Hibrid polimer nanokompozitok kifejlesztése = Development of hybrid polymer nanocomposites

A projekt során epoxi mátrixú, szénszál erősítésű, szén nanocső töltésű hibrid nanokompozitot fejlesztettünk ki. Elsőként a nanocső homogén eloszlatására fejlesztettünk ki mesterkeverékes eljárást, mely módosítás nélkül átskálázható ipari méretekre is. A szén nanocső-mátrix határfelületi adhézióját elektronbesugárzással térhálósított vinilészter hibridizációval javítottuk. A hibrid nanokompozit rétegközi mechanikai tulajdonságinak széleskörű vizsgálatára dinamikus nyíróvizsgálatot és rétegközi húzóvizsgálati módszert fejlesztettünk ki. A rétegközi I. módú kvázistatikus és fárasztásos törésmechanikai vizsgálatokhoz kifejlesztettük az akusztikus emissziós lokalizáción alapuló repedésterjedés követést, amellyel a szabvány által ajánlott közelítő módszerek kiválthatók. A vizsgálatok alapján a nanocső töltés hatására a kvázistatikus repedésterjedési ellenállás 30%-al nőtt, a fárasztásos repedésterjedési sebesség a harmadára csökkent, a tönkremenetelhez tartozó ciklusszám 4-szeresére nőtt, tehát egy megbízhatóbb, hosszabb élettartamú anyagot sikerült kifejleszteni. A hőre keményedő mátrixú kompozit kifejlesztése mellett ciklikus butilén-tereftalátból in situ polimerizált PBT-t adalékoltunk szén nanocsővel a ridegség csökkentésére. A mechanikai vizsgálatok alapján a nanocső adalékolással úgy tudtuk a szívósságot 50%-al növelni, hogy közben a szilárdság és modulus is növekedett 30%-al. | During the project, carbon fiber and carbon nanotube reinforced hybrid nanocomposites with epoxy matrix were developed. First the masterbatch procedure was developed in order to disperse the carbon nanotubes in the epoxy resin homogeneously. This procedure can be upscaled to industrial volume without any modification. The interfacial adhesion between carbon nanotubes and epoxy matrix was increased by hybridization of the base system with unsaturated polyesther resin cured by electron irradiation. The mechanical properties of hybrid nanocomposites were investigated with newly developed mechanical tests, i.e. dynamical interlaminar shear test and interlaminar tensile test. For the interlaminar mode I fracture mechanical tests a new crack propagation tracking method was developed based on acoustic emission localization. This tracking method can substitute the approximate methods recommended by the standard. The quasi-static crack propagation resistance was increased by 30%, the fatigue crack propagation speed decreased by two third, the load cycles until failure increased 4-fold. Consequently a more reliable material with longer lifetime has been developed. Beside the above described development of thermoset matrix nanocomposites in-situ polymerized PBT matrix (IS-PBT) were developed. Since this IS-PBT is brittle, carbon nanotubes were added to decrease this brittleness. The toughness was increased by 50%, while the strength and modulus was also increased by 30%

Derivation of Ply Specific Stiffness Parameters of Fiber Reinforced Polymer Laminates via Inverse Solution of Classical Laminate Theory

The realistic estimation of the ply stiffness parameters of polymer composite laminates is a big challenge nowadays in industrial practice. In this paper a new, innovative concept is introduced that is based on the backward use of Classical Laminate Theory (CLT). The innovation in this new concept is (amongst others): possibility to infer the stiffness constants from the simple mechanical tests of specimens with multidirectional ply stack-up identical to the part to design. In addition the new method is manifested in a form of a compact equation that surely returns the measured deformation of the tested specimen on laminate level. The mathematical background of this concept is slightly more complex than what the conventional techniques offer, however its explicit form allows to code it in any automatic systems (e.g. user script) that can be run in Finite Element environment or as part of the software of a mechanical testing frame

