Student Posters 2019

Student Poster Presentations

Effect of Surface Strains in the Erichsen Cupping Test on Polyester Coatings

Fabian S. Sorce1*, Sonny Ngo2, Chris Lowe2, Ambrose C. Taylor1

1Department of Mechanical Engineering, Imperial College London, UK

2Long Term Development Laboratory, Becker Industrial Coatings Ltd, Liverpool, UK

The Erichsen cupping test has historically been used qualitatively to assess the ductility, formability and adhesion of coatings on sheet metal. However, the failure of coatings on sheet metal is known to be a strain-governed process, so a finite element model has been developed to quantity the surface strains during cupping. The predicted strains have been validated experimentally by 3D digital image correlation, and the shapes of the indentations produced have been validated by three independent methods. A master curve of maximum surface strain versus indentation depth has been generated for coated steel. Quantifying the surface strains and understanding their directional nature has allowed the radial and circumferential cracking observed to be explained. Cupping tests have been performed on thermosetting polyester-coated steel from -70 °C to 60 °C, and failure maps produced, normalised with respect to the glass transition temperature, to identify the ductile to brittle transition. A failure criterion linking the coating behaviour on steel to the free-film behaviour has been proposed to predict free-film material properties. This demonstrates that it is possible to determine key free-film material properties of coatings from industry-standard tests on coated steel, offering a quick and easy method to obtain otherwise time-consuming data.

*Presenting author

Preparation and characterization of CNT based membranes for desalination

Caleb C. C. Chang, Kyle G. Turner, Matthew Morales, Fangyou Xie, Dominique Porcincula and Shanju Zhang

Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, CA 83407

Seawater desalination and purification are critical for alleviating the stresses on clean water supply. Currently, osmosis membrane (OM) technologies are the most widely implemented in industrial seawater desalination and purification plants. However, one of the major issues is their high level of energy consumption. The use of nanotechnology to re-design OMs is an emerging technology with reduced energy consumption. In particular, single walled carbon nanotube (SWNT) based OMs have been showing great promise for seawater desalination and purification. In this study, we used liquid crystal templating methods to fabricate aligned nanotube-polymer composites as osmosis membranes for desalination. Polymerizable liquid crystalline surfactants were used to disperse and orient SWNTs. Out-of-plane alignment was realized using screen-printing technique. Photopolymerization was employed to lock the alignment. As-prepared membranes were characterized by means of optical microscopy, small-angle X-Ray scattering, Fourier transform infrared spectroscopy and scanning electron microscopy. Ion ejection and chemical separation properties were evaluated.

Synthesis and characterization of polymer-grafted cellulose nanofibrils

Dominique Porcincula, Heather B. Ehrgott, Margaret S. Kepler, and Shanju Zhang

Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, CA 83407

Nanocellulose has risen in prominence as a naturally derived additive in various coatings and packaging applications, allowing for major improvements in mechanical strength, gas and liquid barrier properties, UV protection, and corrosion and anti-microbial resistance. However, due to its highly hydrophilic nature imparted by an abundance of surface hydroxyl groups, nanocellulose is limited in its incorporation in hydrophobic coatings and polymers. To enhance the interfacial compatibility of nanocellulose in hydrophobic materials, nanocellulose can be modified through a variety of different surface-modification techniques. In this study, poly(caprolactone) and poly(lactic acid) were grafted to the surface of cellulose nanofibrils via surface-hydroxyl initiated ring-opening polymerization of cyclic esters (ε-caprolactone and L-lactide, respectively). The microstructure of the polymer-grafted nanocellulose, including molecular weight and crystallinity of grafted polymers, was determined by means of DSC, TGA, GPC, SS-NMR, and XRD. Hydrophobicity was evaluated using solubility tests and contact angle measurements. Mechanical properties of materials were determined via tensile testing and DMA. Our data demonstrates that polymer-grafted cellulose nanofibrils are promising as an efficient filler for hydrophobic polymer matrix.

