scholarly journals Formation of Polyethylene Glycol Particles Using a Low-Temperature Supercritical Assisted Atomization Process

Molecules ◽  
2019 ◽  
Vol 24 (12) ◽  
pp. 2235
Author(s):  
Hsien-Tsung Wu ◽  
Hong-Ming Tsai ◽  
Tsung-Hsuan Li
Keyword(s):  
Carbon Dioxide ◽  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Low Temperature ◽  
Flow Rate ◽  
Fine Particles ◽  
Volumetric Flow Rate ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Rate Ratios

Polyethylene glycol (PEG) particles were prepared using low-temperature supercritical assisted atomization (LTSAA) with carbon dioxide as the spraying medium or the co-solute and acetone as the solvent. The effects of several key factors on the particle size were investigated. These factors included the concentration of the PEG solution, precipitator temperature, saturator temperature, ratio of the volumetric flow rate of carbon dioxide to the PEG solution, and the molecular weight of PEG. Spherical and non-aggregated PEG particles, with a mean size of 1.7–3.2 µm, were obtained in this study. The optimal conditions to produce fine particles were found to be a low concentration of the PEG solution, a low precipitator temperature, and low molecular weight of the PEG. The phase behavior of the solution mixture in the saturator presented a qualitative relationship. At the optimized volumetric flow rate ratios, the composition of CO2 in the feed streams was near the bubble points of the saturator temperatures. X-ray and differential scanning calorimetry analyses indicated that LTSAA-treated PEG had a reduced degree of crystallinity, which could be modulated via the precipitator temperature. PEG microparticles prepared by a LTSAA process would be promising carriers for drug-controlled formulations of PEG-drug composite particles.

scholarly journals Effect of DMPA and Molecular Weight of Polyethylene Glycol on Water-Soluble Polyurethane

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1915 ◽  
Author(s):  
Eyob Wondu ◽  
Hyun Woo Oh ◽  
Jooheon Kim
Keyword(s):  
Molecular Weight ◽  
Contact Angle ◽  
Polyethylene Glycol ◽  
Photoelectron Spectroscopy ◽  
Water Solubility ◽  
Soft Segment ◽  
Water Soluble ◽  
Size Exclusion ◽  
Resonance Spectroscopy ◽  
Scanning Calorimetry

In this study water-soluble polyurethane (WSPU) was synthesized from isophorone diisocyanate (IPDI), and polyethylene glycol (PEG), 2-bis(hydroxymethyl) propionic acid or dimethylolpropionic acid (DMPA), butane-1,4-diol (BD), and triethylamine (TEA) using an acetone process. The water solubility was investigated by solubilizing the polymer in water and measuring the contact angle and the results indicated that water solubility and contact angle tendency were increased as the molecular weight of the soft segment decreased, the amount of emulsifier was increased, and soft segment to hard segment ratio was lower. The contact angle of samples without emulsifier was greater than 87°, while that of with emulsifier was less than 67°, indicating a shift from highly hydrophobic to hydrophilic. The WSPU was also analyzed using Fourier transform infrared spectroscopy (FT-IR) to identify the absorption of functional groups and further checked by X-ray photoelectron spectroscopy (XPS). The molecular weight of WSPU was measured using size-exclusion chromatography (SEC). The structure of the WSPU was confirmed by nuclear magnetic resonance spectroscopy (NMR). The thermal properties of WSPU were analyzed using thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC).

Improving Biogas Quality through Circulated Water Scrubbing Method

2015 ◽  
Vol 776 ◽  
pp. 443-448 ◽  
Author(s):  
Hendry Sakke Tira ◽  
Yesung Allo Padang ◽  
Mirmanto ◽  
Hendriono
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Sulfide ◽  
Flow Rate ◽  
Fossil Fuels ◽  
Volumetric Flow Rate ◽  
Calorific Value ◽  
Energy Resources ◽  
Dissolve Carbon Dioxide ◽  
Biogas Purification

The dependence of human being on fossil fuels has decreased significantly the conventional energy resources. To overcome this problem it is required alternative substitute fuels which are cheap and accessible which biogas is one of the fuels. Nevertheless, the use of biogas has not yet been maximized because of the low calorific value which is produced from the process without purification. The circulated water absorption method is one mean of effective biogas purification. Under this method it is expected to increase the level of methane (CH4) and to reduce both the level of carbon dioxide (CO2) and hydrogen sulfide (H2S). In order to obtain the aim, the research was carried out under variations of water and biogas volumetric flow rate. The results show that the highest quality of biogas produced was under the variation of water volumetric flow rate of 15 lt/min with biogas volumetric flow rate of 1 lt/min which increased the level of methane (CH4) from 59.36 % to 62.8 % and decreased the carbon dioxide (CO2) content from 33.53 % to 26.8 %, and hydrogen sulfide (H2S) from 208.33 to 86 ppm. Lower biogas and water volumetric rates allowed longer contact between biogas molecule and absorbent. This resulted in an opportunity for absorbent more active to dissolve carbon dioxide and hydrogen sulfide in biogas. These compounds then flowed outward of the scrubbing unit along with the absorbent. The research proved that the raw biogas purification by circulated water scrubbing method was an effective mean in enhancing the quality of biogas.

