Engineering topics

Yu, Zeyang

Publications and source records attributed to Yu, Zeyang.

7 records

DOE OSTI2024

Flax fiber-reinforced fatty acid vitrimer biocomposite with enhanced chemical recyclability

Here, this study unveils a sustainable, easily recyclable biocomposite, leveraging the dynamic nature of covalently adaptive bonds in a vitrimer matrix. The fabrication involved a fatty acid-derived vitrimer as the polymer matrix and multi-layered, nonwoven flax mat as reinforcing scaffold. The incorporation of these fibers significantly improved the mechanical performance of the vitrimer matrix uniformly. The ester-based covalently adaptive network plays a crucial role in enabling exceptional fiber-matrix bonding, as well as recyclability. The vitrimer matrix dissolves in ethylene glycol through transesterification, facilitating complete material recovery and biocomposite recycling without compromising the original properties of the matrix and reinforcing fibers.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Acrylonitrile-butadiene-lignin thermoplastic rubber adhesive for enhanced metal-to-metal joining

With the growing requirement for lightweight structural materials in automotive, aerospace, and infrastructure applications, multi-material joints made with adhesive have attracted intense research interest. Commercial thermoset adhesives are one-time cures, and difficult to disassemble the bonded components for repair and recycling. Our prior work with a thermoplastic acrylonitrile-butadiene-lignin rubber (ABL) addresses this sustainability/recycling challenge, but the adhesive exhibits deficient joining strength compared to standard thermosets. Here, we modify the ABL matrix by loading particulate fillers to enhance its modulus and toughness. Further, the goal is to manufacture a cure-free thermoplastic adhesive system with a simple dispensing protocol and characteristic ductility combined with a high yield stress for improved shear strength of a bonded joint. Fumed silica (FS) and epoxidized glass spheres (EGS) were used as fillers in the ABL to promote the dispersion of lignin particles that tailored the functionalities and free energy components of the adhesive surface. With optimal loading of FS (5 wt%) and EGS (30 wt%) in the ABL adhesive matrix, the lap-shear strength of the bonded aluminum joint was elevated by 128%, compared to the neat ABL, reaching 21 MPa, which is 90% of the performance of a commercial epoxy-based adhesive.

36 MATERIALS SCIENCE↗

DOE OSTI2023

A renewable lignin-based thermoplastic adhesive for steel joining

Adhesive bonding of metals has become increasingly relevant in recent years due to the demand for reducing weight and improving performance in structural applications such as automobiles and aerospace. We developed renewable thermoplastic adhesives from technical organosolv lignin isolated from hardwood biomass and acrylonitrile butadiene co-polymer rubber (NBR) for joining steel substrates. NBR33, NBR41 and NBR51 with acrylonitrile molar ratios of 33, 41 and 51%, respectively, were blended with lignin to form two-phase thermoplastic adhesives, and their adhesion, viscoelastic and surface properties were measured. Lignin content in the compositions were varied, ranging from 40% to 80% (w/w), to alter toughness, stiffness, and surface energy characteristics of the material. Better interaction or reactivity between the lignin and NBR phases was observed with greater nitrile content in NBR, leading to greater modulus and stiffness of the adhesive. Simultaneously, increasing the proportion of lignin reduced toughness and improved stiffness, with the highest adhesive strength of 13.1 MPa measured in a 60% lignin loading ratio with NBR51. Surface energy measurements revealed that total surface energy (sum of polar and dispersive surface energy) raised with lignin loading, suggesting that both surface energy and matrix strength play a critical role in the adhesive properties of the synthesized materials. A finite element-based cohesive zone model (CZM) was developed and implemented to study the failure strength of the adhesively bonded joint. Here, this study demonstrates the viability of lignin as a valuable building block for adhesives, not only due to its inherent chemical structure and rigidity, but also for its surface energy characteristics.

36 MATERIALS SCIENCE↗

DOE OSTI2023

A Versatile Fiber Coating Process for Efficient Fabrication of Multifunctional Composites

The objective of this research is to demonstrate the versatility of a dip coating process for the efficient integration of piezoelectric barium titanate (BaTiO3) microparticles on a wide variety of fibers to design passive self-sensing composites. The microparticles were deposited on glass, aramid, and basalt fiber weaves through the proposed dip coating technique. A computational framework is established to predict the deposition thickness on the fiber surfaces from the given microparticle concentration, size, coating velocity, and coating fluid viscosity. The deposition quality assessment was performed through scanning electron microscope imaging and subsequent image analysis. BaTiO3-coated fibers were directly used in composite preparation. After fabrication, the BaTiO3-enhanced composites were subjected to high-voltage poling. Finally, their passive self-sensing properties were characterized through experimental studies. The results show the adaptability of the proposed coating process to integrate BaTiO3 microparticles within different types of fiber-reinforced composites enabling passive self-sensing to attain subsurface damage characterization.

