Blends of Polyhydroxyalkanoates (PHAs) - Polyhydroxyalkanoate (PHA) Based Blends, Composites and Nanocomposites - page 71

4.2.3 PHAs/Cellulose Derivatives
Cellulose is a linear polymer made up of glucose molecules linked by b-(1,4)-
glycosidic linkages. Due to its biocompatibility, hydrophilicity and chirality,
cellulose has been widely used in the immobilisation of proteins and anti-
bodies for the separation of enantiomeric molecules and formation of cel-
lulose composites with synthetic polymers and biopolymers. 34 Cellulose
derivatives also have attracted much interest for their compatibility with
P(3HB). 2 Ethyl cellulose (EtC) is also a biomaterial like P(3HB) that is ap-
proved by the FDA (Food and Drug Administration) and is widely used as a
blood coagulant, in coatings for pharmaceutical tablets and matrices for
poorly soluble drugs. Zhang and co-workers 35 investigated the miscibility,
thermal behaviour and morphological structure of P(3HB) with ethyl cellu-
lose (EtC) blends. Thin films of P(3HB)/EtC blends (100/0, 80/20, 60/40,
40/60, 20/80 and 0/100) were prepared by casting from 3% (wt/v) solutions of
the two components in chloroform. According to Zhang and Deng, 36 blending
of P(3HB) with hydroxyethyl cellulose acetate (HECA) would create a new
biodegradable polymer. The blends were prepared as reported by Zhang et al. 35
Phase behaviour and crystallisation kinetics for the binary blend P(3HB)/
cellulose propionate (CP) were performed by Maekawa et al. 37 Cellulose
acetate butyrate (CAB), which has a combination of high T m (160 1C) and T g
(113 1C), is an important thermoplastic cellulose ester that can biodegrade in
a natural environment. In an attempt to make the best use of degradable
polyester P(3HB), Wang et al. 38 blended P(3HB) with CAB and studied the
relationship between the blend morphology and its physical properties.
A cold-drawing procedure was applied to P(3HB)-based blends with
cellulose propionate (CP) to obtain high performance blend films. The
P(3HB)-rich film blends containing 0-30 wt% CP were cut into 3 1cm
strips, hot-pressed between two Teflon sheets at 200 1C and then rapidly
quenched in ice-water (4 1Cto101C) to preserve the state of amorphous
preform. The melt-quenched strip was attached to a portable drawing device
designed to stretch to a maximum of 30 times by hand operation. In con-
trast, CP-rich film blends (50-100 wt% CP) were immediately placed into a
heating oven adjusted to the given drawing temperature (60 1C to 175 1C)
after attachment to the drawing device. Then, they were kept for 1 minute to
be thermally stabilised and then stretched to a given draw ratio. 39
The characteristics and bending performance of the novel electroactive
polymer blend P(3HB)/cellulose in terms of free bending displacement
output, electrical power consumption and lifetime were studied by Zhijiang
et al. 34 Cellulose is a potential smart material which responds to an ith
electric field. Electro-active polymer (EAP) was prepared by dissolving cel-
lulose and P(3HB) in trifluoroacetic acid. The solution was cast to form a
film followed by the deposition of a thin gold electrode on both sides of
the film.
A blend of P(3HB-co-3HV) copolymer and cellulose was prepared using an
ionic solvent by Hameed and co-workers. 40 In their study, the micro granular

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