Preparation of Monodisperse PEG Microspheres by a T-Junction Microfluidic Chip

2012 ◽  
Vol 465 ◽  
pp. 178-181 ◽  
Author(s):  
Yu Min Ren ◽  
Bing Yu ◽  
Hai Lin Cong ◽  
Yu Rong Ma ◽  
Zhen Zhen Ma ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Flow Rate ◽  
Microfluidic Chip ◽  
Uv Exposure ◽  
Microfluidic Channels ◽  
Microfluidic Chips ◽  
Silicon Oil ◽  
Sample Flow Rate ◽  
Rate Ratios

Monodisperse polyethylene glycol (PEG) microspheres were prepared using microfluidic chips coupled with photopolymerization technique. Based on sheath effect in T-junction microfluidic channels, dispersions of uniform PEG prepolymer droplets in silicon oil are formed. The diameters of the formed PEG prepolymer droplets in the dispersions were controlled very well by altering the relative sheath/sample flow rate ratios. After photopolymerization under UV exposure, the uniform PEG prepolymer droplets isolated by silicon oil underwent photocrosslinking and became monodisperse PEG microspheres.

Recrystallization of Caffeine Using Supercritical Carbon Dioxide as Antisolvent

2009 ◽  
Vol 4 (5) ◽  
Author(s):  
Joel Augusto da Silva Romero ◽  
Thiago Leandro Souza ◽  
Guilherme Sunehiro ◽  
Marcos Hiroyuki Kunita ◽  
Nanci Pinheiro
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Flow Rate ◽  
Solution Flow Rate ◽  
Organic Solution ◽  
Scanning Calorimetry ◽  
Experimental Conditions ◽  
Solution Flow ◽  
Amorphous Particles ◽  
Supercritical Carbon

The supercritical antisolvent (SAS) process has been widely used to obtain many types of crystalline and amorphous particles of polymers and drugs. In this process, solute particles precipitate from an organic solution when it is sprayed into a compressed antisolvent continuum. The antisolvent is miscible with the organic solvent, but immiscible with the solute. The objective of this work was to investigate the application of supercritical carbon dioxide as antisolvent for the recrystallization of caffeine; a compound largely employed in pharmaceutical and food industries. The carbon dioxide was pressurized at 100bar and the solution was injected into a precipitation chamber, thereby inducing its supersaturation and particle precipitation. The effect of process parameters such as initial concentration of caffeine in the organic solution (3, 5 and 10mg/mL), organic solution flow rate (3mL/min), concentration of CO2 (96 and 98mol%), drying flow rate (990mL/min) and pressure gradient between the precipitation chamber and the exit of the sprayer tube (110 and 220bar) on the solid state properties of caffeine was investigated. The pressure (100bar) and temperature (60oC) of the precipitation chamber were kept constant. The results showed a great difference between the processed and unprocessed samples. In all experimental conditions a reduction in caffeine mean particle size was observed, with length ranging from 0.6 to 168.3?m and width from 0.1 to 12.7?m, compared to the mean size of unprocessed caffeine particles (16.6 to 214.4?m in length and 7.1 to 131.2?m in width). This fact was confirmed by differential scanning calorimetry (DSC), where the precipitated particles presented lower fusion enthalpy than the unprocessed ones. Smaller crystal needles (0.3?m to 0.4?m) were obtained with crystallization at the lowest caffeine concentration in the presence of 98mol% CO2.

scholarly journals Effect of polyethylene glycol mixtures as ointment base on the physicochemical properties of Lavsan atraumatic wound dressings

2019 ◽  
Vol 14 (5) ◽  
pp. 71-78
Author(s):  
A. A. Korolchuk ◽  
E. S. Zhavoronok ◽  
O. A. Legonkova ◽  
S. A. Kedik
Keyword(s):  
Polyethylene Glycol ◽  
Flow Behavior ◽  
Wound Dressings ◽  
Degree Of Crystallinity ◽  
Polyethylene Glycols ◽  
Dynamic Mode ◽  
Scanning Calorimetry ◽  
Rotational Viscometer ◽  
Molecular Weights ◽  
Ointment Base

