Digital Commons Network^™

Reprapable Recyclebot: Open Source 3-D Printable Extruder For Converting Plastic To 3-D Printing Filament, Aubrey Woern, Joseph Mccaslin, Adam Pringle, Joshua M. Pearce

Joshua M. Pearce

In order to assist researchers explore the full potential of distributed recycling of post-consumer polymer waste, this article describes a recyclebot, which is a waste plastic extruder capable of making commercial quality 3-D printing filament. The device design takes advantage of both the open source hardware methodology and the paradigm developed by the open source self-replicating rapid prototyper (RepRap) 3-D printer community. Specifically, this paper describes the design, fabrication and operation of a RepRapable Recyclebot, which refers to the Recyclebot’s ability to provide the filament needed to largely replicate the parts for the Recyclebot on any type of RepRap 3-D …

Gnygrens18.Pdf, Garrett Nygren

Garrett Nygren

Measurement Of The Temperature Dependence Of Radiation Induced Conductivity In Polymeric Dielectrics, Jodie Corbridge Gillespie

Jodie Corbridge Gillespie

This study measures Radiation Induced Conductivity (RIC) in five insulating polymeric materials over temperatures ranging from ~110 K to ~350 K: polyimide (PI or Kapton HNTM and Kapton ETM), polytetraflouroethylene (PTFE or TeflonTM), ethylene-tetraflouroethylene (ETFE or TefzelTM), and Low Density Polyethylene (LDPE). RIC occurs when incident ionizing radiation deposits energy and excites electrons into the conduction band of insulators. Conductivity was measured when a voltage was applied across vacuum-baked, thin film polymer samples in a parallel plate geometry. RIC was calculated as the difference in sample conductivity under no incident radiation and under an incident ~4 MeV electron beam at …

Distributed Recycling Waste Polymer Into Reprap Feedstock, Christopher Baechler, Matthew Devuono, Joshua M. Pearce

Joshua M. Pearce

Purpose – A low-cost, open source, self-replicating rapid prototyper (RepRap) has been developed, which greatly expands the potential user base of rapid prototypers. The operating cost of the RepRap can be further reduced using waste polymers as feedstock. Centralized recycling of polymers is often uneconomic and energy intensive due to transportation embodied energy. The purpose of this paper is to provide a proof of concept for high-value recycling of waste polymers at distributed creation sites.

Design/methodology/approach – Previous designs of waste plastic extruders (also known as RecycleBots) were evaluated using a weighted evaluation matrix. An updated design was completed and …

Polymer Recycling Codes For Distributed Manufacturing With 3-D Printers, Emily J. Hunt, Chenlong Zhang, Nicholas C. Anzalone, Joshua M. Pearce

Joshua M. Pearce

With the aggressive cost reductions for 3-D printing made available by the open-source self-replicating rapid prototypers (RepRaps) the economic advantage of custom distributed manufacturing has become substantial. In addition, the number of free designs is growing exponentially and the development and commercialization of the recyclebot (plastic extruders that fabricate 3-D printing filament from recycled or virgin materials) have greatly improved the material selection available for prosumer 3-D printer operators. These trends indicate that more individuals will manufacturer their own polymer products, however, there is a risk that an even larger fraction of polymer waste will not be recycled because it …

A Label-Free High Throughput Resistive-Pulse Sensor For Simultaneous Differentiation And Measurement Of Multiple Particle-Laden Analytes, Ashish Jagtiani, Rupesh Sawant, Jiang Zhe

Dr. Jiang Zhe

We describe an all-electronic, label-free, resistive-pulse sensor that utilizes multiple microchannels for parallel detection, counting and differentiation of multiple biological particles simultaneously. Four particle solutions, including 20 µm and 40 µm polymethacrylate particles, Juniper Scopulorum (Rocky Mountain Juniper) pollen and Populus deltidoes (Eastern Cottonwood) pollen, were loaded to the four peripheral reservoirs, respectively, and were driven to the central reservoir through four microchannels, all operating simultaneously for particle detection and counting. Experiments demonstrated that this sensor was able to differentiate and count multiple particle solutions simultaneously through its four microchannels fabricated on polymer membranes. Thus the sensing throughput has been …

