Investigation of properties and structure of polymer coatings based on epoxy polymer and trimethoprim

The main objective of the present work is to develop micro-modelling of elastic modulus of graphene nanoplates (GnPs) reinforced mixture of epoxy resin and PVDF polymer materials. The weight percentage variation of graphene nanoplates are incorporated in the mixture ratio 10:1 of epoxy resin and PVDF polymer materials for the measurement of elastic modulus with the variation of weight percentage of graphene nanoplates under tension and compression. Results indicate that the elastic modulus under tension and compression increases with the increase of weight percentage of graphene nanoplates in the mixture of epoxy resin and PVDF polymer matrix due to inhancement of mechanical properties of mixed PVDF and Epoxy resin polymer matrix.

The aim of the work was the development of optical organic-inorganic composite materials with high absorption of light the visible part of the spectrum and high reflection in the near infrared region of the spectrum. Such materials are used in industry and construction as coatings. To create these optical composites, epoxy and epoxy-polyurethane polymer matrices containing inorganic semiconducting particles (CuS, PbS, Fe3O4) were used. Highly dispersive powders of inorganic pigments were used for the preparation of homogeneous composite materials. The wet precipitation method with the application of organic stabilizing additions was applied for the preparation of dispersive CuS and PbS powders. Optical microscopy and X-ray diffraction analysis helped to study the crystal structure and morphology of the obtained semiconductor pigments. PMT-3 device was applied for microhardness measurements of the prepared composite materials. Based on the data of X-ray diffraction analysis, the average crystallite size was calculated using the Scherrer formula. It was found that freshly precipitated CuS and PbS powders consist of nanocrystals with a size of 11–20 nm. Optical microscopy data indicate the formation of aggregates of semiconductor nanocrystals in powders. Experiments have shown that all synthesized composites have low light reflection coefficient (less than 0.06) in the visible part of the spectrum and an increased light reflection coefficient in the near infrared region of the spectrum (0.13–0.15 and more). The results of the study showed that the use of epoxy-polyurethane polymer matrices provides greater microhardness of composite materials, compared to the composites based on epoxy polymers. The highest microhardness values were observed in composite materials based on epoxy-polyurethane polymers containing highly dispersed Fe3O4 particles. Obtained organic-inorganic composites could be used as materials for light-absorbing coatings in different industrial applications.

Epoxy polymer (EP) was modified by incorporation of DBP, PVC, PVA, and glass fiber reinforcement. The morphology of the unmodified polymer and the various blends was studied by SEM, dispersive X‐ray analysis, and DSC. Results indicated that EP and DBP are miscible in the proportions used in this work (up to 10% of DBP). PVA added to cured EP in a concentration of 10% occurs as a separate phase. The morphology of EP–PVC blends is relatively complex: EP and PVC are immiscible at low concentration of the second component (up to 10% of PVC), but become mutually and increasingly more miscible as the concentration of PVC increases. Incorporation of DBP into EP causes a marked reduction in the heat distortion temperature (HDT), whereas addition of PVC has only a moderate effect. Modified EP containing small amounts of DBP (up to 4%) has moderately lower bond strength than the unmodified polymer, as evidenced by lower ultimate tensile strength of the adhesion sandwich specimens mounted on aluminum substrate. However, as the concentration of DBP in the blend increases, the ultimate tensile strength is slightly higher than that of the unmodified EP. Blending of EP with PVC, PVA, and glass fibers has generally a detrimental effect on the ultimate tensile strength. Outdoor exposure for 100 days (between January and April) generally caused deterioration of the tensile strength of all samples. EP‐based blends containing DBP, however, had better resistance to deterioration in outdoor exposure than the other blends, including unmodified EP.

In the present study, polymeric epoxy and polyester resin reinforced with glass fiber compounds were prepared by adding of flame retardants based on aluminum and magnesium hydroxide in order to evaluate their influence on mechanical properties. An experimental DOE design was developed with two qualitative factors: the resin and retardant type; with two levels each and a quantitative factor: volumetric composition of the retardant with three levels (3%, 6% and 9%). With all possible combinations; tensile, flexural and impact tests were carried out. The results showed that the addition of retardants in different percentages has different influence for each mechanical property. It was evidenced that the 9% HA Aluminum Hydroxide has no significant effect on the tensile strength and its modulus compared to Magnesium Hydroxide HM. Conversely; on the flexural strength, flexural modulus and rupture energy the HM has a slightly lower effect with respect to the HA. For flexural strength and its modulus, the best proportion of retardant was 6%. 3% is the recommendation for rupture energy. The data presented in this document can be used to improve the fire resistance of the existing materials studied.

