Polyhydroxyalkanoates as Packaging Materials: Current Applications and Future Prospects - Polyhydroxyalkanoate (PHA) Based Blends, Composites and Nanocomposites - page 190

derived source and they are therefore considered a biopolymer among the
categories of biopolymer production. 44 These can be summarised as follows:

(a) Polymers from biomass such as the agro-polymers from agro-
resources, e.g., starch, cellulose.
(b) Polymers obtained by microbial production, e.g., poly(hydroxyalkanoates).
(c) Polymers chemically synthesized using monomers obtained from
agro-resources, e.g., poly(lactic acid).
(d) Polymers whose monomers and polymers are both obtained by
chemical synthesis from fossil resources, e.g., poly(caprolactone),
polyester amide, etc.

d n 2 r 4 n g | 3

The first commercialisation of Biopol s was a trial release in 1992 of the
'world's first totally biodegradable product', a Wella t shampoo in an ex-
trusion moulded bottle (Figure 8.3). However, despite a public willingness to
embrace this environmentally-friendly product, high production costs made
long term sustainability uneconomic and rights were eventually transferred
to Metabolix in 2001 (through Monsanto in 1996).
Currently, there are a number of commercial suppliers of PHAs for
application as packaging materials (Table 8.3). All the companies use
vegetable-based feedstocks with sugar beet predominating. Biomer,
Goodfellow and Procter & Gamble Chemicals (P&G) produce P(3HB), while
all companies with the exception of Goodfellow, also produce PHA copolymers
with various loadings of 3-hydroxyvalerate (3HV), 3-hydroxyhexanoate (3HHx)
or 4-hydroxybutyrate (4HB). More recently, Proganic has manipulated
thermoplastic properties and associated economics by blending PHAs with
PLA for its resin, Proganic s , while NaturePlast also have PHA-based resins
ranging from 100 to 55% 'bio-based' (PHI 001).
Manipulation of physical and material properties through PHA com-
position and molecular properties, as well as blending, is standard practice.
Metabolix's Mirel t P3001/F3002 has suitable mechanical flexibility, a rela-
tively high melt strength and is acceptable for food contact (Figure 8.4).

.

Figure 8.3 Wella shampoo bottle produced from biodegradable PHA resins of PHB
and P(HB-co-HV), marketed by ICI as Biopol t , 'Natures Plastic' (image
supplied by Foster).