The Influence of the Hybridization Process on the Mechanical and Thermal Properties of Polyoxymethylene (POM) Composites with the Use of a Novel Sustainable Reinforcing System Based on Biocarbon and Basalt Fiber (BC/BF)

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.

Calibration of Arrhenius Constitutive Equation for B4Cp/6063Al Composites in High Temperatures

Isothermal-compression tests of B₄C_p/6063Al composites containing 20 vol.% B₄C were performed using a Gleeble-3500 device, at strain rates ranging from 0.001 s^-1 to 1 s^-1 and deformation temperatures ranging from 723 K to 823 K. The results showed that the high-temperature flow stress of B₄C_p/6063Al composites increases with the decrease in deformation temperature or the increase in the strain rate. After friction correction, the friction corrected stress was less than the original experimental stress. At the initial stage of deformation, the difference between the rheological stress after friction correction and the measured rheological stress is small, but with the continuous increase in the strain, the difference between the rheological stress after friction correction and the measured rheological stress is grows. Under the same strain, the difference between the rheological stress before and after friction correction becomes more significant with the decrease in the deformation temperature and the increase in the strain rate. Next, the material constants (i.e., α, β, Q, A, n) of B₄C_p/6063Al composites were calibrated based on the experimental data, and a constitutive equation was established based on Arrhenius theory. The experimental values and predicted values of the stress-strain curves are in good agreement with the stress-strain curves of the finite element simulation, and the validity of the constitutive equation was verified.

A Review on Synthetic Fibers for Polymer Matrix Composites: Performance, Failure Modes and Applications

In the last decade, synthetic fiber, as a reinforcing specialist, has been mainly used in polymer matrix composites (PMC’s) to provide lightweight materials with improved stiffness, modulus, and strength. The significant feature of PMC’s is their reinforcement. The main role of the reinforcement is to withstand the load applied to the composite. However, in order to fulfill its purpose, the reinforcements must meet some basic criteria such as: being compatible with the matrix, making chemical or adhesion bonds with the matrix, having properties superior to the matrix, presenting the optimal orientation in composite and, also, having a suitable shape. The current review reveals a detailed study of the current progress of synthetic fibers in a variety of reinforced composites. The main properties, failure modes, and applications of composites based on synthetic fibers are detailed both according to the mentioned criteria and according to their types (organic or inorganic fibers). In addition, the choice of classifications, applications, and properties of synthetic fibers is largely based on their physical and mechanical characteristics, as well as on the synthesis process. Finally, some future research directions and challenges are highlighted.

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

Basalt/glass fiber polypropylene hybrid composites were developed as subjects of investigation, with the aim to characterize their properties. An injection molding machine was used to produce the test samples. The following three different tests, at various specimen temperatures, were conducted: tensile test, three-point flexural test, and Charpy impact test. To determine fatigue behavior, the samples were uniaxially loaded and unloaded. Mechanical hysteresis loops were recorded and the dissipation energy of each loop was calculated. To determine the adhesion and dispersion between the fibers and the matrix, the fractured surfaces of the various specimens, after the tensile test, were investigated using a scanning electron microscope. The results show that the production of a composite with both basalt and glass fibers, in a polypropylene matrix with maleic anhydride-grafted polypropylene, can be successfully achieved. The addition of the two types of fibers increased the tensile strength by 306% and the tensile modulus by 333% for a composition, with 20% by weight, of fibers. The material properties were estimated with the help of a simulation software, and validated with a FEA. A satisfactory correlation between the simulation and measurement data was achieved. The error lays in a range of 2% between the maximum stress values. At a lower strain (up to 0.02), the stress values are very well matched.