scholarly journals First, Do Not Degrade - an Alternative View on Polymer Laser Sintering

2021 ◽  
Author(s):  
Arkadiusz Antończak ◽  
Mateusz Wieczorek ◽  
Paulina Dzienny ◽  
Bartłomiej Kryszak ◽  
Anna Krokos ◽  
...  
Keyword(s):  
Gel Permeation Chromatography ◽  
Laser Sintering ◽  
Polymer Materials ◽  
Alternative View ◽  
Scanning Calorimetry ◽  
Entire Volume ◽  
Beam Laser ◽  
Dual Beam ◽  
Wide Range ◽  
First Time

<p>In the work, for the first time, the method of Dual Beam Laser Sintering of polymers (DBLS) was presented, in which, instead of heating the entire volume of the polymer throughout the entire process, a second, additional laser was used for selective in terms of volume and time heating of the material. The principle of operation and the design of the prototype are presented. Using the developed station, an experiment was carried out for sintering samples from technical polylactide powder as a function of selected process parameters. It confirmed the functionality of the method and proved that the sintering process can be controlled in a fairly wide range for the proposed method. A preliminary comparison of changes in the physicochemical properties of the obtained samples in relation to the samples sintered by standard laser sintering was carried out using Gel Permeation Chromatography, Fourier Transform Infrared Reflectance and Differential Scanning Calorimetry. The experiment showed that the presented method has the potential to limit the thermal degradation of sensitive polymer materials.</p>

scholarly journals First, Do Not Degrade - an Alternative View on Polymer Laser Sintering

2021 ◽  
Author(s):  
Arkadiusz Antończak ◽  
Mateusz Wieczorek ◽  
Paulina Dzienny ◽  
Bartłomiej Kryszak ◽  
Anna Krokos ◽  
...  
Keyword(s):  
Gel Permeation Chromatography ◽  
Laser Sintering ◽  
Polymer Materials ◽  
Alternative View ◽  
Scanning Calorimetry ◽  
Entire Volume ◽  
Beam Laser ◽  
Dual Beam ◽  
Wide Range ◽  
First Time

<p>In the work, for the first time, the method of Dual Beam Laser Sintering of polymers (DBLS) was presented, in which, instead of heating the entire volume of the polymer throughout the entire process, a second, additional laser was used for selective in terms of volume and time heating of the material. The principle of operation and the design of the prototype are presented. Using the developed station, an experiment was carried out for sintering samples from technical polylactide powder as a function of selected process parameters. It confirmed the functionality of the method and proved that the sintering process can be controlled in a fairly wide range for the proposed method. A preliminary comparison of changes in the physicochemical properties of the obtained samples in relation to the samples sintered by standard laser sintering was carried out using Gel Permeation Chromatography, Fourier Transform Infrared Reflectance and Differential Scanning Calorimetry. The experiment showed that the presented method has the potential to limit the thermal degradation of sensitive polymer materials.</p>

scholarly journals Bio-Based Polyurethane Resins Derived from Tannin: Source, Synthesis, Characterisation, and Application

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1516
Author(s):  
Manggar Arum Aristri ◽  
Muhammad Adly Rahandi Lubis ◽  
Apri Heri Iswanto ◽  
Widya Fatriasari ◽  
Rita Kartika Sari ◽  
...  
Keyword(s):  
Natural Resources ◽  
Value Added ◽  
Gel Permeation Chromatography ◽  
Industrial Applications ◽  
Hot Water ◽  
Synthesis Process ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Protective Function ◽  
Wide Range

Tannins are soluble, astringent secondary phenolic metabolites generally obtained from renewable natural resources, and can be found in many plant parts, such as fruits, stems, leaves, seeds, roots, buds, and tree barks, where they have a protective function against bacterial, fungal, and insect attacks. In general, tannins can be extracted using hot water or organic solvents from the bark, leaves, and stems of plants. Industrially, tannins are applied to produce adhesives, wood coatings, and other applications in the wood and polymer industries. In addition, tannins can also be used as a renewable and environmentally friendly material to manufacture bio-based polyurethanes (bio-PUs) to reduce or eliminate the toxicity of isocyanates used in their manufacture. Tannin-based bio-PUs can improve the mechanical and thermal properties of polymers used in the automotive, wood, and construction industries. The various uses of tannins need to be put into perspective with regards to possible further advances and future potential for value-added applications. Tannins are employed in a wide range of industrial applications, including the production of leather and wood adhesives, accounting for almost 90% of the global commercial tannin output. The shortage of natural resources, as well as the growing environmental concerns related to the reduction of harmful emissions of formaldehyde or isocyanates used in the production of polyurethanes, have driven the industrial and academic interest towards the development of tannin-based bio-PUs as sustainable alternative materials with satisfactory characteristics. The aim of the present review is to comprehensively summarize the current state of research in the field of development, characterization, and application of tannin-derived, bio-based polyurethane resins. The successful synthesis process of the tannin-based bio-PUs was characterized by Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), MALDI-TOF mass spectrometry, and gel permeation chromatography (GPC) analyses.

