Milled basalt fibers as reinforcement for polyurea composite spray coatings with improved thermomechanical stability and mechanical performance

Abstract

The novel polyurea-based (PUA) composites modified with milled basalt fibers (BMF), formed with spray coating technology were produced. The addition of 5-30 wt % of BMF into commercial two-component PUA was used as a low-cost modification which allowed to significantly improve the mechanical performance, as well as thermomechanical and thermal stability of the final products. It was found that the incorporation of 30 wt % of BMF resulted in over 30% stiffness improvement and extension using temperature of the coating above 80 °C. Moreover, an increase by 25 °C in thermal stability evaluated by thermogravimetric analysis (TGA) was achieved, without significant changes in the rheological behavior of the compositions, resulting in the presence of structural defects. Finally, an evaluation of crosslink density was conducted in order to ascertain that the applied modification of the thermoset reactive fast-curing system allows to obtain fully cured products which may be used as a spray coating for hydrotechnical objects protection. Mielone włókna bazaltowe jako wzmocnienie polimocznikowych kompozytowych powłok natryskowych o zwiększonej stabilności termomechanicznej i wytrzymałości mechanicznejStreszczenie: Metodą powlekania natryskowego wytworzono nowe kompozyty na bazie polimocznika (PUA) modyfikowanego mielonymi włóknami bazaltowymi (BMF). Komercyjny dwuskładnikowy PUA modyfikowano niskokosztowo za pomocą dodatku 5-30% mas. BMF, co pozwoliło na wyraźną poprawę właściwości mechanicznych, a także stabilności termomechanicznej i termicznej PUA. Stwierdzono, że wprowadzenie do polimocznika 30% mas. BMF zwiększyło o ponad 30% jego sztywność i umożliwiło rozszerzenie zakresu temperatury stosowania powłoki powyżej 80 °C. Metodą analizy termograwimetrycznej (TGA) stwierdzono wzrost stabilności termicznej o 25 °C, bez istotnych zmian w reologicznym zachowaniu kompozycji, mogących prowadzić do tworzenia się wad strukturalnych w gotowych wyrobach. Na podstawie oceny gęstości usieciowania potwierdzono, że przeprowadzona modyfikacja termoutwardzalnego reaktywnego systemu szybkiego utwardzania pozwala na uzyskanie w pełni utwardzonych produktów, które można zastosować jako powłokę natryskową do ochrony obiektów hydrotechnicznych.Słowa kluczowe: polimocznik, kompozyt, powłoka natryskowa, włókno bazaltowe, właściwości termomechaniczne.The growing knowledge of the influence of exploitation and weathering conditions on the durability over the whole life cycle of steel and concrete construction elements requires the development of novel protective methods. One of the most extensively developed protection methods used for large scale civil engineering objects, especially those made of concrete, is the application of polyurea (PUA) and polyurethane (PUR) elastomeric spray coatings [1,2]. Their benefi-

Polyurea for Blast and Impact Protection: A Review

“…Due to a mismatch between the mechanical properties of the materials, delamination between the reinforcement and the substrate often occurs at the interface or in the interphase region due to stress build-up. Large amounts of nano-reinforced and micron-reinforced materials can easily reduce the dispersion and lead to a stress concentration effect that can negatively affect the mechanical properties of polyurea [22,43,[68][69][70].…”

“…High-strength and high-modulus polymer composites are produced by reinforcing the polymer matrix with high-strength and high-modulus fibers, the reinforcing fibers are employed to increase the strength and stiffness of the material, and the load is transferred to the fibers via the viscoelastic displacement of the matrix under stress [74]. The reinforcing fibers that are commonly used for enhancing performance are glass fiber (GF) [20,39,[70][71][72][73]75], basalt fiber (BF) [22,23,76,77] and carbon fiber (CF) [78][79][80][81]. GF are of two types: chopped glass fiber and milled glass fiber (MG), of which MG is mostly used as reinforcing and filling media in plastic composites, adhesives and coatings.…”

“…Moreover, the adhesion properties of BF are higher than those of GF of equal size, giving a distinct advantage among fiber reinforcement materials [76]. Recent work by Barczewski et al [22] has demonstrated that the addition of basalt-milled fiber (BMF) to polyurea can result in Basalt-based products that are utilized in polymer modifications are mainly manufactured from BF as reinforcing agents for the polymer [23]. BF is a reinforcing material with low consumption in production and a higher performance than GF and has also been used by many researchers in recent years for polyurea reinforcement.…”

A review on the applications of polyurea in the construction industry

“…Figure 7 compares the mechanical properties of the polyurea and polyurea–BMF composite at different values of filler weight percentage. Notably, the features (modulus and tensile strength) were improved to a certain extent by increasing the weight percentage of the filler 71 …”

“…Mechanical properties of polyurea and polyurea–BMF composites: (A) Young's modulus and (B) tensile strength 71 …”