Soft Microgripping Using Ionic Liquid Droplet For High Temperature And Vacuum Applications, Abdullah Amin, Ashish Jagtiani, Abhay Vasudev, Jun Hu, Jiang Zhe

Dr. Jiang Zhe

Aqueous droplet-based micro-gripper has been used for micro-assembly. However they cannot be used for high temperature and vacuum applications. Ionic liquids, organic salts that have a lower melting point temperature, appear suitable for droplet-based micro-gripping application in high temperature and vacuum environments because of their nonvolatility and thermal stability. In this paper, we demonstrated the use of ionic liquid as the operating liquid for micro-gripping applications in high temperatures (up to 110 °C) and vacuum (up to 24 inch Hg) environments. Electrowetting was utilized to dynamically change the contact angle of a 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) liquid bridge to control the …

Design, Fabrication, And Properties Of 2-2 Connectivity Cement/Polymer Based Piezoelectric Composites With Varied Piezoelectric Phase Distribution, Xu Dongyu, Cheng Xin, Sourav Banerjee, Huang Shifeng

Sourav Banerjee

The laminated 2-2 connectivity cement/polymer based piezoelectric composites with variedpiezoelectric phase distribution were fabricated by employing Lead Zirconium Titanate ceramicas active phase, and mixture of cement powder, epoxy resin, and hardener as matrix phase with a mass proportion of 4:4:1. The dielectric, piezoelectric, and electromechanical coupling properties of the composites were studied. The composites with large total volume fraction ofpiezoelectric phase have large piezoelectric strain constant and relative permittivity, and thepiezoelectric and dielectric properties of the composites are independent of the dimensional variations of the piezoelectric ceramic layer. The composites with small total volume fraction of piezoelectric phase have large …

Swelling Characteristics Of Acrylic Acid Polyelectrolyte Hydrogel In A Dc Electric Field, Esmaiel Jabbari, Javad Tavakoli, Alireza Sarvestani

Esmaiel Jabbari

No abstract provided.

Implantable Polymer/Metal Thin Film Structures For The Localized Treatment Of Cancer By Joule Heating, Nima Rahbar, Kwabena Kan-Dapaah, Christian Theriault, Wole Soboyejo

Nima Rahbar

This paper presents an implantable polymer/metal alloy thin film structure for localized post-operative treatment of breast cancer. A combination of experiments and models is used to study the temperature changes due to Joule heating by patterned metallic thin films embedded in poly-dimethylsiloxane. The heat conduction within the device and the surrounding normal/cancerous breast tissue is modeled with three-dimensional finite element method (FEM). The FEM simulations are used to explore the potential effects of device geometry and Joule heating on the temperature distribution and lesion (thermal dose). The FEM model is validated using a gel model that mimics biological media. The …

Polymer Based Nanocomposites With Nanofibers And Exfoliated Clay, Michael Meador, Darrell Reneker

Darrell Hyson Reneker

Polymer solutions, containing clay sheets, were electrospun into nanofibers and microfibers that contained clay sheets inside. Controllable removal of polymer by plasma etching from the surface of fibers revealed the arrangement of clay. The shape, flexibility, size distribution and arrangement of clay sheets were observed by transmission and scanning electron microscopy. The clay sheets were partially aligned in big fibers with normal direction of clay sheets perpendicular to fiber axis. Crumpling of clay sheets inside fibers was observed when the fiber diameter was comparable to the lateral size of clay sheets. Single sheets of clay were observed both by catching …

Spectroscopic Investigation Into Oxidative Degradation Of Silica-Supported Amine Sorbents For Co2 Capture, Chakravartula Srikanth, Steven Chuang

