Romanian National Institute for Research and Development in for Textile and Leather

Bucharest, Romania

Romanian National Institute for Research and Development in for Textile and Leather

Bucharest, Romania
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Stelescu M.D.,Romanian National Institute for Research and Development in for Textile and Leather | Manaila E.,National Institute for Laser, Plasma and Radiation Physics | Zuga N.,Colegiul National Constantin Cantacuzino
Polymer Journal | Year: 2011

An investigation has been undertaken to find out the effect of different polyfunctional monomers (PFMs) on the physical properties of chlorinated polyethylene (CPE) crosslinked by electron beam (EB). The following PFMs were used: triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), trimethylolpropane trimethacrylate (TMPT) and ethylene glycol dimethacrylate (EDMA). The physical properties of EB-irradiated CPE sheets were evaluated by measuring the tensile strength, elongation at break, hardness, elasticity and tear strength. The efficiency of the PFMs studied in enhancing crosslinking has been followed up by measurement of physical and mechanical properties of the vulcanized CPE. Physico-mechanical properties of EB-irradiated samples were compared with the dibenzoyl peroxide-cured samples. Dependence of properties on irradiation dose was determined from a dose range of 0-20 Mrad. The results showed an increase in physico-mechanical properties as a result of introducing PFMs; the most efficient being TAC and TAIC. Moreover, on the basis of the comparison between EB and dibenzoyl peroxide vulcanization efficiency, the results show that EB irradiation offers the best results. © The Society of Polymer Science, Japan (SPSJ) All rights reserved.


Stelescu M.D.,Romanian National Institute for Research and Development in for Textile and Leather | Manaila E.,National Institute for Laser, Plasma and Radiation Physics | Craciun G.,National Institute for Laser, Plasma and Radiation Physics | Zuga N.,Colegiul National Constantin Cantacuzino
Polymer Bulletin | Year: 2012

In this study, we have studied the effects of polyfunctional monomers (PFMs) on physical properties of ethylene vinyl acetate (EVA) copolymer crosslinked with electron beam (EB) or peroxides. The PFMs used were triallylcyanurate, triallylisocyanurate, trimethylolpropane trimethacrylate, zinc diacrylate, and ethylene glycol dimethacrylate. Using PFMs has led to (1) optimum cure time t90 decrease from 19′25′′ to 17′3′′-18′45′′, (2) scorch time increase from 2′ to maximum 3045′′, (3) increasing the crosslink density of peroxide or EB-cured systems by increasing the efficiency of productive radical reactions. The most efficient PFM forEVAcopolymer blends has been triallylisocyanurate. Tensile strength and tear strength of samples crosslinked withEBfor all irradiation doses are significantly better than those obtained for samples crosslinked with peroxides (differences up to 19′%). The results show that EB irradiation gave the best results. © 2011 Springer-Verlag.


Budrugeac P.,Romanian National Institute for Research and Development in Electrical Engineering | Cucos A.,Romanian National Institute for Research and Development in Electrical Engineering | Miu L.,Romanian National Institute for Research and Development in for Textile and Leather
Journal of Thermal Analysis and Calorimetry | Year: 2011

Leather products have been useful materials since the dawn of human history. Many leathers objects are valuable treasures due to the history they represent, and their preservation challenges museum custodians and private collectors alike. In this article, the applications of thermal analysis methods (Micro Hot Table (MHT), thermogravimetry/derivative thermogravimetry (TG/DTG), dynamic scanning calorimetry (DSC), differential thermal analysis (DTA), and dynamic mechanical analysis (DMA)) for the characterization of the recently manufactured and old leathers are presented. These methods can be used for the assessment of deterioration degree of leathers, and, therefore, the data obtained by these techniques could be useful for achievement of the suitable preservation procedures as well as the effects of conservation treatments. In addition, it was pointed out that these methods are suitable for qualitative distinction between the recently manufactured leathers and heritage items. © 2011 Akadémiai Kiadó, Budapest, Hungary.


Deselnicu D.C.,Polytechnic University of Bucharest | Militaru G.,Polytechnic University of Bucharest | Deselnicu V.,Romanian National Institute for Research and Development in for Textile and Leather
Materiale Plastice | Year: 2014

The paper presents the obtaining of new biodegradable plastic materials using collagen hydrolysates. As raw materials, to transform into collagen hydrolysates, untanned leathers' wastes were used. The influence of chemical structure and ratio of protein material on thermoplastic processing were investigated. The effect of protein material contents on physico - mechanical and biodegradability properties has been evidenced.


