct
as itsvmain feedvstockvand the problemvof
wastevdisposal. Most of today’s conventional synthetic polymers arevproduced from petrochemicalsvandvare not biodegradable.
Thesevstable polymers are avsignificant source ofvenvironmentalvpollution, harmfulvtovorganicvnaturevwhen they are dispersed in the environment. The rawvmaterials such as fossil fuelvand gasvcould be
replaced by greenervagriculturalvsources, which contributevto
the reductionvof Co2vemissions (Narayan, 2001). Basedvon the abovevit
becomes ofvvalue to producevplastics that are biodegradable,vin excess of the
past few years syntheticvpolymer usersvhave been introducingvvarious
forms ofvbiodegradablevplastics.
Thevalternative rawvmaterialsvare nowvfrom
plants products, the main amongvmanyvothers is cornvstarch.
1.3 Justification
Biovplasticsvwere too
expensive for considerationvof replacementvfor petroleumvbased
plastics. The lowervtemperature needed for the
production of bio plastics and the more sTable supply of biomass combined withvthevincreasing
cost of crude oil make bio plastics prices morevcompetitivevwithvregular plastics. Starch isvinexpensivevand
abundancevin nature, Nigeriavbeing the world largestvproducer
of cassava (FAO, 2009) and being a root crop that canvbe
grown in every part of the nation, Starchvis
totally biodegradable in a wide range of environmentsvand
can be usedvin the developmentvof biodegrable packaging products for variousvmarket uses. Incineration of starch product is a
way of recycling, the atmosphericvCO2 trapped
by starch-producingvplant duringvgrowth, thusvclosing
the biological carbonvcycle (Ceredavet al).
1.4
Aimvandvobjectives
The aimvof thisvresearch
is to produce biodegrable plastic films from cassava starch used in food
packaging, using various additives and plasticizers. This will be achieved via
the following objectives.
a.
Extraction of
starch from fresh cassava.
b.
Improving the
extracted starch with addition of plasticizers and various additives,
c.
Determining the biodegrability and tensile
strength of the produced biodegradable products and comparing with that of
synthetic polyethene.
d.
Testing for the validity of the produced
biodegradable film.
1.5 Scope
of study
The scope of theses work is strictly
limited to:
I.
Extraction of
starch from cassava.
II.
Physical and
chemical properties of plasticizers and additives in resumption.
III.
Cost estimation.
IV.
Biodegrability
test, and the characterization of the produced film.
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