scholarly journals A Greener Enzymatic Oligoesterification of Biobased Renewable Synthons

2021 ◽  
Author(s):  
Juan Villavicencio ◽  
Ferley Orozco ◽  
Ricardo Benitez ◽  
Jaime Martin ◽  
Giovanni Rojas
Keyword(s):  
Molecular Weight ◽  
Molar Mass ◽  
Gel Permeation Chromatography ◽  
Scanning Calorimetry ◽  
Reaction Conditions ◽  
Step Process ◽  
Gel Permeation ◽  
One Step ◽  
First Time ◽  
Temperature Time

Polyesters of xylitol and succinic acid were prepared yielding from 70 to 75% by enzymecatalyzed esterification using a molar mass from 1:1 to 2:5 at 120 and 140 °C employing from 1 to 10% m/m of enzyme. Control over branching degree was achieved by tuning the reaction conditions (temperature, time, comonomer ratio, enzyme content). This one-step process from renewable starting materials avoids protection-deprotection techniques, as well as the use of toxic solvents by introducing limonene as solvent for polyesterification for the first time. All materials were structurally characterized by infrared (IR) and nuclear magnetic resonance (NMR)spectroscopy, their thermal properties were studied by differential scanning calorimetry (DSC)and thermogravimetric analysis (TGA), and the molecular weight of samples were obtained by gel-permeation chromatography (GPC).

scholarly journals THE INFLUENCE OF REACTION TIME ON THE PROPERTIES OF MICROWAVE SYNTHESIZED POLY(LACTIDE)

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Ivan Ristić ◽  
Milovan Jotanović ◽  
Tamara Erceg ◽  
Ljubiša Nikolić ◽  
Suzana Cakić ◽  
...  
Keyword(s):  
Reaction Time ◽  
Renewable Resources ◽  
Gel Permeation Chromatography ◽  
Polymer Materials ◽  
Scanning Calorimetry ◽  
Complete Life Cycle ◽  
Ft Ir ◽  
Synthesis Routes ◽  
Plant Feedstock

The consequence of drastic reduction in fossil fuel reserves has forced the scientific community to find and develop new ways to exploit renewable resources and optimize the process of polymer materials production. The aim is to obtain applicable polymer whose complete life cycle is set in ecological framework. Poly(lactide) (PLA) meets these requirements as biodegradable polyester whose monomer is derived from the plant feedstock containing carbohydrates. PLA could be prepared using the different synthesis routes, but from the point of energy saving, as well as environmental protection, the microwave synthesis of PLA is the best solution. In this work, poly(L-lactide) were synthesized in microwave reactor. Reaction time was varied, while the other parameters of the synthesis were constant. The structures of obtained polymers were confirmed by Fourier – transform infrared spectroscopy (FT-IR). For determination of molar masses of poly(L-lactide) samples, the gel permeation chromatography (GPC) was applied. Thermal properties were investigated by differential scanning calorimetry (DSC).

scholarly journals Synthesis and ionic conductivity of siloxane based polymer electrolytes with pendant propyl acetoacetate groups

2018 ◽  
Vol 90 (6) ◽  
pp. 989-999 ◽  
Author(s):  
Omari Mukbaniani ◽  
Witold Brostow ◽  
Jimsher Aneli ◽  
Tamara Tatrishvili ◽  
Eliza Markarashvili ◽  
...  
Keyword(s):  
Specific Conductivity ◽  
Sol Gel ◽  
Gel Permeation Chromatography ◽  
Polymerization Reaction ◽  
Side Chain ◽  
Anion Receptors ◽  
Scanning Calorimetry ◽  
Molar Ratios ◽  
Wide Range ◽  
Electrolyte Membranes

