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Glass reinforced plastic, so called GRP, is a composite material made of glass strands called fibbers woven together to create a flexible fabric. GRP is a lightweight material with many and diverse applications ranging from the manufacture of reservoirs for different liquids to the manufacture of boats, yachts, chairs and even children playground furniture. The behaviour of this material under static and dynamic loads is still raising interest from the scientific community and a large number of researchers. This continued interest is due to the material versatility for different applications depending on its manufacture process that has a significant weigh-in in the material mechanical properties. These resulting mechanical properties need to be carefully analysed and benchmarked prior to using the obtained material in commercial applications. The scope of this research study is to analyse the behaviour of glass reinforced plastic plate panel with reinforcements on one and two directions under static and dynamic loads employing both experimental and numerical methods for results validation. The methods used in this research study for the dynamic loads can also be applied successfully to other composite materials. Additionally, the stress plots have been analysed in iteration in order to ensure the most optimal reinforcement pattern.

Thermoplastic materials have great usage through FDM 3D printing technology. Today, FDM 3D printer is available to the broad population, and some of the thermoplastic materials is widely used due to their small price and availability. Such thermoplastic materials are ABS (Acrylonitrile butadiene styrene) and PLA (Polylactic acid). In this paper the possibility of drone frame design optimization that can be made from ABS and PLA plastics using FDM 3D printing technology is analyzed.

In the medical field the additive manufacturing process by fused deposition modeling has gained a great importance given the ability to create complex, organic geometries, in a short time period and the possibility of high customization. By fused deposition process the part is created layer by layer and the resulting part is characterized by high anisotropy, dictated mostly by printing parameters. To alleviate the anisotropy and to study the mechanical behavior of the 3D printed parts thermal processing is used. The materials used as filament is a poly (lactic acid) with copper particles embedded for antibacterial purposes. Samples were 3D printed using a commercial printer, thermally processed and tested in compression. On the failed specimens fracture investigations were performed to understand mechanical behavior during compression. The mechanical characteristics showed improvement and the anisotropy decreased as the processing temperature increased, but the samples became brittle. The mechanical behavior changed drastically on the thermally processed samples because of structural changes: a discontinuity between exterior layers and infill layers was created post layer fusion, the first region being the one stressed and failed first during tests.

In order to place a product on the market that is completely safe for users, the manufacturer must go through certain steps: design, prototyping, execution and prototype validation through experimental methods, obtaining documents that allow to sell the product from certain public or private companies (for example homologation certificate) and series production. One of the most important steps is the validation tests of the prototype because it will depend on them that the prototype corresponds to the design requirements.

Obtaining parts made of composite materials through 3D Printing Additive manufacturing have fully proved their usefulness due to a number of advantages such as: the possibility to directly create complex shapes without going through the classic process of transforming the semi-finished products into finished parts through technologies which consume resources and energy and are totally unfriendly to the environment. The main disadvantage of the parts made by 3D Printing technologies is that they are less resistant from a mechanical point of view. This was solved with the emergence of the 3D printers capable of printing composite parts consisting of a plastic matrix reinforced with continuous fibers. This research focuses on studying 4 types of composite materials from the point of view of their mechanical properties: Onyx - a rigid nylon in which micro carbon fibers are inserted and Onyx reinforced with carbon, fiber glass or kevlar. Standardized specimens were made for the uniaxial tensile test and the experimental program was designed evaluating: the Elastic modulus [GPa], the Maximum Tensile stress [MPa], the Tensile strain at maximum Tensile stress [mm/mm]. The principal strains were also determined, by means of the digital image technique made using the Aramis system from GOM. The experimental tests confirm that these new materials will be serious candidates to be used in the engineering applications in various fields.

In time the environmental conditions could damage textiles (materials/ artifacts) causing the need to develop better non-destructive or at least micro-destructive analysis techniques of the samples. There are ethnographic textile artifacts that were treated in the past with various pesticides, that have not been mentioned in any document. These are often re-treated with chemicals by museum staff as a method of preventing pest infestation. Due to the progressive use of many pesticides, this paper was focused on the detection and quantification of three pesticides: malathion, methoxychlor, and permethrin (cis- and trans- isomers). Gas chromatography is one of the most widely used analytical techniques for characterizing volatile organic compounds and therefore was the analytical method of choice for the present study. Because these analytes are found at trace levels, the detection and quantification limits of analytes are very small and it is necessary to optimize and validate a SIM method - that allows the mass spectrometer to detect specific compounds with high sensitivity. In SIM mode, the instrument is set to collect data at selected masses of interest, thus increasing the accuracy and precision of the quantitative results. The present paper is aimed to develop this type of method with specificity and selectivity, high precision (expressed in terms of repeatability and intermediate accuracy), accuracy, suitable working range and linearity, and high degree of series’ homogenity.