The use of nano-SiO2 particles and rubbery particles to give 'hybrid-toughened' epoxy polymers has been analyzed to give a range of novel matrices which lead to an increased delamination toughness of the resulting CFRP composites by resin-transfer molding (RTM) and vacuum-assisted resin-transfer molding (VARTM). The rubbery particles magnificently increase the toughness of the material via interactions of the stress field ahead of the crack tip compared with the pure epoxy polymer. Both particles are introduced to give a multiphase 'hybrid-toughened' polymeric materials. The presence of a relatively high concentration of the nano-SiO2 toughening particles does not lead to a decrease in the modulus of the composite. These mechanisms will lead to further increases in the mechanical performance of 'hybrid-toughened' epoxy polymers, containing a complex multiphase structure of nano- and micro-sized phase inclusions.

A comparative evaluation of the structuring processes of the epoxy polymer system with epoxy polymers modified with polyvinyl chloride solution and epoxy composites filled with finely dispersed titanium oxide powder was carried out. Analysis of the infrared (IR) absorption spectra of the studied epoxy polymer and epoxy composite materials showed the presence of deformation and valence vibrations of certain groups of atoms. The oscillations of groups of atoms with double bonds and regions of existence of triple bonds were also revealed. In the region of high frequencies, absorption bands correspond to valence vibrations of groups containing a hydrogen atom. The presence of triple bonds in the epoxy polymer system was determined, indicating unreacted functional groups. This fact corresponds to the low content of the gel fraction of unmodified epoxy polymers after heat treatment and indicates the formation of a system with insufficient chemical bonds. The absorption bands of the epoxy composite material filled with titanium oxide powder are characterized by a lower optical density and a larger peak area compared to the bands of the unmodified epoxy polymer, which indicates the formation of a higher number of crosslinking nodes of the epoxy composite material. The introduction of polyvinyl chloride into the composition of the epoxy polymer system increases the degree of structuring of epoxy polymers. However, a smaller number of formed chemical bonds of the modified epoxy polymer was recorded compared to epoxy composites containing titanium oxide particles. The highest degree of structuring is provided in polyvinyl chloride-modified epoxy composites containing titanium oxide powder due to intensive structuring and formation of double and triple bonds.

In situ chemical linkage between nanofillers and polymer is challenging, but it is an effective process for enhancing the mechanical and thermal properties of polymer nanocomposites. Herein, novel amine‐functionalized graphene is designed and developed to show the in situ chemical interaction with epoxy matrix. Three different graphene materials, graphene oxide (GO), carboxylic graphene oxide (GOCOOH), and ethylenediamine substituted graphene oxide (GOCONHCH2CH2NH2) is synthesized chemically, and epoxy nanocomposite with different wt% is fabricated. FTIR showed the presence of hydroxyl and amide bond formation, confirmed by 13C‐NMR, where the carboxylic carbon peak of GO at 193 ppm shifted to 184 ppm for GOCONHCH2CH2NH2. Elemental analysis by XPS showed that C: O: N of GO changed from 70:30:0 to 79:13:8 for GOCONHCH2CH2NH2. Three‐point bending studies revealed that maximum flexural strength and modulus for GOCONHCH2CH2NH2 incorporated epoxy polymer composite because of intermolecular chemical bond formation between the epoxy resin and GOCONHCH2CH2NH2. The formation of a chemical bond between GOCONHCH2CH2NH2 and epoxy polymer is confirmed by Raman spectroscopy and XPS analysis. The mechanism of forming an in situ chemical bond between amine‐functionalized graphene and the epoxy polymer is derived based on experimental evidence.

The purpose of this letter is to report a novel observation on the effect of rubber particle-plastic zone interactions on the transition point in the fatigue crack propagation (FCP) behaviour of rubber-modified epoxy polymers. This observation provides useful information relevant to the modelling of FCP behaviour of rubber-modified thermoset polymers. The findings reported here are the preliminary results from more detailed studies on the effect of rubber particle size and volume fraction on the FCP resistance of rubber-modified epoxy polymers [1]. McGarry and co-workers [2, 3] were among the first to show that the poor fracture resistance of epoxy polymers could be enhanced by the incorporation of a dispersed rubbery phase. Since their initial investigations, several studies [4-10] have provided a detailed description of the deformation micromechanisms responsible for the increase in fracture toughness of rubber-modified epoxy polymers. The most commonly observed among these mechanisms, as shown in Fig. 1, include: (i) localized shear yielding, which refers to shear banding in the epoxy matrix that occurs between the rubber particles; (ii) hole or plastic void growth in the epoxy matrix, which is initiated by cavitation or debonding of the rubber particles; and (iii) rubber particle bridging behind the crack tip. Despite numerous experimental investigations on the fracture mechanisms in rubber-toughened epoxy polymers and some success in modelling the fracture behaviour of these materials under static loading conditions [9, 11], very little is known about cracktip shielding mechanisms in rubber-modified epoxies under cyclic loading conditions. Furthermore, no attempt has been made to model the FCP behaviour

