Page 353 - Biodegradable Polyesters

13.5 Application of Biodegradable Polyester-Based Blends and Composites 331

initiated with tetrabutyl ammonium acetate. The blend of PLA and a-PHB is devel-
∘
oped and the composites are prepared using compression molding at 180 C [72].
A small decrease in the elastic modulus and the yield strength is observed in the
blend, whereas a noteworthy increase in the ultimate strain is observed, which
increases with an increase in the content of a-PHB under tension.
The blendedcompositesmadeofpoly-L-lactic acid (PLLA)/poly-DL-lactic
acid (PDLLA) and PLLA/PCL were compared for their mechanical properties
[73]. In comparison with PLLA/PDLLA composites, PLLA/PCL composites
have weaker mechanical properties, such as elastic modulus, yield strength, and
ultimate strength. One approach of preparing these composites involves the use
of methylene chloride solutions [73]. The mixed solution of PLA, PLLA, and
PDLLA was poured into Teflon trays for vaporization of solvent. The composite
laminates can be manufactured using the compression molding technique.
The composites made of PLA/polyurethane (PU) can also be manufactured by
∘
compression molding [74]. The molding process was carried out at 190 Cfor
5 min. The composites exhibited good mechanical properties when compared to
plain PLA composites. The tensile strength of the composites increased with an
increase in the PU content.
Two series of composites hydroxyapatite (HA)/PHB–PHV and tricalcium
phosphate (TCP)/PHB–PHV were prepared using compression molding [75].
The modulus and the micro-hardness of the composites increased with an
increase in the volume percentage of HA and TCP. These composites have greater
application in the field of medical science, owing to the biodegradable property.
It is feasible to change properties of polyesters by mixing them with suitable
polymers [76] and also by changing the structure in the main chain to produce
targeted elastomers, light-responsive polymers, and biodegradable polymers,
thus enabling the growing use of polyesters in the medical field.

13.5
Application of Biodegradable Polyester-Based Blends and Composites

Growing awareness in maintaining a healthy environment has resulted in the
development and implementation of eco-friendly products. Biodegradable
polyester based composites are widely used in biomedical and commodity
applications, because of their degradability and non-toxic properties.

13.5.1
Biomedical Applications

Biodegradable polyester-based composites have been extensively studied for use
in medical applications owing to their biocompatible and degradable properties
in the human body. The major reported examples in biomedical products are
fracture-fixation devices, such as sutures, screws, micro titration plates, and
delivery systems [77]. Cellulosic nanofiber reinforced PLA composite materials