Abstract Hydrosilylation reaction of 2.4.6.8-tetrahydro-2.4.6.8-tetramethylcyclotetrasiloxane (D4H) with allyl acetoacetate at 1:4.1 molar ratios of initial compounds in the presence of platinum hydrochloric acid (0.1 M solution in THF), Karstedt’s catalyst (Pt2[(VinSiMe2)2O]3) and platinum on the carbon have been carried out and D4R type compounds obtained. Reaction order, rate constants and activation energies for hydrosilylation reactions in the presence of Karstedt’s catalyst have been determined. Ring-opening polymerization reaction of D4R in the presence of catalytic amounts of powder-like potassium hydroxide has been carried out. A linear methylsiloxane oligomer with regular arrangement of propyl acetoacetate groups in the side chain has been obtained. The synthesized methylorganocyclotetrasiloxane and oligomers were studied by FTIR, 1H, 13C and 29Si NMR spectroscopy. Comb-type oligomers were characterized by gel-permeation chromatography, wide-angle X-ray diffractometry and differential scanning calorimetry. Solid oligomer electrolyte membranes have been obtained via sol–gel processes involving lithium trifluoromethylsulfonate (triflate) or lithium bis(trifluoromethylsulfonyl)imide. The specific volumetric electrical conductivity of the membranes at room temperature covers a wide range, from 10−10 to 10−4 S · cm−1, and depends on the structures of grafted anion receptors and the polymer backbones. Higher values of the specific conductivity are seen for the membranes containing triflate.

Investigation into the Differences Thermal Properties of SLS Polymer Powder Materials Using Differential Scanning Calorimetry (DSC)

2014 ◽  
Vol 548-549 ◽  
pp. 53-56
Author(s):  
Yusoff Way ◽  
Hadi Puwanto ◽  
M. Aichouni ◽  
Farizahani
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Polymer Materials ◽  
Powder Materials ◽  
Sintering Process ◽  
Scanning Calorimetry ◽  
Polyamide 12 ◽  
Materials Used

In order to produce good functional Laser Sintering (LS) parts, it is important that the powder on the part bed surface receives a sufficient amount of power energy through the laser sintering process. The reason is that sufficient energy density is produced when the energy input increases and is applied to the part bed surface, which causes a higher temperature, and thus better melt flow. The objective of this research is to investigate the thermal properties of polymer materials used in Selective Laser Sintering (SLS) processes. In this experiment, there were five different thermoplastics powders known as polyamide 12 (PA2200), Glass Fill Polyamide (GF3200), Alumide, Duraflex and CastForm were tested using Differential Scanning Calorimetry (DSC). This outcome of this research would assist the SLS users to improve the sintering process and quality of the part surface finish.

Effect of Molecular Weight on Mesomorphic Behavior of Side-Chain Liquid-Crystalline Azopolymers

2015 ◽  
Vol 1765 ◽  
pp. 133-138
Author(s):  
Flores V. Daniela ◽  
Larios L. Leticia
Keyword(s):  
Liquid Crystalline ◽  
Gel Permeation Chromatography ◽  
Side Chain ◽  
Scanning Calorimetry ◽  
Small Shift ◽  
Molecular Weights ◽  
Chemical Structures ◽  
Vis Spectroscopy ◽  
Wide Range ◽  
Hexyl Methacrylate

ABSTRACTThree methacrylic polymers bearing (phenylene)azobenzene moieties in the side-chain were synthesized via free-radical polymerization of monomer (E)-6-(4-((3’-cyano-4’-(hexyloxy) -[1,1’- biphenyl]-4-yl) diazenyl) phenoxy) hexyl methacrylate using 1, 5 and 10 mol% of 1,1’-azobis(cyclohexanecarbonitrile) (ABCN) as initiator. The chemical structures of monomer and polymers were confirmed by 1H NMR and FT-IR spectroscopies. Analysis by gel permeation chromatography (GPC) showed average molecular weights (Mw) of 1.0x105, 7.3x104, and 4.5x104 g/mol for polymers P1%, P5%, and P10%, respectively. These results indicate a clear dependence of the Mw on the amount of initiator used; the higher the amount of ABCN, the lowest the molecular mass. Thermotropic liquid-crystalline properties were analyzed by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). All polymers showed a liquid-crystalline behavior over a wide range of temperatures (>100°C) displaying smectic type mesophases. A small shift (around 8°C) upwards in the clearing temperature was observed on increasing the molecular masses from P10% to P1%. The trans-cis photo-isomerization of polymers was studied in solution and in thin films by UV-Vis spectroscopy. High cis-isomer contents in solution (>90%) were reached in relative short irradiation times.

scholarly journals Lignin as a Partial Polyol Replacement in Polyurethane Flexible Foam

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2302
Author(s):  
Akash Gondaliya ◽  
Mojgan Nejad
Keyword(s):  
Thermal Properties ◽  
Gel Permeation Chromatography ◽  
31P Nmr Spectroscopy ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Hydroxyl Content ◽  
Wide Range ◽  
Foam Properties ◽  
High Flexibility ◽  
Pu Foams

