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Last years research in polymers registered an increase of interest regarding polymer mixtures aiming to obtain materials with properties of the mixed polymers. In this respect many studies are pointing the mixtures between a thermoset polymer and a thermoplastic polymer. It is known the fact that thermoplastic polymers are much more malleable than the thermoset ones and the goal is to obtain a mixture with the general properties of the thermoset polymer and with a machining ability proper to the thermoset polymer. The vitrimers are this type of polymers and, some of them, can be obtained by mixing polymers form the two categories. This study is about using solutions of two thermoset polymers to modify the basic properties of three epoxy resins. The results show that the presence of PMMA, respectively, PLA inside the epoxy resin matrix determines changes of the mechanical properties of the formed materials. Without analysing the adhesive properties of new materials is hard to decide about their value from the composites applications point of view. [ABSTRACT FROM AUTHOR]

This work proposes the comparison of two models of 3D printed hip prostheses, using microscopic and chemical analysis, but also compression and bending testing. The comparison was made using a hip prosthesis designed in the Autodesk Inventor 2020 program and a model freely available on the Internet. The work includes some details about the virtual prototyping of prostheses and results from the chemical analysis of the components of the hip prostheses, carried out using an X-ray spectrometer to identify the elements contained in the PETG (polyethylene terephthalate glycol) material that was used to obtain the samples. The second method of analysis was the microscopic one and finally the samples were subjected to external forces, through bending and compression testing. This comparison aimed to demonstrate the dependence between the shape of the prosthesis and the mechanical properties of the analysed samples. [ABSTRACT FROM AUTHOR]

Pollution is being discussed more and more in the world. It is known that the production of Glass Fiber Reinforced Polyester (GRP) is a polluting process. Also, the implementation of GRP is a process that can cause various ailments to the personnel who apply it. Over time, boats made of GRP suffer degradation due to interaction with the environment: cracks, exfoliation of the outer layer of gelcoat, etc. These degradations must be remedied, operations that involve the application of substances that are also polluting. More and more traditional manufacturers of sports boats are replacing GRP with aluminum. This, although the process of obtaining it from the ore is not without toxic components, is less polluting and friendlier to the executors than GRP. In this paper, we seek to elucidate the advantages that aluminum has over GRP in the construction of sports boats. [ABSTRACT FROM AUTHOR]

The specific heat of nano-ferrites modified composites was studied using differential scanning calorimeter (DSC) method in the temperature range of 30 to 150°C. Initially, nano-ferrites were introduced in epoxy systems in order to improve the electromagnetic properties of formed materials. Together with the changes in electromagnetic properties some modifications occur regarding thermal and mechanical properties. The materials were formed by placing 5g or 10g of ferrite into 250g polymer matrix leading to a very low weight ratio of modifying agent. At so low ratios the effect of ferrite presence should be insignificant according to mixing rule. Anyway there is possible to appear some chelation reaction with effects on thermal properties of materials. Three types of epoxy resins had been used as matrix and barium ferrite and strontium ferrite as modifying agents. The thermal analysis was developed on two heatingcooling cycles and the specific heat was evaluated for each segment of the cycle analysis.

Epoxy resins have been presenting a lot of scientific and technical interests and organic modified epoxy resins have recently receiving a great deal of attention. For obtaining the composite materials with good mechanical proprieties, a large variety of organic modification agents were used. For this study gluten and gelatin had been used as modifying agents thinking that their dispersion inside the polymer could increase the polymer biocompatibility. Equal amounts of the proteins were milled together and the obtained compound was used to form 1 to 5% weight ratios organic agents modified epoxy materials. To highlight the effect of these proteins in epoxy matrix mechanical tests as three-point bending and compression were performed. [ABSTRACT FROM AUTHOR]

In this investigation, the specific heat of four fabric reinforced hybrid composite materials with filled stratified epoxy matrix was analysed. All hybrid composite materials were made of 17 layers, for which were used carbon, aramid, glass and hybrid fabrics. The stratified filled epoxy matrix of fabric reinforced hybrid composites represents a matrix, in whose structure it was used three types of fillers mixtures between certain plies. The investigation of specific heat of hybrid composite materials was performed by using of Differential Scanning Calorimetry instrument. It was analysed the effects of fiber orientation at various angles on specific heat of fabric reinforced hybrid composites with filled stratified epoxy matrix and the influence of fillers mixtures on these thermal properties of epoxy matrix. Also, it was studied the specific heat of hybrid epoxy composites in dependence of carbon and aramid plies number in studied materials structure. [ABSTRACT FROM AUTHOR]

