scholarly journals Sustainable Myrcene-Based Elastomers via a Convenient Anionic Polymerization

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 838
Author(s):  
David Hermann Lamparelli ◽  
Magdalena Maria Kleybolte ◽  
Malte Winnacker ◽  
Carmine Capacchione
Keyword(s):  
Anionic Polymerization ◽  
Sodium Hydride ◽  
Reactivity Ratios ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
Wide Range ◽  
Elastomeric Materials ◽  
Complete Study ◽  
Anionic Copolymerization ◽  
Trialkylaluminum Derivatives

Soluble heterocomplexes consisting of sodium hydride in combination with trialkylaluminum derivatives have been used as anionic initiating systems at 100 °C in toluene for convenient homo-, co- and ter-polymerization of myrcene with styrene and isoprene. In this way it has been possible to obtain elastomeric materials in a wide range of compositions with interesting thermal profiles and different polymeric architectures by simply modulating the alimentation feed and the (monomers)/(initiator systems) ratio. Especially, a complete study of the myrcene-styrene copolymers (PMS) was carried out, highlighting their tapered microstructures with high molecular weights (up to 159.8 KDa) and a single glass transition temperature. For PMS copolymer reactivity ratios, rmyr = 0.12 ± 0.003 and rsty = 3.18 ± 0.65 and rmyr = 0.10 ± 0.004 and rsty = 3.32 ± 0.68 were determined according to the Kelen–Tudos (KT) and extended Kelen–Tudos (exKT) methods, respectively. Finally, this study showed an easy accessible approach for the production of various elastomers by anionic copolymerization of renewable terpenes, such as myrcene, with commodities.

scholarly journals Recent Advancements in Polymer/Liposome Assembly for Drug Delivery: From Surface Modifications to Hybrid Vesicles

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1027
Author(s):  
Vincenzo De Leo ◽  
Francesco Milano ◽  
Angela Agostiano ◽  
Lucia Catucci
Keyword(s):  
Drug Delivery ◽  
First Generation ◽  
Phospholipid Bilayer ◽  
Bioactive Molecules ◽  
Systemic Delivery ◽  
Molecular Weights ◽  
Liposome Preparation ◽  
Wide Range ◽  
Liposome Surface

Liposomes are consolidated and attractive biomimetic nanocarriers widely used in the field of drug delivery. The structural versatility of liposomes has been exploited for the development of various carriers for the topical or systemic delivery of drugs and bioactive molecules, with the possibility of increasing their bioavailability and stability, and modulating and directing their release, while limiting the side effects at the same time. Nevertheless, first-generation vesicles suffer from some limitations including physical instability, short in vivo circulation lifetime, reduced payload, uncontrolled release properties, and low targeting abilities. Therefore, liposome preparation technology soon took advantage of the possibility of improving vesicle performance using both natural and synthetic polymers. Polymers can easily be synthesized in a controlled manner over a wide range of molecular weights and in a low dispersity range. Their properties are widely tunable and therefore allow the low chemical versatility typical of lipids to be overcome. Moreover, depending on their structure, polymers can be used to create a simple covering on the liposome surface or to intercalate in the phospholipid bilayer to give rise to real hybrid structures. This review illustrates the main strategies implemented in the field of polymer/liposome assembly for drug delivery, with a look at the most recent publications without neglecting basic concepts for a simple and complete understanding by the reader.

scholarly journals Analysis of the Impact on the Mechanical Properties of Modification of Oligohydroxyethers in Organic Solvent Solution with Rubbers

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 519
Author(s):  
Vitalii Bezgin ◽  
Agata Dudek ◽  
Adam Gnatowski
Keyword(s):  
Mechanical Properties ◽  
Scientific Paper ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Wide Range ◽  
Strength Tests ◽  
Materials Used ◽  
Styrene Butadiene ◽  
The Impact

