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The study aims to analyze the strength properties obtained from three-point bending tests of epoxy-glass composite samples modified by adding rubber recyclate. A pure epoxy-glass composite is used as a comparative variant. The tested materials, which varies in the percentage of rubber recyclate and distribution, are cut through waterjet cutting to minimize the influence of temperature. The results undergo statistical analysis, and the microstructures are examined using scanning electron microscopy. The decreasing bending strength of the composites is observed, as the content of rubber recyclate in the material increased. However, adding rubber recyclate directly into the resin subtly decreases in bending strength compared to adding in the layers between the glass mat layers. Composites with rubber recyclate exhibits lower deflection under load compared to pure composites. The most favorable bending test parameters are obtained for the material containing 5% rubber recyclate distributed in three layers. [ABSTRACT FROM AUTHOR]

Currently, there is a noticeable trend of modifying new materials by using additives from the recycling of harmful waste. This is to protect the environment by using waste to produce composites and at the same time to reduce the cost of their production. The article presents an analysis of the impact of the use of rubber recyclate obtained from the utilization of car tires as a sandwich layer of epoxy–glass composites and its impact on the strength parameters of the composite. The presented research is an extension of the previously conducted analyses on composite materials modified with the addition of rubber recyclate. The four variants of the materials produced contained the same percentage amount of rubber recyclate, but differed in the way it was distributed and the number of layers. Static tensile tests as well as impact strength and kinetics of damage to samples made with and without the addition of recyclate were carried out. Observation of the structures of the materials with the use of SEM was also performed. A significant influence of the method of distributing the recyclate in layers on the strength parameters of the materials was found. In the case of composites with three and two sandwich layers of recyclate, more favorable results were obtained compared to the blank sample. In addition, the values of the impact strength measurements were subjected to statistical analysis at the significance level of α = 95%. The distributions were tested for normality with the Shapiro–Wilk test, differences between pairs were tested with the Student's t-test for dependent groups, and ANOVA differences were tested for independent groups. Using the Student's t-test, it was confirmed that between the pairs of variables in the configurations reference sample and modified sample, there were significant statistical differences in the distribution of impact strength measurement results for all the analyzed materials. Statistical analysis showed a significant usefulness in the selection of the material with the best strength parameters and a significant role of statistical methods in the study of anisotropic materials. [ABSTRACT FROM AUTHOR]

Polymer composites are materials that are used in many industries. Their wide application has a direct impact on the amount of post-production and post-consumer waste. The global problem with recycling, especially of fiber-reinforced polymeric materials, has prompted research into methods of their use. Previous research on composite materials with polyester–glass recyclate showed a decrease in mechanical properties. The construction material should have the highest mechanical properties. Based on the literature, it was found that the use of nanoadditives may have a positive effect on the parameters of the materials. The use of gamma aluminum nanopowder, in a small amount can significantly increase the mechanical properties of composites with polyester–glass recyclate, and thus can affect the application of these materials to structural elements. The article is devoted to the research on the hardness of composite materials with polyester–glass recyclate and gamma aluminum nanopowder. The main goal is to investigate the possibility of using a nanoadditive as a material, increasing the mechanical properties of composites with polyester–glass recyclate, so as to create a recycled material with the highest possible strength parameters. Hardness tests were performed using the Barcol method. For each composite material, 30 measurements were made in order to subject the results to a statistical analysis. Using parametric statistical tests it was shown that the obtained hardness values at the assumed level of statistical significance pv = 0.05 for comparisons for the samples of the reference material (B0) do not differ by chance, while for the comparisons in the configurations of the reference material (B0) with the modified materials, (R10, A2, R10A2) they do not differ by accident. Studies have shown that the addition of 2% gamma aluminum nanopowder slightly lowers the hardness of a pure polyester–glass composite, but the same additive allows the hardness of composite materials to be increased with the addition of glass recyclate. This is of particular importance for the development of the optimal composition of polyester–glass composites with the addition of recyclate, which will have good strength properties and at the same time enable the reuse of composite waste. [ABSTRACT FROM AUTHOR]