BMe Research Grant
Nowadays, high performance polymer composites (HPPCs) are widely used in several kind of engineering applications, for example in structural parts of airplanes, automobiles, boats and sporting goods. The main aim of my studies is developing HPPCs with tougher behavior and higher energy absorbing abilities, in this way creating opportunity to produce more durable and safer appliances and vehicles.
My researches are connected to the Department of Polymer Engineering at the Budapest University of Technology and Economics (BUTE), where education and R&D activities with polymer composites dates back to the early ‘90s. Commitment to this scientific area by the Department can be best demonstrated by the publishing of their worldwide ranked scientific paper Express Polymer Letters.
A significant proportion of engineering developments of the 21th century aims at improving the performance and efficiency, and maintaining safe operation at the same time. HPPCs are able to satisfy these demands because of their high strength and low density makes them a good candidate to replace many of the currently used metal parts. The low density allows both a decrease in mass and and increase in performance and efficiency in case of vehicles and goods. The underlying phenomena is the tailor-made mechanical properties of fibre reinforced polymer composites, which resulted higher strength to the load directions. This tailor-made structure can be created during the manufacturing process of the composite part, when the fibre reinforcement is being embedded into the matrix material which is the other component of this complex structure. The common direction ways of fibre reinforcement can be observed in Figure 1 .
Figure 1: Structure of long fibre reinforced composite material in case of same oriented (a), normal to each other (cross) oriented (b), and randomly oriented (c) fibre reinforcement 
Additionally to the many advantages, fibre reinforced polymer composites show disadvantages too, compared to most ductile fracturable polymer and metallic materials in terms of toughness, because they show propensity to relatively quick forthcoming failure (Figure 2). This property is called brittleness and it comes from the structure of this kind of material and is connected with the crack formation frequency and spreading velocity in the material .
Figure 2: Brittle fracture of carbon fibre reinforced composite plate (left side) and mountain bike frame (right side) [1, 2]
This problem can be solved by oversizing the composite structure. In case of such designs more structural material is used to build up the composite structure, and lowering this way the safety risks. If tougher fibre reinforced composite materials were used for this applications, the extent of oversizing and also the mass of the composite part and associated safety risks could also be decreased simultaneously.
During my research, I aim at developing reinforced polymer composites with enhanced energy absorbing properties and increased toughness and high strength compared to the common used HPPC materials. Expectations towards the mentioned composite material properties are not confined to the mentioned mechanical ones. Their manufacture must not be complicated or expensive compared to the composite materials currently used in industry, otherwise it could prevent their industrial applications.
A further aim is to describe thermo-mechanical and mechanical properties of developed materials and prepare the implementation of these result to FEM analysis software. This will ease the work of engineers with these kind of materials.
Energy absorbing abilities of composite material can be reached by nano-sized modifications of the structure of its matrix material. This can be accomplished in various ways. One of them is doping with nano-sized particles (for example carbon nanotubes and graphene), which results in polymer nanocomposites – very popular approach these days. A less intensively researched but very promising method is blending immiscible polymer compounds. Here, the immiscible polymer resins are mixed so that a nano-scaled phase structure is created. When these resins get cross-linked, this phase structure (named IPN, interpenetrating polymer network) is fixes (Figure 3) and its advantageous properties, for example increased damping property and energy absorbing ability are being formed. [4–17, T1–T2].
Figure 3: Theoretical scheme of interpenetrating polymer network (IPN) [based on 3]
The main reason of increased energy absorbency can be rooted in the large amount of molecule chain entanglements (promiscuous structure). Because of this structure, in case of loads or deformations, the IPN material is able to deform in an elastic way (in small range) and can give tougher reactions. This behavior demands (absorbs) relatively large amount of energy during the fracture and less energy can be appropriated to the crack propagation.
The mentioned IPN structure resin as a matrix material of a composite can lead to even more interesting effects (Figure 4). In this case, a unique phase structure can be formed with the fibre reinforcement of the composite (Figure 4/b), and a more durable and crack-resistant structural material with increased energy absorbency can be produced in this way.
