Basalt/Glass Fiber Polypropylene Hybrid Composites: Mechanical Properties at Different Temperatures and under Cyclic Loading and Micromechanical Modelling

Study on Recycling of Waste Glass Fiber Reinforced Polypropylene Composites: Examination of Mechanical and Thermal Properties

This study presents the preparation of short glass fiber reinforced polypropylene (PP/FG) composites using with waste (post-consumer) polypropylene composite containing long glass fiber (PP/LFG) obtained from the recycling of battery covers of trucks. Waste PP/LFG composite parts were mechanically grinded before adding to PP/FG composites. An injection molding machine was used to produce the PP/FG composite test samples loading with recycled waste PP/LFG composite in the range of 1-20% by weight. Effects of recycled waste PP/LFG content on the mechanical, thermal, and morphological properties of the PP/FG composites were investigated. The following three different tests, at various waste PP/LFG ratios, were conducted: Izod/Charpy Impact test, bending test, and tensile test. Mechanical test results showed that mechanical strength of prepared PP/FG composites were not influenced by content of waste PP/LFG material up to 10 wt.%. Differential scanning calorimetry (DSC) was used for the evaluation of thermal parameters such as melting point and crystallization temperature of the polymer matrix in the composites studied. Furthermore, by analyzing the values of thermal effects determined using the DSC method, it was possible to determine the degree of crystallinity. The DSC results showed that crystallinity %, melting, and crystallization temperatures of PP/FG composites were not influenced to adding waste PP/LFG at different ratios. The morphology of composite materials was investigated by SEM analysis. Good fiber dispersion was observed in the PP matrix for PP/FG composites containing short glass fiber prepared with all ratios of recycled waste PP/LFG material containing long glass fiber.

Development of a New Type of Flame Retarded Biocomposite Reinforced with a Biocarbon/Basalt Fiber System: A Comparative Study between Poly(lactic Acid) and Polypropylene

A new type of partially biobased reinforcing filler system was developed in order to be used as a flame retardant for polylactic acid (PLA) and polypropylene (PP)-based composites. The prepared materials intended for injection technique processing were melt blended using the novel system containing ammonium polyphosphate (EX), biocarbon (BC), and basalt fibers (BF). All of the prepared samples were subjected to a detailed analysis. The main criterion was the flammability of composites. For PLA-based composites, the flammability was significantly reduced, up to V-0 class. The properties of PLA/EX/BC and PLA/EX/(BC-BF) composites were characterized by their improved mechanical properties. The conducted analysis indicates that the key factor supporting the effectiveness of EX flame retardants is the addition of BC, while the use of BF alone increases the flammability of the samples to the reference level. The results indicate that the developed materials can be easily applied in industrial practice as effective and sustainable flame retardants.

Theoretical and Experimental Substantiation of the Efficiency of Combined-Reinforced Glass Fiber Polymer Composite Concrete Elements in Bending

An essential problem of current construction engineering is the search for ways to obtain lightweight building structures with improved characteristics. The relevant way is the use of polymer composite reinforcement and concrete with high classes and prime characteristics. The purpose of this work is the theoretical and experimental substantiation of the effectiveness of combined-reinforced glass fiber polymer composite concrete (GFPCC) bending elements, and new recipe, technological and design solutions. We theoretically and experimentally substantiated the effectiveness of GFPCC bending elements from the point of view of three aspects: prescription, technological and constructive. An improvement in the structure and characteristics of glass fiber-reinforced concrete and GFPCC bending elements of a new type has been proven: the compressive strength of glass fiber-reinforced concrete has been increased up to 20%, and the efficiency of GFPCC bending elements is comparable to the concrete bending elements with steel reinforcement of class A1000 and higher. An improvement in the performance of the design due to the synergistic effect of fiber reinforcement of bending elements in combination with polymer composite reinforcement with rods was revealed. The synergistic effect with optimal recipe and technological parameters is due to the combined effect of dispersed fiber, which strengthens concrete at the micro level, and polymer composite reinforcement, which significantly increases the bearing capacity of the element at the macro level. Analytical dependences of the type of functions of the characteristics of bent concrete structures on the arguments—the parameters of the combined reinforcement with fiber and polymer composite reinforcement—are proposed. The synergistic effect of such a development is described, a new controlled significant coefficient of synergistic efficiency of combined reinforcement is proposed. From an economic point of view, the cost of the developed elements has been reduced and is economically more profitable (up to 300%).

