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The paper presents two plastic materials from epoxidic resins and compounded polymers families which have properties to visualize stress field produced by mechanical loadings. Using these properties two experimental techniques, photoelasticity and cromoplasticity, were developed for mechanical behaviour investigation of engineering structures. To illustrate the potential of these experimental techniques, in the paper are presented results of a combined analysis undertaken on the state stress in the fastening elements of a hidroagregate, loaded both in elastic and elastoplastic field. Keywords: epoxidic resins, compounded polymers, photoelasticity, cromoplasticity

A series of five new aromatic polyhydrazides containing pendent acetyloxybenzamide groups has been synthesized by low-temperature solution polycondensation of 5-(4-acetyloxybenzamido)-isophthaloyl chloride with dihydrazides of terephthalic, isophthalic, 2,5- or 2,6-pyridin dicarboxylic acids, or with p-aminobenzhydrazide in N-methyl-2-pyrrolidinone (NMP). These polyhydrazides were gradually thermally treated up to 280°C in order to be converted in corresponding poly(1,3,4-oxadiazole)s. The inherent viscosity of polyhydrazides is in the range of 0.31-0.69 dL/g. The polymer structures were confirmed by infrared spectra. The polymers were characterized from solubility and thermal properties point of view. Keywords: polyhydrazides, poly(1,3,4-oxadiazole)s, 5-(4-acetyloxybenzamido) group, thermal stability

Hyperbranched poly (e-caprolactone) copolyesters (hb-PCL) have been prepared by combination of ring opening polymerization (ROP) of e-caprolactone (e-CL) as cyclic AB monomer and concurrent polyconden­sation of 2,2´-bis(hydroxymethyl)butyric acid (BHB) as branching AB2 comonomer unit, using a supported lipase (Candida Antarctica Lipase B, CALB; Novozym 435) as catalyst. By systematic variation of the BHB fraction, hyperbranched copolyester samples with systematically varied degrees of branching (DB) have been obtained. 1H-NMR and 13C-NMR spectra provided detailed information on the DBs. Molecular weights for the hb-PCLs were determined by means of SEC and VPO and exhibited a decreasing tendency with increasing fraction of branching comonomer. Thermal properties of the hb-PCL samples were investigated with respect to the DB. As expected, Tm and DHm were found to decrease with increasing content of BHB (DSC). The crystalline morphology of the samples was investigated by WAXS, revealing the DB-dependent existence of two crystalline polymorphs with different density and chain packing. Light microscopy studies demonstrated both a different crystal habitus for the hyperbranched copolymers, as well as a decrease of the crystalline fraction for the hb-PCL samples in comparison to the linear analogue. With increasing DB, the crystallites became small and irregularly shaped, indicating phase segregation in crystallizable and non-crystallizable material during crystallization. Solution viscosimetry showed low specific and intrinsic viscosity for the branched materials and demonstrated that the hyperbranched samples assume an increasingly compact solution structure with increasing extent of branching. For both CHCl3 and THF solutions, an increase of the temperature from 20 to 50oC results in a decrease of [h] for all analyzed hb-PCLs. Keywords: copolyesters, hyperbranched polymers, degree of branching, polymer morphology

Various bismaleimides and biscitraconimides containing ester and ether units in the main chain and having SO2 groups were synthesized. Monomers with ester units were synthesized by condensation between 3(4)-maleimidobenzoyl chloride or 4-citraconimidobenzoyl chloride with 4,4-hydroxyphenyl sulfone. Bismaleimide and biscitraconimide with ether units were prepared by reaction between maleic anhydride or citraconic anhydride with 4,4-bis (4-aminophenoxy)diphenyl sulfone. Keywords: bismaleimide & biscitraconimide monomers

A recyclable material, that can be incinerated under safety conditions, for humans and environment, the polyvinyl chloride (PVC) is still a largely used polymer, as a compound, inclusively. The PVC -TPU compounds are of interest due to their attrition resistance, chemical resistance, resistance to migration in solvents and oils (low extractibility), high bending under negative temperatures, low densities and erosion, stability to high temperatures, easy processing into finite article, cost efficient. All these properties are superior to a flexible PVC (hot masticated). The paper presents a study on dependency of some usage properties of PVC - TPU compounds on compounds composition. The results of the modification study of PVC with TPU are that new compounds have: the density within the range 1.18 – 1.3 g/cm3 , erosion within the domain 107 – 142 mm3, number of bendings up to breaking at positive temperatures, over 500 000, number of bendings up to cracking at –8 0C, over 500 000 bendings. Keywords: polyvinil chloride, thermoplastic polyurethane, physical modification, abrasion, density

