Journal of Composites Science

The 4D printing of thermo-responsive shape-memory multicomponent polymer composites, which possess the ability to change shape by exposure to heat, has attracted much attention in recent years because of their scientific and technological significance. In the present study, we investigate shape memory performance of a polylactic acid-polycaprolactone-graphene nanocomposite activated directly by increasing the environmental temperature and indirectly, by Joule heating. The incorporation of graphene within the shape-memory biopolymer blend allowed formation of a programmable conduction path, whose electric properties are intimately coupled to thermo-mechanical processes. Advanced rheological, thermal, and thermo-mechanical properties were evaluated and related to the structure of nanocomposite. The electrically and thermally stimulated shape memory and self-healing behavior of the nanocomposite based on polycaprolactone/poly(lactic) acid blend reinforced with graphene nanoplatelets (PCL/PLA/GNP) were investigated. The shape memory tests revealed a good reversibility of 76% between the temporary and permanent states of the samples bent to 180 degrees and a high healing efficiency of 96% if stimulated by Joule heating. The highly electroactive nanocomposite demonstrated a great potential for 4D-printing of objects with complex structures, shapes, and electrically-stimulated shape-memory and self-healing functions. The nanocomposite is biodegradable, recyclable, and reusable, which may reduce the carbon footprint of the rapidly developing additive technology.

Ultra-high-performance concrete exhibits excellent mechanical performance but relies on a high binder content, resulting in substantial carbon emissions. This study investigates sustainable ultra-high-performance concrete incorporating sewage sludge ash, aiming to balance mechanical performance, environmental safety, and life-cycle impacts within an integrated material system. High volumes of sewage sludge ash were incorporated into ultra-high-performance concrete under autoclave curing, with mixture proportions designed based on particle packing theory. Fresh properties, mechanical performance, shrinkage behavior, microstructural characteristics, heavy-metal leaching, as well as life-cycle environmental and economic impacts were systematically evaluated. The incorporation of porous sewage sludge ash modified the pore structure of ultra-high-performance concrete, thereby enabling a substantial reduction in cement content. At a sewage sludge ash replacement level of 60%, life-cycle assessment results indicate a 42.7% reduction in carbon emissions while maintaining a compressive strength of approximately 147 MPa under autoclave curing, remaining within a practically viable range for ultra-high-performance concrete. This confirms that sewage sludge ash can be safely incorporated into ultra-high-performance concrete, delivering a favorable sustainability–performance trade-off alongside significant environmental and economic benefits.

Biochar is a porous material which can be produced by biomass waste pyrolysis and modified using metal oxide to improve its adsorption performance. Activated biochar (AB) was synthesized from patchouli biomass waste to study the effect of calcination tempera-ture on its potency as a drug pollutant adsorbent. Research processes included the bio-mass pyrolysis with CoCl₂ activator, AB impregnation with FeCl₃, FeCl₃/AB calcination at various temperatures, product characterizations (X-ray diffraction, FTIR spectrometry), and paracetamol adsorption test at various concentrations. The paracetamol concentra-tions were analyzed using UV–Vis spectrophotometry. The adsorption data was treated using Langmuir, Freundlich, and Dubinin–Radushkevich (DR) models. The diffracto-grams indicated the α-Fe₂O₃, γ-Fe₂O₃, FeFe₂O₄, and carbon turbostratic structures. The Fe_xO_y crystallinity increased by increasing temperature. The FTIR spectra significantly indicated the functional group changing at 600 °C. In the adsorption test, the Fe_xO_y/AB-800 compo-site gave the highest adsorption capacity of 53.087 mg/g (Langmuir) with a correlation co-efficient of 0.964 (very high correlation), and the physical adsorption mechanism based on adsorption energy of 530.330 J/mol (DR) and 1/n value of 0.62 (Freundlich) provided the favorable adsorption based on both the RL of 0.457 (Langmuir) and the n constant of 1.579 (Freundlich). Thus, the Fe_xO_y/AB-800 composite has potential as an adsorbent of organic pollutants such as paracetamol.