Fast Fourier Transform IR Characterization of Epoxy GY Systems Crosslinked with Aliphatic and Cycloaliphatic EH Polyamine Adducts

The use of fast FT-IR spectroscopy as a sensitive method to estimate a change of the crosslinking kinetics of epoxy resin with polyamine adducts is described in this study. A new epoxy formulation based on the use of polyamine adducts as the hardeners was analyzed. Crosslinking reactions of the different stoichiometric mixtures of the unmodified GY250 epoxy resin with the aliphatic EH606 and the cycloaliphatic EH637 polyamine adducts were studied using mid FT-IR spectroscopic techniques. As the crosslinking proceeded, the primary amine groups in polyamine adduct are converted to secondary and the tertiary amines. The decrease in the IR band intensity of epoxy groups at about 915 cm(-1), as well as at about 3,056 cm(-1), was observed due to process. Mid IR spectral analysis was used to calculate the content of the epoxy groups as a function of crosslinking time and the crosslinking degree of resin. The amount of all the epoxy species was estimated from IR spectra to changes during the crosslinking kinetics of epichlorhydrin

Physico-chemical characterization of mixed-ligand complexes of Mn(III) based on the acetylacetonate and maleic acid and its hydroxylamine derivative

Two new Mn(III) mixed-ligand complexes with two acetylacetonate (acac) ligands and one maleate ligand and its hydroxylamine derivative of the general formula [Mn(C5H7O2)2L] were prepared. Their structure was established by using elemental analysis, FTIR and UV/VIS spectroscopic methods, as well as magnetic measurement. Replacement of the acetylacetonate ligand by the corresponding acid ligand has been confirmed in Mn(III) acetylacetonate. Based on the obtained experimental data and literature indications, structural formulae to these compounds were assigned

Characterization of electrospun poly(lactide) composites containing multiwalled carbon nanotubes

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors would like to thank the Ministry of Education, Science and Technological Development, Republic of Serbia, for funding projects III45022 and 172056 and European Cooperation in Science and Technology (COST) action CA15107.The main aim of this work was to obtain conductive polymer-based materials by incorporation of different amounts of multiwalled carbon nanotubes (MWCNTs) into poly(lactide)(PLA) using the electrospinning technique. Fiber-based nonwovens with 0.2, 0.5, 1, and 3 wt% of MWCNTs were characterized regarding conductivity, morphology, thermal, and mechanical properties. It was confirmed that an increase of the MWCNTs content does not influence the increase of the material conductivity, since the conductivity was 170 ohm sq−1 for all composites. Scanning electron microscopy and transmission electron microscopy analyses revealed that smooth and beadless fibers were obtained, but also average diameters of composite nanofibers decreased with the increase of the MWCNTs content. Differential scanning calorimetry analysis showed that the presence of MWCNTs in the PLA matrix had a significant influence on the crystallization behavior of PLA nanofibers, because the decrease in crystallization temperature (Tc) was detected. Also, the incorporation of MWCNTs into PLA fibers affected the melting process, enabling the generation of α′ form, while had no influence on ordered α crystal. The enthalpy of composite degradation decreased, because MWCNTs are well-known for good heat conductivity, and with that the second step of degradation slowed down, as it was confirmed by thermogravimetric analysis. The addition of MWCNTs improved mechanical properties of composite fibers and caused the increase of both elasticity and tensile strengths of nanofibers.Ministry of Education, Science and Technological Development, Republic of Serbia III45022 and 172056; COST CA15107; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Effects of the acrylic polyol structure and the selectivity of the employed catalyst on the performance of two-component aqueous polyurethane coatings

Two kinds of aqueous acrylic polyols (single step and multi step synthesis type) have been investigated for their performance in the two-component aqueous polyurethane application, by using more selective catalysts. The aliphatic polyfunctional isocyanates based on hexamethylen diisocyanates have been employed as suitable hardeners. The complex of zirconium, commercially known as K-KAT(R)XC-6212, and manganese (III) complexes with mixed ligands based on the derivative of maleic acid have been used as catalysts in this study. Both of the aqueous polyols give good results, in terms of application and hardness, when elevated temperatures and more selective catalysts are applied. A more selective catalyst promotes the reaction between the isocyanate and polyol component. This increases the percentage of urethane bonds and the degree of hardness in the films formed from the two components of aqueous polyurethane lacquers. The polyol based on the single step synthesis route is favourable concerning potlife and hardness. The obtained results show that the performance of the two-component aqueous polyurethane coatings depends on the polymer structure of the polyols as well as on the selectivity of the employed catalyst