In this work, the studied materials are formed with a graduated matrix and reinforced with different types of fabrics. These composites are similar regarding the reinforcement, but the difference between them consists of the epoxy matrix types. Any application of a polymer composite in an outdoor environment invariably involves water absorption and variable thermal conditions. The degradation of composite materials was observed after each cycle, water absorption and frozenunfrozen, from a qualitative (visual) point of view, until the materials reached a saturation degree (the mass of specimens remaining constant after a certain number of cycles). This aspect had led to the conclusion that materials can no longer undergo quantitative changes. The aim of this work is to examine the behavior of materials subjected to environments that simulate atmospheric conditions (water absorption and frozen-unfrozen). The purpose of these materials was to be used in order to form some spare parts of vehicles such as, in case of an impact, to ensure pedestrians protection since they could have controllable strength. This aspect pays a very important role both in economically and environmental terms. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the three point bending properties of doped epoxy resin. Sodium and potassium dichromate doped epoxy resin obtained by ultrasonication strategies is a novelty in the field of the ultra-sonicated composite materials. The epoxy system WWA-WWB from Resoltech had been used as matrix. Bending tests were conducted as recommended by ISO 178/2001. Test speed for all tests was set at 5 mm / min. The tests were carried out on TESTOMETRIC M350-5AT machine. The doping method had been developed as part as research activity under the Project POSCCE 12P01.024/CD111. [ABSTRACT FROM AUTHOR]

In this paper, we describe the influence of ultra-sound exposure time and tribological properties regarding formation of composites with two different salts doped epoxy resin. Potassium dichromate and Sodium dichromate were choosen due to their flexible way of use and the novelty of their usage to form epoxy composites. The time of ultra-sound exposure was, each time, of 1, 2, 3, 4, and 5 minutes. The doping method had been developed as part as research activity under the Project POSCCE 12P01.024/CD111. All the presented experiments and results are performed and obtained at Polymer Composites Laboratory of Dunărea de Jos University of Galaţ i. [ABSTRACT FROM AUTHOR]

Based on traction tests, the authors assessed the influence of the PTFE concentration on the mechanical characteristics of blends PBT + PBT. The studied range of PTFE addition was 0...20% wt. For these samples, the traction limit of PBT is 40.58 MPa, but for the blend PBT+10% PTFE, this characteristic increase to 46 MPa. For 15% PTFE in PBT, the traction limit was 45.59 MPa and for the blend with 20% PTFE, the average value was 42.37 MPa. The tendency of changing the traction limit is similar to that for the elastic modulus. Adding PTFE in PBT is not beneficial for improving the mechanical characteristics, at least for the tested range of concentrations, but they have to known for designing tribological applications. [ABSTRACT FROM AUTHOR]

Fillers are generally used in order to change some basic properties of polymer matrix but the filler particles often tend to aggregate with consequences in terms of the mechanical properties of the final composite. In order to avoid aggregation, many solutions have been proposed and one of them is to use ultrasounds in various stages of composites formation. In this study, the compressive behaviour of filled epoxy was analysed. As filler, at a 10% volume ratio, a mixture of three parts of starch and one part carbon black was used. The aim of the analysis was to identify the effect of ultra-sonication at different frequencies and for different periods of time on the compressive properties of composites. [ABSTRACT FROM AUTHOR]

As ultra-sonication is a mostly used method to disperse the particles into the polymer matrix, the aim of this study is to point out the effect of epoxy's exposure to ultra-sounds over the electrical properties, especially the electrical conductivity. As the epoxy resins are insulators, the method is based on the determination of electrical conductivity via the measurement of electrical insulation resistance. The polymer solution was exposed for 45 minutes to ultra-sounds produced by one, two, three and four generators at different values of ultra-sounds frequency. [ABSTRACT FROM AUTHOR]

While the design problem seems to be essential in order to form a high performance composite one may ask more: is it possible to form a material able to give information about its state? Is it possible to control the properties of a composite through alternation of its various layers? Is it possible, finally, to obtain a multifunctional material based on a right design, on a cheap forming technique, on accessible components? This study is about partially answering the above questions. Two types of fiber fabric were used to form composites with filled epoxy matrix and materials bending and thermo-mechanical properties were evaluated using appropriate recommended methods. [ABSTRACT FROM AUTHOR]

The combination of a filler with a polymer results in a new material with changed properties. Some of these changes are advantageous while others are less favorable. Polymeric dispersions of nanometer-sized metal particles offer the possibility of functionalizing the polymer by properties coming from the large number of surface atoms and the quantum-size effects. Nanosized metals show properties that differ significantly from that of bulk metals, which makes these nano-composite systems intriguing for scientific study and potentially useful for a number of technological applications. This study is about changing the epoxy properties using appropriate fillers. [ABSTRACT FROM AUTHOR]