scholarly journals Drop spreading and gelation of thermoresponsive polymers

Soft Matter ◽  
2018 ◽  
Vol 14 (16) ◽  
pp. 3096-3104 ◽  
Author(s):  
R. de Ruiter ◽  
L. Royon ◽  
J. H. Snoeijer ◽  
P. Brunet
Keyword(s):  
Additive Manufacturing ◽  
Polymer Concentration ◽  
Liquid Droplets ◽  
Gelation Temperature ◽  
Thermoresponsive Polymer ◽  
Thermoresponsive Polymers ◽  
Elementary Processes ◽  
Drop Spreading ◽  
The Difference ◽  
Line P

Spreading and solidification of liquid droplets are elementary processes of relevance for additive manufacturing. With simple drop spreading experiments of a thermoresponsive polymer solution, we found that the final shape is ruled by the difference between the substrate temperature and the gelation temperature. Unexpectedly, spreading also stops below the gelation temperature, due to an increase in polymer concentration induced by evaporation near the contact line.

scholarly journals Effect of pore diameter on the elution behavior of analytes from thermoresponsive polymer grafted beads packed columns

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kenichi Nagase ◽  
Yuta Umemoto ◽  
Hideko Kanazawa
Keyword(s):  
Pore Diameter ◽  
Packed Column ◽  
Packed Columns ◽  
Butyl Methacrylate ◽  
Thermoresponsive Polymer ◽  
Thermoresponsive Polymers ◽  
Column Temperature ◽  
Pore Sizes ◽  
Temperature Responsive ◽  
Elution Behavior

AbstractTemperature-responsive chromatography using thermoresponsive polymers is innovative and can control analyte retention via column temperature. Analyte elution behavior in this type of chromatography depends on the modified thermoresponsive polymer and the structure of the base materials. In the present study, we examine the effect of the pore diameter of silica beads on analyte elution behavior in temperature-responsive chromatography. Poly(N-isopropylacrylamide-co-n-butyl methacrylate) hydrogel was applied to beads of various pore sizes: 7, 12, and 30 nm. Almost the same amount of copolymer hydrogel was applied to all beads, indicating that the efficiency of copolymer modification was independent of pore size. Analyte retention on prepared beads in a packed column was observed using steroids, benzodiazepines, and barbiturates as analytes. Analyte retention times increased with temperature on packed columns of 12- and 30-nm beads, whereas the column packed with 7-nm beads exhibited decreased retention times with increasing temperature. The difference in analyte elution behavior among the various pore sizes was attributed to analyte diffusion into the bead pores. These results demonstrate that bead pore diameter determines temperature-dependent elution behavior.

Shape-driven control of layer height in robotic wire and arc additive manufacturing

2019 ◽  
Vol 25 (10) ◽  
pp. 1637-1646 ◽  
Author(s):  
Bohao Xu ◽  
Xiaodong Tan ◽  
Xizhi Gu ◽  
Donghong Ding ◽  
Yuelin Deng ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Deposition Rate ◽  
Control Method ◽  
Single Layer ◽  
Optimization Method ◽  
Content Type ◽  
Layer Height ◽  
Layer Deposition ◽  
Complex Shapes ◽  
The Difference