Figure 4: Structure of hybrid matrix composite (a) and special phase structure surrounded fibre reinforcement (b) [T3, T4]
In the first phase of this research, two component mixes has been created from several type of polymer resins, and their main properties has been investigated. Epoxy resin (EP), unsaturated polyester resin (UP) and vinyl ester (VE) was used as base material of the mentioned mixes. They were created at various mixing ratios and by using two kind of mixing methods: a simultaneous (#2) and a sequential (#1) one. Next, in the second phase, carbon fibre (CF) and glass fibre (GF) reinforced composites were created using the hybrid resins with the best mechanical properties, and characterized by several kind of mechanical tests.
According to the results of performed tests, most of the hybrid resins have better mechanical properties, especially in terms of energy absorbency, compared to the neat ones both as resin (Figure 5/a) and as composite (Figure 5/b). The underlying reason was verified using atomic force microscopy (AFM). The results showed, that the hybrid resins I produced have a more detailed phase structure than neat resins. The mechanical properties can be attributed to the finely detailed IPN structure with 10–50 nm average domain size [T3–T10].
Figure 5: Energy absorbing abilities of UP/VE hybrid resins (a) and its carbon fibre (CF) reinforced composites (b), and phase structure of investigated resins (c) by AFM images [T4, T5, T6]
My work can pave the way to producing more efficient and safe vehicles, other goods, and machines. During my research, I plan to define not only particular material compositions and manufacturing methods, but also to describe the impacts of nano-scaled modifications on mechanical properties, and provide a solid base for further investigations in the topic.
[T1] Turcsán T, Mészáros L, Khumalo V M, Thomann R, Karger-Kocsis J. Fracture behavior of boehmite-filled polypropylene block copolymer nanocomposites as assessed by the essential work of fracture concept, Journal of Applied Polymer Science 2014;131(13) 8p.
[T2] Turcsán T, Mészáros L, Karger-Kocsis J. A lényegi törésmunka módszerének alkalmazhatósági vizsgálata polimer nanokompozitok esetén (in Hungarian), OGÉT XXIV, Déva, 21–24 April, 2016, 459–462.
[T3] Turcsán T, Mészáros L. Nanostructured polymer matrix composites for high performance engineering applications, Nanotech France 2015 International Conference, Paris, France, June 15–17, 2015, (poster)
[T4] Turcsán T, Mészáros L. Növelt energiaelnyelő képességű szénszál erősítésű polimer kompozitok fejlesztése (in Hungarian), X. Országos Anyagtudományi Konferencia, Balatonalmádi, Hungary, 11–13, October, 2015, (poster)
[T5] Turcsán T, Mészáros L. Nanostrukturált mátrixú kompozitok, az anyagfejlesztés új irányzata (in Hungarian), Polimerek 2016;2(4):109–111.
[T6] Mészáros L, Turcsán T. Development and mechanical properties of carbon fibre reinforced EP/VE hybrid composite systems, Periodica Polytechnica Mechanical Engineering 2014;58(2):127–133.
[T7] Turcsán T, Mészáros L. Egymásba hatoló hálószerkezetű gyanta fejlesztése és vizsgálata (in Hungarian), Műanyagipari Szemle 2013, 12(5):74–84.
[T8] Turcsán T. Növelt energiaelnyelő képességű kompozitok fejlesztése, (in Hungarian), GÉP folyóirat 2013;64(7):58–61.
[T9] Turcsán T, Mészáros L. Development of high-performance fiber-reinforced polymer composite with toughened matrix, The Fiber Society Spring 2014, Technical Conference, Liberec, Czech Republic, May 21–23, 2014, 69–70.
[T10] Horváth K, Turcsán T, Mészáros L. A fázisarány hatása hibrid polimer rendszerek esetén (in Hungarian), OGÉT XXIV, Déva, Romania, 21–24 April, 2016, 210–213.
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