Properties and Degradation of Poly hydroxyalkanoate s

In terms of mechanical properties, with a Young s modulus of about 3.5 GPa and a tensile strength of 40 MPa, P(3HB) is similar to PP, but is a stiff and brittle material (Table 6.2). It exhibits low elongations at break of about 5% (similar as PS). With the incorporation of 3HV units into the polyester chain, a 

Polymer Melting temperature, °C Glass transition temperature, °C Young s modulus, GPa Tensile strength, MPa Elongation at break, % 

The mclPHAs, compared to the sclPHAs, are polymers with lower crystallinity, flexible and soft and exhibit behavior like those of thermoplastic elastomers, with low tensile strengths and high elongations at break. Copolymers of sclPHA and mclPHA, with low contents of mclPHA units, have improved properties compared to brittle sclPHAs and exhibit properties similar to poly(propylene). 

P(3HB) and copolymers P(3HB-co-3HV) possess piezoelectricity, a property which could be useful in medical applications for bone healing and repair through electrical stimulation of bone pins derived from these materials.  

P(3HB) is soluble in various solvents, such as chloroform, dichloromethane and alcohols with more than three carbon atoms. However, to completely solubilize crystalline P(3HB) even at a low concentration, refluxing in chloroform for up to 24 h is required. P(3HB) is sparingly soluble in toluene, pyridine, dioxane and octanol and is insoluble in water, lower alcohols, aromatic hydrocarbons, diethyl ether and hexane. 

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