This paper proposes and presents the chemical modification of linear hydroxyethers (LHE) with different molecular weights (380, 640, and 1830 g/mol) with the addition of three types of rubbers (polysulfide rubber (PSR), polychloroprene rubber (PCR), and styrene-butadiene rubber (SBR)). The main purpose of choosing this type of modification and the materials used was the possibility to use it in industrial settings. The modification process was conducted for a very wide range of modifier additions (rubber) per 100 g LHE. The materials obtained in the study were subjected to strength tests in order to determine the effect of the modification on functional properties. Mechanical properties of the modified materials were improved after the application of the modifier (rubber) to polyhydroxyether (up to certain modifier content). The most favorable changes in the tested materials were registered in the modification of LHE-1830 with PSR. In the case of LHE-380 and LHE-640 modified in cyclohexanol (CH) and chloroform (CF) solutions, an increase in the values of the tested properties was also obtained, but to a lesser extent than for LHE-1830. The largest changes were registered for LHE-1830 with PSR in CH solution: from 12.1 to 15.3 MPa for compressive strength tests, from 0.8 to 1.5 MPa for tensile testing, from 0.8 to 14.7 MPa for shear strength, and from 1% to 6.5% for the maximum elongation. The analysis of the available literature showed that the modification proposed by the authors has not yet been presented in any previous scientific paper.

scholarly journals Effects of Molecular Weight of Functionalized Liquid Butadiene Rubber as a Processing Aid on the Properties of SSBR/Silica Compounds

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 850
Author(s):  
Donghyuk Kim ◽  
Byungkyu Ahn ◽  
Kihyun Kim ◽  
JongYeop Lee ◽  
Il Jin Kim ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Anionic Polymerization ◽  
High Performance ◽  
Crosslink Density ◽  
Functional Group ◽  
Vital Role ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Mooney Viscosity ◽  
Silica Dispersion

Liquid butadiene rubber (LqBR) which used as a processing aid play a vital role in the manufacturing of high-performance tire tread compounds. However, the studies on the effect of molecular weight, microstructure, and functionalization of LqBR on the properties of compounds are still insufficient. In this study, non-functionalized and center-functionalized liquid butadiene rubbers (N-LqBR and C-LqBR modified with ethoxysilyl group, respectively) were synthesized with low vinyl content and different molecular weights using anionic polymerization. In addition, LqBR was added to the silica-filled SSBR compounds as an alternative to treated distillate aromatic extract (TDAE) oil, and the effect of molecular weight and functionalization on the properties of the silica-filled SSBR compound was examined. C-LqBR showed a low Payne effect and Mooney viscosity because of improved silica dispersion due to the ethoxysilyl functional group. Furthermore, C-LqBR showed an increased crosslink density, improved mechanical properties, and reduced organic matter extraction compared to the N-LqBR compound. LqBR reduced the glass transition temperature (Tg) of the compound significantly, thereby improving snow traction and abrasion resistance compared to TDAE oil. Furthermore, the energy loss characteristics revealed that the hysteresis loss attributable to the free chain ends of LqBR was dominant.

Flow curves of mixtures of acrylonitrile–styrene copolymers with different molecular weights at extremely high shear rates (abstract)

1991 ◽  
Vol 35 (4) ◽  
pp. 706-706
Author(s):  
Hideroh Takahashi ◽  
Yoshinori Inoue ◽  
Satoru Yamamoto ◽  
Osami Kamigaito
Keyword(s):  
High Shear ◽  
Flow Curves ◽  
Shear Rates ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
High Shear Rates

scholarly journals Copolymerization of 4-Acetylphenyl Methacrylate with Ethyl Methacrylate: Synthesis, Characterization, Monomer Reactivity Ratios, and Thermal Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Gamze Barim ◽  
Mustafa Gokhun Yayla
Keyword(s):  
Thermal Stability ◽  
Nonlinear Least Squares ◽  
Reactivity Ratios ◽  
Spectroscopic Techniques ◽  
Monomer Reactivity Ratios ◽  
Scanning Calorimetry ◽  
Ethyl Methacrylate ◽  
Wide Range ◽  
Monomer Feed ◽  
Copolymer Poly

