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Some photosensitive structurally different polyamides were obtained using as starting monomers various dicarboxylic acids and 2’-(cinnamoyloxy)ethyl-3,5-diaminobenzoate. Their synthesis is based on the Yamazaki-Higashi procedure. The characterization of the prepared polyamides was accomplished by spectroscopic and thermal measurements.

Multitude of methods for the synthesis of nanoparticles express interest and importance of this field. In the present study, are addressed the aspects of obtaining nanoparticles by milling, in order to be used at nanostructured coatings in asphalt. Materials used for obtaining nanoparticles were powdery volcanic tuff with 0.4-1.6 mm grain and calcium carbonate. Stearic acid, sodium lauryl ether sulphate, a mixture of fatty acid imidazoline, a block copolymer polyethylene oxide- polipropilenoxid -polyethylene oxide and polyethylene glycol were used as additives. For grinding of inorganic particles was used a laboratory planetary mill Fritsch Pulverisette 6, equipped with a stainless steel grinding bowl. Grinding dry powdered volcanic tuff in the presence of additives influences particle size distribution. Wet milling of powdered volcanic tuff in the presence of ROT favours getting a bimodal distribution and decreasing the average particle size. Keywords: nanoparticles, grinding, additives, particle size distribution

Due to physical properties of the composite materials based on resin – textile fibres cover, in the present different utilisation areas such as: terestrial, aerian and naval transport, civil and industrial engineering, medical tehnique, food industry, sportive articles etc. This paper present ssthe determination of the water’s absorption in composites resin – flax, resin – cotton, resin – hemp.

Photochromic properties of copolyethers and copolyesters based on bisphenol-A 4,4’-dihydroxydiphenyl, 4, 4’-dihydroxy-azobenzene and 3,3-bis (chloromethyl) oxetane both embedded in a polymer matrix [polymethyl metha crylate (PMMA), polyxinil alchol (PVA)] and the pure state, deposed on quartz disks or as powder, have been studied. The photocromic effects have been studied by means of electronic absorption spectra in visible range. This effect is reversible. A general characteristic of the compounds studied in this paper is that the azobenzene groups belonging to the polymer chain are aligned along the polymer chain structure. The nature of the thermally stimulated discharge current for polyether and polyester samples in the temperature range from room temperature to above glass-rubber transition temperature of the studied compounds, with crystallinity degree of about 0.45, is analyzed. Processing the experimental data according to the Gauss’ function (1) has lead to a good agreement between them and the dipolar polarization model that uses the Langevin’s function, L(b) (2). The thermally stimulated current spectrum of the studied compounds shows two peaks at a temperature about 330 and 3444 K. The a peak is at temperature ( 323 –333)K and r peak at (340-355) K. The disorientation of the main chain dipoles (diazo groups) and the realizing of the trapped electrons are probably responsible for the a peak. The changes in the r peak is caused by carries of charges generated in the polar groups of the polymer chain by the thermochromic effect of the diazobenzen groups.

By exposure to the environment of polymer wastes, the disintegration and degradation processes take place by simultaneous and concurrent mechanisms, as photodegradation, hydrolisys, thermooxidation and biodegradation. The latter may be described as a complex process taking place in several steps. In a first step of the biodegradation process, the polymer with low molecular mass suffer a hydrolisys reaction enzymatically catalyzed, resulting in a mixture of oligomers and intermediates with low molecular mass and different chemical structures. The next step is preceded by microorganisms invasion, transforming the carbon and the hydrogen of polymers and respective intermediates into CO2 and H2O. In the study there are presented some reaction and initiation mechanisms of the biodegradation processes of some synthetic polymers susceptible to biodegradation.

In this paper a relaxation model for polymeric materials is presented.

The copolymerization of octamethylcyclotetrasiloxane and methylhydrogensiloxane oligomers was carried out using a styrene-divinylbenzene copolymer with sulphonic groups as catalyst (VIONIT CS-34C). The conversion versus time function was studied at different temperatures. It was found a first order reaction towards monomers.

This work presents a study on the interaction that a phenolic hindered antioxidant (Irganox-1076) and new reactive dyes derivated from 3H-aza-1-oxa-2H-thioxo-5,8-phenalendisulphonic acids, have upon izopolipropylene thermooxidation. The study was performed by chemiluminescence technique (CL). Synergetic effects were observed between reactive dyes used and phenolic antioxidant in thermooxidation protection of the polymer.

The paper shows and analyzes the results of some researches on a plastic composite material as fiberglass reinforced polyester (FGRP) that is considered for being used for manufacturing the blades of small power wind turbines, such is the 5 kW wind turbine from Ciugud site in Alba County, Romania. During their operation the wind turbine blades are continuously subject to variable loadings developed by the stochastic and uncontrollable wind flow. Consequently has been performed mechanical strength researches done on a real blade, as well as, by lab testing on test specimens sampled from the original material of one blade tested at SC CLAGI Srl Company. The results of this research work came to confirm the quality of the FGRP used for blade fabrication, as well as, its capacity to bear well the loads and implicitly the structural stresses produced by the wind upon the wind turbine blades, although a metallic reinforcement included within the inner part enhances the whole mechanical strength of the blade structure. Keywords: fiberglass reinforced polyester (FGRP), wind turbine, aerodynamic forces, loads, stresses, mechanical strength

In this paper, some models for gel and glass effects – a new empirical model and Chiu’s model – are checked under batch and semibatch, isothermal and nonisothermal reaction conditions. The chemical initiated free radical polymerization of methyl methacrylate is considered to be achieved in a bulk process and the reaction mechanism takes into account the azobisisobutyronitrile decomposition, propagation, chain transfer to monomer and termination by disproportionation. In the exponential relations that represent the dependence of termination and propagation rate constants on monomer conversion (gel and glass effects), the coefficients are polynomials of forth degree in temperature. For batch operating conditions, the simulations performed at different temperatures and initiator concentrations give results close to experimental ones. In semibatch operation, an instantaneous addition of initiator at different reaction times and different temperatures was considered. Step changes in temperature performed at different reaction times represent an other type of operation taken into account in this paper. In the semibatch and nonisothermal reaction conditions, the simulation results of the two models agree with experimental data even if the same values of parameters as for batch isothermal operation were used. This paper demonstrates the generality of the exponential models and also emphasizes the possibility of controlling polymer properties and reaction time by semibatch and nonisothermal operations.