Calibration of the PA6 Short-Fiber Reinforced Material Model for 10% to 30% Carbon Mass Fraction Mechanical Characteristic Prediction

Short-fiber reinforced composites are widely used for the mass production of high-resistance products with complex shapes. Efficient structural design requires consideration of plasticity and anisotropy. This paper presents a method for the calibration of a general material model for stress-strain curve prediction for short-fiber reinforced composites with different fiber mass fractions. A Mori-Tanaka homogenization scheme and the J2 plasticity model with layered defined fiber orientation were used. The hardening laws: power, exponential, and exponential and linear were compared. The models were calibrated using experimental results for melt front, orientation tensor analysis, fiber length, and diameter and tension according to ISO 527-2, for samples of PA6 which were either non-reinforced, or reinforced with 10%, 15%, 20%, and 30% carbon fiber mass fractions. The novelty of this study lies in the transition from the strain-stress space to the strain-stress-fiber fraction space in the approximation of the material model parameters. We found it necessary to significantly reduce the fiber aspect ratio for the correct prediction of the mechanical characteristics of a composite using the Mori-Tanaka scheme. This deviation was caused by the ideal solution of ellipsoidal inclusion in this homogenization scheme. The calculated strength limits using Tsai-Hill failure criteria, based on strain, could be used as a first approximation for failure prediction.

Processing and Mechanical Properties of Basalt Fibre-Reinforced Thermoplastic Composites

Basalt fibre is derived from volcanic rocks and has similar mechanical properties as glass fibre. However, poor fibre-matrix compatibility and processing issues are the main factors that have restricted the mechanical performance of basalt fibre-reinforced thermoplastic composites (BFRTP). In this work, basalt continuous fibre composites with polypropylene (PP) and polycarbonate (PC) matrices were studied. The composites were processed by compression moulding, and a processing study was conducted to achieve good quality composites. For the BF-PC composites, the optimisation of material preparation and processing steps allowed the polymer to impregnate the fibres with minimal fibre movements, hence improving impregnation and mechanical properties. For BF-PP composites, a compatibiliser was required to improve fibre-matrix compatibility. The compatibiliser significantly improved the tensile and impact strength values for short BF-PP composites and continued to increase at 40 wt%. Furthermore, the analytical modelling of the Young’s moduli indicated that the induced fibre orientation during processing for short BF-PP composites and unidirectional (UD) BF-PC composites had better stress transfer than that of UD BF-PP composites.

Quantitative and Qualitative Aspects of Composite Action of Concrete and Dispersion-Reinforcing Fiber

The interest in using polymer-dispersed reinforcement in the construction industry in the context of sustainability has led to significant research on this scientific problem. The article is devoted to studying the processes of fiber interaction depending on its dispersion and the concrete matrix, and their combined contact work during the formation of a concrete structure, work under stresses arising in a concrete body, and during a collapse. The physical and mechanical processes of deformation and destruction of the “matrix–fiber” system were studied using high-precision microscopic equipment, and the nature of the work and deformation of fibers in concrete were revealed. The work aimed to establish and characterize the quantitative and qualitative aspects of the concrete matrix and dispersion-reinforcing fiber combined work. It was established that the best values of the adhesion index were observed at a volume content of fiber in the amount of 2% by weight of cement, regardless of the type of dispersion-reinforcing fiber. It was shown that the microstructure of polydispersion-reinforced fiber-cement specimens was denser, and microcracks formed during fracture in polydispersion-reinforced specimens had a smaller opening width. It was established that polydispersion-reinforced concrete had higher values of strength (up to 126%) and deformation (up to 296%) characteristics compared to monodispersion fiber-reinforced concrete.

Reinforced Concrete Structures Containing Chopped Carbon Fibers with Polymer Composite Materials

In this paper, the reinforcement of concrete combining composite materials with carbon, glass and aramid fibers is discussed. Accordingly, cement specimens reinforced with chopped carbon fibers were manufactured via the retrofitting method and coated using various different types of fabrics (carbon, glass and aramid), and epoxy resin systems were developed and studied using compressive strength tests. In addition, polymeric matrix (epoxy resin) composite materials reinforced with different types of fabric (carbon, glass and aramid (Kevlar^® 49)) were manufactured and their shear and bending strengths were measured. Before reinforcing cement specimens, all fabrics (carbon, glass and aramid (Kevlar^® 49)) were placed in a vacuum chamber and were processed via pre-impregnation. This specific reinforcing method significantly improved the mechanical properties of cementitious structures with compressive strength values that reached 81 MPa. In a similar way, the bending and shear strengths of the materials under study were measured at 405 MPa and 33 MPa, respectively.