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Plastics have light weight and excellent performance, which are widely used in all kinds of automobiles. Polypropylene (PP) and its reinforcing materials are used in automotive components, where the surfaces of bumpers and fenders are coated with paint. Traditional recycling can frequently generate various pollutants, such as paint sludge. Microwave pyrolysis is a more environmentally friendly pyrolysis method with a higher heating coefficient than traditional electric pyrolysis. This study first explores the elemental composition of two types of automotive PP plastics and uses thermo-gravimetric analysis and the Kissinger-Akahira-Sunose method to preliminarily calculate the activation energy of automotive PP. The calculation results show that the activation energy of PP containing paint ranges from 189.145 kJ/mol- 199.513 kJ/mol, with an average value of 193.903 kJ/mol. The activation energy of PP without paint is between 215.506 kJ/mol-265.794 kJ/mol, with an average value of 242.425kJ/mol. Then, pyrolysis experiments on PP for vehicles without paint are conducted using a microwave atmosphere tube furnace at different temperatures and microwave powers. The experimental results showed that, when the pyrolysis temperature increased from 500oC to 620 oC, the total proportion of gas products rose from 0.75 wt.% to 4.81 wt.%, and the content of alkanes in the liquid products improved from 26.21 wt.% to 34.37 wt.%; when the microwave power increased from 900 W to 1100 W, the gas product rose to 20.77 wt.%, and the content of aromatic compounds in the liquid product improved to 17.78 wt.%. In addition, the pyrolysis experiment of automotive PP containing paint showed that paint had a relatively minor effect on the pyrolysis products of automotive PP. This study shows that using microwave pyrolysis to treat automotive PP and PP with paint is feasible, which provides a reference for the clean treatment of automotive polymers.

Carbon fiber-reinforced polymer composites are widely used materials in the aircraft industry, automotive sector, marine applications, civil engineering, and daily consumer goods, due to their superior mechanical properties at a relatively low density compared to metallic materials. The studied composites are composed of an epoxy resin matrix in which three layers of carbon fiber fabric are embedded, oriented at 0 and 90 degrees. Carbon fiber-reinforced polymer composites were manufactured using the Vacuum Assisted Resin Transfer Molding technique. The tensile failure mechanism in carbon fiber-reinforced polymer composites is an extremely complex phenomenon influenced by numerous factors. This study aims to evaluate the mechanical behavior of carbon fiber-reinforced composites through tensile testing and to compare experimentally obtained results with those calculated using the mixture rule. Additionally, the behavior of the materials under tensile stress was analyzed using the digital image correlation method. Estimating mechanical properties based on the mixture rule is a common practice in the design phase of polymer composites. This study`s novelty and originality lie in its anticipation of the tensile strength and modulus of elasticity of the studied composites. This anticipation was achieved using a virtual instrument developed in the LabVIEW graphical programming environment. The experimentally obtained results for the tensile characteristics of the studied materials are suitable for this type of composite. These results were compared with estimates derived from the mixture rule, and the absolute error was determined.

Acrylonitrile-butadiene-styrene (ABS) material is widely used as a protective rigid shell and impact absorber in bike helmets, providing vital protection against head injuries under specific working conditions. However, ABS aging in helmets could affect the safety factor of helmets and shorten the service life. Exploring the transformation during aging process for real assembled helmets made of ABS out shells is crucial for the investigation and fabrication of high performance helmets. Herein, the effect of long-term aging on the physical properties of practical helmets made of ABS outer shells has been discussed systematically. Four different types of helmets were subjected to different aging conditions, i.e., outdoor environment, ultraviolet exposure, hot air, and humid-heat conditions. The impact property and stiffness tests were carried out as a function of aging time and aging conditions. The measured helmets were capable of meeting engineering tolerances when aged under outdoor, ultraviolet, and hot air conditions, and could deliver competitive mechanical performance to their pristine helmets. Yet, after aging under humid-heat for 800 h, the helmets showed an obvious decrease in impact strength, gloss, and stiffness. The influence of different aging conditions was further investigated by thermal and spectral characterizations. The study might provide some valuable advice for helmet performance evaluation.

This study investigated the effects of different solutions (artificial saliva, Listerine Cool Mint-alcohol containing and Colgate Plax-alcohol free) on the nanohardness, elastic modulus and surface roughness of enamel surface and composite materials (Admira Fusion, Clearfil Majesty Esthetic and Mosaic Universal). Specimens of 2 mm depth and 5 mm diameter were stored in solutions for 12 h at 37°C. Baseline and final measurements were obtained using a HYSITRON TI 950 TriboIndenter testing machine. The applied force to each specimen increased from 0 to 1000 µN. For SEM images, one sample in each group was covered with a thin layer of mix of gold and palladium using a sputter coater (Quorum Q150R ES, UK). Scanning electron microscopy (SEM) images were taken at 5000× magnifications to evaluate the surface morphology. Statistical analysis for hardness, elastic modulus and roughness was performed by Two-way ANOVA, Benferroni and Tukey HSD at a significance level 0.05. The results of this study showed that the highest value of surface roughness and lowest hardness and elastic modulus were presented by Admira (p[0.001). Listerine caused significantly increased surface roughness (p[0.001) and decreased hardness and elastic modulus parameters (p[0.001). The mouthrinse containing alcohol caused more significant changes in the nanohardness, elastic modulus, surface roughness values of enamel and composite surfaces.