Multiple Objective Optimization of Coating Resin Synthesis using Evolutionary Search

Authors: Stanley Armstrong*, Anthony Griffin, André Lagron, Madeline Schultz, William Thompson, Erik Sapper

Kenneth N. Edwards Western Coatings Technology Center, Department of Chemistry & Biochemistry, California Polytechnic State University, San Luis Obispo, CA, 93407

Abstract: Modern methods of polymer discovery often rely on arduous and iterative empirical processes, where design spaces are explored using resource-inefficient experimental enumeration. These methods are restricted by the initial boundaries of the design space, and very often result in resin materials for coating applications that are optimized within the given experimental design (every experiment has a winner!) but are sub-optimized across all possible compositional spaces (is your winner really the best possible winner?). Evolutionary programming provides a means of computationally exploring large and nearly boundaryless polymer resin design spaces, using paradigms of in silico synthesis and performance evaluation. These methods, such as genetic algorithms, create a list of possible materials that are predicted to perform in the desired manner as specified by the user. Evolutionary programs create new materials through iterative steps of material creation, mutation, and scoring. Of key importance is the design of robust and objectively accurate scoring or fitness functions, which are used to numerically assess and rank candidate materials. The creation of these functions is straightforward in single objective optimization problems, but becomes complex when multiple competing targets are sought at once. Here, we present strategies for developing multiobjective fitness functions for the autonomous discovery of high performance polymers to be used in coatings applications. These methods are able to aid in the automated discovery of new resins for coatings that have sets of well-defined properties, such as Tg, thermal decomposition temperature, refractive index, and surface free energy.

Preparation of graphene/amyloid hybrid composites

Alice Lin, Nicholas Beaver, Russell Chang, Fangyou Xie, Claire Drewery, and Shanju Zhang

Department of Chemistry and Biochemistry, California Polytechnic State University, San Luis Obispo, CA 83407

1D/2D hybrid nanocomposites show great promise for various emerging applications owning to the unique combination of different size dimensions. The hybrids exhibit new properties that are not found in either 1D or 2D nanomaterials alone. Such unique hybrid nanocomposites endorse new paradigms that are expected to overcome the fundamental limitations of functional nanomaterials. Amyloids are 1D fibrillar assemblies of proteins that are emerging building blocks for artificial functional biomaterials. Graphene is a 2D monatomic layer of sp2-hybridized carbon atoms in a honeycomb lattice and possesses the unique combination of intriguing Dirac-like electronic properties, exceptional mechanical properties, and high thermal conductivities. Amyloids are capable of adhering to graphene sheets via stacking, forming a unique laminated microstructures analogous to 1D collagen-2D apatide hybrids in bone. In this study, we prepared graphene/amyloid hybrids from graphene oxide (GO) and beta-lactoglobulin (BLG) or lysosyme (Lys). The thin films with various ratios of graphene and amyloids were fabricated using a vacuum filtration approach. Microstructures and properties of films were investigated by means of Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), four-point probe for conductivity. Some chemical separation of thin films was also explored.

Formation of Atomically-Precise Surfaces using Size-Selected Clusters

Krisztina Topeà, Marty DeWittà, Scott G. Sayresà,§

à School of Molecular Science, Arizona State University, Tempe, Arizona 85281, United States

§ Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, Arizona 85287

One primary goal of surface coating chemistry is to protect objects and materials from the environment and prevent degradation. Gas phase clusters, defined here as an aggregation of less than 50 atoms, have been a focus of fundamental experimental research due to their ability to model bulk materials and ease of production. Their remarkable chemical and physical properties, including magnetic and catalytic behavior, change with the addition or subtraction of just a single atom. Therefore, it has been proposed that clusters can be utilized as building blocks for the bottom-up assembly of new materials that could exhibit the tunable chemical and physical properties that are retained from the individual clusters. However, the industrial development of new cluster assembled materials that capitalize on these unique properties have suffered from a paucity of information related to the cluster/surface and cluster/cluster interactions and their propensity to aggregate on surfaces. Cluster-support interactions (stabilization of the clusters due to interaction with the surface or neighboring clusters) allows for improved stability making these atomically precise surfaces and coatings possible. We have fabricated high purity heterostructures by combining laser ablation of pure metals with soft-landing techniques to deposit atomically precise gas-phase aluminum clusters onto well-characterized substrates. I will describe our recent efforts in synthesis and deposition of size-selected aluminum clusters to identify the relationship between surface coverage, mobility, and size of individual target clusters with their ability to retain their unique properties when deposited. The fundamental insights gained from this work will lead to significant improvements in the fabrication of new coatings, containing tunable properties that originate from the quantum confinement in clusters.

