STRENGTHENING OF HISTORICAL BUILDINGS WITH COMPOSITE POLYMERS

Većina građevina kulturne ili graditeljske baštine su zidane zgrade koje su izgrađene najčešće od kamenih ili opečnih zidnih elemenata povezanih mortom, a zidane su prije postojanja znanja i propisa o protupotresnom građenju. Kompleksnost sanacije povijesnih građevina uvjetuje nekompatibilnost tradicionalnih i novih gradiva te poštivanje njihovog izvornog postojanja, zbog čega se ne preporučuje ni uporaba armiranog betona. U radu je opisana inovacijska metoda ojačanja povijesnih građevina tehnikom postavljanja kompozitnih polimera te prednosti navedene tehnike u odnosu na tradicionalne metode ojačanja i njezina primjena na postojećim građevinama.Most buildings of cultural or architectural heritage are masonry buildings constructed mostly of stone or brick walls. Those kinds of buildings were built before the existence of seismic knowledge and regulations. The complex issue of rehabilitation of historic buildings is based on incompatibility of traditional and new materials as well as on the necessity to preserve the original appearance of these buildings. The use of reinforced concrete is not recommended in rehabilitation of historical buildings. This paper will describe the innovative method of reinforcement of historic buildings with composite polymer technology and the advantages of the aforementioned technique compared to some traditional reinforcement methods and its application to existing buildings

Surface Modification & Characterization of Nano-Composite Polymers

We have studied the modification of surfaces of both PMMA and nano-composite polyhedral oligomeric silsesquioxane (POSS) containing acrylics. These nano-composites can be spun cast from a variety of solvents and the surface chemistry can be modified by exposure to oxygen-containing plasmas. However, we have found that interesting surface structure evolve over the space of several hours after these films are deposited. We have also found that the solvent used for the spin casting of these layers can alter the behaviors of these surfaces. In particular, we found that halogenated solvents can form complexes with the PMMA backbone to increase the adhesion of noble metal layers on the surface of these polymer

Novel thermoresponsive assemblies of co-grafted natural and synthetic polymers for water purification

Water contamination and its purification are a global problem. The current approach to purify water is reduction of impurities to acceptable levels. One of the ways to achieve this is by use of water-soluble polymers that extract organic and metallic contaminants, from water. This paper presents a blend of composite polymers that eliminates both the contaminants simultaneously by the principle of adsorption at lower critical solution temperature. These composite polymers have been synthesized by grafting poly(N,N-diethylacrylamide), poly(N-isopropylacrylamide) and poly(N-vinylcaprolactam) on-to the natural polymer chitosan or its derivatives, giving smart graft polymeric assemblies (GPAs). One of the graft polymers, GPA-2, exhibits excellent adsorption properties able to remove metal ions like cadmium, cobalt, copper, lead, iron and also organic impurities like chlorophenol and phthalic anhydride. Studies reveal that 6 mg/ml GPA-2 is able to effect a 100% removal of organic impurities – chlorophenol (50 ppm) and phthalic anhydride (70 ppm) – from water, while complete removal of the heavy metal ions (Cu+2, Co+2 and Cd+2) together at 30 ppm concentration has been achieved with 7.5 mg/ml GPA-2. The reduction in level of impurities along with recyclability and reproducibility in the elimination spectrum makes these assemblies promising materials in water treatment.</jats:p

Impact of Ionic Liquids on Silver Thermoplastic Composite Membrane Polyurethane for Propane/Propylene Separation

This work describes newly synthesized composite polymeric membranes and their utilization in propane/propylene separation in a gas mixture. The nonporous composite polymers were successfully synthesized by using thermoplastic polyurethane (TPU) and several silver salts/silver salts with ionic liquids (ILs). Our studies showed that silver bis(trifluoromethanesulfonyl)imide (Ag[Tf2N]) containing membranes outperformed other silver salt containing membranes in terms of selectivity. In addition, to this finding, ILs, as additives for the membranes, enhanced the selectivity by facilitating improved coordination of the olefin with the silver ions in the dense composite polymers.Scopu

Thermal and Electromagnetic Properties of Polymer Holey Structures Produced by Additive Manufacturing

