Tamás Barany - Profile on Academia.edu (original) (raw)

Papers by Tamás Barany

Journal of Polymer Research

We prepared different thermoplastic elastomers (TPEs) using an internal mixer. We investigated th... more We prepared different thermoplastic elastomers (TPEs) using an internal mixer. We investigated the properties of thermoplastic polyurethanes (TPUs) produced from prepolymers with various isocyanate content and two different chain extenders to select the most appropriate TPU matrix for preparing thermoplastic vulcanizates (TPVs). Based on the results, we selected a prepolymer with moderate isocyanate content (10%) and the more flexible 1,6-hexanediol as a chain extender and prepared TPVs by dynamic vulcanization with in situ produced TPU. The rubber phase was acrylonitrile-butadiene rubber (NBR) with peroxidic and sulfuric curing with different accelerators. Dynamical mechanical analysis (DMA) results show that the room temperature storage modulus of the TPVs decreases due to the rubber phase. The TPU/NBR-CBS TPV with delayed action accelerator yields the highest tensile and tear strength and elongation at break. TPU/NBR-DCP made with a peroxide-based rubber blend shows similar tensi...

The goal of this study is to produce injection molded all-polypropylene composites at a low injec... more The goal of this study is to produce injection molded all-polypropylene composites at a low injection temperature. As a matrix, we used an amorphous poly-alpha-olefin-based melt-adhesive, as its melting temperature is significantly lower than the melting temperature of the polypropylene homopolymer reinforcement. The composites were produced by injection molding of an impregnated pre-product, and by overmolding of the reinforcing fabric. The composites made of the impregnated pre-product showed unsatisfactory mechanical properties, so the latter method seems to be more promising. Kivonat A kutatas celja alacsony hőmersekleten froccsonthető onerősitett kompozitok kifejlesztese. Matrixkent amorf poli-alfa-olefin tartalmu omledekragasztot hasznaltunk, amelynek az olvadasi hőmerseklete a polipropilen homopolimer erősitőanyagenal lenyegesen alacsonyabb. A kompozitokat extruzios impregnalassal keszult előgyartmany froccsontesevel, valamint a matrix szovetre tortenő rafrocssontesevel allit...

Periodica Polytechnica Chemical Engineering, 2017

In this work the effect of cyclic butylene terephthalate (CBT) was studied on the curing, rheolog... more In this work the effect of cyclic butylene terephthalate (CBT) was studied on the curing, rheological, morphological and mechanical properties of styrene butadiene rubber (SBR), oil extended styrene butadiene rubber (oSBR), acrylonitrile butadiene rubbers (NBR) with various acrylonitrile (AN) content and a carboxylated acrylonitrile butadiene rubber (XNBR). The effect of CBT on the oil resistance of the NBR and XNBR based compounds was also investigated. Viscosities of the uncured compounds were signiicantly decreased by CBT and it also acted as a semi-active iller, effectively reinforcing the tested rubbers, therefore it is suggested to be a bifunctional additive for tested rubbers. CBT also showed to have a positive effect on the oil resistance of NBR compounds.

Materials, 2020

Fibrous carbon nanotubes (CNTs) and lamellar graphene oxide (GO) exhibit significant advantages f... more Fibrous carbon nanotubes (CNTs) and lamellar graphene oxide (GO) exhibit significant advantages for improving the fatigue properties of rubber composites. In this work, the synergistic effect of CNTs and GO on the modification of the microstructure and fatigue properties of natural rubber (NR) was comprehensively investigated. Results showed that CNTs and GO were interspersed, and they formed a strong filler network in the NR matrix. Compared with those of CNT/NR and GO/NR composites, the CNT-GO/NR composites showed the smallest crack precursor sizes, the lowest crack growth rates, more branching and deflections, and the longest fatigue life.

Scientific Reports, 2020

We devulcanized ground tire rubber (GTR) in a laboratory microwave oven and an internal mixer, me... more We devulcanized ground tire rubber (GTR) in a laboratory microwave oven and an internal mixer, measured the soluble content and the cross-link density of the samples, and then used Horikx’s analysis. The results showed that microwave treatment caused severe degradation of the polymer chains, while in the case of thermomechanical devulcanization, the selective scission of covalent cross-links is more common. Four devulcanized ground tire rubber (dGTR) samples were chosen for further study and three groups of samples were produced: dGTR samples containing vulcanizing agents and different amounts of paraffin oil (dGTR-based mixtures), natural rubber-based rubber mixtures with different dGTR contents and reference rubber mixtures with dGTR-based mixtures (increased vulcanizing agent contents). Cure characteristics showed a plasticizer-like effect of dGTR. Tensile and tear strength decreased drastically with increasing dGTR content; however, elongation at break values did not follow such...

