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Title of article :
Surface modification of tricalcium phosphate for improvement of the interfacial compatibility with biodegradable polymers
Author/Authors :
Carmen Kunze، نويسنده , , Thomas Freier، نويسنده , , Ekaterina Helwig، نويسنده , , Barbara Sandner، نويسنده , , Dieter Reif، نويسنده , , André Wutzler، نويسنده , , Hans-Joachim Radusch، نويسنده ,
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روزنامه با شماره پیاپی سال 2003
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Abstract :
The surface of tricalcium phosphate (TCP) filler particles was activated by treatment with dilute aqueous phosphoric acid. ATR-IR spectra indicated the formation of calcium hydrogen phosphate dihydrate at the surface. Oligo(lactone)s were formed by the subsequent reaction of the activated TCP with -lactide and -caprolactone, respectively, at 150°C without any additional catalysts. After extraction of the oligo(lactide), the residue of modified TCP-included calcium lactate whereas the water of crystallization of the dihydrate disappeared as shown by ATR-IR spectroscopy. Owing to the insolubility of TCP in common solvents, the analogous reaction between water-soluble disodium hydrogen phosphate dihydrate and -lactide was used to study the kind of chemical bonds by high-resolution NMR spectroscopy. The 1H and 13C NMR spectra of the reaction product also pointed out the presence of calcium lactate. Additionally, signals were found indicating a covalent attachment of lactic acid units onto the phosphorus. For the preparation of composites, poly( , -lactide) was mixed with TCP and modified TCP, respectively, in a ratio of 75/25 (w/w) and directly injection moulded into tensile test specimens at a barrel temperature of 180°C. Although mechanical properties were not improved, scanning electron microscopy (SEM) indicated a better interfacial phase interaction in the composite with the modified TCP. Chemical bonds between filler and polymer matrix are assumed to be formed by transesterification reactions.
Keywords :
Interfacial bonding , Composite , Lactone polymerization , Tricalcium phosphate
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