Polystyrene / boron nitride nanotube composites: synthesis, processing and characterization

Balık, Erdem
In recent years, boron nitride nanotubes (BNNTs) have been added to polystyrene (PS) which is a widely used thermoplastic polymer in order to improve its thermal and mechanical properties. Solution mixing and melt blending techniques are commonly used methods to prepare polymer-boron nitride nanotube (BNNT) composites. However, these two composite preparation methods have a common problem about the dispersion of fillers in the polymer matrix. In this study, PS-BNNT composites were prepared using masterbatch with extrusion method at 0.5, 1, and 3 wt % BNNT loadings in order to disperse the nanotubes in the polymer matrix homogeneously. The composites with 0.5 wt% BNNTs were also obtained from in-situ polymerization and extrusion method, separately. Neat PS and all the composites were characterized in terms of their morphology, mechanical and thermal properties. PS was synthesized using solution and bulk polymerization techniques. The effect of polymerization time and initiator concentration in bulk polymerization on the vi molecular weight of PS was studied in order to find the best synthesis conditions for PS production. The best synthesis conditions were determined as a polymerization reaction time of 3 hrs, an initiator concentration of 0.01 mol/L and a reaction temperature of 95 oC. Fourier Transform Infrared (FTIR), X-ray diffraction (XRD), viscosity average molecular weight (Mv), Melt Flow Index (MFI) and Gel Permeation Chromatography (GPC) characterization methods were used to compare the properties of synthesized PS with commercial PS. The results of all the characterization methods revealed that PS was successfully synthesized and its molecular weight was close to that of commercial PS. BNNTs used in the polymer composite were successfully synthesized from the reaction of ammonia gas with a powder mixture of elemental boron and iron oxide. The formation of hexagonal boron nitride was proved by XRD analysis. Results of SEM analyses indicated that the nanotubes were dispersed homogeneously for the composites with 0.5 wt% BNNTs prepared by masterbatch with extrusion method. The tensile and impact strengths of these composites were improved remarkably with respect to neat polymer and the composites prepared using the other methods. The agglomeration of BNNTs in the polymer matrix increased with an increase in BNNT addition. Differential Scanning Calorimetry analysis showed that the glass transition temperature of the composites prepared by masterbatch with extrusion method was decreased with respect to the synthesized PS. Also, no significant change in terms of glass transition temperature of the composites was observed with the addition of BNNTs. Thermal gravimetric analysis (TGA) of the composites prepared by masterbatch with extrusion method showed that the thermal stability of composites remained unchanged with the addition of BNNTs.


Titanium-magnesium based composites: Mechanical properties and in-vitro corrosion response in Ringer's solution
ESEN, ZİYA; Dikici, Burak; Duygulu, Ozgur; Dericioğlu, Arcan Fehmi (Elsevier BV, 2013-06-20)
Ti-Mg composite rods exhibiting both bioinert and biodegradable characteristics have been manufactured by hot rotary swaging from elemental powders of titanium and magnesium. As a result of processing, spherical magnesium powders elongated in the direction of deformation and the dendritic structure in starting magnesium powders transformed into highly equiaxed grains. Magnesium particles in the outer layer of the composites were decorated by thin layer of MgO while the interior parts were free from oxides. ...
Usability of three boron compounds for enhancement of flame retardancy in polyethylene-based cable insulation materials
İBİBİKCAN, Esin; Kaynak, Cevdet (SAGE Publications, 2014-03-01)
It is known that for the production of halogen-free cable insulation materials based on polyethylene, very high amounts of traditional metal hydroxide flame retardants such as 65 wt% aluminum hydroxide are required to fulfill international directives. In this respect, the aim of this study was to reveal possible enhancement effects of three boron compounds on the flame retardancy of two cable insulation materials: low-density polyethylene and its blend with ethylene vinyl acetate both loaded with aluminum h...
Electrical transport, optical and thermal properties of polyaniline-pumice composites
YILMAZ, KORAY; Akgoz, A.; Cabuk, M.; Karaagac, H.; KARABULUT, ORHAN; YAVUZ, Mustafa (2011-11-01)
In this study, electrical conductivity, photoconductivity, absorbance and thermal properties of polyaniline (PANI) and polyaniline-pumice composites were investigated. Temperature dependent conductivity and photoconductivity measurements were carried out in the temperature range of 80-400K. The measurements revealed that the dominant conduction mechanisms in polyaniline and 15% pumice doped composite were hopping conduction. The low activation energies calculated for 36% pumice doped composite indicated tha...
Sonat, Emine Evren; Özerinç, Sezer; Department of Mechanical Engineering (2021-12-10)
Carbon fiber reinforced polymer (CFRP) composites are increasingly used in the aerospace industry due to their high specific strength compared to conventional metallic materials. However, a significant shortcoming of these composites is their increased susceptibility to damage. Structural repair is a common method to restore the load-carrying capacity of a damaged part when the damage size exceeds the pre-defined tolerances. Scarf and stepped bonded repair methods are the primary choice for cases that requi...
Microstructure hierarchy - Mechanical property relationship for hypereutectic Al-Si alloy powders solidified far from equilibrium
Kalay, Yunus Eren; Chumbley, L.s. (2006-12-01)
Microstructural selection in aluminum silicon powder alloys can directly influence the consolidated materials' mechanical properties. However, due to processing and characterization difficulties, a complete understanding of powder microstructure as a function of undercooling and solidification velocity, and the role microstructure plays on mechanical properties, remains an elusive goal. In this study high pressure gas atomization processing was used to produce rapidly solidified hypereutectic Al-Si alloys. ...
Citation Formats
E. Balık, “Polystyrene / boron nitride nanotube composites: synthesis, processing and characterization,” M.S. - Master of Science, Middle East Technical University, 2015.