Steven S.C. Chuang

Oxidative degradation characteristics of silica-supported amine sorbents with varying amounts of tetraethylenepentamine (TEPA) and polyethylene glycol (PEG; P200 or P600 represents PEG with molecular weights of 200 or 600) have been studied by IR and NMR spectroscopy. Thermal treatment of the sorbents and liquid TEPA at 100 °C for 12 h changed their color from white to yellow. The CO2 capture capacity of the TEPA/SiO2 sorbents (i.e., SiO2-supported TEPA with a TEPA/SiO2 ratio of 25:75) decreased by more than 60 %. IR and NMR spectroscopy studies showed that the yellow color of the degraded sorbents resulted from the formation of …

Application Of The Thermal Flash Technique For Low Thermal Diffusivity Micro/Nanofibers, Michael T. Demko, Zhenting Dai, Han Yan, William P. King, Miko Cakmak, Alexis R. Abramson

Mukerrem Cakmak

The thermal flash method was developed to characterize the thermal diffusivity of micro/nanofibers without concern for thermal contact resistance, which is commonly a barrier to accurate thermal measurement of these materials. Within a scanning electron microscope, a micromanipulator supplies instantaneous heating to the micro/nanofiber, and the resulting transient thermal response is detected at a microfabricated silicon sensor. These data are used to determine thermal diffusivity. Glass fibers of diameter 15 mu m had a measured diffusivity of 1.21x10(-7) m(2)/s; polyimide fibers of diameters 570 and 271 nm exhibited diffusivities of 5.97x10(-8) and 6.28x10(-8) m(2)/s, respectively, which compare favorably with bulk …

Surface And Biomolecular Forces Of Conducting Polymers, Michael J. Higgins, Gordon G. Wallace

Gordon Wallace

In this review, we provide insight into the surface forces of conducting polymers, a class of intelligent materials that offer unique strategies for controlling biomolecular interactions in wide-ranging biomedical applications. Critical to the success of these applications is that the polymer interface is exposed to biological fluids whose interactions are controlled through the polymer surface chemistry and electrochemical switching of the surface properties. There is, however, little known about the intermolecular and surface forces that govern these interactions. Therefore, the purpose of this review is to more closely examine the forces that mediate interactions with biological entities, including forces such …

Microstructures Of Conducting Polymers: Patterning And Actuation Study, Babita Gaihre, Bo Weng, Syed A. Ashraf, Geoffrey M. Spinks, Peter C. Innis, Gordon G. Wallace

Gordon Wallace

The conducting polymers exhibit electrochemically driven expansion and shrinkage due to ingress and egress of dopant ions in response to potential applied. In this paper, we report on patterning of microdots and microsquares of polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,3-dihexyl-3-4-dihydro-2H-thieno[3,4b][1,4]-dioxepine PProDOT(Hx) 2 and their behaviour under voltage change. Stainless steel mesh was used to deposit microdots and inkjet-printed cellulose girds were used to deposit microsqures of the conducting polymers on the ITO surface. It was found that PPy showed distinct actuation in the z direction while colour change was prominent in the case of PEDOT and PProDOT(Hx)2.

Colour Tunable Electrochromic Devices Based On Pprodot-(Hx)2 And Pprodot-(Ethx)2 Polymers, Bo Weng, Syed Ashraf, Peter C. Innis, Gordon G. Wallace

Gordon Wallace

The most commonly used method to tune the colour transition states of an ECD is to modify the chemical structure of the electrochromic polymers to achieve the desired transparent to dark state switching colours. However, this approach can present significant synthetic challenges that typically result in a compromise in device performance parameters such as contrast range or stability as well as solvent processability. In this study we have investigated tuning the dark-state colour of an ECD (at +0.8 V) by solution mixing poly(3,3-dihexyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine) (PProDOT-(Hx)2), which has an excellent contrast performance but with an esthetically undesirable purple colour transition, with poly(3,3-bis(2-ethylhexyl)-3,4-dihydro-2H-thieno …

