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A series of poly(ester urethane)s were synthesized, containing, poly(e-caprolactone) diol of Mn= 2000 as soft segments. Each series used the same diisocyanate in the hard segment, i.e., 1,6 hexamethylene diisocyanate, with the same content. The polyurethane polymers were prepared by a two-step polymerization in the absence of catalyst, at the molar ratio of OHsoft segment /NCO/ OH chain extenders = 1/2/1. The chain extenders were 1,12-dodecan diol, glycerin and castor oil. For all polymers the structures were determined by FTIR, the physico-chemical and thermal properties were determined by thermogravimetric analysis and additionally tensile properties as well as Shore A hardness were analyzed. Poly(ester urethane)s with castor oil exhibited higher tensile strength (up to 27 MPa vs 30 MPa) and elongation at break (up to ~780% vs. 1000%) in comparison with the corresponding glycerin poly(ester urethane)s. Keywords: polyurethane elastomers, chain extenders, crosslinkers, mechanical properties, thermal behaviour

The paper presents the preparation of two new 3-D nanocomposite porous materials, based on collagen type I (COL) and b-tricalcium phosphate nanopowder (n-b-TCP) and the selection of the best method for their chemical cross-linking using 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide hydrochloride (EDC). To our knowledge, no EDC cross-linked COL/n-b-TCP composite materials for orthopedic use were reported. The physico-chemical and biological properties of the cross-linked composite materials were investigated by porosity, dissolution, enzymatic degradation and cytotoxicity analyses. Key words: carbodiimide, nano-beta-tricalcium phosphate, collagen, cross-linking, biocompatibility

The paper presents the results of the research work on the evaluation of the mechanical properties (bending strength, MOE, shearing strength of the adhesive bond) of the laminated wood-textiles composite materials made of wood veneer (beech and poplar wood) and textiles: natural fabric made of jute (sackcloth) and woven fabric with synthetic fiber insertions (MTR-polyester, cotton, staple rayon). The layers of veneer and textiles were glued together by two types of adhesives, successively: a natural one (bone glue) and a polyvinyl adhesive (Jowacoll 107.10). Four types of wood-textile composite samples have resulted, as follows: beech veneer – sackcloth glued with bone glue, beech veneer – sackcloth glued with polyvinyl adhesive, poplar veneer – sackcloth glued with bone glue and beech veneer – woven fabric with MTR glued with bone glue. The samples resulted were loaded to the bending strain and the bending strength and MOE were calculated with the value of breaking force obtained for each tested sample. The shearing strength of adhesive bond has been also experimentally determined in order to establish which adhesive is more appropriate to be used both with wood and textile materials into the composites. The influence of the flexibility of the synthetic fibers on the elastic properties of the resulted composites has been also investigated by determining MOE of the corresponding composites. Based on the results obtained, it is concluded that the synthetic fibers (67%) contained by woven fabric with MTR does not increase MOE of the composites, whilst the natural jute fabric behaviour into the wood-textile composites gives unexpected results in strength and elasticity of the new product. Keywords: synthetic fibers, MOE, bending strength, shearing strength, composite, elasticity

The paper describes aspects concerning the effects of the immersion time in water, on some mechanical characteristics of some composite materials reinforced with E-glass woven fabrics. The specimens were manufactured by reinforcing a polyester resin Copoly 7233 with both woven fabric EWR300 made of E-glass fibres and chopped E-glass fibres. The hand lay-up technology was used to manufacture the specimens with different pressures in the moulding step: low pressure and high pressure, respectively. The first of all, some specimens were immersed in water and the data regarding the moisture content were periodically recorded. Then, the wet composite specimens were subjected to the flexural test (three point method) after 3500 h of immersion and 7417 h of immersion, respectively. Finally, the experimental results obtained in case of the immersed specimens were comparatively analysed with the results recorded in case of the dried specimens subjected to the bending test too. Moreover, the mechanical characteristics of the specimens were analysed taking into account the different manufacture methods used. It is also shown a comparison concerning the results obtained in cases of the two kinds of reinforcements used. Keywords: composite; moisture; absorption; flexural test

An assay on the thermal stability of isotactic polypropylene stabilized with Sanduvor PR 31, a hindered amine (O1-(1,2,2,4,6,6-hexamethyl-4-piperidyl) O3 - (1,2,2,6,6-pentamethyl-4-piperidyl) (2Z) – 2 - [(4-methoxyphenyl) methylene] propanedioate, was performed. The oxidability of modified polymer previously subjected to weathering treatment or UV irradiation was investigated in air by isothermal (1550C) and isobaric (normal pressure) oxygen uptake. The exposure time was sufficient enough to attend a slow degradation rate (281 days for weathering test and 550 h for accelerated UV ageing). The main kinetic parameters, oxidation induction time and oxidation rate, were determined from the dependencies of chemically consumed oxygen on testing time. Comparative results on reference samples (control or stabilized polypropylene) and degraded materials are analyzed for depicting the influence of ageing factors on the polypropylene durability. Keywords: polypropylene, UV degradation, weathering, oxygen uptake, Sanduvor PR 31

