Development of a multicomponents degradable plastics, through the combination of the sago starch and polyethylene/poly (ε-caprolactone) blends
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Date
2007
Authors
Lim, Wei Lee
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Abstract
In this research, sago starch (SS), poly(ε-caprolactone) (PCL) were incorporated
into low density polyethylene (LDPE). Poly(ethylene-co-acrylic) acid (EAA) was added
into the blend to study the effect on thermo-oxidative ageing (TOA). Pro-oxidants such
as manganese stearate (MnS) and elastomers, epoxidized natural rubber with 50 mol%
epoxidation (ENR-50) and styrene butadiene rubber (SBR) were added to increase the
degradability of the blends. The compounding of the blend was done by using Brabender
Plasticorder internal mixer at 160oC and 30 rpm for 6 minutes. The blends were then
compressed into 1 mm thick film using Kao Tieh Go Tech moulding machine. Dumb-bell
shape samples were cut and used throughout the whole research. TGA shows that the
decomposed temperature was shifted lower as the pro-oxidants were added intbo the
blends. This shows that the pro-oxidant helped to increase the degradability of the
blends. Tensile strength (TS) and elongation at break (EB) decreased as SS and prooxidants
were added into LDPE/PCL. This was due to the agglomeration of SS
(supported by Scanning Electron Microscope) and incompatibility of the PCL, SS and the
additives added (supported by Dynamic Mechanical Analyzer). This is supported by
using Dynamic Mechanical Analyzer (DMA) and scanning electron microscope (SEM).
Young’s modulus increased as SS was added into LDPE/PCL. This is because SS is
stiffer that LDPE and PCL. LDPE/PCL/SS blends samples were immersed in water for
24 weeks. Reduction in TS and EB were observed after the water absorption test. This is
due to the swelling effect of the SS leading to voids and cracks were observed after
water absorption by using SEM. Increased in TS and EB was observed after drying the
immersed samples in oven for 24 hours. This is due to less plasticizing effect as there
was no moisture in the blends.Ultra-violet (UV) ageing test was performed by using QUV
Accelerated Weathering Tester. Reduction in TS, EB and melt flow index (MFI) were
observed. Fourier transform infra-red (FTIR) spectrum shows increment in carbonyl
index which indicating increment in carbonyl group formed in samples. SEM micrograph
shows that cracks in the form of mosaic pattern were formed on the surface of the
LDPE/PCL/SS blends which explain the dramatically reduction in EB. TOA test shows
reduction in TS, EB and MFI. FTIR spectrum shows increased in carbonyl index
indicating increased in carbonyl group formed as the duration of TOA increase. Two
types of soil burial tests were done. LDPE/PCL/SS blends were incubated in soil and in
oven at 50oC for 3 months. Increment in carbonyl index was observed. Voids were
formed on the surface of the LDPE/PCL/SS blends after 3 months of incubation showed
attack of micro-organisms to the SS and PCL particles. The other type of soil burial test
was done in the natural environment where LDPE/PCL/SS blends were buried in the soil
at natural environment. Reduction in TS and EB were also observed after the natural soil
burial test due to the voids formed after the assimilation of PCL and SS particles on the
surface of LDPE/PCL/SS blends.
Description
Master
Keywords
Science Chemistry , degradable plastics , sago starch , Polyethylene/poly blends