Stelescu M.D.,Romanian National Institute for Research and Development in for Textile and Leather
Proceedings of the 3rd International Conference on Advanced Materials and Systems, ICAMS 2010 | Year: 2010

In this paper, the influence of the neutralization degree on the properties of terpolymer ethylene-propylene elastomers grafted with maleic anhydride (EPDM-g-AM) is studied. For this purpose, two types of EPDM-g-AM elastomers with different content of maleic anhydride (1% and 0.5% respectively) and different structure (amorphous and semicrystalline respectively) have been used, and zinc oxide as neutralizing agent in the presence of stearic acid. From the analysis of physical-mechanical properties it is noticed that, together with the increase of the neutralization degree, due to the property of groups specific to maleic anhydride existing on the macromolecular chain of reacting with oxides of divalent metals (zinc oxide), ionic bonds form similar to sulphur bridges from vulcanized rubber. This ionic crosslinking has led to an improvement in the value of the module, in tensile and tear strength. The optimal time of vulcanization decreases as the quantity of ZnO increases, and the minimum and maximum moments increase as a result of the reinforcing effect due to ionic bond formation. This type of materials can have important applications in making thin flexible membranes, protection equipment, rubber goods etc.


Stelescu M.D.,Romanian National Institute for Research and Development in for Textile and Leather
Leather and Footwear Journal | Year: 2010

In this paper, characteristics of silicone rubber blends cross-linked with various cross-linking systems based on benzoyl peroxide and benzoyl peroxide in the presence of the triallylcyanurate (TAC) coagent were analyzed. For analyzed samples, physical-mechanical properties, rheologic characteristics, gel fraction and cross-link density were determined.


Deselnicu D.C.,Romanian National Institute for Research and Development in for Textile and Leather
Leather and Footwear Journal | Year: 2010

Characterization of protein materials, such as leather, is still an unsolved problem, due to its non-homogeneity, being a natural product. Chemical and physical-mechanical methods currently available for leather characterization are laborious and consume large quantities of chemical reagents and material, and their application requires a lot of time. By using non-destructive methods, such as NIR spectroscopy, and by using studies of statistical-mathematical modeling of analytical data, "hidden" connections between related chemical systems or between stages of physical-chemical processes a given system undergoes can be highlighted. In this paper 130 leather samples belonging to heritage items have been analyzed by NIR spectroscopy. The obtained data have been gathered in a comprehensive, searchable database, which structures complex analysis results in a simple, easily accessible and intelligible manner in view of applying statistic techniques. The paper presents the results obtained by applying SPSS and chemometric statistical software.


Stelescu M.D.,Romanian National Institute for Research and Development in for Textile and Leather
Studia Universitatis Babes-Bolyai Chemia | Year: 2014

This article presents the process of obtaining ionic thermoplastic elastomers based on maleinized styrene-butadiene block-copolymers (SBS-g-AM) by melt mixing. The following were studied influence of the amount of maleic anhydride, mixing time and degree of neutralization on physico-mechanical properties of blends based on SBS-g-AM rubber. © 2014 Universitatea Babes-Bolyai, Catedra de Filosofie Sistematica. All rights reserved.


Stelescu M.D.,Romanian National Institute for Research and Development in for Textile and Leather | Manaila E.,National Institute for Laser, Plasma and Radiation Physics | Craciun G.,National Institute for Laser, Plasma and Radiation Physics
Journal of Applied Polymer Science | Year: 2013

Elastomers are materials used in a large range of industrial and household applications. A common physical-chemical treatment is curing (crosslinking), imparting the rubber mechanical and thermal stability. Elastomers show low thermal conductivity values, and therefore, require complex and high-cost heating methods; thus, the ionizing (accelerated electrons) method shows high interest for the grafting and crosslinking processes. In addition to the lack of environmental impact, reliability, flexibility, and low costs render the radiation technologies especially attractive. The article presents the results concerning trimethylolpropane-trimethacrylate coagent concentration effect, on the mechanical properties of the ethylene-propylene-terpolymer (EPDM) rubber vulcanized by electron beam (EB). Mechanical properties of EB irradiated samples were compared with the dibenzoyl peroxide cured samples. Dependence of mechanical properties on irradiation dose was determined from a dose range of 0 kGy to 200 kGy. Dibenzoyl peroxide vulcanization at 160°C was carried out on the EPDM samples as well. Two types of blends have been analyzed: fillers and nonfillers. The results showed an increase in mechanical properties as a function of increasing polyfunctional monomer level. Also, based on the comparison between EB and dibenzoyl peroxide vulcanization efficiency, the results show that EB irradiation gave the best results. Copyright © 2012 Wiley Periodicals, Inc.


Manaila E.,National Institute for Laser, Plasma and Radiation Physics | Stelescu M.D.,Romanian National Institute for Research and Development in for Textile and Leather | Craciun G.,National Institute for Laser, Plasma and Radiation Physics
Leather and Footwear Journal | Year: 2011

This paper presents the effect of the polyfunctional monomers (PFMs) triallyl cyanurate (TAC), triallyl isocyanurate (TAIC), trimethylopropane trimethacrylate (TMPT) and zinc diacrylate (ZDA) on the mechanical properties of the NR (natural) rubber crosslinked by electron beam (EB) and microwave processing. The control samples were obtained by crosslinking with benzoyl peroxide in a hydraulic press at 160°C. The most effective polyfunctional monomer which led to getting the best properties was TMPT followed by ZDA. The results indicate that the application of new technologies will lead to a significant improvement in physical and mechanical properties of finished products and to optimizing the curing stage, the most important operation of the technological process for obtaining elastomeric materials.

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