Polymers, 2020

We developed polypropylene-based single-polymer composites (PP-SPC) with blends of amorphous poly... more We developed polypropylene-based single-polymer composites (PP-SPC) with blends of amorphous poly-alpha-olefin (APAO) and random polypropylene copolymer (rPP) as matrix material and polypropylene (PP) woven fabric as reinforcement. Our goal was to utilize the lower melting temperature of APAO/rPP blends to increase the consolidation of the composites and decrease the heat load of the PP reinforcement. We produced the composites by film-stacking at 160 °C, and characterized the composites with density, peel, static tensile and dynamic falling weight impact tests, and by scanning electron microscopy. The results indicate that consolidation can be enhanced by increasing the APAO content of the matrix. We found that the APAO content of 50% is optimal for tensile properties. With increasing APAO content, the perforation energy decreased, but even the well-consolidated composites showed very high perforation energy. In the case of a pure APAO matrix, fiber content can be increased up to 8...

Polymers, 2019

The aim of this paper was the detailed investigation of the properties of one-shot bulk polymeriz... more The aim of this paper was the detailed investigation of the properties of one-shot bulk polymerized thermoplastic polyurethanes (TPUs) produced with different processing temperatures and the properties of thermoplastic dynamic vulcanizates (TDVs) made by utilizing such in situ synthetized TPUs as their matrix polymer. We combined TPUs and conventional crosslinked rubbers in order to create TDVs by dynamic vulcanization in an internal mixer. The rubber phase was based on three different rubber types: acrylonitrile butadiene rubber (NBR), carboxylated acrylonitrile butadiene rubber (XNBR), and epoxidized natural rubber (ENR). Our goal was to investigate the effect of different processing conditions and material combinations on the properties of the resulting TDVs with the opportunity of improving the interfacial connection between the two phases by chemically bonding the crosslinked rubber phase to the TPU matrix. Therefore, the matrix TPU was synthesized in situ during compounding fr...

Journal of Applied Polymer Science, 2019

Rubber recycling is a major environmental challenge, as their covalently crosslinked structure ma... more Rubber recycling is a major environmental challenge, as their covalently crosslinked structure makes it impossible to reprocess via conventional polymer processing technologies. Devulcanization of rubber waste, whereby crosslinks are selectively broken, may provide a solution, as it allows it to be remolded into new shapes. We used two types of ground tire rubbers (GTRs) for this study; mechanically ground and waterjet-milled GTRs with different particle sizes. First, we revealed the effects of GTR particle size on the devulcanization process. We examined the sol content of the samples before and after devulcanization with two different microwave ovens, a power-controlled conventional one, and a temperature-controlled laboratory oven. In the latter one, heating rate and maximum temperature were controlled. We studied the effects of temperature, atmosphere in which the rubber was treated, heating rate, and holding time at maximum temperature. We prepared styrene-butadiene rubber-based rubber compounds containing GTR and optimally devulcanized GTR (dGTR_WJ). The physical and mechanical properties of the samples were assessed. The results indicate that both GTR_WJ and dGTR_WJ have an accelerating and a mildly softening effect on curing and dGTR_WJ has a less significant negative effect on mechanical properties: 15 phr GTR_WJ has the same effect as 45 phr dGTR_WJ.

Polymers, 2018

Because of the chemically crosslinked 3D molecular structure of rubbers, their recycling is a cha... more Because of the chemically crosslinked 3D molecular structure of rubbers, their recycling is a challenging task, especially when cost efficiency is also considered. One of the most straightforward procedures is the grinding of discarded rubber products with subsequent devulcanization. The devulcanized rubber can be used as a feedstock for fresh rubber compounds or can be blended with uncured virgin rubber and thermoplastic polymers to form thermoplastic dynamic vulcanizates (TDVs). TDVs combine the beneficial (re)processability of thermoplastics and the elastic properties of rubbers. Our current work focuses on the development of polypropylene (PP)-based TDVs with the use of a tire model rubber (MR) composed of natural rubber (NR) and styrene-butadiene rubber (SBR) in a ratio of 70/30. The research target was the partial substitution of the above fresh MR by microwave devulcanized crumb rubber (dCR). TDVs were produced by continuous extrusion, and the effects of composition (PP/MR/dC...

