The preparation of high-filled composites by combining inorganic fillers (such as quartz sand and CaCO3) with resins has garnered significant attention for its ability to effectively reduce composite material costs. Adjusting the ratio of inorganic fillers represents an effective approach to enhancing the properties of high-filled composites. This study incorporated quartz sand fillers of varying grades into unsaturated polyester resin (UPR) to create composites with elevated filler content. The mechanical properties, degree of cure, component distribution, and phase structure of the blends were analyzed using three-point bending tests, compression tests, dynamic thermal analysis, and scanning electron microscopy. The study shows that optimizing the gradation of quartz sand can notably improve the strength of composite materials. The refined composite material structure exhibits increased compactness, leading to a 37.56 % enhancement in bending strength and a 27.53 % rise in average compressive strength. Optimizing the filler gradation improved the UPR conversion rate of the composite material, thereby enhancing its curing degree. Gradation optimization reduced interface defects between the filler and UPR, resulting in a structurally compact and uniformly distributed composite. This study proposes a novel method for preparing composites by integrating the close-packed theory with high-filled composites.
Films and coatings enhance quality and shelf life for packaging applications. In this study, we investigate the effect of different celluloses on poly (vinyl alcohol)-based composite film. Toward this, cellulose is extracted from corncob (using the kraft pulp process), and also commercially available cellulose is used to synthesize the composite films. The films were characterized using field emission scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, UV spectroscopy, water vapor permeability, moisture content, swelling index, and rheological techniques. The results demonstrate that adding extracted cellulose and commercial cellulose to the PVA film-forming solution enhanced tensile strength and decreased its elongation at break upon drying. The optimized results show that there is an increment of 192.4 % in the tensile strength (up to 53.52 MPa) compared to the neat PVA film. The commercial cellulose exhibits better crystallinity than the extracted cellulose in the XRD test. Also, rheological experiments were carried out to understand the film-forming solutions' viscoelasticity as a function of temperature. The sol-gel transition shows that the extracted cellulose exhibits higher shear modulus and low gelation temperature compared to the other.
Abstract Multilayer plastic packaging is difficult to recycle because of its complex composition. Asphalt mixtures tolerate heterogeneous inputs, offering a practical valorization route. This study evaluates polypropylene-based multilayer plastic waste as a bitumen modifier for polymer modified bitumen (PMB). Mixtures containing 0, 3, 4, and 5 wt% plastic were assessed by the Marshall method. Plastic content significantly affected all seven Marshall parameters (two-way ANOVA, p < 0.001), most strongly Marshall Quotient ( η 2 = 0.76) and flow ( η 2 = 0.54). Tukey HSD contrasts showed the 4 and 5 wt% mixtures differed from the unmodified control while 3 wt% did not, placing the effective threshold between 3 and 4 wt%. Flow and volumetric properties (VMA, VIM, VFB) remained within Bina Marga 2018 limits throughout. Optimum asphalt content decreased stepwise from 5.93 wt% (unmodified) to 5.90, 5.83, and 5.70 wt% at 3, 4, and 5 wt% PMB – a 0.23 wt% reduction at equivalent specification compliance. The 5 wt% mixture combined full compliance with the highest stability (1,619 ± 67 kg) and lowest binder demand. Polypropylene-based multilayer waste is, therefore, viable as an asphalt modifier at mix-design level; durability and binder-level characterization remain necessary before field application.
Abstract Carbon fiber–reinforced composites (CFRP) are widely used in the aerospace industry due to their excellent properties. The quality of drilling in CFRP components has a significant impact on their structural integrity and in-service performance. Tool wear is a key factor determining drilling quality. To achieve data-driven process control, this study developed an integrated signal acquisition platform capable of simultaneously capturing acoustic emission (AE) and axial force signals during the drilling of CFRP. Under controlled and repeatable drilling conditions, acoustic emission and axial force signals were systematically recorded at each stage. A five-layer decomposition thresholding method based on the db4 wavelet was applied to the acoustic emission signals. This method effectively suppresses broadband noise while preserving the transient impact characteristics associated with the progressive degradation of the cutting edge. By analyzing acoustic emission signals and axial force in the time and frequency domains, among other methods, characteristic parameters highly correlated with the tool’s wear state were identified based on the Passion correlation coefficient. Finally, a classification method based on a convolutional neural network (CNN) under batch processing conditions was proposed to enable effective identification of tool wear under various operating conditions. This lightweight convolutional neural network achieved 94.44 % identification accuracy for tool wear, demonstrating strong potential for engineering applications.
Solar-driven simultaneous clean water production and organic pollutant photodegradation represent an effective strategy for sustainable treatment of organic wastewater. Here, we design a hybrid hydrogel composed of natural down fiber (DF) and Cu co-doped TiO2 (DF-Cu@TiO2) combined with DF-derived carbon (DFC) within a chitosan-polyvinyl alcohol matrix. The resulting DF-Cu@TiO2/DFC hybrid hydrogel achieves exceptional light absorption, sufficient water supply, and visible light-driven catalytic activity. Consequently, under one-sun illumination, the hydrogel demonstrated an evaporation rate of 1.87 kg m-2 h-1 and achieved a concurrent methyl orange (MO) degradation efficiency of 93.50 % within 5 h. Furthermore, the hydrogel exhibited self-floating capability, maintaining buoyancy continuously for over 7 days. Actual outdoor experiments yielded an evaporation rate of 1.21 kg m-2 h-1 at 12:00 p.m. and a simultaneous MO degradation efficiency of 95.71 % over a 10-h operational period (8:00 a.m.-6:00 p.m.). These findings provide valuable insights for designing multifunctional, self-floating evaporators for advanced wastewater treatment applications, particularly for wastewater containing harmful organic contaminants.