Objectives. Modern atraumatic wound dressings are based on polyethylene terephthalate, or Lavsan, which is shaped to form threads. The aim of the study was to determine the reasons for Lavsan woven nets’ hardening and becoming more trauma-prone during storage, and to find ways of eliminating these effects.Methods. We used differential scanning calorimetry, performed on a NETZSCH DSС 204 F1 Phoenix device, in a dynamic mode with a temperature range from 20 to 300 °C in argon flow to determine phase states, glass transition temperatures, and melting temperatures of Lavsan fibers (including those treated with polyethylene glycol mixtures). We performed rheoviscometry studies on a Brookfield DV2TLV rotational viscometer, with a SC4-16 thermostatic control unit, at the following temperatures: 25, 36.6, 40, 45, 50, and 55 °C, with shear rates ranging from 120 to 200 s–1 to determine dynamic viscosity and investigate the mixing characteristics of polyethylene glycols with different molecular weights.Results. We have established that samples of Lavsan woven nets, stored long-term in laboratory conditions (up to 2, 3, and 16 years), are in the crystalline state with a high degree of crystallinity. Upon heating these nets to 300 °C, it is possible to reduce the degree of crystallinity by 19–32%, but it does not completely eliminate the effect. Polyethylene glycols and their mixtures which exhibit non-Newtonian flow behavior and are used as an ointment base, have a significant effect on Lavsan’s crystallinity. We have determined that the optimal ratio of polyethylene glycols for the modification of Lavsan nets is PEG-400:PEG-1500 = 80:20 wt %. Upon storing Lavsan woven nets in this mixture at room temperature, the Lavsan’s crystallinity is greatly reduced, and upon heating the system, the crystallinity practically disappears.Conclusions. The effect of polyethylene glycol mixtures (the base for therapeutic ointments) with various molecular weights on the phase organization of Lavsan has been evaluated. As a result of this study, we can offer a new approach to reduce the injuring effect of synthetic (Lavsan) bases of atraumatic wound dressings.

Effect of Poly(D-Lactic Acid)-co-Polyethylene Glycol on the Crystallization of Poly(L-Lactic Acid)

2017 ◽  
Vol 751 ◽  
pp. 283-289 ◽  
Author(s):  
Ployrawee Kaewlamyai ◽  
Amornrat Lertworasirikul
Keyword(s):  
Lactic Acid ◽  
Polyethylene Glycol ◽  
Weight Ratio ◽  
Crystallization Rate ◽  
Heat Stability ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Infrared Spectrometry ◽  
Scanning Calorimetry

Poly (lactic acid) (PLA) is a biopolymer derived from renewable resources and can be disposed of without creating harm to the environment. PLA can be formed by thermoplastic processes and has good mechanical properties. However, its disadvantages are a high crystallization temperature, slow crystallization rate, poor heat stability and low ductility. In the past, it was found that poly (D-lactic acid) (PDLA) can form complexes with poly (L-lactic acid) (PLLA) and the complexes could accelerate the crystallization and increase the degree of crystallinity of the PLA, but decrease the ductility. It is known that polyethylene glycol (PEG) can improve the ductility of PLLA. In this research, PDLA was copolymerized with PEG in an attempt to improve both crystallization behavior and ductility of PLLA. Poly (D-lactic acid)-co-polyethylene glycol (PDEG) was synthesized by ring opening polymerization using D-lactide and PEG at a D-lactide:PEG weight ratio of 10:3. The PDEG was blended with PLLA with a PDEG content of 0wt% to 50wt% by melt blending process. Fourier transform infrared spectrometry (FT-IR) and X-Ray diffractometry (XRD) confirmed the stereocomplex formation between PDEG and PLLA. Characterization by differential scanning calorimetry (DSC) revealed that crystallization temperatures of the blends were decreased in the presence of PDEG. Storage moduli and tan of the blends obtained from dynamic mechanical analysis (DMA) decreased as PDEG content increased. Polarized optical microscopy (POM) micrographs of blends with PDEG content of 1wt% to 5wt% obviously showed that crystallization rate was increased. PDEG has the potential to be an effective nucleating agent and efficient plasticizer for PLLA.

scholarly journals Crystallinity of Electrospun and Centrifugal Spun Polycaprolactone Fibers: A Comparative Study

