Biomedical subjects

Mosto Bousmina

Publications and source records attributed to Mosto Bousmina.

5 recordsLinked to original sources

PubMed2006

Phase separation in PS/PVME thin and thick films.

Phase separation in both thin and thick films of polystyrene (PS) and poly(vinyl methyl ether) (PVME) was studied by small-angle laser light scattering (SALLS), atomic force microscopy (AFM), optical microscopy, and X-ray photoelectron spectroscopy (XPS). Blend films with controlled thickness were obtained by spin-coating polymer-toluene solutions with various concentrations. Films with thicknesses smaller and larger than the maximum wavelength of concentration fluctuations were considered. Morphology of the blend films was characterized during and after phase separation. The obtained peculiar morphology was related to surface enrichment with the lower-surface-energy component, as was verified by XPS analyses.

Journal Article↗

PubMed2006

Intercalation/Exfoliation mechanism of hybrid formation in polypropylene/lamellar mesostructured silica nanocomposites.

Understanding the optimal processing conditions for the fabrication of polymer nanocomposites is of fundamental importance in designing materials with balance of properties. To understand these conditions in the case of maleic anhydride grafted polypropylene (PP-g-MA)/layered mesostructured silica (LMS) nanocomposites, the effect of temperature, shear rate, and residence time during processing on the structure of the nanocomposites were studied. The results showed that the combination of temperature, residence time, and mechanical shears have strong effect on the structure of the nanocomposites, rather than just interfacial interactions between the polymer matrix and silicate layers. However, interfacial interactions between the polymer matrix and silicate layers primarily play an important role to the intercalation of polymer chains into the silicate galleries. On the basis of our experimental results, a first explanation of the formulation mechanism of PP-g-MA/LMS nanocomposites is proposed. Finally, a general concept of processing conditions for manufacturing of polymer nanocomposites by melt-compounding process in a batch-mixer is described.

Nanotechnology↗

PubMed2006

Phase separation of polystyrene/poly(vinylmethylether)/organoclay nanocomposites.

The effect of addition of organically modified montmorillonite (OMMT) on the phase separation of polystyrene (PS)/poly(vinyl methyl ether) (PVME) blend was examined. Using two types of OMMT modified with two different kinds of surfactants, the effect of organic modification on nanocomposites was investigated by focusing on three major aspects: phase transition, morphological study, and melt rheological behavior both below and above the critical transition temperature. X-ray diffraction (XRD) patterns revealed the formation of intercalated nanocomposites and transmission electron micrographic (TEM) observations showed that the ordering of silicate layers in blend matrix is well matched with the XRD patterns. The addition of clay was found to affect both the mechanism of phase separation and the final morphology. Such effects resulted in uncommon rheological behavior of the blend both below and above the critical transition temperature. Surface phase separation of thin films for virgin blend and nanocomposites was also examined by atomic force microscopy (AFM). Morphology resulting after phase separation was found to be dependent on the nature and the amount of OMMT added to the polymer blend.

Aluminum Silicates↗

PubMed2006

Polyethylene/clay nanocomposites prepared by polymerization compounding method.

A new technique for the preparation of high density polyethylene/clay nanocomposite, "polymerization compounding," is reported. This technique was based on the chemical anchoring of a Ziegler-Natta catalyst on organically modified clay surface containing an ammonium cation bearing primary hydroxyl groups. The polymerization of ethylene was initiated after adequate activation and the growing polyethylene chains are directly adsorbed on to the clay surface through the hydroxyl-functionalized surfactant. Finally, the nanocomposite was prepared by diluting polyethylene adsorbed clay in the high density polyethylene (HDPE) matrix using a batch mixer at 180 degrees C. The as-synthesized nanocomposite was typically characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) that revealed the formation of intercalated nanocomposite. Tensile property measurements exhibit substantial increase in stiffness (approximately 50%) and strength (approximately 20%) of nanocomposite as compared to that of neat HDPE. Dynamic mechanical analysis under molten state revealed 25% increase in storage modulus when compared to that of neat HDPE.

Aluminum Silicates↗

PubMed2006

Dispersion of multi-walled carbon nanotubes in biodegradable poly(butylene succinate) matrix.

This communication describes the preparation, characterization and properties of biodegradable poly(butylene succinate) (PBS)/multi-walled carbon nanotubes (MWCNTs) nanocomposite. Nanocomposite was prepared by melt-blending in a batch mixer and the amount of MWCNTs loading was 3 wt%. State of dispersion-distribution of the MWCNTs in the PBS matrix was examined by scanning and transmission electron microscopic observations that revealed homogeneous distribution of stacked MWCNTs in PBS matrix. The investigation of the thermomechanical behavior was performed by dynamic mechanical thermal analysis. Results demonstrated substantial enhancement in the mechanical properties of PBS, for example, at room temperature, storage flexural modulus increased from 0.64 GPa for pure PBS to 1.2 GPa for the nanocomposite, an increase of about 88% in the value of the elastic modulus. The tensile modulus and thermal stability of PBS were moderately improved after nanocomposite preparation with 3 wt% of MWCNTs, while electrical conductivity of neat PBS dramatically increased after nanocomposite formation. For example, the in plane conductivity increased from 5.8 x 10(-9) S/cm for neat PBS to 4.4 x 10(-3) for nanocomposite, an increase of 10(6) fold in value of the electrical conductivity.

Biodegradation, Environmental↗