Periodica Polytechnica Mechanical Engineering, 2015

In this paper the effect of a novel bifunctional additive [cyclic butylene terephthalate (CBT)] w... more In this paper the effect of a novel bifunctional additive [cyclic butylene terephthalate (CBT)] was investigated on the rheological, curing and mechanical properties of natural rubber (NR), styrene butadiene rubber (SBR), oil extended styrene butadiene rubber (oSBR), acrylonitrile butadiene rubber (NBR) and ethylene propylene diene rubber (EPDM). Results showed, that CBT acted as an effective lubricant, decreasing the viscosity of the raw mixtures significantly. Furthermore CBT recrystallized upon cooling and acted as semi-active filler, slightly increased the mechanical properties of the tested non straincrystallizable synthetic rubbers. The polarity of the rubber matrix had a strong effect on the adhesion between rubber and CBT, the higher the polarity of the rubber, the better the adhesion between the two phases was.

Express Polymer Letters, 2015

This paper is aimed at studying the failure behavior of polyolefin-based self-reinforced polymer ... more This paper is aimed at studying the failure behavior of polyolefin-based self-reinforced polymer composites (SRPCs) via acoustic emission (AE). Three matrix materials (ethylene octene copolymer (EOC), polypropylene-based thermoplastic elastomer (ePP), random polypropylene copolymer (rPP), and three kinds of reinforcing structures of PP homopolymer (unidirectional (UD), cross-ply (CP) and woven fabric (WF)) were used. SRPCs were produced by compression molding using the film-stacking method. The composites were characterized by mechanical tests combined with in situ assessment of the burst-type AE events. The results showed that rPP matrix and UD reinforcement produced the greatest reinforcement, with a tensile strength more than six times as high as that of the matrix and a Young's modulus nearly doubled compared to the neat matrix. The number of the detected AE events increased with increasing Young's modulus of the applied matrices being associated with reduced sound damping. The AE amplitude distributions shows that failure of the SRPC structure produces AE signals in a broad amplitude range, but the highest detected amplitude range can be clearly linked to fiber fractures.

Polymers, 2016

The flame retardant synergism between highly stretched polymer fibres and intumescent flame retar... more The flame retardant synergism between highly stretched polymer fibres and intumescent flame retardant systems was investigated in self-reinforced polypropylene composites. It was found that the structure of reinforcement, such as degree of molecular orientation, fibre alignment and weave type, has a particular effect on the fire performance of the intumescent system. As little as 7.2 wt % additive content, one third of the amount needed in non-reinforced polypropylene matrix, was sufficient to reach a UL-94 V-0 rating. The best result was found in self-reinforced polypropylene composites reinforced with unidirectional fibres. In addition to the fire retardant performance, the mechanical properties were also evaluated. The maximum was found at optimal consolidation temperature, while the flame retardant additive in the matrix did not influence the mechanical performance up to the investigated 13 wt % concentration.

Silk-Containing Polymeric Systems

Handbook of Engineering Biopolymers, 2007

Express Polymer Letters, 2013

In this work, all-polypropylene composites (all-PP composites) were manufactured by injection mou... more In this work, all-polypropylene composites (all-PP composites) were manufactured by injection moulding. Prior to injection moulding, pre-impregnated pellets were prepared by a three-step process (filament winding, compression moulding and pelletizing). A highly oriented polypropylene multifilament was used as the reinforcement material, and a random polypropylene copolymer (with ethylene) was used as the matrix material. Plaque specimens were injection moulded from the pellets with either a film gate or a fan gate. The compression moulded sheets and injection moulding plaques were characterised by shrinkage tests, static tensile tests, dynamic mechanical analysis and falling weight impact tests; the fibre distribution and fibre/matrix adhesion were analysed with light microscopy and scanning electron microscopy. The results showed that with increasing fibre content, both the yield stress and the perforation energy significantly increased. Of the two types of gates used, the fan gate caused the mechanical properties of the plaque specimens to become more homogeneous (i.e., the differences in behaviour parallel and perpendicular to the flow direction became negligible).

