Abstract:
Global trend in packaging is shifting towards environmentally friendly, natural materials
that can be decomposed easily. Among the bio-based packaging materials, starch is a
renewable, biodegradable, bio-compatible and easily accessible source. However, starchbased
biodegradable films depict weaker mechanical properties compared with synthetic
polymers. This problem can be solved by incorporating reinforcement fillers into the
starch matrix. Palmyrah fruit (Borassus flabellifer L.) waste can be a good source to
obtain fillers due to its high cellulose content. The aim of the study was to investigate
the reinforcement of starch-based biodegradable films with the incorporation of pure
cellulose nanofiber (CNF) obtained from palmyrah fruit fiber (PFF). Chemical treatments
such as alkaline treatment, bleaching, and acid hydrolysis were done successively
to obtain pure CNF from PFF. CNF was characterized using FTIR and particle size
distribution (PSD) was analyzed by granulometry. The results of FTIR depicted CNF
was synthesized successfully. Five different biodegradable films were prepared by varying
the amount of palmyrah tuber starch (4.5-2.5 w/w %) and CNF (0.0-2.0 w/w %) while
the amount of glycerin (1.5 w/w %) and gelatin (1 w/w %) were kept constant. The
yield of CNF from PFF was 37.89 ± 0.008 %. PSD results revealed that nano-sized
CNF (10-100 nm) was synthesized successfully. Optimized film was selected based on
the tensile strength and low water vapor transmission rate. Optimized film formulation,
with palmyra tuber starch (3 w/w %) and CNF (1.5 w/w %) showed desirable physical,
mechanical and optical properties, including the thickness, moisture content, water
vapor transmission rate, water uptake, transparency at 600 nm, water activity, water
solubility and tensile strength of 0.192±0.004 mm, 11.07±0.04 %, 3.87±0.005 g/m2.day,
22.34±0.05 %, 3.97±0.01 %, 0.44±0.001, 51.68±0.140 % and 9.55 MPa respectively.
All films showed excellent soil biodegradability within two weeks period. In conclusion,
palmyrah fruit CNF can be effectively used to reinforce starch based biodegradable
packaging films.
