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Pyrotechnic compositions using polyurethane as binder were designed to maximize the temperature of combustion and the burn rate. The flares consisted in mixtures of potassium perchlorate/Mg-Al alloy/polyurethane/additives. In order to determine the optimum input ratio that conducts to the most appropriate solution in terms of theoretical amount of heat released, specific volume of gaseous products and chemical composition, Explo5® thermochemical software runs were executed. Further, the temperature of combustion and the burn rate were determined by infrared thermography, while the heat of combustion and the specific volume of gases were obtained using an adiabatic calorimeter coupled with a Julius-Peters volumeter. The fuel ratio was varied in the compositions in order to optimize the combustion, and the addition of chlorinated rubber confirmed a significant enhancement in both parameters.

This paper presents some of the authors’ theoretical and experimental research related to the use of low-power lasers (diode laser) for the engraving, photoengraving and cutting of the parts made of plastics. There shall be presented the research carried out using a small machine, covering a net area of 150x150mm2. Small-sized companies or the persons having such pursuits can afford this type of machines. The authors also put forward several solutions to improve the performance of such machines by introducing at least one new axis of the “Z” or “A” type.

Using a drop casting method, stronger absorbent and photosensitive composite thin films based on a copper-phthalocyanine (CuPc) oligomer and a poly (N-epoxypropylcarbazole) (PEPC) copolymer were developed. Morphology, structural behavior and optical properties of CuPc:PEPC composite thin films have been studied using scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-VIS spectroscopy. The SEM images of pure CuPc organic thin films show the formation of some elongated shapes, while the morphology of CuPc:PEPC composite thin films is mainly controlled by the content of CuPc. XRD analysis of the CuPc:PEPC composite thin films reveal good crystallinity and the beta-copper phthalocyanine phase. Study of optical properties of CuPc:PEPC composite thin films after annealing in hydrogen atmosphere show decrease of the average optical transmittance. In addition, the broadening of the absorption bands increases the light harvesting capacity of the composite material for photovoltaic applications.

The study presents the synthesis and characterization of two series of hydrophilic chitosan derivatives, based on imine or amine linkage through PEGylation. The impact of PEGylation on the morphology and supramolecular architecture along with the wettability were studied. The obtained results proved that PEGylation is an appropriate method for tuning chitosan’s hydrophilicity. Adding to that, the properties of the derivatives can be designed according to the targeted application.

Controlled drug release is a promising pathway of biomedicine, meant to suppress side effects with the aim of increasing patient`s comfort. A route to achieve this goal represents the encapsulation of drugs into matrixes, capable to develop physical forces, which further can control the drugs release. To this purpose, mathematical modeling is an important tool, which offers the possibility to understand the drug release mechanisms and to further design new performant systems. In this paper, a theoretical model for drug release from an amphiphilic matrix is presented. This is achieved using a conservation multifractal law of probability density followed by validation of the model. Moreover, because non-steroidal anti-inflammatory drugs (NSAIDs), such as diclofenac, are widely used in endometriosis as painkillers for dysmenorrhea management or Asherman syndrome for reducing the endometrial inflammation, some implications of our model for drug delivery systems applied in the field of gynecology have been discussed.

Type II collagen has been perceived as the indispensable element and plays a crucial role in cartilage tissue engineering. Thus, materials based on type II collagen have drawn farther attention in both academic and research for developing new systems for the cartilage regeneration. The disadvantage of using type II collagen as a biomaterial for tissue repairing is its reduced biomechanical properties. This can be solved by physical, enzymatic or chemical cross-linking processes, which provide biomaterials with the required mechanical properties for medical applications. To enhance type II collagen properties, crosslinked collagen scaffolds with different cross-linking agents were prepared by freeze-drying technique. The present research work studied the synthesis of type II collagen biomaterials with and without crosslinking agents. Scaffolds morphology was observed by MicroCT, showing in all cases an appropriate microstructure for biological applications, and the mechanical studies were performed using compressive tests. DSC showed an increase in denaturation temperature with an increase in cross-linking agent concentration. FTIR suggested that the secondary structure of collagen is not affected after the cross-linking; supplementary, to confirm the characteristic triple-helix conformation of collagen, the CD investigation was performed. The results showed that the physical-chemical properties of type II collagen were improved by cross-linking treatments.

Cationic dextran hydrogels having pendent 51-59 mol% N-alkyl-N,N-dimethylammonium chloride groups were synthesized and tested as adsorbents for sodium cholate. The bile acid salt sorption by these gels was evaluated by equilibrium analysis in water and 10 mM NaCl solution. The best adsorption results were obtained with amphiphilic dextran-based gels having two types of pendant ammonium chloride groups with different polarities. Experimental adsorption data for all polymers fitted good with Langmuir, Dubinin-Raduskevich and Temkin models over the entire range of ligand concentrations. The maximum experimental adsorption capacity of dextran sorbents for sodium cholate was in the range 850–1075 mg/g.

Paper explores the influence of the infill density (%), as a process parameter in additive manufacturing (3D printing), upon the mechanical (tensile, impact) and thermo-physical properties of PLA samples. The results indicated degradation of both tensile strengths and moduli with decrease of samples’ relative density from 100% to 25% with 49.9% and 42.0%, respectively. Similar behaviour holds on impact strength values that degrades with 56.0% for the samples printed using a 25% infill density. The Young’s modulus variation with relative density values was approximated using a 3rd order polynomial function, in accordance with the expression for closed-cell thick edge rhombus cellular structures. All PLA samples revealed small difference on their coefficients of linear thermal expansion, irrespective of their infill densities, with a decrease of 6.34% in the lowest relative density value specimens, indicating enhanced stability within selected temperature range. Glass transition temperatures were approximately located at 65°C whereas cold-crystallization around 80°C, thus unaffected by selected process parameter.

Due to the good properties related to wear resistance and vibration absorption capacity, the polymeric materials successfully replace the metallic materials. These are used in the production of sliding motion couples. Rubbing couples whose materials are polymer / steel based are of particular interest for technical use. In order to operate any mechanical system with sliding motion at optimum parameters, the indication of tribological characteristics for the materials of the frictional coupling is a convenient means of characterizing faster the tribological behavior, when the working conditions are modified. In this paper it is analyzed by the help of an experimental study, the factors affecting the wear of a coupling of polymer material/steel. Materials subjected to tribological analysis are polymeric materials, such as polyamide (PA) and polytetrafluoroethylene (PTFE) in contact with a metallic material (steel). The connection between the friction coefficient and the operating parameters (load, speed) and the rate of wear of these materials under experimental conditions will be established. Testing of the two materials was made on a pine stand on disc. The tribological tests were performed varying load and speed for a given length of friction, traveled pine. The wear of the two materials tested for the experimental conditions was measured. The experimental researches were carried out in dry friction conditions.

The experimental study conducted for this article was made using the butt fusion welding procedure for high density polyethylene (HDPE) pipes. PE100 (SDR 17, PN 10) water pipes were used, as for the experimental study parts of around 200 to 300 mm were welded, using different welding parameters. The influence of the welding parameters on the pipes resistance was analyzed, through visual examination and experimental tests such as tensile, bending and pressure tests.