Basic Study of Continuous Ultrasonic Devulcanization of Unfilled Silicone Rubber

1999 ◽  
Vol 72 (1) ◽  
pp. 152-164 ◽  
Author(s):  
B. Diao ◽  
A. I. Isayev ◽  
V. Y. Levin
Keyword(s):  
Mechanical Properties ◽  
Silicone Rubber ◽  
Structural Characteristics ◽  
Density Measurement ◽  
Gel Permeation Chromatography ◽  
Processing Conditions ◽  
Basic Study ◽  
Gel Permeation ◽  
Branched Structure ◽  
Better Than

Abstract The present paper describes a basic study of the devulcanization of unfilled model silicone rubber vulcanizates using a continuous ultrasonic reactor. The devulcanization was conducted under several processing conditions. Cure behavior, rheological properties, structural characteristics of the devulcanized rubber, and mechanical properties of revulcanized rubbers were studied. Gel fraction and crosslink density measurement indicate that the rubber is partially devulcanized. The gel permeation chromatography (GPC) results imply that the creation of a branched structure in the network is a possibility after devulcanization. Under the optimal devulcanization condition, the mechanical properties of revulcanized rubber are better than those of the virgin rubber. Devulcanized silicone rubber was also blended with the virgin one. The blends show the same tensile strength and modulus as the virgin rubber but higher elongation.

Novel Ultrasonic Technology for Devulcanization of Waste Rubbers

1995 ◽  
Vol 68 (2) ◽  
pp. 267-280 ◽  
Author(s):  
A. I. Isayev ◽  
J. Chen ◽  
A. Tukachinsky
Keyword(s):  
Mechanical Properties ◽  
Structural Characteristics ◽  
Three Dimensional ◽  
Ultrasonic Waves ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Processing Conditions ◽  
Laboratory Reactor ◽  
Plant Level ◽  
Theological Properties

Abstract A novel patented process and several reactors have been developed for devulcanization of waste rubbers. The technology is based on the use of the high power ultrasonics. The ultrasonic waves of certain levels in the presence of pressure and heat rapidly break up the three-dimensional network in crosslinked rubbers. The devulcanized rubber can be reprocessed, shaped and revulcanized in much the same way as a virgin rubber. The first laboratory reactor has been scaled up to pilot-plant level by the National Feedscrew and Machining, Inc. Various devulcanization experiments were carried out with model styrene-butadiene rubber (SBR) and with ground rubber tire (GRT). Curing behavior, Theological properties, and structural characteristics of rubbers devulcanized at various processing conditions were studied, as well as mechanical properties of revulcanized rubber samples. A possible mechanism of the devulcanization is discussed. The performed measurements indicate that the rubbers are partially devulcanized, and the devulcanization process is accompanied by certain degradation of the macromolecular chains. In spite of these observations, the processing conditions are identified at which the retention of the mechanical properties is found to be good. A further work is in progress to find the optimal conditions of devulcanization and to improve the selectivity of the process towards breaking up the chemical network only.

scholarly journals Extraction, Structural Characterization, and Anti-Hepatocellular Carcinoma Activity of Polysaccharides From Panax ginseng Meyer

2021 ◽  
Vol 11 ◽  
Author(s):  
Hui Jia ◽  
Bin Zhao ◽  
Fangfang Zhang ◽  
Ramesh Kumar Santhanam ◽  
Xinying Wang ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Hepg2 Cells ◽  
Cytotoxic Effect ◽  
Structural Characteristics ◽  
Gel Permeation Chromatography ◽  
Salting Out ◽  
Gel Permeation ◽  
Acidic Polysaccharides ◽  
Hepg2 Cell Lines ◽  
First Time

Polysaccharides are the main active ingredients of ginseng. To extract the most effective polysaccharides against hepatocellular carcinoma (HCC), we isolated and characterized the polysaccharides from the mountain cultivated ginseng (MCG) and compared their composition and cytotoxic effect with cultivated ginseng (CG) polysaccharide against HepG2 cell lines for the first time. MCG polysaccharides and CG polysaccharides were fractionated into two fractions such as MTPS-1, MTPS-2 and CTPS-1, CTPS-2 by salting out, respectively. Compared to CG, MCG possessed appreciable cytotoxic effect against HepG2 cells among that MTPS-1 possess fortified effect. Then, MTPS-1 was selected for further isolation process and seven acidic polysaccharides (MCGP-1–MCGP-7) were obtained using ethanol precipitation, ion-exchange, and gel permeation chromatography techniques. Structural characteristics of the polysaccharides (MCGP-1–MCGP-7) were done by adapting methylation/GC-MS and NMR analysis. Overall, MCGP-3 polysaccharide was found to possess significant cytotoxic effect against HepG2 cells with the IC50 value.