Cellulóz alapú anyagokkal erősített/töltött biodegradábilis polimer kompozitok kifejlesztése, és tulajdonságainak elemzése = Developing of cellulose based reinforced/filled biodegradable polymer composites and investigation its properties

Pályázatunkban részben, ill. teljesen lebomló új polimer és polimer kompozit anyagokat, valamint gyártástechnológiákat fejlesztettünk ki általános-, ipari- és orvostechnikai alkalmazásokhoz. Munkánk során elemeztük a cellulóz és más természetes alapú szálak, valamint mátrixok tulajdonságait, új számítási modellt alkottunk a viselkedésük pontosabb leírására. Az alkalmazott mátrixok, szálak és adalékanyagok számos kombinációjával új receptúrákat fejlesztettünk ki javított reológiai- és mechanikai tulajdonságú rendszerek létrehozása érdekében. A kompozitokat felépítő egyes alkotók közötti kapcsolat ellenőrzésére új eszközt fejlesztettünk a szál/mátrix határfelületi adhézió, a nyírószilárdság megbízhatóbb mérésére. A kifejlesztett kompozitok biodegradábilis tulajdonságait lebomlásvizsgálatokkal ellenőriztük. Az új típusú anyagokból gyártandó termékek előállításához gyártástechnológiát fejlesztettünk és meghatároztuk a gyártási paraméterek optimális intervallumát. Félüzemi és üzemi kísérletekkel prototípus termékeket gyártottunk az anyagok és technológiák ipari alkalmazhatóságának alátámasztására. | In our project partly and fully degradable polymers, polymer composites and production technologies have been developed for general, industrial and biomedical applications. In our work properties of cellulose based and other natural fibers and matrices have been analyzed, a new predictive model has been developed to describe their behavior more precisely. Using several combinations of the matrices, fibers and additives new formulations have been developed to achieve systems with improved rheological and mechanical properties. A new device has been developed to test the interactions between the components constituting the composites, which allows a more reliable determination of fiber/matrix adhesion and shear strength. Biodegradability of the newly developed composites has been proved by degradability studies. Production technologies have been developed for manufacturing products from the new materials and the optimum intervals of production parameters have been determined. In pilot plant scale and in full scale experiments prototype products have been manufactured to prove the industrial viability of the materials and technologies

Development of a novel color inhomogeneity test method for injection molded parts

Abstract Nowadays most research and development concerning injection molded products are focused on their mechanical properties although visual appeal plays an even more important role on the market. There are several standards and recommendations for the testing of mechanical properties, but appearance cannot be quantified easily. The visual aspects are almost completely neglected, and there is not a commonly accepted method for measuring color inhomogeneity. The appearance and color homogeneity of injection molded parts depends on the coloring method itself, the applied technology and several other conditions. The method used nowadays to evaluate color inhomogeneity is based on visual inspection by humans. This research focuses on developing a new and automated method that can replace visual inspection. The functionality and precision of the new method and software have been tested and compared with visual inspection to prove its applicability

Preparation and characterization of in situ polymerized cyclic butylene terephthalate/graphene nanocomposites

Graphene reinforced cyclic butylene terephthalate (CBT) matrix nanocomposites were prepared and characterized by mechanical and thermal methods. These nanocomposites containing different amounts of graphene (up to 5 wt%) were prepared by melt mixing with CBT that was polymerized in situ during a subsequent hot pressing. The nanocomposites and the neat polymerized CBT (pCBT) as reference material were subjected to differential scanning calorimetry (DSC), dynamical mechanical analysis (DMA), thermogravimetrical analysis (TGA) and heat conductivity measurements. The dispersion of the grapheme nanoplatelets was characterized by transmission electron microscopy (TEM). It was established that the partly exfoliated graphene worked as nucleating agent for crystallization, acted as very efficient reinforcing agent (the storage modulus at room temperature was increased by 39 and 89% by incorporating 1 and 5 wt.% graphene, respectively). Graphene incorporation markedly enhanced the heat conductivity but did not influence the TGA behaviour due to the not proper exfoliation except the ash content