Optical Switching Of Protein Interactions On Photosensitive-Electroactive Polymers Measured By Atomic Force Microscopy, Amy Gelmi, Michele Zanoni, Michael J. Higgins, Sanjeev Gambhir, David L. Officer, Dermot Diamond, Gordon G. Wallace

Gordon Wallace

The ability to switch the physico-chemical properties of conducting polymers opens up new possibilities for a range of applications. Appropriately functionalised materials can provide routes to multi-modal switching, for example, in response to light and/or electrochemical stimuli. This capability is important in the field of bionics wherein remote and temporal control of the properties of materials is becoming attractive. The ability to actuate a film via photonic stimuli is particularly interesting as it facilitates the modulation of interactions between host binding sites and potential guest molecules. In this work, we studied two different poly-terthiophenes: one was functionalised with a spiropyran …

In Vitro Growth And Differentiation Of Primary Myoblasts On Thiophene Based Conducting Polymers, Anita F. Quigley, Klaudia K. Wagner, Magdalena Kita, Kerry J. Gilmore, Michael J. Higgins, Robert D. Breukers, Simon E. Moulton, Graeme M. Clark, Anthony Penington, Gordon G. Wallace, David L. Officer, Robert M. Kapsa

Gordon Wallace

Polythiophenes are attractive candidate polymers for use in synthetic cell scaffolds as they are amenable to modification of functional groups as a means by which to increase biocompatibility. In the current study we analysed the physical properties and response of primary myoblasts to three thiophene polymers synthesized from either a basic bithiophene monomer or from one of two different thiophene monomers with alkoxy functional groups. In addition, the effect of the dopants pTS- and ClO4 - was investigated. In general, it was found that pTS- doped polymers were significantly smoother and tended to be more hydrophilic than their ClO 4 …

Highly Piezoelectric Biocompatible And Soft Composite Fibers, J. Morvan, E. Buyuktanir, John L. West, Antal Jakli

Antal Jakli

We report the fabrication of highly piezoelectric biocompatible soft fibers containing barium titanate ferroelectric ceramic particles dispersed in electrospun poly lactic acid (PLA). These fibers form mats that have two orders of magnitude larger piezoelectric constant per weight than single crystal barium titanate films. We propose that the observed apparent piezoelectricity results from the electrospinning induced polar alignment of the ferroelectric particles that pole the fibers similar to ferroelectret polymer foams that are poled by corona discharge. Due to the biocompatibility of PLA that encases the ferroelectric particles, these mats can be used in biological applications such as bio-sensors, artificial …

Large Flow Birefringence Of Nematogenic Bent-Core Liquid Crystals, C. Bailey, Katalin Fodor-Csorba, Rafael Verduzco, Jim T. Gleeson, Samuel N. Sprunt, Antal Jakli

Antal Jakli

We have found that bent-core liquid crystalline materials show exceptionally large intrinsic flow birefringence in their isotropic liquid phase. This effect is more than 100 times larger than typical values measured for low molecular weight liquid crystals. The specific flow birefringence (i.e., normalized by the flow viscosity) is an order of magnitude larger than in both side-chain polymeric as well as low molecular weight liquid crystals. We propose that this large enhancement for bent-core compounds may be attributed to nanoscale smecticlike clusters that persist above the nematic-isotropic transition temperature, and shear align under shear flow; however, this mechanism has not …

Compendium Of Polymer Terminology And Nomenclature: Iupac Recommendations, 2008 (Book Review), Jeffrey H. Glans

Jeffrey H. Glans

Book review by Jeffrey Glans. Polymer Division, International Union of Pure and Applied Chemistry. Compendium of Polymer Terminology and Nomenclature: IUPAC Recommendations, 2008. Royal Society of Chemistry, 2009.