Service Life Prediction as a Coating Resin Design Trait: Genetic Algorithms using Failure Data

Authors: Anthony Griffin*, André Lagron, Stanley Armstrong, Erik Sapper

Kenneth N. Edwards Western Coatings Technology Center, Department of Chemistry & Biochemistry, California Polytechnic State University, San Luis Obispo, CA, 93407

Abstract: Traditional material design methodologies focus on performance. While these methods are capable of producing new materials with interesting functionalities, the serviceable life of these materials is usually an afterthought. Service life prediction methodologies can be successful in estimating performance over time, but are usually exercised in the domain of the end-user, after the material design cycle is completed. Advances in applied artificial intelligence and machine learning methods are enabling a new class of material design methodologies. These approaches utilize genetic algorithms and evolutionary programming, along with principles of autonomous science, in order to automatically and efficiently design new materials that fulfill specified performance functions. However, these methods still focus on initial, optimal, or “time zero” performance, and do not incorporate knowledge of service life, outdoor exposure, or performance deterioration with time. This work proposes a new methodology, which incorporates service life prediction concepts into autonomous material design cycles. The objective is to create computer programs that can design new, functional polymeric materials that can also meet rigorous serviceable life requirements common to many industrial applications. Emphasis will be placed on how present understanding of failure modes can be translated to autonomous materials discovery algorithms currently being developed.

Synthesis of Polystyrene Magnetic Nanoparticle Composites for Magneto-Optic Applications

Tobias Kochenderfer, à Lindsey Holmenà, Dr. Nicholas Pavlopoulosà, Dr. Robert Norwood§, Dr. Jeffrey Pyunà,

 à Department of Chemistry and Biochemistry, University of Arizona, 1306 East University Boulevard, Tucson, Arizona 85721, United States

§ College of Optical Sciences, University of Arizona, Tucson, 1630 East University Blvd, Arizona 85721, United States

School of Chemical and Biological Engineering, Program of Chemical Convergence of Energy and Environment, The National Creative Research Initiative Center for Intelligent Hybrids, Seoul National University, Seoul 151-744, Korea

Magnetoencephalographic techniques rely on detecting the varied magnetic fields, induced by weak electrical current, in organs such as the brain. As these biological systems produce such weak magnetic fields, often much weaker than ambient magnetic signals, very sensitive detectors must be used. We have developed a system based on magnetic nanoparticles composed of 5 nm CoFe2O4 nanoparticles dispersed in a polystyrene matrix that offers a facile materials solution to this problem and exhibit high Verdet constants. We will discuss our recent efforts on the synthesis, processing and optical characterization of these materials.

Exploring the Limits of Additive Molar Functions for Predicting Coating Resin Properties

Authors: Madeline Schultz*, André Lagron, Anthony Griffin, Stanley Armstrong, William Thompson, Erik Sapper

Kenneth N. Edwards Western Coatings Technology Center, Department of Chemistry & Biochemistry, California Polytechnic State University, San Luis Obispo, CA, 93407

Abstract: Additive molar functions have been used for decades to predict the thermal, chemical, and physical properties of polymers used in coatings and engineering applications. An underlying assumption in the usage of these models is the linear additivity of properties based on functional group contributions, relative monomer amounts, and the absence of interaction between monomer residues along a polymer chain. These calculation methods have supported the development and theoretical understanding of simple homopolymers and copolymers, especially those comprising standard vinyl monomers and in situations where resistive thermoplastic and thermoset polymers are desired. However, modern coating development challenges necessitate a more evolved and finely-tuned class of additive molar function methods. Here, we consider the ability of additive molar functions to properly predict not only basic polymer properties of interest to a coatings formulator, but also extended or derived polymer properties such as minimum film formation temperature and phase separation during or after film formation. Consideration of calculated versus empirically observable changes in predicted properties is given. Finally, the incorporation of cheminformatics descriptors into the additive molar function workflow is explored, with an emphasis on how these computational tools may be used to explore novel coating resin design spaces.

