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Oestrogen hormones play key roles in the human body, are involved in complex mechanisms, both beneficial and unwanted. Because semisynthetic oestrogens are commonly used today in various hormonal therapies, they has inevitably been linked to the appearance of certain carcinogenic processes, which are primarily based on oestrogen-based drugs, either as initiators or promoters. A promising alternative that can help reduce unwanted effects is to capture the active substance in a polymeric matrix that is capable of retaining its biological activity. In this study, activity on the viability of breast cancer cells with expressed oestrogen receptors of a polymeric formulation with ethinylestradiol and polylactic acid was evaluated.

This research focuses on the analysis of acacia wood reinforced PLA/PHA blend composites. Acacia wood was processed into small chip particles, which were mixed with pure PLA, pure PHA and PLA/PHA blend. The wood was treated using acetic acid and sodium bicarbonate. It was then compressed into sheet film. The micrograph shows that the PLA and PHA mixture create an interlocking continuous structure and the addition of wood strengthens interlocking between PLA and PHA. Mixtures of this blend also reduce bubble and crack, and create new properties superior than the earlier properties of existing PHA and PLA.

This work deals with the problem of developing vibration damping polymeric materials which are effective at low temperatures (from minus 40 to 0°C). Due to the fact that the vibration damping efficiency in the composite is mainly determined by the properties of the polymer matrix, it is necessary to study its properties depending on the type and amount of structure-forming parameters. The purpose of the work is to determine the changes in the dynamic properties of the polymer composition based on butyl rubber, EPDM, ethylene-vinyl acetate copolymer (EVA) filled with increasing amount of calcium carbonate. The leading methods of studying this problem were the method of scanning electron microscopy and the method of dynamic mechanical analysis. It has been stated that the selected polymers can be considered as competent candidates for damping materials at low temperatures, and the calcium carbonate filler allows more fully to realize the vibration damping properties of the polymer. The obtained dependences can be used as initial data for analytical predicting of damping properties of polymer composites.

The three-dimensional printing is a manufacturing method involving the addition of materials by using certain principles valid in printing techniques. There are various techniques of a three-dimensional printing method and the most of them could be applied inclusively to generate objects of polymers. The objective of the research presented in this paper was to analyze the capabilities of 3D printing process or equipment of generating fine details and to identify a way of evaluating these capabilities when using polyester PLA as filament material. The systemic analysis of the printing techniques which use a fused polymer filament deposition showed that there are some groups of factors able to affect the obtaining of fine details. An experimental research was designed in order to highlight the influence exerted by the diameter of the nozzle orifice and by the values of sharp angles of isosceles triangles on the heights of these triangles, thus obtaining an image concerning the possibilities of generating sharp edges by three-dimensional printing. To evaluate the capacity of the 3D printing process of obtaining thin walls, a spiral including linear segments with a decreasing thickness from 1 mm was also achieved on the test piece. By mathematical processing of the experimental results using a specialized software, empirical mathematical models were determined to evaluate the intensity of influences exerted by the two process input factors on the heights corresponding to isosceles triangles characterized by sharp angles.

The main factors that affect the strength of adhesive joints are the exposure to moist environments and high and/or low temperatures. The objective of this paper is to measure the water diffusion in adhesives modified with thermally expandable particles (TEPs) and assess the joint strength of water saturated modified adhesives. Bulk specimens were used to measure the diffusion coefficient of water in a TEPs-modified adhesive. The tensile data as a function of TEPs content, moisture uptake and temperature was measured. It was found that the presence of moisture and the temperature affect the mechanical properties of TEPs-modified adhesive. Further, a scanning electron microscope (SEM) analysis was performed in order to examine the fracture surfaces of the tensile specimens tested as a function of temperature and water uptake. SEM analysis showed that the absorbed moisture and temperature change the fracture mechanisms and the morphology of the specimens.

In this study, capillary rheological tests were performed on polypropylene filled with multi-walled carbon nanotubes (PP/MWCNT) to determine the melt flow curves and pressure-Volume-Temperature (pVT) diagrams. Based on the experimental data, master viscosity curves were constructed using the time-temperature-superposition principle and the Cross and Carreau-Winter models, while the pVT data were fitted to the Tait equation in both liquid and solid states. Results show that the melt shear viscosity decreases with increasing melt temperature and shear rate and increases with MWCNT wt.%. All composites display shear-thinning behavior in the range of medium to high shear rates. The specific volume of PP/MWCNT composite decreases with increasing MWCNT wt.% and pressure and increases with increasing temperature.

The aim of this study is proposing a combination of measurements to assess the functional variability of collagen membranes used in Guided Bone Regeneration (GBR) and Guided Tissue Regeneration (GTR) techniques. As far as clinical applications are concerned, a proper qualification is critical when deciding, among commercially available collagen membranes, upon the most appropriate one for each specific clinical case. Two commercially available collagen membranes, namely Collprotect® and Jason®, were considered for the experimentation. After thickness and density measurements, the quasi-static behavior was studied for both membranes by means of conventional mechanical tests, i.e. tear and tensile tests, whereas their time-dependent behavior was evaluated by means of stress relaxation tests and dynamic mechanical analysis. Collagen membranes showed an elevated among samples variability. The variability within the same kind of membrane is of the same order of magnitude of the between membrane kinds variability. All the membranes showed strong time dependence both in stress relaxation and in dynamic mechanical tests. This fact should be taken under consideration for the membrane final application.

Shape Memory Polymer Composites (SMPCs) are a class of smart materials in which the structural properties of long-fiber polymer-matrix composites and the functional behavior of Shape Memory Polymers (SMP) are combined together. In this study, the frozen stresses resulting from fixing a deformed shape have been investigated. Two different samples were manufactured, with and without significant shape memory properties, and a three point flexural test equipment was used in order to fix a deformed shape. The forces and the resulting stresses were measured during the samples deformation and after the shape freezing. The experimental tests have shown that the shape memory sample has a better ability to fix a deformed shape, since its frozen stress is higher in all the tests.

Biodegradable polymers became one of the most important materials with large applicability, as they do not generate wastes after life cycle. An important application is food packaging fabricated by injection molding processing. In this paper, we present the investigation of the mechanical properties of some biodegradable polymers based on PLA composites obtained by melting processing and their morphology studied by SEM analyses, in comparison to polypropylene and neat PLA. We found out that tensile strength, elongation at break and Young modulus exhibit values appropriate to injection molding processing and they are very close related to crystalline or amorphous character of the materials.

Surface chemistry and micro-nanoscale topography of biomaterials can significantly influence tissue engineering and cell biology. In this study, polystyrene (PS) Petri dishes were subjected to microtexturing by compression molding process, which resulted in three-dimensional (3D) microscale surface topographies. Three different micropatterned surfaces were fabricated using bronze sintered molds with different mean pore pitch sizes. The surface changes and the morphological aspects were analyzed by 3D surface analyzer. The dishes were then used to investigate the cell behavior of Mouse Embryonic Fibroblasts (MEF) P4 cells. The surface micropatterning have affected in different ways the MEF cell adhesion and proliferation, related to the morphological changes in comparison with unmodified PS. At the increasing of the sintered particle dimensions of the mold, the cavities dimensions on the molded Petri increase and also the cells adhesion in the cavities seems to increase independently from the roughness inside them.