This research explores the potential and significance of 3D printing natural fiber composite (NFC) materials. The primary objective is to investigate the mechanical, thermal, and environmental properties of NFC filaments, mainly focusing on biodegradable, renewable fibers such as jute, hemp, flax, and kenaf. In addition to studying the properties of NFCs, our research delves into the challenges associated with processing, including moisture absorption and fiber-matrix interfacial bonding. The novelty of this work lies in the convergence of traditional composite materials with the versatility of 3D printing technology. NFC filaments offer unique advantages in terms of sustainability, and we examine their potential contributions to the circular economy. By using eco-friendly NFC materials in 3D printing, we aim to present a viable, environmentally responsible alternative to conventional synthetic composites. The importance of 3D printing NFCs stems from the ways their use can align with sustainability goals. These materials provide the advantages of renewability, reduced carbon impact, and in some cases, biodegradability. Their applications extend to various industries, such as automotive, construction, and packaging, where eco-friendly materials are increasingly sought. Such applications showcase the ways in which NFC-based 3D printing can contribute to a more environmentally responsible and sustainable future. This research explores the mechanical, thermal, and environmental properties of NFC materials, highlighting their unique advantages for 3D printing and the potential to have eco-friendly applications in diverse industries.

The phenomenon of ferrofluid-water mixing is investigated using a double-layer magnetic micromixer, in which a layer of micromagnet bars is placed immediately below the fluid layer. A wavy pattern of the ferrofluid–water interface is surprisingly observed at each micromagnet responsible for improved mixing. The mechanism causing the wavy mixing is discovered and analyzed through experimental measurements and numerical simulations, and the mixing efficiency under different flow conditions is discussed. For flows with Re $\ll$ 1, the resultant steep gradient of opposing magnetic forces by micromagnets in the ferrofluid region gives rise to a local pressure source that induces a transverse/spanwise pressure gradient and activates momentum transfer between fluids. The current finding enables effective localized mixing of ferrofluids with a small footprint and, thus, has great potential to achieve fast mixing for high-throughput flows with an integrated parallel system of multiple microfluidic channels and micromagnets.

This article explores using biomass, namely rice husks, as a reinforcement material in thermoplastic copolyester (TPC) composites. Rice husks were subjected to three chemical pretreatments: single-stage sulfuric acid hydrolysis, first-stage sulfuric acid hydrolysis followed by a second-stage methanesulfonic acid (MSA) treatment, and first-stage sulfuric acid hydrolysis followed by a second-stage sodium hydroxide alkali treatment. We studied the effects of these treatments on the rheological, thermal, interfacial, and mechanical properties of composites. The fibers were mixed with polymers at high shear rates and temperatures, and 3D-printed filaments were produced using a desktop 3D printer. The printed parts were analyzed using tensile tests, torque and viscosity measurements, and thermogravimetric analysis to obtain their mechanical, rheological, and thermal properties. SEM imaging was performed to understand the fiber–polymer interface and how it affects the other properties. The results showed that first-stage sulfuric acid hydrolysis followed by a second-stage pretreatment of the fibers with MSA showed better fiber–polymer adhesion and a 20.4% increase in stress at 5% strain, a 30% increase in stress at 50% strain, and a 22.6% increase in the elastic modulus as compared to untreated rice husk composites. These findings indicate that readily available and inexpensive rice husks have significant potential for use in natural fiber-reinforced composites when pretreated using dilute sulfuric acid followed by methane sulfonic acid hydrolysis.

Concrete was prevailed in construction since ancient times. Over the years, numerous developments have been carried out to upgrade the concrete. One such development is Concrete that self-compacts and binds to itself is known as Self Compacting Concrete (SCC) and is used in areas where reinforcements are crowded and conventional compaction is difficult. However, the increased use of cement has led to a significant amount of CO2 emissions into the atmosphere. The cement manufacturing industry alone accounts for 5%-7% of global CO2 emissions. To reduce these emissions, pozzolanic materials can replace cement in concrete. By employing fly ash (FA) in SCC is common because it enhances the ability to flow. To further reduce the carbon footprint from cement production, High-Volume Fly Ash Self Compacting Concrete (HVFA SCC) uses more than 30% FA in place of cement. This increases the durability of concrete by reducing chloride penetration but reduces compressive strength. The addition of FA increases the rheology too. The work aims in understanding the rheological and hardened state behaviour of HVFA SCC and comparing the cost of construction of HVFA SCC with Normal concrete.