Length Scales Of Interactions In Magnetic, Dielectric, And Mechanical Nanocomposites, Ralph Skomski, Balamurugan Balamurugan, Eva Schubert, Axel Enders, David J. Sellmyer

Axel Enders

It is investigated how figures of merits of nanocomposites are affected by structural and interaction length scales, Aside from macroscopic effects without characteristic lengths scales and atomic-scale quantum-mechanical interactions there are nanoscale interactions that reflect a competition between different energy contributions. We consider three systems, namely dielectric media, carbon-black reinforced rubbers and magnetic composites. In all cases, it is relatively easy to determine effective materials constants, which do not involve specific length scales. Nucleation and breakdown phenomena tend to occur on a nanoscale and yield a logarithmic dependence of figures of merit on the macroscopic system size. Essential system-specific differences …

The Gamete And Embryo Compatibility Of Various Synthetic Polymers., Stephen Hunter, J. Scott, D. Hull, R. Urry

Stephen K. Hunter

Several popular and well-characterized polymeric materials were evaluated for their biocompatibility toward the cells unique to reproduction. To accomplish these studies, several in vitro tests were developed that evaluated biocompatibility between the polymers and spermatozoa, ova, and embryos. The data indicated significant differences between the materials with respect to their biocompatibility toward sperm motility, the sperm's ability to penetrate zona-free hamster eggs, and the ability of two-cell mouse embryos to divide. Polytetrafluoroethylene (PTFE-Teflon; PTFE, Chemplast Inc., Wayne, NJ), polyethylene glycol (PEG), and polyhydroxyethyl methacrylate (PHEMA) appear to be the most inert of the materials studied. Polyvinyl chloride (PVC; Tygon-Norton, Akron, …

Promotion Of Neovascularization Around Hollow Fiber Bioartificial Organs Using Biologically Active Substances, Stephen Hunter, J. Kao, Y. Wang, J. Benda, V. Rodgers

Stephen K. Hunter

A limiting factor of the long-term function of bioartificial organs is oxygen delivery to the encapsulated tissue. This study determined whether incorporation of endothelial cell growth factor (ECGF) into the alginate core of a hollow fiber bioartificial organ will induce neovascularization around the hollow fiber. Polyethersulfone (PES) and polyvinylidine difluoride (PVDF) hollow fibers were examined. Endothelial cell growth factor was incorporated into sodium alginate, extruded into the lumen of hollow fibers, and cured in calcium chloride. Samples without ECGF were fabricated and used as controls. Hollow fibers were implanted into 16 rats. For each rat, two implants were placed subcutaneously …

Resolving Sub-Molecular Binding And Electrical Switching Mechanisms Of Single Proteins At Electroactive Conducting Polymers, A Gelmi, M J. Higgins, Gordon G. Wallace

Gordon Wallace

Polymer-based electrodes for interfacing biological tissues are becoming increasingly sophisticated. Their many functions place them at the cross-roads of electromaterials, biomaterials, and drug-delivery systems. For conducting polymers, the mechanism of conductivity requires doping with anionic molecules such as extracellular matrix molecules, a process that distinguishes them as biomaterials and provides a means to control interactions at the cellular-electrode interface. However, due to their complex structure, directly observing the selective binding of target molecules or proteins has so far eluded researchers. This situation is compounded by the polymer's ability to adopt different electronic states that alter the polymer-dopant interactions. Here, the …

A Galvanic Cell Driven Controlled Release System Based On Conducting Polymers, Caiyun Wang, Chee O. Too, Philip G. Whitten, G G. Wallace

Gordon Wallace

A self-powered controlled release system is achieved via galvanic coupling of a conducting polymer and a zinc anode. Release of an anionic dye molecule, phenol red (PR), as the polymer is reduced is quantified. Triggered release using the galvanic cell is demonstrated in a freeze-thaw experiment when melting of the electrolyte completes the galvanic cell and enables oxidation/reduction to occur.

