Hydroxyapatite/poly-L-lactide (HAp/PLLA) is a ceramic/polymer composite, whose application as a resorbable biomaterial for the substitution and repair of hard bone tissue is widely promising in orthopedic, oral, maxillofacial, and reconstructive surgery. Hot processing is a necessary step for obtaining HAp/PLLA composite blocks with mechanical properties similar to those of bones. In this article, the changes in structure and physicochemical properties of HAp/PLLA composite, hot pressed for different pressing times (5, 15, 30, 45, and 60 min), were studied. Because the morphology of HAp/PLLA composite biomaterial is very sensitive to this procedure, its surface microstructure was analyzed by scanning electron microscopy (SEM) coupled with an energy-dispersive X-ray (EDX) detector system. Structural changes occurring in the material, mostly changes in crystallinity of PLLA, were studied by wide-angle X-ray structural analyses (WAXS) and infrared (FTIR) spectroscopy. Using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC), the influence of hot pressing on the properties, crystallization kinetics, and decomposition of HAp/PLLA composite biomaterial was analyzed.
SYNOPSISInteraction between polypropylene matrix and carbon black was examined by measuring physical, mechanical, and electrical properties. It has been shown that presence of carbon black influences the morphology and crystallinity of the matrix. Strong interaction was observed directly by electron microscopy and indirectly by the rise of the modulus of elasticity. The effect of carbon black on strength and physical properties of the composites is discussed.
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