Band 16, Heft 6

High internal phase emulsion templated-polymer (polyHIPE) composites were prepared from spirulina modified halloysite (HL) nanotube containing styrene/divinylbenzene based water-in-oil type concentrated emulsions. In order to obtain a stable emulsion for neat polyHIPE’s synthesis, at least 5 vol% Span-80 as a non-ionic surfactant, with respect to organic phase was needed. For syntheses of polyHIPE composite structures, this amount was decreased to 2 vol%, even in presence of 0.25 wt% modified nanotube with respect to the organic phase. All the polyHIPE composites exhibited open pore structures with pore interconnections together with partially or completely closed pores. The composite having 0.25 wt% modified nanotube and 2 vol% surfactant was found to have about 260% higher dye adsorption capacity and the highest onset degradation temperature in comparison with neat polyHIPE.

Photocured simultaneous epoxy-acrylate interpenetrating polymer networks (IPNs) were formed both under irradiation by UV-lamp and natural sunlight. The conversion degrees of functional groups were calculated by using data obtained from Fourier transform infrared (FTIR) spectroscopy. The influence of N-vynilcarbazole (NVC) as a photosensitizer on the kinetics of IPN photopolymerization was investigated. The conversion degrees of epoxy groups were revealed to increase significantly with the addition of NVC to the given systems. The phase morphology of IPNs was analyzed by optical and scanning electronic microscopy as well as by dynamic mechanical analysis (DMA). The data obtained using DMA method, which was used for analyzing the IPN samples with different component ratios, indicate the formation of both phase-separated and single-phase IPNs. The phase separation is occurred only in NVC-containing 50:50 IPN.

In this work, epoxy resin (EP), glass fiber (GF), and modified GF (MGF) were used in the modification of room-temperature-vulcanizated (RTV) silicone rubber, and their properties were investigated and characterized. The properties such as tensile strength, elongation at break, dimensional stability, and thermal stability were studied. Results revealed that RTV/EP-3/MGF-3 exhibited the best tensile properties. Meantime, the dimensional stability of these composites was improved in a certain degree. Thermogravimetric (TG) analysis, X-ray diffraction (XRD), scanning electron microscope (SEM), and differential scanning calometry (DSC) were also used in the investigation of the microtopography, structure and properties of these RTV mold rubbers.

The modification of pristine nanoclay and its application in wood plastic composite (WPC) have been investigated in this paper. Pristine nanoclay was modified using transition metal ion (TMI) which was copper (II) chloride to achieve good dispersion and to improve properties of WPC. The morphology, composition, structure, and thermal stability of TMI-modified nanoclay were studied by field emission scanning electron microscopy (FESEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) analysis. The pristine (WPC/MMT) and TMI-modified (WPC/MMT Cu) nanoclay based WPC were made from polypropylene (PP), wood flour (WF), and maleic anhydride grafted polypropylene (MAPP) coupling agent. Pristine and modified nanoclay with different concentration (1 wt%, 2.5 wt%, 4 wt% and 5 wt%) were used as a reinforcing filler for WPC. Mechanical, physical, morphological, and thermal properties of the prepared composites were evaluated. Result exhibit that at 1 wt% nanoclay content, the tensile, flexural, and impact strength of WPC/MMT improved by approximately 6%, 4%, and 8%, respectively, compared to WPC without nanoclay. For the WPC/MMT Cu, the improvements in these properties were about 2.6, 2.1 and 3 times higher than the WPC/MMT. The physical and thermal properties also improved by incorporating modified nanoclay in WPC.

Waterborne polyurethane (WDPU) comprising polycaprolactone diol and hexamethylene diisocyanate was prepared by using tartaric acid (TA) as an ionomer. WDPU was further modified with polymethyl methacrylate (PMMA). Hybrid WDPU-PMMA coatings were formed by using unsaturate end capping agents such as 2-hydroxyethylmethacrylate. WDPU-PMMA blend coatings were formed by using chain extenders such as ethylene glycol, ethylene diamine and mixed with PMMA. Thermal behavior and structural characterizations were investigated by means of thermogravimetric analysis and Fourier transformm infrared (FT-IR) spectroscopy, respectively. Chemical and solvent resistance was checked against various chemicals and solvents. Bio-stability was evaluated in CoCl 2 /H 2 O 2 solution. Gloss, film flexibility, tackiness, abrasion resistance and adhesive prosperities of WDPU-PMMA coatings were also checked by applying these coatings on a leather sheet.

The aim of the research was to study the influence of the bioactive modifiers such as 7 wt.% of micrometric tricalcium phosphate (TCP) and 0.3 wt.% of nanometric hydroxyapatite (HAP) on the accelerated degradation process of composite resorbable implants based on poly(L-lactide) (PLA) matrix. The degradation was assessed on the basis of microstructural, structural and mechanical alterations. The measure of the PLA degradation progress was the gradual decrease in its molecular weight and mechanical strength. As the degradation proceeded, the plastic properties of materials decreased. In the case of composites such changes took place faster, which implies the accelerating influence of modifiers on the degradation process. Moreover, modifiers act as crystallization seeds, accelerating and stimulating the matrix organization and appearance of crystalline areas. The properties of the two composites differ. Adding TCP alone influenced the structural changes in the polymer more significantly than the addition of TCP/HAP, thus affecting the faster degradation.

In the present study, special effort was focused on increasing permeability of matrimid membranes. For this objective, a bromination reaction was carried out. The reaction of bromine with polymer was investigated using Fourier transform infrared (FTIR) spectroscopy analysis. A combination of pristine and brominated matrimid was used to prepare modified membranes due to the fact that brominated matrimid membranes were too delicate. Employing a gas separation membrane unit, the permeability of pristine and modified membranes for pure gases (CO 2 and CH 4 ) was studied. Modified membranes were much more permeable and less selective than pristine membranes. In fact, the increase in permeability of modified membranes can be attributed to the rise in the fractional free volume of modified membranes. Thermal properties of modified and unmodified membranes were also studied by thermal gravimetric and differential scanning calorimetry analysis. As a result, thermal resistance of modified membranes decreased in a limited temperature range. Modified membranes indicated smaller values of tensile strength than pristine membranes which were assessed using tensile strength analysis. The parameters which can affect the pure gases permeation through membranes such as, bromine concentration in modified membranes and operating pressure were considered as variables and the experimental design was carried out.

In this study an attempt has been made to incorporate a radiation resistant filler like boron carbide (B 4 C) nanopowder along with multi walled carbon nanotubes (MWCNT) in a high performance polymer namely poly aryl ether ketone (PAEK) for potential applications in the nuclear industry. The dispersion of nanofillers in PAEK was established by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Infra red (IR) spectroscopy indicated the interaction between functionalized MWCNT (F-MWCNT) and PAEK. The optimum combination of B 4 C and F-MWCNT was obtained from the tensile property analysis. It was found from the dynamic mechanical analysis that the storage modulus of the composite at elevated temperature was enhanced by B 4 C inclusions. Mechanical damping factor spectra showed the shift of PAEK glass transition temperature to higher values due to the presence of B 4 C and F-MWCNT. Thermogravimetric analysis (TGA) presented the resistance offered by B 4 C to the degradation of PAEK especially at elevated temperatures.