Methacrylates have high glass transition temperature (Tg) values and high thermal stability. A new methacrylate copolymer, poly(4-acetylphenyl methacrylate-co-ethyl methacrylate) (APMA-co-EMA), was synthesized. The thermal behaviors of copolymers were investigated by differential scanning calorimetry and thermogravimetric analysis. They behaved as new single polymers with singleTg’s and the thermal stability of the copolymers increased with increasing 4-acetylphenyl methacrylate (APMA) fraction, leading to the manufacture of copolymers with desiredTgvalues. Structure and composition of copolymers for a wide range of monomer feed ratios were determined by Fourier transform infrared (FT-IR) and1H-nuclear magnetic resonance (1H-NMR) spectroscopic techniques. Copolymerization reactions were continued up to 40% conversions. The monomer reactivity ratios for copolymer system were determined by the Kelen-Tüdös (ra(APMA)=0.81;rb(EMA)=0.61) and extended Kelen-Tüdös (ra=0.77;rb=0.54) methods and a nonlinear least squares (ra=0.74;rb=0.49) method.

Reactivity ratios for the anionic copolymerization of ethylene oxide and butylene oxide in bulk

1993 ◽  
Vol 29 (2-3) ◽  
pp. 281-286 ◽  
Author(s):  
Stewart Dickson ◽  
Ga-Er Yu ◽  
Frank Heatley ◽  
Colin Booth
Keyword(s):  
Ethylene Oxide ◽  
Reactivity Ratios ◽  
Anionic Copolymerization

scholarly journals The Effect of the Isomeric Chlorine Substitutions on the Honeycomb-Patterned Films of Poly(x-chlorostyrene)s/Polystyrene Blends and Copolymers via Static Breath Figure Technique

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 167 ◽  
Author(s):  
Leire Ruiz-Rubio ◽  
Leyre Pérez-Álvarez ◽  
Julia Sanchez-Bodón ◽  
Valeria Arrighi ◽  
José Luis Vilas-Vilela
Keyword(s):  
Voronoi Tessellation ◽  
Contact Guidance ◽  
Polymeric Thin Films ◽  
Styrene Copolymers ◽  
Breath Figure ◽  
Wide Range ◽  
Breath Figure Method ◽  
Patterned Films ◽  
Figure Technique ◽  
Potential Use

Polymeric thin films patterned with honeycomb structures were prepared from poly(x-chlorostyrene) and statistical poly(x-chlorostyrene-co-styrene) copolymers by static breath figure method. Each polymeric sample was synthesized by free radical polymerization and its solution in tetrahydrofuran cast on glass wafers under 90% relative humidity (RH). The effect of the chorine substitution in the topography and conformational entropy was evaluated. The entropy of each sample was calculated by using Voronoi tessellation. The obtained results revealed that these materials could be a suitable toolbox to develop a honeycomb patterns with a wide range of pore sizes for a potential use in contact guidance induced culture.

The conformational composition of and structure formation in polyvinylchloride over a wide range of molecular weights

1972 ◽  
Vol 14 (9) ◽  
pp. 2119-2131 ◽  
Author(s):  
V.P. Lebedev ◽  
V.I. Zegel'man ◽  
D.Ya. Tsvankin ◽  
Ye.N. Zil'berman
Keyword(s):  
Structure Formation ◽  
Conformational Composition ◽  
Molecular Weights ◽  
Wide Range

Materials Compatibility With Pyrolysis Biofuel

2001 ◽  
Author(s):  
D. W. Kirk ◽  
Z. R. Li ◽  
D. Fuleki ◽  
P. C. Patnaik
Keyword(s):  
Stainless Steel ◽  
Alloy Steel ◽  
Polymeric Materials ◽  
304L Stainless Steel ◽  
Chromium Alloy ◽  
Stainless Steel 316L ◽  
Diesel Fuels ◽  
Wide Range ◽  
Elastomeric Materials ◽  
Pyrolysis Oils