Purpose Once an uneven substrate is aligned, traditional control theories and methods can be used on it, so aligning is of great significance for the development of wire and arc additive manufacturing (WAAM). This paper aims to propose a shape-driven control method for aligning a substrate with slopes to expand the application of WAAM. Design/methodology/approach A substrate with slopes must be aligned by depositing weld beads with slopes. First, considering the large height differences of slopes, multi-layer deposition is needed, and the number of layer of weld beads must be ascertained. Second, the change in the deposition rate is controlled as a ramp function to generate weld beads with slopes. Third, the variation of the deposition rate must be fine-tuned to compensate for the deviation between the actual and theoretical layer heights at the deposition of each layer. Finally, the parameters of the ramp functions at the deposition of each layer are determined through an optimization method. Findings First, to model the response function of layer height to deposition rate, the experiments are conducted with the deposition rate jumping from 4 to 8 mm/s and from 8 to 4 mm/s. When the deposition rate jumps from 4 to 8 mm/s and from 8 to 4 mm/s, the difference in the height of each layer decreases as the number of layer increases. Second, the variation of the deposition rate can be fine-tuned based on the deviation between the measured and theoretical layer heights because the variation of the deposition rate is proportional to the layer height when the initial and end deposition rates are near 4 or 8 mm/s, respectively. Third, the experimental results demonstrate that the proposed method is effective for single-layer aligning and aligning a substrate with one or more slopes. Originality/value The proposed method can expand the application of WAAM to an uneven substrate with slopes and lays the foundation for aligning tasks focused on uneven substrates with more complex shapes.

scholarly journals Strength Comparison of FDM 3D Printed PLA Made by Different Manufacturers

TEM Journal ◽  
2020 ◽  
pp. 966-970
Author(s):  
Damir Hodžić ◽  
Adi Pandžić ◽  
Ismar Hajro ◽  
Petar Tasić
Keyword(s):  
Experimental Study ◽  
Additive Manufacturing ◽  
Fused Deposition Modelling ◽  
Fused Deposition ◽  
Manufacturing Technique ◽  
Plastic Materials ◽  
Wide Range ◽  
3D Printed ◽  
The Difference ◽  
Printing Parameters

Widely used additive manufacturing technique for plastic materials is Fused Deposition Modelling (FDM). The FDM technology has gained interest in industry for a wide range of applications, especially today when large number of different materials on the market are available. There are many different manufacturers for the same FDM material where the difference in price goes up to 50%. This experimental study investigates possible difference in strength of the 3D printed PLA material of five different manufacturers. All specimens are 3D printed on Ultimaker S5 printer with the same printing parameters, and they are all the same colour.

PLASMA NEW SELECTIVE PROPERTIES FOR EFFICIENT USE IN ELECTRONICS AND TELECOMMUNICATIONS

2021 ◽  
Vol 2 (64) ◽  
pp. 171-174
Author(s):  
Oleksandr Shefer ◽  
Vitalii Marchenko ◽  
Galina Cherneva
Keyword(s):  
Gaseous Medium ◽  
Charge Carriers ◽  
Practical Implementation ◽  
Large Area ◽  
Elementary Processes ◽  
Molecular Gases ◽  
Radio Signals ◽  
The Difference ◽  
Functional Purpose ◽  
Gas Pressures

In terms of active and passive electronic counteraction, detection of geophysical phenomena of artificial andnatural origin is becoming increasingly important. Discovering new properties of plasma enables to improve the informationcomponent of radio signals more effectively and use the obtained properties in related fields. Elementary processes in thelongitudinal and transverse directions of the discharge, depending on natural and artificial conditions, under different typesof gaseous medium used; at different gas pressures and different pulse-periodic application of an electric field is studied inthe article. The difference of discharge properties in inert and molecular gases with different designs and electrodes of thelaboratory device is shown. It is established that the change of functional purpose between the cathodes and the anodes doesnot change the shape of the discharge. The presence of ambipolar diffusion of charge carriers acting on a large area of plasmawas determined. Partial charge carrier homogeneity has been established, which is observed only along the plasma surface,and homogeneity is violated in the perpendicular direction. The difference in energy input in the discharge, depending on thedesign of the electrodes other things being equal is determined. The identified properties of plasma enable them to be usedmore effectively for practical implementation in the field of electronics and telecommunications and other industries.