Materials, 2014

Water-assisted, or more generally liquid-mediated, melt compounding of nanocomposites is basicall... more Water-assisted, or more generally liquid-mediated, melt compounding of nanocomposites is basically a combination of solution-assisted and traditional melt mixing methods. It is an emerging technique to overcome several disadvantages of the above two. Water or aqueous liquids with additives, do not work merely as temporary carrier materials of suitable nanofillers. During batchwise and continuous compounding, these liquids are fully or partly evaporated. In the latter case, the residual liquid is working as a plasticizer. This processing technique contributes to a better dispersion of the nanofillers and affects markedly the morphology and properties of the resulting nanocomposites. A survey is given below on the present praxis and possible future developments of water-assisted melt mixing techniques for the production of thermoplastic nanocomposites.

In this study all-poly(ethylene terephthalate) composites were developed and their (fracture)mech... more In this study all-poly(ethylene terephthalate) composites were developed and their (fracture)mechanical properties were investigated. Glycol modified poly(ethylene terephthalate) (PETG) and high tenacity PET multifilament were used as matrix material and reinforcement, respectively. The reinforcement was aligned in unidirectional (UD) and crossply (CP) manner and its content varied between 30...70 wt%. The composite plates were prepared via winding the reinforcing filament onto alumina plates and matrix film were placed in-betweens. This pre-product was consolidated by compression molding. The tensile mechanical properties and the density of the composite plates were determined. To characterize fracture behavior of the matrix material and the all-PET composites, Essential Work of Fracture (EWF) and J-integral methods were adopted. Based on the results one can state that the UD and CP reinforcement could enhance significantly the mechanical properties respect to PETG but in case of fracture toughness only the UD composite passed matrix value and CP composite remained much below.

Composites Part A: Applied Science and Manufacturing, 2015

Available under license CC-BY-NC-ND. Flame retarded self-reinforced poly(lactic acid) composites ... more Available under license CC-BY-NC-ND. Flame retarded self-reinforced poly(lactic acid) composites of outstanding impact resistance

Materials Science Forum, 2010

In the present work the weldability of self-reinforced composite was investigated. As reinforceme... more In the present work the weldability of self-reinforced composite was investigated. As reinforcement a fabric, woven from highly stretched split PP yarns, whereas as matrix materials of two kinds of random polypropylene copolymer (with ethylene) were used. The composite sheets were produced by film-stacking method and compression molded with different thickness (1 mm, 2 mm) with different contents at different processing temperatures keeping the holding time and pressure constant. The SRPPC sheets were welded by ultrasonic welding machine with different welding parameters. The welds were qualified by mechanical and microscopic tests. The results showed that the thermoplastic reinforcement has not got melted; therefore the reinforcement was kept the strength-increasing effect.

$Research paper thumbnail of Plane-stress fracture behavior of syndiotactic polypropylenes of various crystallinity as assessed by the essential work of fracture method$

Plane-stress fracture behavior of syndiotactic polypropylenes of various crystallinity as assessed by the essential work of fracture method

Polymer Engineering & Science, 2002

The fracture behavior of 1-mm-thick syndiotactic polypropylene (sPP) sheets of various crystallin... more The fracture behavior of 1-mm-thick syndiotactic polypropylene (sPP) sheets of various crystallinity (owing the various stereo- and regioregularity) was studied by the essential work of fracture (EWF) concept. The specific work of fracture parameters were determined on tensile-loaded deeply double-edge notched (DDEN-T) specimens at various deformation rates (v = 1, 10 and 100 mm/min) at ambient temperature. As the DDEN-T specimens showed full ligament yielding prior to subsequent necking, the energy partitioning method was adopted for data reduction. The specific essential work of fracture slightly increased as a function of crystallinity. Its yielding-related constituent increased with both crystallinity and deformation rate similarly to that of the yield strength and E-modulus. The specific plastic work parameters were less sensitive to crystallinity and deformation rate. The strain-induced crystalline phase transition from helical toward all-trans conformation was accompanied by voiding and crazing.