The development of sustainable, cost-effective, efficient water collection materials and methods for continuous freshwater production is crucial for many regions especially in arid and semiarid regions of the world. The world population growth, urbanization, depleting water resources, and global climate change have intensified this crisis. The concern is drastically increasing and therefore scientists and engineers are challenged with urgently developing viable solutions for this problem. Also, the production of different plastic wastes is increasing day-by-day, and therefore, a growing concern to the serious environmental challenges. These wastes are rarely dissolved by microorganisms, and hence, the recycling of these plastic wastes into value-added materials could be a sustainable solution to addressing environmental issues. In this work, recycled expanded polystyrene (REPS) foam with various proportions of titanium dioxide (TiO2) nanoparticles and aluminum (Al) microparticles were spun into superhydrophobic nanocomposite fibers using electrospinning technique and used for harvesting fog from the atmosphere. The fiber morphology, surface hydrophobicity, and fog harvesting capacity of the nanocomposite fibers were investigated. Test results reveal that the as-prepared nanocomposite fibers exhibit superhydrophobic characteristics with a water contact angle of 152.03° and an efficient fog harvesting capacity of 561 mg/cm2 /hr. The nanotechnology-based collection systems are unique because of the fine structures of the nanomembranes. Thus, the electrospun superhydrophobic nanocomposite fibers from REPS have various industrial applications including water collection, water filtration, tissue engineering, and composites, etc and the produced water can be used for drinking, agriculture, industrial, and other purposes.
Conventional manufacturing techniques include removing the excess materials to get the desired shapes; however, additive manufacturing include direct manufacturing of the objects using computer aided design model through adding a layer of material at a time. Strength and durability of the final products are important issues in designing 3D printed functional objects. Primary considerations of 3D printing process include some specifications of the printing process, printing orientation, materials selection and overall design (complexity, size, pore volume and shape). Infill structures are printed in selected patterns with a desired solid percentage, which is arranged using the slicing software. Percent rate and designed pattern are two key parameters for infill specimens which affect the print time, material usage, weight, strength, and decorative assets, as well. Polylactic acid (PLA) is a biodegradable and bioactive thermoplastic derived from renewable resources, such as corn starch, sugarcane, cassava and so on. In this study, five different infill shapes (e.g., solid, diamond, hexagonal, square, and triangle) of PLA were designed using CATIA program, and then 3D printed with 20, 40, 60, 80 and 100 vol.% to determine the effects of the infill shapes on the compressive strengths of the materials. The purpose of this study is to investigate the infill shapes, volumes, and orientation of infill shapes in the 3D printed specimens. Compression test results showed that infill shapes and volume percentages affect the mechanical properties of the 3D printed parts. This study indicated that mechanical properties of 3D printed materials could be maximized using the different infill shapes and volume percentages in 3D printing process.
Fiber reinforced polymer (FRP) composites provide a lot of benefits, including strength-to-weight ratio / light weight, superior mechanical properties, low maintenance, prolonged service life, as well as corrosion, fatigue and creep resistance. However, sustainability of the FRP composites have not been studied in detail in terms of long term productions in various industries, such as aerospace, wind energy, automotive and defense. Carbon fibers are relatively expensive because of the energy intensive production systems, and lack of easy production options, which forces many companies to recycle and reuse the FRP composites in the same or different manufacturing industries. This study mainly deals with two important issues, including the disposal of composite wastes generated during the manufacturing of composite parts, and the disposal of the products at the end of their useful life. It is believed that the carbon fibers in the used composites will have still high mechanical strengths to use in different composite manufacturing after its end of life. The major manufacturing costs come from the labor and raw materials, so using the recycled carbon fibers will make sustainable composite productions in other industries. This paper presents the current status and outlook of the FRP composite recycling and re-manufacturing techniques in the same or different industries. A future vision of the FRP composites will be investigated with sustainability point of views. This study will also mention about the sustainability issues in laminate and honeycomb composites, new product design and developments and potential applications in different manufacturing industries.
Adhesives are widely utilized materials in aviation, automotive, energy, defense, and marine industries. Adhesive joints are gradually supplanting mechanical fasteners because they are lightweight structures, thus making the assembly lighter and easier. They also act as a sealant to prevent a structural joint from galvanic corrosion and leakages. Adhesive bonds provide high joint strength because of the fact that the load is distributed uniformly on the joint surface, while in mechanical joints, the load is concentrated at one point, thus leading to stress at that point and in turn causing joint failures. This research concentrated on the analysis of bond strength and failure loads in adhesive joint of composite-to-composite surfaces. Different durations of plasma along with the detergent cleaning were conducted on the composite surfaces prior to the adhesive applications and curing processes. The joint strength of the composites increased about 34% when the surface was plasma treated for 12 minutes. It is concluded that the combination of different surface preparations, rather than only one type of surface treatment, provides an ideal joint quality for the composites.