This study was focused on evaluating the suitability of a wide range of lignins, a natural polymer isolated from different plant sources and chemical extractions, in replacing 20 wt.% of petroleum-based polyol in the formulation of PU flexible foams. The main goal was to investigate the effect of unmodified lignin incorporation on the foam’s structural, mechanical, and thermal properties. The hydroxyl contents of the commercial lignins were measured using phosphorus nuclear magnetic resonance (31P NMR) spectroscopy, molar mass distributions with gel permeation chromatography (GPC), and thermal properties with differential scanning calorimetry (DSC) techniques. The results showed that incorporating 20 wt.% lignin increased tensile, compression, tear propagation strengths, thermal stability, and the support factor of the developed PU flexible foams. Additionally, statistical analysis of the results showed that foam properties such as density and compression force deflection were positively correlated with lignin’s total hydroxyl content. Studying correlations between lignin properties and the performance of the developed lignin-based PU foams showed that lignins with low hydroxyl content, high flexibility (low Tg), and high solubility in the co-polyol are better candidates for partially substituting petroleum-based polyols in the formulation of flexible PU foams intended for the automotive applications.

Deterioration of polyamide powder properties in the laser sintering process

2008 ◽  
Vol 222 (11) ◽  
pp. 2163-2176 ◽  
Author(s):  
D T Pham ◽  
K D Dotchev ◽  
W A Y Yusoff
Keyword(s):  
Gel Permeation Chromatography ◽  
Powdered Material ◽  
Laser Sintering ◽  
Influential Factors ◽  
Process Conditions ◽  
Scanning Calorimetry ◽  
Polyamide 12 ◽  
Powder Properties ◽  
Polyamide Powder

Polyamide 12 (PA12)-based powders are the most used materials in the laser sintering (LS) process for rapid manufacturing of functional parts. An average of 80–90 per cent of the powdered material in the LS building chamber is not sintered and could be reused. However, the properties of the recycled powder vary, which ultimately affects the quality of produced parts. These differences are due to the process conditions such as temperature and time, the LS machine design, and properties of the powder used for parts fabrication. This paper analyses the LS processing conditions and current recycling practices in relation with the deterioration or ageing of the PA12-based powders. Samples of new and recycled grades of PA2200 powder were artificially aged in a temperature-controlled oven and then tested using differential scanning calorimetry, melt flowrate indexer, and gel permeation chromatography. It has been found that the temperature and the time at which the unsintered powder was exposed are the most influential factors for the deterioration of LS powder properties.

scholarly journals Crystallization of Polytetrafluoroethylene in a Wide Range of Cooling Rates: Nucleation and Diffusion in the Presence of Nanosilica Clusters

Molecules ◽  
2019 ◽  
Vol 24 (9) ◽  
pp. 1797 ◽  
Author(s):  
Nicolas Bosq ◽  
Nathanaël Guigo ◽  
Jacques Persello ◽  
Nicolas Sbirrazzuoli
Keyword(s):  
Crystallization Behavior ◽  
Silicate Solution ◽  
Scanning Calorimetry ◽  
Slow Cooling ◽  
Cooling Rates ◽  
Fast Scanning Calorimetry ◽  
Wide Range ◽  
Fast Cooling ◽  
First Time ◽  
And Diffusion

Polytetrafluoroethylene (PTFE) is a polymer that displays exceptional properties. This synthetic fluoropolymer is also known to crystallize very fast upon cooling. The present work highlights for the first time the influence of nanosilica clusters on PTFE crystallization at fast cooling rates (up to 5000 K·s−1). The silica was synthesized from aqueous silicate solution and the surface modification was performed using TriEthoxyFluoroSilane (TEFS). In order to understand the crystallization behavior of PTFE/silica nanocomposite at a fast cooling rate, the measurements were carried out by Fast Scanning Calorimetry (FSC). The data were consequently combined with the measurements performed by conventional Differential Scanning Calorimetry (DSC). Interestingly, the results displayed variation of the crystallization behavior for the nanocomposite at fast cooling rates compared to slow cooling rates. The differences in crystal morphologies were then observed by Scanning Electron Microscopy (SEM) after slow and fast cooling rates. Finally, the effective activation energies (Eα) obtained from the crystallization under various cooling rates were combined in order to obtain one set of Hoffman-Lauritzen parameters. This procedure allowed us to show that the crystallization of PTFE in the presence of silica is promoted or hampered according to the cooling rates employed.

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