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The work presents a study on a possible solution of metal replacement for pneumatic drives rods working in dry friction condition. If the total absence of lubricant and others contaminating agents is required, due to specific working environment, the pneumatic drives use is recommended. The rod sealing system is elastomeric lip seal based and works, in this case, in linear sliding dry condition. The authors tried to establish the way that polymeric material replacing the metallic rod behaves, taking into account the working conditions. Considering that the sealing system failure is due to wear, a closer investigation is performed at surfaces level by optical and 3D reconstruction methods. The observations allowed an optimization of polymeric rod rubber lip seal system in dry sliding conditions from the materials choosing point of view. Keywords: dry friction, elastomer-plastomer couple, linear sliding motion

Working on high structures is one of the jobs in the cities vertically developed. The abilities of climbing workers are used for the purpose of mounting publicity banners, cleaning building face, mounting objects on buildings etc. The use of fall arrester equipment is made under strict surveillance and training of the workers because of imminence of the accidents. Before sailing, the fall arrester equipment is tested and certified. Keywords: polyethylene, shock absorber, fall arrester, climbing, HBM MGC

Conventional methods for processing and shaping plastics parts (mold injection, thermoforming, extrusion etc) require heating (melting) process in which plastics material is soften or liquefied firstly and then imparted by using different dies and techniques. However, plastics material could be formed without any heating and for that purpose a few non-conventional procedures have been developed. An alternative to conventional shaping of plastic parts offers metal forming processes and cold forming technique.In this paper results of theoretical, numerical and experimental investigation of cold forming of plastics are present. Traditional metal forming processes such as upsetting and backward extrusion were applied for shaping billets made from HDPE and PA. Both processes are simulated by FEM and Simufact.Forging 8.1 program package. Numerically predicted load-stroke diagrams are compared to those experimentally recorded. All necessary material data and process parameters were determined according to the methodology which is used in metal forming processes. Keywords: thermoplastics, cold forming, FEM

The main characteristics of pressure sensitive adhesives are: peel resistance, shear and tensile strength. This work presents the tensile tests and related phenomena of pressure sensitive adhesives based on polychloroprene rubber with wood and steel substrates. The tensile breaking mechanism for the adhesive assembly is proposed and discussed within this article. Keywords: pressure sensitive adhesives, elastomers, tensile strength, wood, steel

In this paper were investigated influences of various types and concentrations of crosslinking agents on the properties of thermoplastic vulcanizates based on ethylene-propylene terpolymer rubber (EPDM) and plasticized poly (vinyl chloride) (PVC). Three different crosslinking systems were used: (a) common method with sulphur and vulcanization accelerators (tetramethylthiuram disulfide and mercaptobenzothiazole); (b) crosslinking with di(tert-buthyl peroxi-isopropyl) benzene Perkadox 14-40B-GR and co-agent trimethylol-propane trimethacrylate TMPT DL 75 (c) vulcanization with phenol resin Ribetak 75-30E and tin chloride dehydrate. The influence of each crosslinking systems on cross-link density, mechanical properties and DSC analysis of samples were investigated. The hardness shows a slight decrease as a result of dynamic vulcanization, because this is a way to disperse large amounts of elastomer in the thermoplastic matrix, resulting in a refined morphology. It was observed that the highest values of crosslinking density and 100% modulus were obtained by using the classic cross-linking with sulphur and accelerators, and that for a reduced amount of crosslinking agents used, there was a decrease in crosslinking density. Elastomer crosslinking led to an increased Tg and decreased Tm. These blends can be used in the manufacture of hoses, gaskets, footwear constituents etc. Keywords: TPV, EPDM, PVC, cross-link density, differential scanning calorimetry

Acid polyurethane of hard type was prepared to be further treated in hydrothermal conditions at high pressures of 20, 40, 60 and 80 atm. The influence of pressure on chemical structure and morphology of macromolecular chains have been investigated using Fourier transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC). Three endothermic peaks appear in hydrothermally treated polyurethanes, being related to conformational changes due to polymer shrinking, decomposition and melting. Their corresponding enthalpies increase with pressure, probably due to a more compact polymer structure at high pressure. Under the influence of pressure, macromolecular chains modify their conformation and approach each other, leading to an increased density of the hydrogen bonds. Stretching vibrations of the –C=O group are shifted from 1746 to 1724 cm-1. There is an optimum pressure (60-80 atm) range where the polyurethane presents an increased capacity of interaction through carbonyl groups (r1 =1.295 at 60 atm) which is favorable for further composite synthesis. Keywords: acid polyurethane, high pressure, hydrothermal process, IR spectroscopy, DSC

The replacement of classical materials used in industry with other more important, cheaper and environment friendly ones and also the prevention of corrosion is one of the goals in the research area. Electrotechnical industry and engineering needs this special material. The conductive and semiconductive coatings belong to these special materials and occupy a large application domain in modern industry, used to remove the electrostatic charges, and for the shielding effects (i.e. Faraday screen, protective coat for the high voltage cables etc.).In this paper it is studied the stability in time of semiconductive lacquers based on polianiline.

This paper presents the radiation stability of epoxy resin modified with different amounts of titania (1, 5 and 10 %). The isothermal chemiluminescence investigation performed at 1500C has pointed out the high radiation stability of investigated systems. The sharp decrease in the early stage of oxidation emphasizes the benefit brought by the filler. Even though the initial chemiluminescence intensity enhances with filler content, the oxidation level after 20 min does not essentially differ. The application of high irradiation doses up to 1000 kGy does not affect the thermal stability of composites. Keywords: radiation stability, epoxy resin, chemiluminescence intensity, filler

The present paper studies the effect of the diameter of single walled carbon nanotubes (SWCNTs) on mechanical properties of SWCNTs reinforced epoxy resin composites. Bulk atomistic models of epoxy resin-SWCNTs with different compositions were built and were subject of an extensive multistage equilibration procedure. Molecular dynamics simulations were used to estimate glass transition temperature (Tg) and Young’s modulus of epoxy resin and epoxy resin/SWCNTs composites. The Young’s moduli generally increased with increasing of SWCNTs content and values range from 1.83 GPa in the case of pure epoxy resins to 3.21 GPa for epoxy resin/SWCNTs (8,8) composite system. Overall, the agreement between predicted values of the material properties and experimental data in the literature is satisfactory. Keywords: atomistic molecular modeling; mechanical properties; SWCNTs- epoxy resin composites, glass transition temperature

This work presents the main mechanical properties of the pressure sensitive adhesives solutions based on carbocatenary elastomers: peel, shear and tensile strength. Polychloroprene rubber was chosen as the main component of the adhesive system and its adhesive performances were evaluated. The mechanisms of fracture of the adhesive bond and breaking at the tensile test were also discussed. Keywords: pressure sensitive, adhesives, elastomers, polychloroprene rubber