Wet Blending of Pregelatinized Starch and Poly(butylene succinate)

2012 ◽  
Vol 557-559 ◽  
pp. 1121-1126
Author(s):  
Hong Kai Ni ◽  
Biao Yang ◽  
Hui Sun ◽  
Guo Zhi Xu
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Starch Content ◽  
Gel Permeation Chromatography ◽  
Crystallization Time ◽  
Biodegradable Films ◽  
Butylene Succinate ◽  
Gel Permeation ◽  
Pregelatinized Starch ◽  
Thermal Stability Of

The biodegradable films of the blend of pregelatinized starch and poly(butylene succinate) were prepared by using mixture of water and glycerin as plasticizing agent. The mechanical properties, thermal performance of the films and molecular weight of PBS were investigated. Gel permeation chromatography (GPC) results indicate that the molecular weight of PBS has no obvious change in spite of the presence of water. Starch can be well plasticized and uniformly dispersed in PBS matrix without obvious particles and agglomeration observed. When starch content was 10 wt% of total resin, the mechanical properties of the blend film is similar to that of pure PBS. With the further increase in the starch content, the mechanical properties were reduced; the crystallization temperature of the blend increased and the crystallization time is shortened. The thermogravimetric analysis found that pregelatinized starch and PBS decomposed in their respective temperature, the thermal stability of materials decreased.

scholarly journals Structure and Neuroprotective Effect of Polysaccharide from Viscera Autolysates of Squid Ommastrephes bartrami

Marine Drugs ◽  
2019 ◽  
Vol 17 (3) ◽  
pp. 188 ◽  
Author(s):  
Peng Ye ◽  
Peipei Li ◽  
Wenge Yang ◽  
Yue Zhao ◽  
Yuqin Zhao ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Glucuronic Acid ◽  
Structural Characteristics ◽  
Neuroprotective Effect ◽  
Gel Permeation Chromatography ◽  
Neuroprotective Activity ◽  
Gas Chromatography Mass Spectrometry ◽  
Methylation Analysis ◽  
Sod Activity ◽  
Gel Permeation

To explore bioactive polysaccharides from the byproducts of squid processing, a heteropolysaccharide, named SV2-1, was isolated from the viscera of squid Ommastrephes bartrami by autolysis, anion-exchange and gel-permeation chromatography and measured for its neuroprotective activity. It was a homogeneous polysaccharide with a molecular weight of 2.3 kDa by HPSEC analysis. SV2-1 contained glucuronic acid, galactosamine and fucose in the ratio of 1.0:1.1:1.2. Its structural characteristics were elucidated by methylation analysis, gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR). The backbone of SV2-1 was composed of alternant →4)-α-l-Fucp-(1→ and →3)-β-d-GlcUA-(1→ Most of →4)-α-l-Fucp-(1→ (90%) was substituted by single α-d-GlcNAc as the branches. SV2-1 can protect against the death of PC12 induced by 6-OHDA, and effectively improves cell viability and reduces extracellular LDH release in PC12 cells after injury. Moreover, SV2-1 significantly increases SOD activity but decreases MDA levels.

scholarly journals Synthesis, Characterization and Copolymerization of N-(phenylamino)maleimide with MMA

2007 ◽  
Vol 4 (2) ◽  
pp. 265-271
Author(s):  
B. L. Hiran ◽  
S. N. Paliwal ◽  
Jyoti Choudhary ◽  
P. R. Choudhary
Keyword(s):  
Thermal Stability ◽  
Molecular Weight ◽  
Density Measurement ◽  
Gel Permeation Chromatography ◽  
Radical Copolymerization ◽  
Free Radical Copolymerization ◽  
H Nmr ◽  
Gel Permeation ◽  
Ft Ir ◽  
Thermal Stability Of

The free radical copolymerization of N-(phenylamino)maleimide (N-PAMI) was carried. The copolymerization with methyl methacrylate (MMA) was performed at 65°C with AIBN as the initiator in THF solvent. Resulting copolymer was characterized by density measurement, intrinsic viscosity, solubility, FT-IR &1H NMR spectroscopy. Effect of the solvent and time on copolymer yield was also investigated. The molecular weight of copolymer was determined by gel permeation chromatography (GPC). The thermal stability of copolymer was determined by Thermogravimetric analysis (TGA).