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Eva Kuzelova Kostakova ◽  
Laszlo Meszaros ◽  
Gabriela Maskova ◽  
Lenka Blazkova ◽  
Tamas Turcsan ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Production Technology ◽  
Average Molecular Weight ◽  
Degree Of Crystallinity ◽  
Fibrous Materials ◽  
Scanning Calorimetry ◽  
Crystallinity Degree ◽  
A Minor ◽  
Technology Effects ◽  
The Degree Of Crystallinity

Crystalline properties of semicrystalline polymers are very important parameters that can influence the application area. The internal structure, like the mentioned crystalline properties, of polymers can be influenced by the production technology itself and by changing technology parameters. The present work is devoted to testing of electrospun and centrifugal spun fibrous and nanofibrous materials and compare them to foils and granules made from the same raw polymer. The test setup reveals the structural differences caused by the production technology. Effects of average molecular weight are also exhibited. The applied biodegradable and biocompatible polymer is polycaprolactone (PCL) as it is a widespread material for medical purposes. The crystallinity of PCL has significant effect on rate of degradation that is an important parameter for a biodegradable material and determines the applicability. The results of differential scanning calorimetry (DSC) showed that, at the degree of crystallinity, there is a minor difference between the electrospun and centrifugal spun fibrous materials. However, the significant influence of polymer molecular weight was exhibited. The morphology of the fibrous materials, represented by fiber diameter, also did not demonstrate any connection to final measured crystallinity degree of the tested materials.

Measurement and Analysis on Dynamics Cold Crystallization Parameter of High-Density Polyethylene (HDPE) Sheet by Vibration Force Field

2011 ◽  
Vol 103 ◽  
pp. 447-451
Author(s):  
Bing Li ◽  
Xue Mei Qin ◽  
Bao Shan Shi
Keyword(s):  
Molecular Weight ◽  
Low Temperature ◽  
Crystalline Structure ◽  
High Density Polyethylene ◽  
Crystalline Polymer ◽  
High Density ◽  
Polymer Materials ◽  
Heat Of Fusion ◽  
X Ray Diffraction ◽  
Scanning Calorimetry

Physics mechanics properties of polymer materials don’t only depend on their chemical constitution, molecular weight and distribution of molecular weight, but also depend on their agglomerate configuration. The effect of vibration on the microstructure and mechanical properties of high-density polyethylene (HDPE) sheets, obtained through vibration plasticating extruder in low temperature, were studied systematically. Crystalline polymer is analyzed by differential scanning calorimetry(DSC), wide angle X ray diffraction(WAXD). The test result which represents parameters of crystalline structure is helped to judge the outside factors for crystalline structure, such as melting point, crystallinity and heat of fusion by DSC and crystallinity, crystal plane distance and grain size by WAXD, and canning electron microcopy (SEM). The results indicate that the vibration extrudate in low temperature has higher crystallinity, perfect crystallite, and strong inter-spherulite ties.

scholarly journals Crystallization behavior of diblock copolymers based on PCL and PLLA biopolymers

2014 ◽  
Vol 47 (6) ◽  
pp. 1948-1957 ◽  
Author(s):  
Iván Navarro-Baena ◽  
Angel Marcos-Fernandez ◽  
José M. Kenny ◽  
Laura Peponi
Keyword(s):  
Molecular Weight ◽  
Crystallization Behavior ◽  
Diblock Copolymers ◽  
Type Equation ◽  
Melting Behavior ◽  
Degree Of Crystallinity ◽  
Copolymer Composition ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Cell Parameters

This paper aims to increase the knowledge on the crystallinity features of diblock copolymers based on poly(∊-caprolactone) (PCL) and poly(L-lactic acid) (PLLA). Six diblock copolymers have been synthesized starting from a synthesized PCL with a molecular weight of around 5000 g mol−1, varying the molecular weight of the PLLA block. The crystalline unit cells for both PCL and PLLA blocks have been studied with wide-angle X-ray diffraction analysis. The effects of the copolymer composition on the crystalline cell parameters as well as on the degree of crystallinity and the crystallite sizes, determined using the Scherrer equation, are discussed. The double-crystalline nature of the diblock copolymer was confirmed by small-angle X-ray scattering experiments. This technique was also used to study the melting behavior of the copolymers by studying the variation of the diffraction spectra with temperature. The effects of PCL chains on the packing of the PLLA lamellae are discussed. Finally, the crystallization behavior was studied by differential scanning calorimetry analysis, performing experiments at different crystallization temperatures and studying the results by fitting the experimental data with an Avrami-type equation. The influence of each block on the crystallization parameters of the other block are discussed. This study allows a better understanding of the effects of the chemical structure on the crystalline behavior of these block copolymers, leading to the possibility to tailor the materials for specific applications.

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