Multifunctional 3D-printed holey structures made of composite polymers loaded with nanocarbon were designed to serve simultaneously as GHz-radiation absorbing layers and heat conductors. The geometry of the structures was devised to allow heat to be easily transferred through, with special attention paid to thermal conductivity. Numerical calculations and a simple homogenization theory were conducted in parallel to address this property. Different structures have been considered and compared. The electromagnetic shielding effectiveness of the produced holey structures was measured in the microwave range

Composite Polymers Development and Application for Polymer Electrolyte MembraneTechnologies—A Review

Nafion membranes are still the dominating material used in the polymer electrolyte membrane (PEM) technologies. They are widely used in several applications thanks to their excellent properties: high proton conductivity and high chemical stability in both oxidation and reduction environment. However, they have several technical challenges: reactants permeability, which results in reduced performance, dependence on water content to perform preventing the operation at higher temperatures or low humidity levels, and chemical degradation. This paper reviews novel composite membranes that have been developed for PEM applications, including direct methanol fuel cells (DMFCs), hydrogen PEM fuel cells (PEMFCs), and water electrolysers (PEMWEs), aiming at overcoming the drawbacks of the commercial Nafion membranes. It provides a broad overview of the Nafion-based membranes, with organic and inorganic fillers, and non-fluorinated membranes available in the literature for which various main properties (proton conductivity, crossover, maximum power density, and thermal stability) are reported. The studies on composite membranes demonstrate that they are suitable for PEM applications and can potentially compete with Nafion membranes in terms of performance and lifetime

High refractive index composite materials for THz waveguides: trade-off between index contrast and absorption loss

Polymer compounds from titania-doped polyethylene are fabricated and their linear optical properties characterized by THz-TDS. We show that high concentration of dopants not only enhances the refractive index of the composite material, but also can dramatically raise its absorption coefficient. We demonstrate that the design of Bragg reflectors based on lossy composite polymers depends on finding a compromise between index contrast and corresponding losses. A small absorption value is also shown to be favorable, compared to an ideal lossless reflector, as it enables to smooth the transmission passbands. Transmission measurements of a fabricated hollowcore Bragg fiber confirm simulation results

Development of Transdermal Patches for the Delivery of Chlorpheniramine in Infants using Hypromellose and Cassava Starch Composite Polymers

Background: Chlorpheniramine is an antihistamine that is used in the treatment of rhinitis and other allergies. Objectives: The objectives of this research was to develop and evaluate transdermal patches for improved delivery of chlorpheniramine in infants using hypromellose and cassava starch composite polymers. Methods: Chlorpheniramine transdermal patches were formulated by solvent casting method using varying amounts of hypromellose (hydroxypropyl methylcellulose), cassava starch and polyethylene glycol 4000. The formulated transdermal patches were characterized by Fourier Transform Infra-red Spectroscopy (FT-IR), folding endurance, elongation breaking test, percentage moisture uptake/loss and ex vivo permeation studies. Results: The spectra showed no chemical interaction between the ingredients. The transdermal patches showed elastic qualities and high folding endurance. Patches with consistently high moisture uptake (around 40%) were observed to contain high concentration of cassava starch while those with higher amounts of HPMC lost more water (around 35%). The ex vivo study showed efficient permeation and flux for the target purpose. Conclusion: Transdermal patches may be used to deliver low dose chlorpheniramine drug through the skin possibly soft and thin infant skin. Keywords: Transdermal; permeation; flux; allergy; chlorpheniramin

Substitution of antibodies and receptors with molecularly imprinted polymers in enzyme-linked and fluorescent assays

A new technique for coating microtitre plates with molecularly imprinted polymers (MIP), specific for low-molecular weight analytes (epinephrine, atrazine) and proteins is presented. Oxidative polymerization was performed in the presence of template; monomers: 3-aminophenylboronic acid, 3- thiopheneboronic acid and aniline were polymerized in water and the polymers were grafted onto the polystyrene surface of the microplates. It was found that this process results in the creation of synthetic materials with antibody-like binding properties. It was shown that the MIP-coated microplates are particularly useful for assay development. The high stability of the polymers and good reproducibility of the measurements make MIP coating an attractive alternative to conventional antibodies or receptors used in ELISA