Anterior skull base reconstruction is a complex surgical procedure that requires careful evaluation of the patient`s condition and the expertise of a skilled surgical team. Skull base reconstruction objectives focus on providing water-tight separation between the intracranial and extracranial contents, closing dead space, and returning reasonable form and function. Regarding the reconstruction options, the main categories are non-vascular grafts, loco-regional flaps, free tissue transfer or bony-free flaps. The major challenge in reconstructive surgery is the effective sealing of the defect due to its uneven edges and the conformation of the anterior skull base. Given this challenge, we are considering the possibility of designing a prosthetic for anterior skull base defects using the 3D printer.

Part dimensional inaccuracies serve as a barrier from adopting Additive Manufacturing (AM) processes in mass production. Fused Deposition Modeling (FDM) is a thermoplastic based low cost AM process which can create conceptual models, prototypes and end user industrial parts. The current study involves predicting the optimal parameter settings and significant parameter for reduced geometric deviations in printed part using Nylon filament reinforced with 20% carbon fiber. Five input factors such as build orientation, layer thickness, infill density, raster angle and infill pattern have been considered for preparing the experimental layout through taguchi’s mixed fractional factorial design. The changes in length, width and thickness of the printed part from CAD value have been evaluated individually through ANOVA and Signal to Noise Ratio method (Smaller the better). Layer thickness is significant only for variations in length, but build orientation affects both width and thickness dimensions. The geometric deviations are further analyzed using combined multi criteria decision making (MCDM) approaches such as Entropy-CoCoSo and PCA-TOPSIS. The optimal parameter settings obtained for reduced geometric deviations is found to be Flat orientation, 0.1mm layer thickness, 50% infill density, 0° raster angle and cubic infill pattern. Layer thickness is found to be highly significant parameter influencing the geometric deviations subsequently followed by build orientation from both the MCDM methods. The multi response performance index values obtained from Entropy-CoCoSo has been trained using classification algorithms such as decision tree, random forest and Naive Bayes. Naive Bayes algorithm outperformed other methods with highest classification accuracy of 99.4% in a training-testing split ratio of 75:25.

In this paper, new epoxy resin/rubber powder/hollow beads three-phase composites were prepared by designing the incorporation of fly ash hollow beads with different mass fractions (5%, 10%, 15%, and 20%) as new reinforcing phases into epoxy resin/rubber powder two-phase composites with 5% mass fraction of carbon black rubber powder. Quasi-static compression tests were conducted at room temperature to test the compressive properties of the oxygen resin/rubber powder/hollow beads composites. Calculate the energy absorption properties and energy absorption efficiency of the composites from the compression curves. Fracture characteristics of compressed material specimens with microscopic morphology were observed by scanning electron microscopy. By systematically analyzing the effect of fly ash hollow beads content on the mechanical properties of epoxy resin/rubber powder/hollow beads three-phase composites, it was found that fly ash hollow beads as reinforcing materials can effectively improve the brittleness and yield strength of epoxy resin/rubber powder as well as the energy-absorbing properties and efficiency of the composites. The energy absorption properties of the epoxy resin/rubber powder/hollow beads composites increased and then decreased with the increase in the mass fraction of fly ash hollow beads. In the epoxy resin/rubber powder/hollow beads composites, the most significant performance was observed when the mass fraction of fly ash was 10%.

Additive technologies are continually evolving and are crucial in numerous industries, including medical, aerospace, and automotive, but they can also play an important role in the prototyping phase. Due to additive manufacturing, amateurs and enthusiasts can construct simple projects as well as large projects with specialized usage in specific applications. When it comes to complex pieces, traditional manufacturing technologies such as milling, chipping, drilling, and so on have specific constraints, often need even additional production processes to complete the item. All of these constraints can be solved with additive technologies. This work investigates Fused Deposit Modeling (FDM) printing of many specimens with varying properties in order to analyze PLA (Poly Lactic Acid) material behavior following tensile testing. The collected findings will be analyzed in order to determine the specimens with the most significant behavior according on the modified parameters.

Polymers are commonly utilized sophisticated materials that may be found in nearly every item we use daily. Polymers` relevance has recently been highlighted due to their applications in several fields of science, technology, and industry, ranging from fundamental usage to biopolymers and medicinal polymers. The research aims to study the effect of annealing with irradiation on the optical properties of PMMA films used in many industrial and medical applications. Where UV-Vis spectroscopy was used to study the absorption and emission spectra in calculating the optical parameters, it was found that the optical energy gap of the indirect transmission type decreases with the increase in the thickness of the thin films. Also, the optical parameters such as the absorption coefficient, refractive index, attenuation coefficient, and dielectric constants increase with increasing thickness. The character of FTIR spectra and the locations of the bands have been demonstrated to change with different time annealing temperatures with irradiation. Irradiation has been demonstrated to change the shape of FTIR Spectra and the placement of the peaks.

The aim of the study was to experimentally verify the enhancement of certain mechanical properties of a composite material consisting of unsaturated polyester matrix reinforced with fiberglass, by incorporating specific proportions of sodium aluminosilicate (SAS) powders and talc as fillers for the fabrication of large wind turbine blades. Samples composed of these materials, with varying combinations of the added components, underwent testing for tensile and bending strength, and experiments were conducted to determine their modulus of elasticity. The findings indicate that the inclusion of SAS in the matrix material resulted in increased values of tensile strength and modulus of elasticity up to certain proportions. Solely adding talc to the matrix material led to a rise in bending strength. Increasing the talc percentage in the matrix material reinforced with 20% fiberglass resulted in decreased tensile strength and elastic modulus of the samples, while incorporating a blend of SAS and talc into the matrix material reinforced with 20% fiberglass significantly boosted the elastic modulus and tensile strength of the samples under tensile conditions.