Energy Efficient Poly(Lactide) Obtaining by Microwave Synthesis

The world is faced with the consequences of drastic reduction in fossil fuel reserves, because of their widespread use, not only as an energy source, but also as a feedstock for monomers obtaining. In order to solve this problem, the scientific community has focused on finding the new ways to exploit renewable resources and optimize the process of polymer materials production. The aim is to obtain applicable polymer whose complete life cycle is put in ecological framework. Poly(lactide) (PLA) meets these requirements as biodegradable polyester whose monomer is derived from plant feedstock containing carbohydrates. Different methods can be applied for PLA synthesis, but from the point of energy saving, as well as environmental protection, the microwave synthesis of PLA is the best solution. The use of microwaves enables homogenous heating of reaction mixture, lower consumption of organic solvent and drastic reduction in polymerization time, obtaining, in the same time, high molecular weight polymers.10th International Conference on Sustainable Energy and Environmental Protection, (June 27th-30th, 2017, Bled, Slovenia

Thermo-mechanical properties of rigid polyurethane foams with cement addition

The parameters of foam preparation, such as addition of fillers, have a significant effect on the properties of polyurethane foams. The goal of this work was to study the effect of the cement addition on the thermo-mechanical properties of rigid polyurethane foams. Isocyanate component was based on polymeric diphenylmethane diisocyanate, and polyol component was polyether type, with addition of castor oil as polyol. It was estimated that the addition of cement increased the values of foam compressive strength and permanent deformation. Compressive strength increased even more than 90% with 20 wt% of cement. Further increase of the cement loading deteriorates the mechanical properties of foamed material because it distorts cellular structures of obtained materials. Addition of cement increased the value of the glass transition temperature of polyurethane foam. The highest increase in the value of glass transition temperature, for 7.5ºC, was achieved by the addition of 20 wt% of cement

Decomposition of poly(N-isopropylmethacrylamide) homopolymer network

Poly(N-isopropylmethacrylamide) homopolymer, which belongs to thermosensitive hydrogels, was synthesized by free radical polymerization method with 1.5 mol% of ethylene glycol dimethacrylate as cross-linker. The structure of obtained homopolymer network was confirmed by Fourier transform infrared spectroscopy analysis. The hydrogel in the gelatinous state was subjected to gamma irradiation in order to additionally form a three-dimensional network in a solid state. Suddenly, the synthesized gelatinous homopolymer was transformed into the liquid state after irradiation instead of expected additional crosslinking. Breakdown of poly(Nisopropylmethacrylamide) homopolymer was confirmed by using different methods: gel permeation chromatography, the static headspace gas chromatography mass spectrometry and gas chromatography/flame ionization detection methods. New compounds, different from the homopolymer, monomer and crosslinker were detected after irradiation. As result, the gamma irradiation will be applicable for the poly(N-isopropylmethacrylamide) homopolymer decomposition and useful to further recyclability analysis

The influence of reaction time on the properties of microwave synthesized poly(lactide)

The consequence of drastic reduction in fossil fuel reserves has forced the scientific community to find and develop new ways to exploit renewable resources and optimize the process of polymer materials production. The aim is to obtain applicable polymer whose complete life cycle is set in ecological framework. Poly(lactide) (PLA) meets these requirements as biodegradable polyester whose monomer is derived from the plant feedstock containing carbohydrates. PLA could be prepared using the different synthesis routes, but from the point of energy saving, as well as environmental protection, the microwave synthesis of PLA is the best solution. In this work, poly(L-lactide) were synthesized in microwave reactor. Reaction time was varied, while the other parameters of the synthesis were constant. The structures of obtained polymers were confirmed by Fourier – transform infrared spectroscopy (FT-IR). For determination of molar masses of poly(Llactide) samples, the gel permeation chromatography (GPC) was applied. Thermal properties were investigated by differential scanning calorimetry (DSC)