The effect of mold conditions was investigated in terms of mold temperature (30oC and 90oC) and cooling time (30 s and 60 s) on the heat resistance of injection-molded bars for stereocomplex polylactide-b-polyethylene glycol-b-polylactide (scPLA-PEG-PLA). Comparative study was performed for poly(L-lactide) (PLLA) and PLLA-b-PEG-b-PLLA (PLLA-PEG-PLLA). scPLA-PEG-PLA was 90/10 (w/w) PLLA-PEG-PLLA/poly(D-lactide) blend. scPLA-PEG-PLA exhibited the easiest crystallization upon cooling scan as shown by differential scanning calorimetry (DSC). Higher mold-temperature and longer cooling-time induced higher degree of crystallinity as assessed by X-ray diffractometry (XRD) except for PLLA bars. The heat resistance of both PLLA-PEG-PLLA and scPLA-PEG-PLA bars was improved with increased mold-temperature and cooling-time as shown by dynamic mechanical analysis (DMA), vicat softening temperature (VST) and heat distortion-resistance tests except for PLLA bars. In conclusion, the heat resistance of injection-molded bars prepared at 90˚C mold temperature was in the order scPLA-PEG-PLA ] PLLA-PEG-PLLA ] PLLA. The results suggested that flexible PLLA-PEG-PLLA and scPLA-PEG-PLA with high degrees of crystallinity were successfully obtained by injection molding for use as good heat-resistant bioplastic products.

The azo-chalcone dye of theophylline namely (E)-1-(4-((E)-(theophyllin-8-yl) diazenyl)phenyl-3-(4-dimethylaminophenyl)prop-2-en-1-one (TDPP) has been prepared and characterized by H-NMR, infrared, and electronic spectra, elemental analysis. Three solid complexes Mn(II), Ni(II) and Cu(II) of TDPP dye have been prepared and characterized by IR, electronic spectra, magnetic and conductivity measurements. The antibacterial and antifungal activities of the TDPP ligand and metal (II) complexes of Ni, and Cu are notable, with the copper(II) complex being more potent than the others. The TDPP ligand has interesting spectral properties as a pH sensor, solvent polarity sensor, and switches.

Propargylamines are a promising but quite poorly studied category of organic compounds. This work aimed to study the photochemical properties of propargylamines polymers containing porphyrin fragments with electron transfer reactions. The study was carried out in 2019 at the Institute of Organic Chemistry (RAS, Moscow, Russia). The obtained polymer was irradiated with a luminous source. The absorption spectra were studied by electron paramagnetic resonance using a radio spectrometer. The presence of porphyrin and propargylamine in the polymer solution has been established to promote the reaction of complexation. This is due to the presence of double bonds in the amino groups, whereas also porphyrin and bromanil, which is an electron acceptor. The resulting data allow explaining the processes involved in photochemical reactions during the irradiation of the porphyrin complex in the presence of bromanil. In the long-wavelength part of the spectrum (above 540 nm), electron phototransfer inside the polymer molecule to the porphyrin side and between molecules from the porphyrin anion radical to the neutral polymer molecule take place.

A series of methods were employed to assess the performances of advanced coating materials based on components that can modify the spectral parameters of the surfaces on which these materials are applied in order to obtain passive military camouflage. Powder materials with high infrared (IR) reflectance were used to obtain this type of coatings, which also ingrain in their structure a significant volume of air that allow limitation of the radiative heat transfer of the coated source. The components were embedded in a polyurethane matrix, which facilitated the coating process on different surfaces. The bicomponent polyurethane-based binder used within the different composition tested is transparent to incident IR radiation, has no organic solvents, is highly flexible and possesses remarkable physical, chemical and mechanical properties: high surface adhesion, high flexibility and resistance against a number of chemical agents and external factors with destructive effect. The efficiency of these composite materials was further demonstrated by analyzing the thermal images of different objects.