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Prepared by:-
Monica
Vikas Bansal

Green Plastic – fruit container

Introduction:
The problem of plastic packaging waste
? Use of plastic –
a) European countries- 60kg/person/year
b) US - 80kg/person/year
c) India – 2kg/person/year
? Basic material used in packaging include:-
a) paper b) paperboard
c) cellophane d) steel
e) glass f) wood
g) textiles h) plastics

Food Packaging – Plastic Tray

Important properties - plastics
? Strength and stiffness
? Barrier to gases, Moisture & grease
? Resistance to food components attack &
flexibility
? Good processability
? Good melt flow behaviour
? Good thermal properties
? Good optical properties i.e. should be
highly transparent (very imp for consumer)
? Good sealability and printing properties

Waste management
? Recycling
? Source reduction of packaging material
? Composting of degradable wastes
? Incineration

Application for biodegradability
? Sacks and bags – used for composting
waste
? Foamed tray - food packaging
? Cups & cutlery - fast food sector
? Soluble foams - industrial packaging
? Film wrapping
? Laminated paper
? Mulch films
? Nursery pots
? Plant labels - agricultural products
? Diapers & tissues – hygiene products

INTRODUCTION:
? 2 main groups of biodegradable plastics:-
a) polylactic acid (PLA)
b) starch based polymers
degradable but full degradability
will occur only when the pdts made from
these polymers are disposed off properly in
a composting site

Lactic acid
To replace conventional plastics with plant
derived alternatives by three approaches :-
? Converting plant sugar into plastics
? Producing plastic inside m.o
? Growing plastic in corn & other crops
? Sugar lactic acid polymerization polylactic
acid

Lactic acid can be produced by following
method:-
a) produced synthetically from hydrogen
cyanide & acetaldehyde
b) naturally from fermentation of sugar, by
Lacobacillus

Polylactic acid (PLA)
? Behaves quite similarly as polyolefines
? Converted to plastic by extrusion &
injection moulding
? Drawbacks:-
a) high price of raw material
b) lack of composting
infrastructure
? Polymers that are mostly selected for use :-
a) 90% L-lactide
b) 10% racemic D,L-lactide

Properties of these PLA:-
a) Readily polymerized
b) Easily meltprocessable
c) Easily oriented
d) Tg – 60oc
e) m.p temp. – 155oc

f) Tensile strength – 80-110 Mpa with
elongation at break of up to 30%
g) similar as polystyrene
h) used in direct food contact with aqueous,
acidic & fatty foods under 60oc &
aqueous & acidic drinks served under
90oc

Native Starch
? Mostly used for industrially extracted starch
? Inexpensive
? Abundant product available from potato,
maize, wheat and tapioca
? Starch means storing energy & found in :-
- granule form in seeds
- roots
- tubers
- stems, leaves & fruits of plant
? Biodegradable in nature

2 main components of starch are:-
a) Amylose (linear)
b) Amylopectin (branched) – largest
macromolecule & major component of
starch

Fundamentals of Green Plastics in Food Technology

Thermoplastic starch (TPS)
? Also called destructurised starch
? Homogeneous thermoplastic substance
? Made from
native starch
swelling in a solvent
(plasticizer)
extrusion treatment
(kneading & heating)
Thermoplastic starch
? Water & glycerol – used as plasticizers

Water resistance of starch based
products
? TPS – common thermoplastic polymer
? TPS shows – low permeability for oxygen
(TPS 43 cm3/m2/min/bar
LDPE 1880 cm3/m2/min/bar)
this makes it suitable for
packaging applications
? High Permeability for water vapor & Quick
ageing - unsuitable
(4708 cm3/m2 compared to 0.7 cm3/m2 of LDPE)

? Problem can be overcome by :-
a) blending (thermoplastic starch +
hydrophobic synthetic polymers)
b) by the production of more hydrophobic
TPS derivatives
? Expensive
? Mechanically instability

Polyhydroxyalkanoates (PHA)
? Plant sugar fermentation polyhydroxyalkanoates
? Are thermoplastic, water insoluble biopolymers
of alkanoic acids containing a hydroxyl
group+ a functional group to the carboxyl
group.
? Approved as food contact material
? Biodegradable in nature

Synthetic polyester
? Formed by polycondensation of glycols and
dicarboxylic acids
? Have tensile & tear strength comparable to
LDPE
? Can be processed into blown or extruded
films, foams & injection moulded pdts
? Used in refuse & compost bags , cosmetic &
beverage bottles

? Used in combination with starch due to
their high price
? For thermoplastic starch & polyester type
they show a decrease in water sensitivity
? In case of thermoforming cannot provide
sufficient stiffness

Polycaprolactone
? Made from synthetic sources
? Limited use
? Used in starch blends
because of low tg of -60oc &
melting temp. 60oc

polyvinylalcohol
? water soluble
? Prepared by the hydrolysis of
polyvinylacetate
? Used for
- not used as food packaging
- agricultural chemicals
- dye & pigments
- water soluble laundry bags for
hospitals
- Detergent pouches

Developing novel biodegradable
materials
? Major problem-Water Permeability
& Swelling Behaviour
? Thermoplastic Starch
-Packaging Chips
-Packaging for Capsules
-Packaging for food products
? Nano Composite Concept

Developing novel biodegradable
materials
1) Barrier effect of nano clay particles
in a biopolymer matrix
? Incorporation of nano clay sheets into
biopolymers – large + effect on water
sensitivity & stability problems
? + effect make clay particles as barrier
element for oxygen & water
? Increased mechanical properties
? Increased long time stability
? Reduction of ageing effect

2) Extrusion
? Starch & modified clay are mixed at a
temp. above the softening pt. of polymer
by polymer melt processing
? At this temp. the polymer melt intercalates
? Success of polymer intercalation depends
on:-
- Modification of clay
- Degree of increased interlayer distance
- Interaction between the modifier and the
matrix material

3) properties of the starch – clay
nanocomposities
? Decrease in hydrophilicity
? Stiffness, the strength & the toughness –
improved & can be adjusted by varying the
water content
? Clay will decrease the water permeability
? Transparent & homogeneous film can be
formed

1) starch based foams in food packaging
2) PHA in food packaging
3) PLA in food packaging
4) Proteins in food packaging

Starch based foams in food packaging
? Poly styrene Clamshells
? Novamont
? Apack
-Sainsbury-a retailer in UK

? STARCH LOOSEFILL is comprised of various
starches (corn, wheat, and potato)
? STARCH LOOSEFILL readily biodegrades in
compost heaps
? Since it dissolves in water, you can sprinkle
it on you lawn and the rain will wash it into
the soil
? Renewable
? Better for the Environment

PHA in food Packaging
? Monsanto develop process to grow
PHA in plants.
? 300% more energy requirement
than LDPE (29 mega joule).

PLA in Food Packaging
? Energy Problem
? Applications
-Candy twist wrap
- Laminates for packaging
-Coffee packs
-Flavoured crewels
-Pet foods

Proteins in Food Packaging
? Corn Zein, Wheat gluten, Soya
protein
? Milk protein, Collagen, Gelatine,
Keratin, Myofibriller proteins
? Mainly used because:-
- Biodegradable in nature
- Edible
- renewalabe

Future trends
? Present market for:-
biodegradable food packaging material –
nonexistent ( compared to conventional
packaging)
? Since 2001 market is growing

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Fundamentals of Green Plastics in Food Technology

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