Este trabalho descreve as propriedades biológicas in vitro de três formulações epoxídicas usando o monômero do tipo éter diglicidílico do bisphenol-A (DGEBA) com três co-monômeros do tipo poliamina alifática de maneira independente; trietilenotetramina (TETA), 1-(2-aminoetil)piperazina (AEP) e isoforonodiamina (IPD). As interações biológicas entre os polímeros obtidos e o sangue foram estudadas in vitro utilizando quatro métodos biológicos diferentes. Estudos de adsorção protéica, adesão plaquetária, formação de trombos e citotoxicidade são apresentados e discutidos. Os ensaios de adsorção protéica mostraram que a superfície dos polímeros adsorve mais albumina humana do que fibrinogênio humano. Os resultados de adesão plaquetária e formação de trombos indicaram que os sistemas DGEBA-IPD e DGEBA-AEP exibem boa hemocompatibilidade. Os três polímeros epoxídicos não revelaram toxicidade com células de ovário de hamster chinês. Os resultados obtidos indicam que os polímeros epoxídicos baseados no IPD obedecem aos critérios de hemocompatibilidade e citotoxicidade exigidos de um biomaterial. Os polímeros epoxídicos baseados nas aminas AEP e TETA exibem apenas um comportamento não citotóxico.

We study the structure and thermomechanical properties of systems based on epoxy polymer, metal oxides, and polyaniline. It is shown that iron oxide in a mixture with polyaniline begins to reveal its crystalline structure in the composite for a fairly low concentration level (1.0 vol.%) unlike aluminum oxide, which does not reveal its structure even for its high contents. The investigations reveal a strong dependence of the microheterogeneous structure of composites on the type of metal atoms in oxides. By the method of thermomechanical analysis, we show that the composites based on the epoxy polymer and a mixture of polyaniline with one of the metal oxides ( Al2O3 or Fe2O3) are characterized by the abnormal expandability (α1 = 25%).

The utilization of reclaimed asphalt pavement (RAP) could reduce the cost of pavements containing epoxy polymer (EP) materials. This study was aimed at improving the homogeneity of an EP-reclaimed asphalt mixtures (ERAMs) at both the micro- and meso-scale to provide a reference for an ERAM production process. At the microscale, nanoindentation tests were conducted to characterize the diffusion between the EP and aged asphalt mastic. At the mesoscale, computerized tomography (CT) X-ray scanning and MATLAB analysis were employed to investigate the distribution of the aggregate within the ERAM. The results revealed that mixing temperature played a significant role in the diffusion and distribution between the EP and the aged asphalt mastic, thus impacting the mechanical properties of the material. Heating at 180 °C (the recommended mixing temperature of EP) resulted in a wider blending zone between the EP and the aged asphalt mastic compared to heating at 160 °C (the usual mixing temperature of ordinary reclaimed asphalt mixtures). The overall dispersion of the aggregate in the ERAM exhibited greater homogeneity in the vertical direction than in the horizontal direction. Adjusting the gradation of the RAP was found to be effective in reducing horizontal variability in the distribution of the coarse aggregate, fine aggregate, and air voids in the ERAM. Adjusting the RAP gradation further enhanced the vertical homogeneity in the distribution of the fine aggregate, while its impact on the vertical distribution of the coarse aggregate was minimal. Short-term aging led to increased variability in the distribution of the coarse aggregate, fine aggregate, and air voids within the ERAM. However, adjusting the gradation was effective in mitigating the adverse effects of short-term aging on both horizontal and vertical homogeneity in the aggregate distribution.

Reinforcement of Bisphenol-F epoxy resin composites with fluorinated carbon nanotubes

Various analytical methods were employed to elucidate the effects of filling nano-calcium-silicate or nano-silica on the electronic property, water-uptake, and thermal stability of an amine-crosslinked epoxy (EP) polymer. Molecular-mixture models consisting of a nanofiller or several calcium ions and EP crosslinked macro-molecules were used to simulate local regions of nanofiller/matrix interface or ion-infiltrated matrix, calculating their density of electron-states by first-principles method to determine whether and how the nanofillers introduce charge traps into EP matrix. Calcium cations on nanofiller surface dissociate away from coordinating with silicon-oxygen tetrahedron and infiltrate into void spaces in EP matrix, leaving a larger free volume at filler/matrix interface than in matrix. Calcium cations dissolved in EP matrix are adsorbed in the low electrostatic potential region or coordinate with carbonyl groups in EP matrix and thus introduce a miniband of deep electron traps at energy levels >1 eV lower than conduction band minimum of the amine-crosslinked EP polymer. Even at room temperature, thermal vibrations can break coordinate bonds between calcium cations and silicon-oxygen framework on calcium-silicate nanofiller surface and make considerable calcium ions infiltrating void spaces within EP matrix, leading to comprehensive improvements of cohesive energy, thermal stability, and charge trapping ability in the calcium-silicate/EP nanocomposite.

The demonstration of organic magnetic materials has offered the challenge of finding polymer (organic) materials in which there is sufficient electronic exchange as well as stability in both thermally and chemically. This paper gives an overview of the synthesis of promising new complex polymer building blocks that have allowed the fabrication of high Q and L inductors. New materials from the saccharide, epoxy, and other polymers materials are also explained. Some devices made from these materials are discussed.

For Abstract see ChemInform Abstract in Full Text.