Graphite-based Teflon composites find various applications in many engineering fields. For certain applications, the use of composites rather than metals has in fact resulted in savings of both cost and weight. The usage in many fields demands several machining operations to be performed on engineering polymers. The paper deals with two different materials: polytetrafluoroethylene with regenerated graphite (PTFE GR) and polytetrafluoroethylene with 32% carbon and 3% graphite (PTFE CG 32-3). At the beginning of the study it was performed an advanced characterization for both materials that have been used: PTFE GR and PTFE CG 32-3. The chemical composition was determined using X-ray photoelectron spectroscopy (XPS). Complementary information about the chemical structure is obtained with Fourier transform infrared spectroscopy (FTIR). This combination of spectroscopic methods was used to establish individual differences between the chemical structures for the used materials. Second part of the present paper investigates the effect cutting parameters on the cutting force in the turning of PTFE GR and PTFE CG 32-3 materials. The effects of different parameters on cutting force are analyzed and presented in this study. This paper presents that the success of the machining operation is affected by the chemical structure of the work material. Keywords: engineering polymers, spectroscopy analysis, cutting force, turning

The UHMWPE has a plastic behaviour but it is specified only the surface wear, unless the evaluation of the great importance of this behaviour of plasticity for the calculation of the depth of penetration. This work tries to demonstrate the fact that there are components of the wear by plastic deformation. Also, by this type of wear an explanation of smooth surface of the UHMWPE in the contact zone, after millions of gaits cycles may be explained Keywords: hip endoprosthesis, wear, penetration depth, roughness, plastic behavior

This paper presents the synthesis of complex nanostructures of the Fe3O4-n[SiO1.5g-(CH2)3(NH2)](NH2)nd-(GL)ne type [Fe3O4 = magnetic core; n[SiO1.5g-(CH2)3(NH2)] = coated layer; (NH2)nd,-NH2= surface and deep amino groups which play an important role in biochemical interfacing; (GL)ne= exterior superficial glutaraldehyde layer]. These nanostructures have several interesting physical and chemical characteristics, such as: biochemical fixing without destructing the microorganisms on the Fe3O4-n[SiO1.5g-(CH2)3(NH2)](NH2)nd-(GL)ne surface and the ability to differentiate the microorganisms in magnetic field, according to the mass and volume. In order to obtain superior biochemical fixing performances we have analysed and determined the chemical and physical distributional mechanisms of (NH2)nd, -NH2 groups on the surface and in the depth of the above-mentioned nanostructure. For this purpose we have deduced the control equations according to the synthesis parameters, which triggers the growth of the silicone polymer layer and the distribution of the amino groups in its structure. Keywords: Magnetite, coated nanoparticle, biochemical fixing, crosslinking molecules

This paper presents the influence of processing temperature on the mechanical-physical properties of thermoplastic polyurethanes (TPU) used at injection moulding of performance sport products. The test-pieces were moulded at the following real injection temperatures : 200°C, 210°C, 220°C, 230°C and 240°C. It was determined that the in-mould pressure decreased with increasing of the processing temperature. Also the following thermal analysis were performed : Thermogravimetry (TG), Differential Scanning Calorimetry (DSC) and Dynamic-Mechanical Analysis (DMA). It was established that the processing temperature has a significant influence on the thermal stability and on the glass transition temperature of polymer while the flow temperature is slightly influenced by the processing temperature. Keywords: thermoplastic polyurethane (TPU), injection moulding, Thermogravimetry (TG), Differential Scanning Calorimetry (DSC) , Dynamic-Mechanical Analysis (DMA)

This paper presents a study of the reactivity new carbosiloxane cyclic structures in anionic ring opening polymerization reactions in the presence of catalyst potassium siloxanolate. For this purpose, 2,2,5,5-tetramethyl-3,4-diphenyl-1-oxa-2,5-disilacyclo-pentane, 2,2,5,5-tetramethyl-3,3-diphenyl-1,4-dioxa-2,5-disilacyclopentane, 2,2,7,7-tetra-methyl-3,3,6,6-tetraphenyl-1-oxa-2,7-disilacycloheptane and bis-[1,4-bis-(dimethylsiloxanyl)-dihydronaphthalene] were used. The evolution of the polymerization reaction was observed through measurements of the reaction mixture inherent viscosity at various temperatures. The obtained results were processed in order to obtain the influence of the chemical structures on the processes conditions of development and kinetic parameters related to the transformation of the cycles to linear compounds. Keywords: cyclocarbosiloxanes, siloxanes, anionic polymerization, ring opening polymerization, organo-silicon compounds