Derived from poplar leaves graphene-modified silicone rubber composites

2019 ◽  
Vol 33 (12) ◽  
pp. 1591-1602 ◽  
Author(s):  
Weili Wu ◽  
He Huang
Keyword(s):  
Mechanical Properties ◽  
Silicone Rubber ◽  
Silane Coupling Agent ◽  
Rubber Composites ◽  
Elongation At Break ◽  
Green Materials ◽  
Silane Coupling ◽  
Thermal Stability Of ◽  
Better Than ◽  
Poplar Leaves

Poplar leaves graphene (PLG) was synthesized from the poplar leaves. Modified poplar leaves graphene (M-PLG) was obtained by graphene treated with silane coupling agent γ-aminopropyltriethoxysilane (KH550). The M-PLG-modified silicone rubber (methyl ethylene silicon rubber [MVQ]) composites were prepared by mechanical blending. The effects of M-PLG on the mechanical properties, thermal properties, and morphology structure of MVQ were investigated. The results showed that the carbon content and purity of the PLG were high. The M-PLG can be evenly dispersed into MVQ compared with the PLG, the mechanical properties of the M-PLG/MVQ composites were better than those of the PLG/MVQ when M-PLG content was 0.1 parts per hundred rubber (phr), the tensile strength and elongation at break are increased by 36.2% and 19.4% respectively, and wear resistance increased by 57.1%. The thermal stability of the M-PLG/MVQ was also better. This concept of combining PLG with MVQ demonstrated the potential of preparing novel green materials with excellent properties.

Degradation of ABS in ABS/CaCO3 Composites during Reprocessing

2012 ◽  
Vol 455-456 ◽  
pp. 845-850 ◽  
Author(s):  
Xiao Juan Bai ◽  
Zhe Wu ◽  
Nan Feng
Keyword(s):  
Mechanical Properties ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Impact Strength ◽  
Acrylonitrile Butadiene Styrene ◽  
Gel Permeation Chromatography ◽  
Gel Permeation ◽  
Rubber Phase ◽  
The Impact ◽  
Butadiene Styrene

Acrylonitrile-Butadiene-Styrene (ABS)/CaCO3 composites were reprocessed under normal conditions. The effects of reprocessing on the degradation of ABS were investigated by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The mechanical properties of the reprocessed materials were measured. In this paper, a method to evaluate the degradation of ABS in ABS/CaCO3 composites by FTIR was described. The results show that within the range of the reprocessing cycles studied, as the number of reprocessing cycles increased, the impact strength of composite was significantly reduced if the content of CaCO3 is lower than 10%, due to the degradation of rubber phase. However, the impact strength was almost unchanged when the content of CaCO3 was higher than 15%.

scholarly journals In Vivo Stability of Polyurethane-Based Electrospun Vascular Grafts in Terms of Chemistry and Mechanics

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 845
Author(s):  
Alexander A. Gostev ◽  
Inna K. Shundrina ◽  
Vitaliy I. Pastukhov ◽  
Alexey V. Shutov ◽  
Vera S. Chernonosova ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
Wistar Rats ◽  
Vascular Grafts ◽  
Gel Permeation Chromatography ◽  
Initial Value ◽  
Gel Permeation ◽  
The Stability

The biostability of the polyurethanes Tecoflex EG-80A and Pellethane 2363-80A, used as basic polymers of the vascular grafts (VGs) produced by electrospinning, as well as the tensile strength of Tecoflex VGs, are studied. Solutions of Tecoflex or Pellethane with gelatin and bivalirudin in 1,1,1,3,3,3-hexafluoroisopropanol are used for VG production. After 1, 12, and 24 weeks of VG implantation in the infrarenal position of the abdominal aorta of Wistar rats, VGs are explanted, fixed in formalin, freed from outer tissues, dialyzed, and dried. The polyurethanes are extracted from VGs by dispersion/extraction in tetrahydrofuran (THF) and freed from the excess of THF-insoluble biopolymers. The stability of polyurethanes is assessed by IR spectroscopy and gel permeation chromatography. Pellethane has emerged to be stable at all experimental points. