scholarly journals Low Energy Processing of Polymeric Materials

Materials ◽  
2017 ◽  
Author(s):  
Maša Knez Hrnčič ◽  
Gregor Kravanja ◽  
Željko Knez
Keyword(s):  
Polymeric Materials ◽  
Low Energy ◽  
Energy Processing

scholarly journals End-of-life upcycling of robust polyurethanes using a room temperature, mechanism-based degradation

2021 ◽  
Author(s):  
Ephraim Morado ◽  
Douglas Ivanoff ◽  
Hsuan-Chin Wang ◽  
Alayna Johnson ◽  
Mara Paterson ◽  
...  
Keyword(s):  
End Of Life ◽  
Energy Input ◽  
Room Temperature ◽  
Degradation Products ◽  
Polymeric Materials ◽  
Synthetic Polymers ◽  
Low Energy ◽  
Waste Streams ◽  
Rapid Degradation ◽  
Oxocarbenium Ion

Abstract A major challenge in developing recyclable polymeric materials is the inherent conflict between the properties required during and after its life span. In particular, materials must be strong and durable when in use, but undergo complete and rapid degradation upon end-of-life. We report a new mechanism for degrading polyurethanes called CyclizAtion-Triggered CHain (CATCH) cleavage that achieves this duality. CATCH cleavage features a simple glycerol-based acyclic acetal unit as a kinetic and thermodynamic trap for gated chain-shattering. Thus, an organic acid induces transient chain breaks with oxocarbenium ion formation and subsequent intramolecular cyclization to depolymerize fully the polyurethane backbone at room temperature. With minimal chemical modification, the resulting degradation products can be repurposed into strong adhesives and photochromic coatings demonstrating the potential for upcycling. The CATCH cleavage strategy for low-energy input breakdown and subsequent upcycling may be generalizable to a broader range of synthetic polymers and their end-of-life waste streams.

scholarly journals Investigation of polymer-based BaO and rGO nanocomposites for application in low energy X ray attenuation

2019 ◽  
Vol 7 (2B) ◽  
Author(s):  
LILIANE Aparecida SILVA ◽  
Adriana Batistab ◽  
Jefferson Nascimentoc ◽  
Clascidia Furtadoc ◽  
Luiz Faria
Keyword(s):  
Thin Films ◽  
Attenuation Coefficient ◽  
Vinylidene Fluoride ◽  
Polymeric Materials ◽  
Radiation Shielding ◽  
Low Energy ◽  
Linear Attenuation Coefficient ◽  
Graphene Oxides ◽  
X Ray ◽  
Multilayered Sample

Polymeric materials can serve as a matrix for the dispersion of nanomaterials with good attenuation features, resulting in lightweight, conformable, flexible, lead-free and easy-to-process materials. Thus, some well-known radiation shielding materials could be used in low proportion as a filler, for the formation of new materials. On the other hand, nanostructured carbon materials, such as graphene oxide (GO) have been reported recently to show enhanced attenuation properties. For the present work, poly(vinylidene fluoride) [PVDF] homopolymers and its fluorinated copolymers were filled with metallic oxides and nanosized reduced graphene oxides (rGO) in order to produce nanocomposites with increased low energy X ray attenuation efficiency. We objective is to investigate the X ray shielding features of multilayered PVDF/rGO and P(VDF-TrFE)/BaO composites. PVDF/rGO overlapped with P(VDF-TrFE)/BaO thin films were sandwiched between two layers of kapton films of different thickness. The linear attenuation coefficients were measured for monochromatic X ray photons with energy of 8.1 keV. The samples were characterized by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Ultraviolet–visible (UV-vis) and Fourier-Transform Infrared (FTIR) Spectroscopy. The linear attenuation coefficient of the multilayered sample was evaluated and compared with the linear attenuation of the individual constituents. It was observed an increase in the attenuation coefficient of the overlapping samples. It is demonstrated that thin films of rGO nanocomposite with thickness of only 0.32 mm can attenuate up to 50% of X ray beams with energy of 8.1 keV, justifying further investigation of these nanocomposites as X ray or gamma radiation attenuators

scholarly journals 3D Printing with the Commercial UV-Curable Standard Blend Resin: Optimized Process Parameters towards the Fabrication of Tiny Functional Parts

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 292 ◽  
Author(s):  
Valentina Bertana ◽  
Giorgio De Pasquale ◽  
Sergio Ferrero ◽  
Luciano Scaltrito ◽  
Felice Catania ◽  
...  
Keyword(s):  
3D Printing ◽  
Polymeric Materials ◽  
Acrylic Resin ◽  
Tensile Tests ◽  
Low Energy ◽  
Mechanical Resistance ◽  
Optimal Conditions ◽  
Uv Curable ◽  
The Right ◽  
Printing Parameters

Stereolithography 3D printing is today recognized as an effective rapid prototyping technique in the field of polymeric materials, which represents both the strengths and the weaknesses of this technique. The strengths relate to their easy handling and the low energy required for processing, which allow for the production of structures down to the sub-micrometric scale. The weaknesses are a result of the relatively poor mechanical properties. Unfortunately, the choice of the right material is not sufficient, as the printing parameters also play a crucial role. For this reason, it is important to deepen and clarify the effect of different printing conditions on final product characteristics. In this paper, the behavior of commercial Standard Blend (ST Blend) acrylic resin printed with stereolithography (SL) apparatus is reported, investigating the influence of printing parameters on both the tensile properties of the printed parts and the build accuracy. Twenty-four samples were printed under different printing conditions, then dimensional analyses and tensile tests were performed. It was possible to find out the optimum printing setup to obtain the best result in terms of mechanical resistance and printing accuracy for this kind of resin. Finally, a micrometric spring was printed under the optimal conditions to demonstrate the possibility of printing accurate and tiny parts with the commercial and inexpensive STBlend resin.

scholarly journals Investigating Pervaporation as a Process Method for Concentrating Formic Acid Produced from Carbon Dioxide

2020 ◽  
Vol 6 (2) ◽  
pp. 42 ◽  
Author(s):  
Jerry J. Kaczur ◽  
Liam J. McGlaughlin ◽  
Prasad S. Lakkaraju
Keyword(s):  
Ion Exchange ◽  
Formic Acid ◽  
Energy Requirement ◽  
Electrochemical Process ◽  
Low Energy ◽  
Separation Performance ◽  
Process Step ◽  
Membrane Area ◽  
Capital Costs ◽  
Energy Processing

New methods in lowering energy consumption costs for evaporation and concentration are needed in many commercial chemical processes. Pervaporation is an underutilized, low-energy processing method that has a potential capability in achieving lower energy processing costs. A recently developed new electrochemical process that can generate a 5–25 wt% pure formic acid (FA) from the electrochemical reduction of CO2 requires a low-energy process for producing a more concentrated FA product for use in both on-site and commercial plant applications. In order to accomplish this, a 25 cm2 membrane area pervaporation test cell was constructed to evaluate the FA-H2O system separation performance of three distinct types of membrane candidates at various FA feed concentrations and temperatures. The selection included one cation ion exchange, two anion ion exchange, and two microporous hydrophobic membranes. The permeation flux rates of FA and H2O were measured for FA feed concentrations of 10, 20, 40, and 60 wt% at corresponding temperatures of 22, 40, and 60 °C. The separation performance results for these particular membranes appeared to follow the vapor liquid equilibrium (VLE) characteristics of the vapor phase in the FA-H2O system as a function of temperature. A Targray microporous hydrophobic high-density polyethylene (HDPE) membrane and a Chemours Nafion® N324 membrane showed the best permeation selectivities and mass flux rates FA feed concentrations, ranging from 10 to 40 wt%. The cation and anion ion exchange membranes evaluated were found not to show any significant enhancements in blocking or promoting the transport of the formate ion or FA through the membranes. An extended permeation cell run concentrated a 10.12% FA solution to 25.38% FA at 40 °C. Azeotropic distillation simulations for the FA-H2O system using ChemCad 6.0 were used to determine the energy requirement using steam costs in processing FA feed concentrations ranging from 5 to 30 wt%. These experimental results indicate that pervaporation is a potentially useful unit process step with the new electrochemical process in producing higher concentration FA product solutions economically and at lower capital costs. One major application identified is in on-site production of FA for bioreactors employing new types of microbes that can assimilate FA in producing various chemicals and bio-products.

scholarly journals Low Energy Implantation of Carbon into Elastic Polyurethane

Coatings ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 274 ◽  
Author(s):  
Ilya A. Morozov ◽  
Alexander S. Kamenetskikh ◽  
Anton Y. Beliaev ◽  
Marina G. Scherban ◽  
Dmitriy M. Kiselkov
Keyword(s):  
Deformation Behavior ◽  
Polymeric Materials ◽  
Free Surface Energy ◽  
Low Energy ◽  
Carbon Ions ◽  
Hard Phase ◽  
Soft Phase ◽  
Treatment Regimens ◽  
Subsequent Investigation ◽  
Induced Defects

Ion modification of polymeric materials requires gentle regimens and subsequent investigation of mechanical and deformation behavior of the surfaces. Polyurethane is a synthetic block copolymer: A fibrillar hard phase is inhomogeneoulsy distributed in a matrix of soft phase. Implantation of carbon ions into this polymer by deep oscillation magnetron sputtering (energy—0.1–1 keV and dose of ions—1014–1015 ion/cm2) forms graphene-like nanolayer and causes heterogeneous changes in structural and mechanical properties of the surface: Topography, elastic modulus and depth of implantation for the hard/soft phase areas are different. As a result, after certain treatment regimens strain-induced defects (nanocracks in the areas of the modified soft phase, or folds in the hard phase) appear on the surfaces of stretched materials. Treated surfaces have increased hydrophobicity and free surface energy, and in some cases show good deformability without any defects.

The accumulation of volume charges in polymeric materials during irradiation by low energy electrons under vacuum

1983 ◽  
Vol 25 (5) ◽  
pp. 1206-1215
Author(s):  
A.P. Tyutnev ◽  
V.S. Sayenko ◽  
G.S. Mingaleyev ◽  
Ye.D. Pozhidayev
Keyword(s):  
Polymeric Materials ◽  
Low Energy ◽  
Low Energy Electrons

scholarly journals In-sensor classification with boosted race trees

2021 ◽  
Vol 64 (6) ◽  
pp. 99-105
Author(s):  
Georgios Tzimpragos ◽  
Advait Madhavan ◽  
Dilip Vasudevan ◽  
Dmitri Strukov ◽  
Timothy Sherwood
Keyword(s):  
Embedded Systems ◽  
Energy Efficient ◽  
State Of The Art ◽  
Data Representation ◽  
Low Energy ◽  
Ensemble Classifiers ◽  
Trade Offs ◽  
Practical Design ◽  
Energy Processing ◽  
Algebraic Operations

When extremely low-energy processing is required, the choice of data representation makes a tremendous difference. Each representation (e.g., frequency domain, residue coded, and log-scale) embodies a different set of tradeoffs based on the algebraic operations that are either easy or hard to perform in that domain. We demonstrate the potential of a novel form of encoding, race logic, in which information is represented as the delay in the arrival of a signal. Under this encoding, the ways in which signal delays interact and interfere with one another define the operation of the system. Observations of the relative delays (for example, the outcome of races between signals) define the output of the computation. Interestingly, completely standard hardware logic elements can be repurposed to this end and the resulting embedded systems have the potential to be extremely energy efficient. To realize this potential in a practical design, we demonstrate two different approaches to the creation of programmable tree-based ensemble classifiers in an extended set of race logic primitives; we explore the trade-offs inherent to their operation across sensor, hardware architecture, and algorithm; and we compare the resulting designs against traditional state-of-the-art hardware techniques.

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