Development of Biodegradable Plastics from Sago and Bario Rice Blends

Development of
Biodegradable Plastics from
Sago and Bario Rice Blends

Syed Mohammed Sajl
Semester 6
B Tech – PS & E

Monday, December 17, 2012 Review Seminar - Semester 5 1

Abstract
• In this study, Bioplastics with mechanical
and water absorption properties are
prepared from Natural Polymers.
• Biodegradable plastic composites were
prepared by casting thermoplastic
starches (Bario Rice/Sago starch at ratio
2:3) with natural rubber (0.5 - 10 %) in the
presence of a plasticizer (glycerol).


• Mixtures of Sago and Bario Rice starch
are blended with natural rubber latex with
the presence of Plasticizer.
• Here, thermoplastic starch is the dispersed
phase and natural rubber latex as filler.
• Bioplastics produced were characterized
by Differential Scanning Calorimetry
(DSC), Fourier Transform Infrared
Spectroscopy (FTIR), Water absorption
test, Biodegradable Test and Mechanical
analysis.

Ecological Relevance
• Plastics are widely used since 1980s.
• Petroleum-derived plastics have poor
biodegradability and may last hundreds of
years when buried in typical solid waste
sites.
• This leads to environmental pollution
which is a real threat to total ecosystem.
• So, there is much interest in Edible and
Biodegradable Films from Natural
Polymers as alternatives to Synthetic
Polymers.

Biodegradable Plastics
• Biodegradable plastics are plastics that can
be biologically broken down, in a reasonable
amount of time, into their base compounds.
• They may be composed of:
1)"Bioplastics", whose components are
derived from renewable raw materials
2)Traditional petroleum-based plastics
containing biodegradable additives which
allow them to enhance the biodegradation
of plastic.

• Under proper conditions biodegradable
plastics can degrade to the point where
microorganisms can completely metabolize
them to carbon dioxide and water.
• Examples:
•Naturally Produced:
Polyhydroxyalkanoates (PHAs) like the
poly-3-hydroxybutyrate (PHB),
polyhydroxyvalerate (PHV) and
polyhydroxyhexanoate (PHH)
•Renewable Resource: Polylactic acid
(PLA)
•Synthetic: Polybutylene succinate (PBS),
polycaprolactone (PCL).

Sago
• Sago is a starch extracted in the spongy
center, or pith, of various tropical palm
stems, especially, Metroxylon sagu.
• Sago is often produced commercially in
the form of "pearls".
• Sago pearls can be boiled with water or
milk and sugar to make a sweet sago
pudding.
• Sago starch is also used to treat fibre,
making it easier to machine.

Sago Pearls


Bario Rice
• Bario Rice is a local product cultivated by
hand with no pesticides or herbicides and
represents a valuable ecological niche.
• The Kelabit tribe, who live solely Malaysian
village located in the centre of the Kelabit
Highlands grow the rice.
• Bario Rice is a medium grain rice, marble
white in color. This variety is famous for its
excellent sweet taste and slightly sticky
texture, and is a favorite among Malaysian
chefs that use it to prepare traditional recipes.


Bario Rice


Experiment


Materials
• Natural Rubber Latex from Hevea
brasilensis trees.
• Sago Starch supplied from any foodstuff
Company
• Rice Starch derived from Bario rice
cultivar
• Glycerol
• Sodium Hydroxide

Film Preparation
• Films are prepared from rice and sago starch.
• Rice and Sago starches (3% w/w) are
gelatinized in an autoclave at 120 C, 100 kPa O

for 30 minutes.
• Glycerol is added as the Plasticizer at 30%
(w/w) relative to starch.
• Thermoplastic Starch/Natural Rubber Latex
(TPS/NRL) samples of 100/0, 99.5/0.5,
98.51.5, 97.5,2.5, 96.5/3.5, 93.0/7 and 90/10
are prepared by adding natural latex in
required proportions.

• The prepared solutions are homogenized
with an ultrasonic homogenizer with 30%
power for 5 minutes.
• The products are dried at room
temperature for 3 days before overnight
o
oven drying at 50 C.