Because of the superior properties, composites have been used in many industrial applications, including aerospace, wind turbines, ships, cars, fishing rods, storage tanks, swimming pool panels, and baseball bats. Each application may require different combinations of reinforcements and matrices, which make the manufacturing safety even more challenging while working on these substances. In this study, safety issues in composite manufacturing and machining were investigated in detail, and latest developments were provided for workers. The materials most frequently used in composite manufacturing, such as matrix (polyester, vinylester, phenolic, epoxies, methyl ethyl ketone peroxide, benzoil peroxide, hardeners, and solvents), and reinforcement materials (carbon, glass and Kevlar fibers, honeycomb and foams) can be highly toxic to human body. These materials can also be very toxic to the environment when dumped out uncontrollably, creating major future health and environmental concerns. Throughout the manufacturing process, workers inhale vapors of the liquid matrix, hardeners and solvents / thinners, as well as reinforcement materials (chopped fibers and particles) in airborne. Milling, cutting and machining of the composites can further increase the toxic inhalations of airborne composite particles, resulting in major rashes, irritation, skin disorders, coughing, severe eye and lung injury and other serious illnesses. The major portions of these hazardous materials can be controlled using appropriate personal protective equipment for the chemicals and materials used in composite manufacturing and machining. This study provides best possible safety practices utilized in composite manufacturing facilities for workers, engineers and other participants.
Many of the sunscreens are used during the hot summer time to protect the skin surface. However, some of ingredients in the sunscreens, such as oxybenzone, retinyl palmitate and synthetic fragrances including parabens, phthalates and synthetic musk may disrupt the cells on the skin and create harmful effects to human body. Natural oils may be considered for substitution of harmful ingredients in sunscreens. Many natural oils (e.g., macadamia oil, sesame oil, almond oil and olive oil) have UV protective property and on top of that they have natural essences. Among the natural oils, olive oil has a long history of being used as a home remedy for skincare. Olive oil is used or substituted for cleanser, moisturizer, antibacterial agent and massage reliever for muscle fatigue. It is known that sun protection factor (SPF) of olive oil is around eight. There has been relatively little scientific work performed on the effect of olive oil on the skin as sunscreen. With nanoencapsulation technique, UV light protection of the olive oil can be extended which will provide better coverage for the skin throughout the day. In the present study, natural olive oil was incorporated with DI water and surfactant (sodium dodecyl sulfate - SDS) and sonicated using probe sonicators. Sonication time, and concentrations of olive oil, DI water and surfactant were investigated in detail. The produced nanoemulsions were characterized using dynamic light scattering, and UV-Vis spectroscopy. It is believed that the nanoencupsulation of olive oil could provide better skin protection by slow releasing and deeper penetration of the nanoemulsion on skin surface. Undergraduate engineering students were involved in the project and observed all the process during the laboratory studies, as well as data collection, analysis and presentation. This experience based learning will likely enhance the students’ skills and interest in the scientific and engineering studies.
Fiber reinforcement increases many properties of the concretes, such as toughness, strength, abrasion, and resistance to corrosion. Use of recycled carbon fibers from industrial waste offers many advantages because it will reduce the waste, contribute the economy, protect natural resources and improve the property of structural units. The City of Wichita, KS is known to be “Air Capital of the World” where many aircraft companies have been producing aircraft, parts and components. Due to the superior properties of composites (e.g., light weight, low density, high impact resistance), they have been highly used by aircraft industry. Prepreg is the most preferred combination of the fiber and resin due to the easy application, but it has a limited shelf life (e.g., three months to one year at most) and scrap has no use after all in the same industry. Every year tons of un-used prepreg or after use scrap are being collected in Wichita, KS. Recycling prepreg from the post-consumer waste offers great advantages of waste reduction and resource conservation in the city. Reusing the carbon fibers obtained from outdated prepreg composites for concrete reinforcement will offer double advantages for our environment and concrete structures. In this study, recycled carbon fibers of the outdated prepreg composites were collected, and then incorporated with concretes at different ratios prior to the molding and mechanical testing. An undergraduate student was involved in the project and observed all the process during the laboratory studies, as well as data collection, analysis and presentation. We believe that experience based learning will enhance the students’ skills and interest into the scientific and engineering studies.