6 Ghz Microstrip Patch Antennas With Pedot And Polypyrrole Conducting Polymers, Akhilesh Verma, Bo Weng, Roderick L. Shepherd, Christophe Fumeaux, Van Tan Truong, Gordon G. Wallace, Bevan D. Bates

Gordon Wallace

Two 6 GHz microstrip patch antennas made from conducting polymers with relatively low DC conductivity such as PEDOT (10000 S/m) and PPy (2000 S/m) are presented. The performance of these patch antennas is compared with a similar copper patch antenna. The results indicate that it is possible to obtain reasonable performance albeit with modest radiation efficiencies. The PEDOT antenna achieved a maximum gain of 2.2 dB, while the PPy antenna reached a gain of 3.8 dB, as against 6.0 dB for a corresponding Cu patch antenna The results confirm the potential of polymer materials for microwave antennas and suggest that …

Conducting Polymers With Fibrillar Morphology Synthesized In A Biphasic Ionic Liquid/Water System, J.M. Pringle, Orawan Ngamna, Carol M. Lynam, Gordon G. Wallace, Maria Forsyth, Douglas Macfarlane

Gordon Wallace

The synthesis of poly(pyrrole), poly(terthiophene), and poly(3,4-ethylenedioxythiophene) with unusual fibrillar morphologies has been achieved by chemical polymerization in a biphasic ionic liquid/water system. Use of aqueous gold chloride as the oxidant, with the monomers dissolved in a hydrophobic ionic liquid, allows the polymerization to occur at the ionic liquid/water interface. The resultant conducting polymer fibrils are, on average, 50−100 nm wide and can be thousands of nanometers long. The polymers produced in this ionic liquid system are compared to those synthesized in a biphasic chloroform/water system.

Synthesis, Modeling, And Characterization Of Conducting Polymers, Geoffrey M. Spinks, Lianbin Zhao, Weihua Li, Yanzhe Wu, Dezhi Zhou, Gordon G. Wallace

Gordon Wallace

This paper presents synthesis and characterization of polypyrrole based conducting polymers in terms of electronic and mechanical disciplines. Using the electrochemical polymerization approach, conducting polymer samples with different dimensions (length, width, and thickness) was fabricated. For each sample, both sinusoidal and step excitations were used to study its mechanical and electrical properties. An equivalent electric circuit based on constant phase element (CPE) is proposed to model such responses. Electrochemical impedance spectroscopy (EIS) method was used to identify the relationship between the dimensions of conducting polymers and model elements parameters.

Comparative Displacement Study Of Bilayer Actuators Comprising Of Conducting Polymers, Fabricated From Polypyrrole, Poly(3,4- Ethylenedioxythiophene) Or Poly(3,4-Propylenedioxythiophene), Babita Gaihre, Syed Ashraf, Geoffrey M. Spinks, Peter C. Innis, Gordon G. Wallace

Gordon Wallace

The stress gradient generated due to electrochemical oxidation/reduction of a conducting polymer in a bilayer actuator causes a bending movement. Here we report a comparative study of the displacement of bilayer actuators prepared using different conducting polymers. The effects of conducting polymers obtained from electrochemical or chemical synthesis route: different polymers (polypyrrole (PPy), poly(3,4-ethylenedioxythiophene) PEDOT and poly(3,3-dihexyl-3-4-dihydro-2H-thieno[3,4b][1,4]-dioxepine [PProDOT(Hx) 2]); and different electrolytes (0.1 M lithium trifluromethanesulfonate/propylenecarbonate (LiTFSI/PC) and 1-ethyl-3-methyl imidazolium trifluromethanesulfonate (EMITFSI)) on the displacement amplitude and displacement patterns of these actuators were investigated and compared. The results indicate that the bilayer actuator consisting of an electrochemically synthesized conducting polymer …