The use of biodegradable material in membrane technology will be a great solution in reducing non-biodegradable
waste in the landfill. Membranes can often be useful as the recycle stream can usually be much cleaner than with other
techniques. This article describes the preparation of poly(l-lactic acid)-poly(ethylene glycol) (PLLA-PEG) free standing flat
sheet membranes with the presence of 5 wt. % activated carbon filler. PLLA-PEG crosslinked copolymer was synthesized
using PLLA with different molecular weight PEG prepolymers i.e. 4000, 6000 and 10000 g/mol; and excess hexamethylene
diisocyanate to form urethane linkages between the polymers. The reaction was carried out in a dichloromethane/
tetrahydrofuran dual-solvents system. The PLLA-PEG/AC membranes in the weight ratio of 7:3:0.5 were then fabricated
using solution casting and phase inversion techniques. The performance of the membranes was evaluated in terms of
permeation water flux (PWF), palm oil mill effluent (POME) permeation, flux decline and contact angle. It was found that
membrane containing 10000 g/mol PEG has the highest total mean in PWF, POME flux and hydraulic permeability with
values of 100.9 L/m2
.h, 51.45 L/m2
.h and 64.9º;62.9º, respectively, due to high porosity. All of the membranes were more
stable towards the flux decline of POME compared to water. At the same time, addition of AC to the copolymer considerably
enhances the texture and porosity of the fabricated membranes.
Ultra-high temperature is a process that involves heating of milk to a very high temperature to produce sterile milk products.
However, food poisoning due to consumption of UHT milk still happen in Malaysia. This study was done to develop a
film that is made by poly(L-lactic acid) (PLLA) to detect the presence of microorganisms in UHT milk products. UHT milk
that was used in this study was full cream milk. Contaminated milk that contained Bacillus cereus was made to conduct
a model system on the relationship between colony forming unit of microorganisms and contact angle. Contaminated
milk was also used as a control sample to study the difference of milk properties between fresh and contaminated milk.
Physicochemical analysis (Brix, colour, pH and contact angle) and microbiological analysis (total plate count) were
done to UHT milk sample as soon as the packaging of the milk was unsealed. Analysis was done with 30 min time interval
until 4 h and 30 min since the unsealing of packaging. The results showed that presence of microorganisms in UHT milk
was detected after the milk product was unsealed and exposed to environment for 3 h and 30 min. Contact angle resulted
from the presence of microorganisms in UHT milk was 64.34 - 65.44° with its colony forming unit, 2.1 – 3.9 cfu/mL.
Therefore, the potential usage of contact angle on PLLA thin film with respect to colony forming unit (cfu) in detecting
the presence of microorganisms in UHT milk product was attained and well modelled.
Poly(ethylene glycol)-polydimethylsiloxane (PEG-PDMS) crosslinked copolymers with mol ratios PEG:PDMS:Glycerol
of 5:3:2, 6:2:2 and 7:1:2 have been prepared and characterized. The synthesis of the copolymers was carried out
by the reaction between hydroxyl groups of PEG, PDMS and glycerol with isocyanate groups of 1,6-hexamethyelene
diisocyanate (HMDI). In the reaction, glycerol was acted as the cross linker. The copolymers were then characterized
by FTIR spectroscopy. The thermal behaviour was investigated by DSC and TGA. Based on FTIR results, the crosslinked
structure of the copolymers was confirmed by the presence of absorption peak at 3350 and 1710 cm-1 which indicated
the (-N-H) stretching and carbonyl (-C=O) correspond to urethane links. This showed that the hydroxyl groups of PEG,
PDMS and glycerol have reacted to isocyanate groups of HMDI. The copolymers showed melting temperature (Tm) of PEG
segments from 22°C to 27°C and glass transition temperature (Tg
) from -11°C to -6°C. Meanwhile, the PDMS segment
showed values from -53°C to -56°C for Tm, and Tg
from -118°C to -122°C. Data obtained from the thermal analysis
indicate that thermal stability increases with increasing PDMS mol ratio.