The conversion of biomass such as wood and wood byproducts via pyrolysis into a liquid fuel is important in maximizing the use of material resources and in providing alternative and renewable sources of energy. Pyrolysis oils (or biofuels) have good combustion characteristics but are compositionally different from conventional diesel fuels. This difference requires that materials in contact with the biofuel be tested for compatibility. Three types of biofuels were tested for compatibility with a variety of polymeric materials and metal alloys. The test temperatures were set at 80°C to represent aggressive field usage conditions. The tests were conducted using coupons, which were fully immersed in the fluid for periods up to 15 days. These tests revealed that the metals 304L stainless steel, 316L stainless steel, 430 stainless steel and 20M04 stainless steels had corrosion rates of less than 0.007 mm/y and are suitable for use with the oils tested. A non-traditional low chromium alloy steel, MASH, was also examined and was found to be highly susceptible to all fuels at the high temperature tested and corroded at rates up to 3.7 mm/y. At room temperature, the alloy showed good resistance with a corrosion rate less than <0.009 mm/y. The polymeric materials showed a wide range of properties in the oils tested. Non-elastomers such as polytetrafluoroethylene, polypropylene and high-density polyethylene in general showed little swelling or staining in the oils. The elastomeric materials were much more susceptible to swelling, weight gain and change of surface properties. The attack on elastomeric materials was quite rapid with significant volume expansion seen within 24 hours. Viton, Buna-N and EPDM had volume changes up to 100% during a 10-day test and were not considered suitable seal materials for these oils. Multiple day tests for the low alloy steel at 80°C revealed that the corrosion attack was linear in nature leaving a corrosion scale, which slowed but did not prevent further attack. Details of the material degradation will be discussed.

Mechanical Seal with Elastomeric Rotating Element. Part 2: Experimental Study

1994 ◽  
Vol 67 (1) ◽  
pp. 62-75 ◽  
Author(s):  
Michael Rivkin ◽  
Arnold Kholodenko
Keyword(s):  
Silicon Carbide ◽  
Friction Coefficient ◽  
Water Pressure ◽  
Original Data ◽  
Friction Behavior ◽  
Effective Contact ◽  
Original Length ◽  
Wide Range ◽  
Elastomeric Materials ◽  
P Type

Abstract An innovative flexible faced mechanical shaft seal using common elastomeric materials was designed and tested to determine its friction coefficient at a wide range of temperatures and speeds, its rate of heat generation, and its feasibility for use in the process industry. The new seal was constructed using an elastomeric rotating element stretched over the sleeve to at least 20 percent of its original length and an unlapped silicon carbide stationary annular ring. It was found that the main advantage of the elastomeric seal is its ability to maintain stable lubrication with a fluid film considerably thinner than that of traditional hard face seals, and consequently achieve negligible net leakage. This is particularly significant with respect to control of volatile organic carbon emissions. An experimental device was designed for precise measurement of the friction coefficient as well as the long term friction behavior of seal pairs in a wide range of liquid pressure and temperature. The original data were obtained for friction coefficient of EPDM, HNBR, FKM, and TFE/P type elastomers in contact with silicon carbide in the temperature range 15–110°C, linear speeds 0–12 m/s, water pressure 0.15–0.40 MPa, and effective contact pressure 0.8–1.2 MPa. Experiments showed that the friction coefficient constantly grows, typically from 0.05 to 0.15 at sliding speeds of 2–12 m/s, with temperature increases from 15 to 70°C. The temperature behavior of the friction coefficient above 70°C greatly depends on the elastomer. For high temperature elastomers, such as FKM, the friction coefficient may decrease slightly at 70°C; whereas, for EPDM, it continues to increase as temperature increases.

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