Synthesis and characterization of a novel blend of polypropylene with Chlorella

A novel blend of polypropylene (PP) with Chlorella, a natural microalga, wa s synthesized successfully by a melt-mixing method with maleic anhydride-mo dified polypropylene (MPP) as a compatibilizer. The adhesion of hydrophobic PP to hydrophilic Chlorella is based on the formation of chemical bonds be tween the maleic anhydride groups of MPP and hydroxy groups of Chlorella th rough solid-phase esterification. The single maleic anhydride groups have t he highest reactivity with Chlorella. From the comparison with PP-Chlorella blends without MPP, the ester bonds between MPP and Chlorella cause a decr ease in crystallinity of the MPP matrix which is a primary origin of the de crease in melting and solidification enthalpies of the MPP-Chlorella blend, and induce intensive expansion of the MPP matrix around the Chlorella part icles which decreases the glass transition temperature. Consequently, the P P-Chlorella blend with MPP exhibits a marked increase in tensile strength a nd Young's modulus compared with the blend without MPP because of the stron ger interactions between MPP and Chlorella than those between Chlorella cel ls.