Automated Geometric Correction System for Additive Manufacturing Considering Build Orientation

2021 ◽  
pp. 1-30
Author(s):  
Seyedeh Elaheh Ghiasian ◽  
Kemper Lewis
Keyword(s):  
Additive Manufacturing ◽  
Optimization Model ◽  
Experimental Validation ◽  
Minimal Amount ◽  
Feature Size ◽  
Build Orientation ◽  
Computational Performance ◽  
The Difference ◽  
Processing Effort ◽  
Correction System

Abstract One of the current challenges for the additive manufacturing (AM) industry lies in providing component designs compatible with the AM manufacturability and constraints without compromising the component structural functionalities. To address this challenge, we present an automated correction system that provides geometrically feasible designs for additive processes by applying locally effective modifications while avoiding substantial changes in the current designs. Considering a minimum printable feature size from the process parameters, this system identifies the problematic features in an infeasible part's design using a holistic geometric assessment algorithm. Based on the obtained manufacturability feedback, the system then corrects the detected problematic regions using a set of appropriate redesign solutions through an automated procedure. In addition, to reduce the difference between the current and modified part geometries, a novel optimization model for build orientation is presented. Using this model, one can identify appropriate orientations for obtaining a feasible design with a minimal amount of corrections while also reducing the post-processing effort by minimizing the area of contact with the support structure. The functionalities of the presented correction system and the optimization model are illustrated using a number of case studies with varying geometries. The computational performance of the system and an experimental validation are also presented to demonstrate the effectiveness of the implemented detection and modification approaches.

Liquid supercoolings and droplet cooling rates of remelted argon-atomized Fe–30Ni powder particles

1988 ◽  
Vol 3 (3) ◽  
pp. 441-452 ◽  
Author(s):  
Matthew R. Libera ◽  
Pedro P. Bolsaitis ◽  
R. Erik Spjut ◽  
John B. VanderSande
Keyword(s):  
Standard Deviation ◽  
Cooling Rate ◽  
Metal Droplet ◽  
Liquid Droplets ◽  
Interfacial Velocity ◽  
Gas Atmosphere ◽  
History Of ◽  
Powder Particles ◽  
The Difference ◽  
Individual Particles

Individual particles of argon-atomized Fe-30Ni powder are electrodynamically levitated and remelted by a CO2 laser pulse. The thermal history of each droplet during remelting and solidification is monitored by single-color radiation pyrometry at each of three wavelengths (850, 750, and 550 nm). Experiments are done in an atmosphere of either air or nitrogen. The average supercooling of six experiments performed in nitrogen is 298 K with a standard deviation of 14 K. This value is of the same order as several others reported in the literature using bulk levitation and emulsification techniques. The average supercooling of seven experiments performed in air is 163 K with a standard deviation of 20 K. The difference suggests that oxides are forming in the air-remelting experiments and catalyzing nucleation at relatively low supercoolings. The average cooling rate of the liquid droplets prior to solidification in nitrogen is 1.5 × 105 K/s. This measured cooling rate is somewhat higher than that predicted by Newtonian heat flow modeling, and the difference is attributed to radiative losses not considered in the Newtonian model. The measured cooling rate is used to estimate the total heat transfer coefficient characterizing cooling of a small metal droplet in a quiescent gas atmosphere. A lower bound of 1.5 × 106 K/s on the droplet heating rate during recalescence and a minimum average liquid/solid interfacial velocity during recalescence of 0.1 m/s are estimated.

Ceramic Additive Manufacturing Using VAT Photopolymerization

2018 ◽  
Author(s):  
Diptanshu ◽  
Erik Young ◽  
Chao Ma ◽  
Suleiman Obeidat ◽  
Bo Pang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Thermal Processing ◽  
Biomedical Applications ◽  
Ceramic Materials ◽  
Ceramic Suspension ◽  
Alumina Particles ◽  
Compressive Testing ◽  
The Difference ◽  
Porosity Percentage