Characterization
• Mechanical Properties: Film products are
tested for elongation at break and tensile
strength using Universal Testing Machine.
• Differential Scanning Calorimetry (DSC):
Film products of 15mg were encapsulated in
Tzero Aluminum Pans. Sample Pans are
o o
heated at 20 C/min from 20 to 200 C. Tm is
recorded.
• Fourier Transform Infrared Spectroscopy
(FTIR): Fourier Transform Infrared Spectra
are recorded between 4000 and 400 cm-1

• Water Absorption: Water absorption test
was conducted by using film products of
sixze 1.5 x 3.0 cm. The films are dried for 6
o
hours at 50 C and weighed. The samples are
o
then soaked in distilled water at 23 1 C.
Samples are weighed periodically every week
for 4 weeks.
• Biodegradability Studies: 3
Biodegradability tests are conducted.
Water Hydrolysis Test is carried out by
soaking the samples of size 1.5 x 3.0 cm in
o
in 20 ml of distilled water at 70 C. The
changes in weight are recorded every 2

Alkaline Hydrolysis Test is carried out by
soaking the samples of size 1.5 x 3.0 cm
in in 20 ml of 0.1M Sodium Hydroxide
o
solution at 70 C. The changes in weight
are recorded every 30 minutes.
Soil burial test was conducted by burying
the samples of size 3.0 x 3.0 cm into
mineral soil. Samples are rinsed with
distilled water and dried in an oven at
o
50 C for 24 hours and weighed. The test is
conducted at 15, 30, 60 and 90 days after
soil burial

Results

Mechanical Properties
• The tensile strength and elongation at break
of Thermoplastic Starch/Natural Rubber
Latex (TPS/NRL) blends are summarized in
the table.
• The addition of increasing natural rubber
latex resulted in decreasing tensile strength
and increased elongation at break in
Thermoplastic Starch/Natural Rubber Latex
(TPS/NRL) blends.
• Blends which had 7 and 10% (w/w) natural
rubber latex content were found to have
elongation at break of 483% and 570%
respectively.

BLENDS Mechanical Properties
(TPS/NRL) Tensile Strength (MPa) Elongation at Break
(%)
100/0 11.2 16.7
99.5/0.5 9.4 16.7
98.5/1.5 6.7 16.7
97.5/2.5 6.0 13.3
96.5/3.5 4.7 20.0
93.0/7.0 4.4 483.3
90.0/10.0 3.6 570

Table: Mechanical Properties of Thermoplastic Starch/Natural Rubber
Latex Blends


Thermal Profile
• Results revealed that endotherms of pure
thermoplastic starch, the blend with lowest
natural rubber latex content and the blend with
highest natural rubber latex content showed
o
complete melting at 138, 146 and 161 C
respectively.
• This indicates a higher melting point (Tm)for
blends with higher natural rubber latex content
than that for thermoplastic. It is clear that melting
temperature increased as the rubber content
increased in Thermoplastic Starch/Natural
Rubber Latex blends.

BLENDS Melting Temperature
o
(TPS/NRL) Tm ( C)

100/0 138
99.5/0.5 146
98.5/1.5 155
97.5/2.5 155
96.5/3.5 154
93.0/7.0 156
90.0/10.0 161

Table: DSC Thermal Profile of Thermoplastic
Starch/Natural Rubber Latex Blends


Fourier Transform Infrared
Spectroscopy (FTIR)
• The FTIR spectra of thermoplastic starch
alone showed characteristic O-H stretching
bands within the 3650-3000 cm-1 region, C-H
stretching bands within 2927 cm-1 region,
C=C stretching bands within 1680-1620 cm-1
region, cyclohexane ring vibrations bands
within 1055-925 cm-1 region and O-H
deformation bands within 900-400 cm-1
region.
• All the bands were present in Thermoplastic
Starch/Natural Rubber Latex (TPS/NRL)
blends except at 1567 cm-1 and 1538 cm-1

Figure: FTIR Spectra of Thermoplastic Starch/Natural Rubber
Latex Blends: (a) Blend TPS/NRL 90/10 (b) Blend TPS/NRL 100/0


Water Absorption
(TPS/NRL) blends with higher natural rubber latex
blends with higher natural rubber latex content
exhibited better water resistance compared to samples
with less natural rubber content.
• In the first 7 days, the blend containing 10% natural
rubber latex absorbed 31.4% of water.
• However, the blend without natural rubber latex
absorbed 47.5% of water in the first week.
• The water absorption slowly increased over a period of
28 days.
• Blends of 93.0/7.0 and 90.0/10.0 composition have
lower water absorption compared to others.


