Engineering Commons^™

Functionalized Thermoplastic Polyurethane Nanofibers: An Innovative Triboelectric Energy Generator, Julia I. Salas, Diego De Leon, Sk Shamim Hasan Abir, Mohammed Jasim Uddin, Karen Lozano

Mechanical Engineering Faculty Publications and Presentations

A triboelectric nanogenerator (TENG) is one of the most significantly innovative microdevices for built-in energy harvesting with wearable and portable electronics. In this study, the forcespinning technology was used to synthesize a nanofiber (NF) mat-based TENG. Polyvinylidene fluoride (PVDF) membrane was used as the negative triboelectric electrode/pole, and chemically designed and functionalized thermoplastic polyurethane (TPU) was used as the positive electrode/pole for the TENG. The electronic interference, sensitivity, and gate voltage of the synthesized microdevices were investigated using chemically modified bridging of multi-walled carbon nanotubes (MWCNT) with a TPU polymer repeating unit and bare TPU-based positive electrodes. The chemical functionality …

Development Of Zinc Oxide/Hydroxyapatite/Poly(D,L-Lactic Acid) Fibrous Scaffold For Tissue Engineering Applications, Victoria Padilla-Gainza, Heriberto Rodríguez-Tobías, Graciela Morales, Antonio Ledezma-Pérez, Carmen Alvarado-Canché, Raúl Loera-Valencia, Cristóbal Rodríguez, Robert Gilkerson, Carlos Trevino De Leo, Karen Lozano

Mechanical Engineering Faculty Publications and Presentations

Scaffolds based on polymeric fibers represent an engaging biomedical device due to their particular morphology and similarity with extracellular matrices. The biggest challenge to use fibrous materials in the biomedical field is related to their favorable platform for the adhesion of pathogenic microorganisms. Therefore, their optimum performance not only depends on their bioactive potential but also on their antimicrobial properties. The aim of this work was the design of antimicrobial (zinc oxide, ZnO) and bioactive (hydroxyapatite, Hap) fibrous materials using poly(D, L-lactic acid) (PDLLA) as the polymer fiber substrate. Fiber based composite scaffolds were developed using the Forcespinning® technique. For …

Efficient Near Infrared To Visible Light Upconversion From Er/Yb Codoped Pvdf Fibrous Mats Synthesized Using A Direct Polymer Doping Technique, Saptasree Bose, Jack Ryan Summers, Bhupendra B. Srivastava, Victoria Padilla-Gainza, Manuel Peredo, Carlos Trevino De Leon, Bryan Hoke, Santosh K. Gupta, Karen Lozano

Mechanical Engineering Faculty Publications and Presentations

Highlights

• Direct Rare Earth doping in PVDF Polymer to overcome powder limitation.

• PVDF Fiber with smooth and defect free texture designed by Forcespinning.

• Doping Enhances Beta fraction of PVDF without affecting thermal Stability.

• Efficient upconversion of NIR into visible light in PVDF:Yb3+,Er3+ fibrous mats.

• Two-Photon absorption for both green and red upconversions.

Abstract

Upconverting-materials are capable of converting near infra-red (NIR) excitation into lower wavelengths. These materials could have a myriad of promising potential applications. However, in some areas, its use has been hindered by its low upconversion luminescence (UCL) efficiency and processing/handling disadvantages from luminescent materials in powder form. …

Piezoelectric Properties Of Pvdf-Zn2geo4 Fine Fiber Mats, Fariha Rubaiya, Swati Mohan, Bhupendra B. Srivastava, Horacio Vasquez, Karen Lozano

Mechanical Engineering Faculty Publications and Presentations

The current paper presents the development and characterization of polyvinylidene fluoride (PVDF)-Zn₂GeO₄ (ZGO) fine fiber mats. ZGO nanorods (NRs) were synthesized using a hydrothermal method and incorporated in a PVDF solution to produce fine fiber mats. The fiber mats were prepared by varying the concentration of ZGO NRs (1.25–10 wt %) using the Forcespinning^® method. The developed mats showed long, continuous, and homogeneous fibers, with average fiber diameters varying from 0.7 to 1 µm, depending on the ZGO concentration. X-ray diffraction spectra depicted a positive correlation among concentration of ZGO NRs and strengthening of the beta …

Processing-Structure-Property Relationships Of Biopolyester/Zinc Oxide Fibrous Scaffolds Engineered By Centrifugal Spinning, Victoria Padilla-Gainza, Heriberto Rodríguez-Tobías, Graciela Morales, Antonio Ledezma-Pérez, Carmen Alvarado-Canché, Cristobal Rodriguez, Robert Gilkerson, Karen Lozano

Mechanical Engineering Faculty Publications and Presentations

This study addresses the processing of nonwoven fibrous materials obtained by centrifugal spinning method, namely Forcespinning; a high yield and low production cost technique little explored in this field. Poly(D, L-lactic acid) (PDLLA) and poly(3-hydroxybutyrate) (PHB) were used as matrices and reinforced with zinc oxide nanoparticles (n-ZnO). The morphology, mechanical, and thermal performance of the developed composites were analyzed as well as the antibacterial effect of n-ZnO. Fibrous materials with n-ZnO concentrations of 1, 3, and 5 wt. % for PDLLA and 1 and 3 wt. % for PHB were evaluated. The results showed that the incorporation of n-ZnO produces …

Development Of Antimicrobial Chitosan Based Nanofiber Dressings For Wound Healing Applications, Lee Cremar, Jorge Gutierrez, Jennifer Martinez, Luis A. Materon, Robert Gilkerson, Fenghua Xu, Karen Lozano

Mechanical Engineering Faculty Publications and Presentations

Objective(s): Chitosan based composite fine fibers were successfully produced via a centrifugal spinning technology. This study evaluates the ability of the composites to function as scaffolds for cell growth while maintaining an antibacterial activity.

Materials and Methods: Two sets of chitosan fiber composites were prepared, one filled with anti-microbial silver nanoparticles and another one with cinnamaldeyhde. Chitosan powder was dissolved in trifluoroacetic acid and dichloromethane followed by addition of the fillers. The fiber output was optimized by configuring the polymer weight concentration (7, 8, and 9 w/w% chitosan) and applied angular velocity (6000-9000 RPM) within the spinning process.

Results: …

Fabrication Of Cellulose Fine Fiber Based Membranes Embedded With Silver Nanoparticles Via Forcespinning, Fenghua Xu, Baicheng Weng, Luis A. Materon, Anxiu Kuang, Jorge A. Trujillo, Karen Lozano

Mechanical Engineering Faculty Publications and Presentations

This study presents the successful development of cellulose fiber based membranes embedded with silver nanoparticles. These fine fiber membranes were developed utilizing the Forcespinning (FS) technique followed by alkaline hydrolysis treatment. The fiber morphology, homogeneity and yield were optimized by varying spinning parameters such as polymer concentration and angular velocity of the spinnerets. The structure, thermal and mechanical properties, and water absorption capability of the developed membranes were investigated. The cellulose acetate (CA) present in the membrane was converted to cellulose in the presence of embedded silver nanoparticles by alkaline hydrolysis. The silver nanoparticles embedded cellulose membrane exhibits outstanding water …