NAGWA A. KAMEL*#, SALWA L. ABD-EL-MESSIEH*, SAMIA H. MANSOUR**, K.N. ABD-EL-NOUR*
*Microwave Physics and Dielectrics Department, National Research Centre, Dokki, Cairo, Egypt
**Polymers and Pigments Department, National Research Centre, Dokki, Cairo, Egypt
Biodegradable and injectable composites based on polypropylene fumarate (PPF) as unsaturated polyester filled with 60 wt% of calcium sulphate dihydrate (gypsum) incorporated with different concentrations of chemically treated natural bone powder (NBP) (5, 10 and 15 wt%) to be used in treatment of orthopedics bone diseases and fractures was prepared. Three different monomers namely N-vinyl pyrrolidone (NVP), methyl methacrylate (MMA) and a mixture of NVP and MMA (1:1 by weight ratio) was used as crosslinking agent each separately. The composite samples were immersed in the simulated body fluid (SBF) for 30 days and studied through Fourier transform infrared (FTIR), scanning electron microscope (SEM), energy dispersive X-ray (EDX) in addition to dielectric measurements. The degradation time and the change in the pH of the SBF during the period of immersion were studied. From the FTIR, the increase intensity of absorption bands observed at 1076 cm–1, 843 cm–1, 711 cm–1, and 578 cm–1 after immersion in SBF can be considered as good evidence for the formation of calcium phosphate layer which was also confirmed with the SEM and EDX tools. The dielectric measurements carried out on these prepared composites at frequency range from 100 Hz–100 kHz indicate that the permittivity ε’ and dielectric loss ε” follow the order NVP > NVP / MMA > MMA. Both parameters were found to increase by increasing the percentage of natural bone powder. The relaxation times obtained could be attributed, respectively, to Maxwell-Wagner effect and to the relaxation process related to carboxyl, hydroxyl, and ester functions associated with main chain.
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