Figure: Percentage Weight Gain of Thermoplastic Starch/Natural
Rubber Latex Blends during Water Absorption


Biodegradability Studies
• The blends with low thermoplastic starch lost
weight significantly in the first 2 hours.
• A constant weight was achieved for all blends
after 2 hours of treatment.
• In alkaline hydrolysis test, high rubber blends
showed significant weight losses in the first
30 minutes and then maintained a constant
weight.
• Accelerated alkaline hydrolysis resulted in
higher weight losses as compared to water

• The soil burial test has been known to be a
slow process due to the low percolation rate.
• The test indicated lower losses than those
determined by both types of hydrolysis
testing after 15 days, but at the end of 90
days, the measured losses almost equaled
the losses in samples subjected to water
hydrolysis for 12 hours or alkaline hydrolysis
for 150 minutes.
• Samples with only thermoplastic starch were
degraded faster than samples that had been
added with natural rubber latex.
• Samples with the highest rubber latex content
showed the lowest degradation rate.

Table: Weight Loss % of Thermoplastic Starch/Natural Rubber
Latex (TPS/NRL) blends after exposure to Water and Alkaline
Hydrolysis at Temperature 70oC and buried in soil.


Discussio
n

Mechanical Properties
• Addition of natural rubber latex results in
decreased tensile strength and increased
elongation at break in Thermoplastic
Starch/Natural Rubber Latex (TPS/NRL)
blends .
• The elongation at break was found to
correlate with the theoretically predicted
values for systems with good adhesion and is
generally considered to be highly sensitive to
the state of interface.

Thermal Profile
• The study revealed that endotherms for blends
with lower natural rubber latex content and blends
with higher natural rubber latex content, it showed
o
complete melting at 146 and 161 C respectively.
(TPS/NRL) blends are thermoplastic polymers and
upon application of heat, undergo a process of
fusion or melting where the crystalline character is
destroyed.
• The crystallinity of blends with higher natural
rubber content was found to be more than
thermoplastic starch alone.

Fourier Transform Infrared
Spectroscopy (FTIR)
• The FTIR spectra of blends showed a
similar region of wave number and
characteristic bands for starch.
• The NR band found in the blend with
natural rubber latex was due to addition of
Ammonia solution in latex for stabilization.
• The OH bands are unreliable for
quantitative analysis due to their
dependence on water content and
atmospheric condition.

Water Absorption
• The blends with higher natural rubber latex
content exhibited poorer water absorption.
• The addition of hydrophobic particles
(natural rubber latex) to a hydrophilic
component enhances the water resistance
of the blended samples.


Biodegradability Studies
• Accelerated alkaline hydrolysis resulted in
higher weight loss as compared to water
hydrolysis due to the presence of the NaOH,
which enhances the solubilization and
gelatinization of starch in the polymer blend.
• The soil burial test showed that the higher the
natural rubber latex content of the sample,
the lower the degradation rate because the
latter structure has higher miscibility and
compatibility and formed a dense structure
within the sample.

Conclusio
Monday, December 17, 2012
n
Review Seminar - Semester 5 36

Conclusion
• Rubber latex and Starch blends showed a
wide range of physical and mechanical
properties.
• Natural rubber latex acted as a good inert
filler as it decreased the tensile strength but
increased the elongation at break.
• Addition of natural rubber latex demonstrated
higher product elongation at break, water
resistant ability, melting temperature and
slower biodegradability.
• The blends with higher natural rubber latex
fitting were less vulnerable to degradation.

Reference
Monday, December 17, 2012
s
Review Seminar - Semester 5 38

References
•Development of Biodegradable Plastics
from Sago and Bario Rice Blends
Sie-Cheong Kiing, Shir-Yih Ee, Sie-Chuong
Wong, Amartalingam Rajan and Pang
Hungyiu
Journal of Polymer Materials (Vol 28, No 3)
– July – Sept 2011
•www.wikipedia.com
•www.google.com

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Development of Biodegradable Plastics from Sago and Bario Rice Blends

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