Effects of multi-walled carbon nanotubes (MWNTs) on flame retardation as well as thermal stabilization efficiency of two phosphorus-containing flame retardant systems i.e., ammonium polyphosphate/pentaerythritol (APP/PER) and red phosphorus (RP) in polypropylene (PP) have been investigated. Limiting oxygen index, thermo-gravimetric analysis, melt flow index, and tensile tests have been performed in this study. Moreover, the structure of the nanocomposites was characterized by scanning electron microscopy (SEM). SEM images revealed good dispersion of fillers in the polymer matrix. Furthermore, it was shown that the addition of MWNTs alone at a minimum loading level of 4 wt% improves thermal stability of PP considerably without any undesirable effect on its flow-ability and mechanical properties. Moreover, addition of MWNTs alone resulted in a slight improvement of flammability of the polymer. However, comparison between thermal stability and flame retardancy of PP samples containing a combination of MWNTs and APP/PER or RP and those of the samples containing APP/PER or RP alone proved that MWNTs interfere with thermal stabilization and flame retardation efficiency of both APP/PER and RP in the polymer.

Fibroin is a protein that has been extensively studied for biomedical application. In the present study, silk was dissolved in CaCl 2 -C 2 H 5 OH-H 2 O in order to obtain silk fibroin (SF) solution, and it was then lyophilized in freeze-dryer. The electrospinning of SF sponge was performed at different fibroin concentrations. SF nanofibers were modified by crosslinking PAMAM dendrimers to carboxylic-terminated fibroin, via EDC and NHS. The modified SF nanofibers scaffold was evaluated by SEM, X-Ray diffraction, FTIR and MTT assay. SEM micrograph showed that the electrospun containing 7% (w/w) fibroin had continuous fibers and an average diameter of 80 nm. Through treatment, conformational transitions of the SF nanofibers from random coil to b-sheet occurred rapidly, confirmed by FTIR and X-Ray diffraction. FTIR spectrum showed amide peaks, which confirmed the existence of fibroin.The modification results of analysis demonstrated that the amino groups were more established on the surface of the SF nanofiber scaffold. Biocompatibility tests were carried out through seeding fibroblasts cell line L929 on nanofibers. Adhesion and proliferation of fibroblasts were investigated by MTT assay, which showed no cytotoxicity. Therefore, fibroin nanofibers scaffolds appear to be a probable choice for potential use in tissue engineering.

Effects of multi-walled carbon nanotubes (MWNTs) on flame retardation as well as thermal stabilization efficiency of two phosphorus-containing flame retardant systems i.e. ammonium polyphosphate/pentaerythritol (APP/PER) and red phosphorus (RP) in polypropylene (PP) have been investigated. Limiting oxygen index (LOI), thermo-gravimetric analysis (TGA), melt flow index (MFI) and tensile tests have been performed in this study. It was shown that the addition of MWNTs alone at a minimum loading level of 4 wt% improves thermal stability of PP considerably without any undesirable effect on its flow-ability and mechanical properties. Furthermore, addition of MWNTs alone resulted in a slight improvement of flammability of the polymer. However, comparison between thermal stability and flame retardancy of PP samples containing a combination of MWNTs and APP/PER or RP with those of the samples containing APP/PER or RP alone proved that MWNTs interfere with thermal stabilization and flame retardation efficiency of both APP/PER and RP in the polymer.