Surfactant Effects on the Rheology of HEUR-Thickened Latex/Thickener Mixtures and Fully Formulated Paints

Juan Ortiz Salazar, Bishop Hammack, David Chisholm, Abby Cheng, and Ray Fernando

California Polytechnic State University

Chemistry and Biochemistry Department

San Luis Obispo, CA, USA

ABSTRACT

Surfactants and thickeners are important additives used in waterborne coatings to provide colloidal stability, thickening, and other functionality. The behavior of each ingredient in a coating must be understood and controlled to maintain colloidal stability and to balance other desired properties of the dry paint film. In this work, aqueous mixtures of latex, thickener, and surfactant were investigated to further the understanding of their behavior in coatings. The thickener used was a well characterized HEUR with C18 terminal hydrophobes. Two experimental latexes, a butyl acrylate/styrene and a butyl acrylate/methyl methacrylate, each containing a small amount of methacrylic acid were used. Six different surfactants, three non-ionic and three-anionic, were used. Addition of surfactants caused a shear-thickening maximum associated with bridging of latex particles by the HEUR to shift to higher shear rates; also, surfactants lowered the viscosities within the low shear region. Dynamic viscoelastic measurements shed further light into the behavior of the mixtures. The results will be explained on the basis of surfactant and latex surface polarities and the competitive adsorption between the surfactant and HEUR hydrophobes and their applicability to fully-formulated coatings will be discussed.

Renewable anticorrosion waterborne polyurethane from dimer fatty acid-based isocyanate

Cheng Zhang, Qixin Zhou
National Center for Education and Research on Corrosion and Materials Performance, Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH, 44325, USA
*Corresponding author: Qixin Zhou

As the sustainable development concept become more popular, the research and usage of bio-based coatings is growing rapidly. Bio-based coatings especially vegetable oil-based coatings are the potential alternatives to conventional petroleum-based coatings in the future. 2-heptyl-3,4-bis(9-isocyanatononyl)-1-pentylcyclohexane (DDI) is a special bio-based aliphatic diisocyanate which derived from dimer fatty acid. It exhibits excellent flexibility, low water sensitivity, outstanding water resistance, non-yellowing performance, low toxicity, and low viscosity. However, previous study indicated the DDI-based waterborne polyurethane showed inadequate mechanical properties for coatings application. In addition, the anti-corrosion property of DDI-based coating is unknown.

This work aims at improving for the final performance of the renewable DDI-based waterborne polyurethane dispersions (WPU) as well as discussing the
structure/property relationships. A series of high bio-based carbon content WPU were synthesized from dimer fatty acid diisocyanate (DDI), (3-isocyanatopropyl) triethoxysilane, dimethylolpropionic acid (DMPA), and castor oil. Nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile test, and electrochemical impedance spectroscopy (EIS) were applied to characterize the chemical structure and film properties. The effect of alkoxysilane and NCO/OH ratio on DDI-based WPU were investigated by thermal analysis, mechanical tests, and corrosion resistance measurements.

Modified cardanol as bio-based reactive diluents for alkyd coatings

Author:  Haoran Wang, Qixn Zhou

National Center for Education and Research on Corrosion and Materials Performance, Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, OH 44325, USA

Due to the need to minimize Volatile Organic Compounds (VOCs) emissions, there are great interests to develop high solid oxidizing alkyd coatings. The use of reactive diluents is one of the most preferred means of achieving high solid oxidizing alkyd coatings. Properties for a good reactive diluent include low intrinsic viscosity, good compatibility with alkyd resins, no evaporation during drying, and the ability to join in the autoxidation process.

As a byproduct of the cashew food industry, cardanol is extracted from cashew nut shell and it is annually renewable. The unsaturated alkyl phenolic structure makes cardanol an ideal precursor for the reactive diluents of oxidizing alkyd coatings.

The objective of this study is to develop new cardanol-based materials as reactive diluents to replace the organic solvents in alkyd coatings and enhance the film properties of alkyd coatings. In this study, methacrylated cardanol (MACO) and triethoxysilane-functionalized cardanol (TSCO) have been investigated as bio-based reactive diluents for formulating alkyd coatings as a substitute for volatile solvents. The synthesized reactive diluents were applied in a soybean oil-based alkyd coating and a zinc phosphate pigmented alkyd coating. The prepared coatings were thorough characterized in terms of mechanical property, viscoelastic property, corrosion resistance, and other coating properties.