The popularity of additive manufacturing for producing porous bio-ceramics using vat photopolymerization in the recent years has gained a lot of impetus due to its high resolution and low surface roughness. In this study, a commercial vat polymerization printer (Nobel Superfine, XYZprinting) was used to create green bodies using a ceramic suspension consisting of 10 vol.% of alumina particles in a photopolymerizable resin. Four different sizes of cubical green bodies were printed out. They were subjected to thermal processing which included de-binding to get rid of the polymer and thereafter sintering for joining of the ceramic particles. The porosity percentage of the four different sizes were measured and compared. The lowest porosity was observed in the smallest cubes (5 mm). It was found to be 43.3%. There was an increase in the porosity of the sintered parts for the larger cubes (10, 15 and 20 mm). However, the difference in the porosity among these sizes was not significant and ranged from 61.5% to 65.2%. The compressive testing of the samples showed that the strength of the 5-mm cube was the maximum among all samples and the compressive strength decreased as the size of the samples increased. These ceramic materials of various densities are of great interest for biomedical applications.

scholarly journals Novel thermoresponsive polymer outperforming Pluronic® F127

2020 ◽  
Author(s):  
Anna Constantinou ◽  
Valeria Nele ◽  
James Doutch ◽  
Roman Moiseev ◽  
Vitaliy Khutoryanskiy ◽  
...  
Keyword(s):  
Self Assembly ◽  
Biomedical Applications ◽  
Ex Vivo ◽  
Structural Characteristics ◽  
Thermoresponsive Polymer ◽  
Scanning Calorimetry ◽  
Thermoresponsive Polymers ◽  
Crosslinked Networks ◽  
Gelation Concentration ◽  
Physically Crosslinked

Abstract Thermoresponsive polymers featuring the appropriate combination of structural characteristics, i.e. architecture, composition, and molar mass (MM), can form physically crosslinked networks in a solvent upon changes in temperature. This fascinating class of polymers finds utility in various sectors such as formulation science and tissue engineering. Here, we report a novel thermoresponsive triblock terpolymer which out-performs the most commonly used and commercially available thermoresponsive polymer, Poloxamer P407 (also known as Pluronic® F127) in terms of gelation concentration. Specifically, the in-house synthesised polymer forms gels at lower concentrations that is an advantage in biomedical applications. To elucidate the differences in their macroscale gelling behaviour, we investigate their micellization via differential scanning calorimetry, and their nanoscale self-assembly behaviour in detail by means of small-angle neutron scattering by simultaneously recording their rheological properties (Rheo-SANS). Two different gelation mechanisms for the two polymers are revealed and proposed. Ex vivo gelation study upon intracameral injections demonstrated excellent potential for its application to improve drug residence in the eye.

Effect of Substrate Concentrations of the BZ Reaction on Period of Self-Oscillation for Non-Thermoresponsive Polymer Chain

2011 ◽  
Vol 480-481 ◽  
pp. 357-362 ◽  
Author(s):  
Yusuke Hara
Keyword(s):  
Polymer Chain ◽  
Main Chain ◽  
Polymer Concentration ◽  
Solution Viscosity ◽  
Thermoresponsive Polymer ◽  
Bz Reaction ◽  
Ru Catalyst ◽  
Initial Substrate ◽  
Covalently Bonded ◽  
Substrate Concentrations

In this study, effect of the initial substrate concentrations of the Belouzov-Zhabotinsky (BZ) on a period and transmittance self-oscillating behavior for a polymer chain were investigated under the constant temperature condition (T = 20 °C). The polymer chain was composed of a non-thermoresponsive poly-vinylpyrrolidone (PVP) main-chain covalently-bonded to the 10 wt% ruthenium catalyst (Ru(bpy)3) of the BZ reaction. The transmittance self-oscillation originates from the different solubility of the Ru catalyst moiety in the reduced and oxidized state. The waveform and period of the non-thermoresponsive polymer chain was significantly affected by the initial concentration of the BZ substrates. Moreover, as the concentration of the Ru catalyst increased due to the increase in the polymer concentration, the period hardly changed because of the high solution viscosity.

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