Gupta, Sumit↗

DOE OSTI2022

Multilayer Chitin–Chitosan–Cellulose Barrier Coatings on Poly(ethylene terephthalate)

Currently, effective barrier properties over a wide range of humidity are achieved by layering multiple plastics, resulting in structures that are nearly impossible to recycle through current systems. There is strong interest in developing barriers that are recyclable, biodegradable, or compostable. Chitin and cellulose nanomaterials are promising alternatives because of their high crystallinity, renewable sourcing, strong electrostatic interactions, and potential for biodegradation or composting. In this paper, we explore the potential to create multilayer materials with effective oxygen and water vapor barrier properties at elevated humidity by combining recyclable poly(ethylene terephthalate) (PET) films with single-layer and bilayer coatings of chitin nanowhiskers (ChNWs), chitosan (CS), and cellulose nanocrystals (CNCs). The addition of CS to the ChNW suspension improved the gas barrier properties of ChNW coatings, likely by filling voids, and short ChNWs (SChNW, 114 nm) performed better than long ChNWs (LChNW, 230 nm). At the optimal mass ratio of 1:1 SChNW/CS, the oxygen permeability (OP) of SChNW/CS-coated PET films was 5.1 cm 3 μm m –2 day –1 kPa –1 versus 15.9 cm 3 μm m –2 day –1 kPa –1 for neat PET. To take advantage of electrostatic attraction and hydrogen bonding, CNC was first coated on the PET, followed by coating with ChNW/CS, resulting in an OP as low as 3.6 cm 3 μm m –2 day –1 kPa –1 at 50% relative humidity (RH), and 6.4 cm 3 μm m –2 day –1 kPa –1 at 80% RH. Furthermore, after thermal treatment (120 °C, 2.5 h), the OP dropped to 2.2 cm 3 μm m –2 day –1 kPa –1 (50% RH) and 4.8 cm 3 μm m –2 day –1 kPa –1 (80% RH). The ChNW/CS and CNC coating can be efficiently removed with alkali treatment enabling possible recycling of the coated PET films.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2022

Significant slowdown of plasma-optimized surface energy deactivation by vacuum sealing for efficient adhesive bonding

This work proposes an approach to minimize surface energy deactivation of plasma-treated metal and carbon fiber-reinforced polymer (CFRP) surfaces by vacuum sealing. Plasma treatments enhance adhesive wettability on post-treated surfaces for adhesive joints, but the treated surfaces deactivate quickly in air. The surface energy of aluminum alloy AA6061 and carbon fiber-reinforced polymer-polyamide (CFRP-PA66) optimally treated by a blown air plasma instrument returns to the original surface energy within one hour. Vacuum sealing of AA6061 and CFRP-PA66 reduced the surface energy deactivation over 7 days by at least 230 times and 970 times compared to in air. Double Cantilever Beam (DCB) tests performed on adhesively-bonded AA6061/CFRP-PA66 joints showed that the total energy release and energy dissipation before failure of plasma-treated and vacuum-sealed materials was up to 60% more than plasma-treated materials without vacuum sealing and up to 125% more than non-plasma-treated materials.

42 ENGINEERING↗

DOE OSTI2020

Chitin- and cellulose-based sustainable barrier materials: a review

Abstract The accumulation of synthetic plastics used in packaging applications in landfills and the environment is a serious problem. This challenge is driving research efforts to develop biodegradable, compostable, or recyclable barrier materials derived from renewable sources. Cellulose, chitin/chitosan, and their combinations are versatile biobased packaging materials because of their diverse biological properties (biocompatibility, biodegradability, antimicrobial properties, antioxidant activity, non-toxicity, and less immunogenic compared to protein), superior physical properties (high surface area, good barrier properties, and mechanical properties), and they can be assembled into different forms and shapes (powders, fibers, films, beads, sponges, gels, and solutions). They can be either assembled into packaging films or used as fillers to improve the properties of other biobased polymers. Methods such as preparation of composites, multilayer coating, and alignment control are used to further improve their barrier, mechanical properties, and ameliorate their moisture sensitivity. With the growing application of cellulose and chitin-based packaging materials, their biodegradability and recyclability are also discussed in this review paper. The future trends of these biobased materials in packaging applications and the possibility of gradually replacing petroleum-based plastics are analyzed in the “Conclusions” section.

36 MATERIALS SCIENCE↗