The atactic polypropylene (APP) recovery as hydro insulation membranes and / or bitumen presents two main advantages: the great quantities that can be reprocessed and the elevated usage life of the obtained products, a consequence of lack of the photo and thermal degradation during usage. It is well know that the photo and thermal degradation rapidly diminishes the utilization properties, namely the usage life. The recovery into hydro insulation membranes and / or bitumen is possible if the APP was selected based on thermo – oxidative stability criteria typically for a good incorporation into the melt bitumen at 180 0 C for 4 – 10 hours and for RTFOT or TFOT tests. The RTFOT thermo – oxidative stability criterion, according to which the mass loosing at 163 0C for 80 min. must be smaller than 0, 8 %, is fulfilled only if the APP has a weight molecular mass greater than 8000 and a solid consistency. If these two criteria are not fulfilled the APP can be recovered as hot melt adhesives. Keywords: atactic polypropylene, practical application, hydro insulation membranes and bitumen

For the transport of gas or water, it is generally welding by heater which is used for the butting together of the tubes. The quality of the joint is influenced by the choice of the parameters of welding, the geometry of the tubes and the environment. It is not possible of determine analytically the optimal parameters of welding according to dimensions of the tubes. This paper describes the models of extrapolation, which makes it possible to transpose the optimal parameters and strong thickness of welding for tubes of large diameter previously determined using smaller tubes. The first chapter of the paper is primarily centred on an analysis of the process of welding end to end by heater. A mathematic description of the various phases of the process leads to coefficients without dimension. The models used for the determination of the parameters of welding result in the invariance of these coefficients. Keywords: optimization, mathematical model, heated tool butt welding, hydro – carbon (HD-PE), transporting pipelines

We synthesized and characterizated two bromine containing monomers, 2-(2-bromopropyloxy) ethyl methacrylate (BPEM) and 2-(2-bromoisobutyriloxy) ethyl methacrylate (BIEM), to be used as radiopaque agents in acrylic bone cements. Using methyl methacrylate (MMA) and each one of the bromine containing monomers in different concentrations we have synthesized ten copolymers. The copolymerizations were carried out directly in the thermostatic, cell of an NMR Spectrometer. Analyzing the 1H-NMR spectra, we have determined the reactivity ratios of the monomers. Preliminary studies showed that acrylic bone cements which include in the liquid phase these bromine containing acrylic monomers, have a very good radioopacity. Keywords: bromine containing monomers, copolymerization, parameters of reactivity

This article presents literature data regarding the synthesis and properties of some sulfonated aromatic polymers, such as polyethersulfones, poly(etherketone)s, polybenzimidazoles, polyimides, which can be used for proton-exchange membrane in fuel cell applications. The polymers were prepared by two procedures: postsulfonation of existing polymers and direct copolymerization of sulfonated monomers. Some characteristics of the sulfonated polymers in correlation with their structure were also presented. Key words: sulfonation, sulfonated polymers, good solubility, thermal properties

The influence of propylene, polyethylene and maleinized polyethylene on the characteristics of thermoplastic elastomers based on maleinized ethylene-propylene terpolymer rubber was investigated. As the amount of the added polyolefine is increased, the hardness, tensile strength and tear strength increase, and elasticity and elongation at break decrease. The resistance to swelling in toluene and resistance to 50 % nitric acid and 40 % sodium hydroxide are also increased with the increase in the amount of the added polyolefine. The blends containing maleinized PE show higher characteristics than those with PE as such. The rheologic characteristics of the above mentioned blends were studied and compared. The thermoplastic ionic elastomers based on maleinized EPDM and polyolefines can be used in obtaining some materials with specific characteristics (high hardness, tensile strength, elasticity, resistance to acids and alkalis, resistance to swelling in toluene etc.). Key words: polyolefines, maleinized EPDM, thermoplastic ionic elastomer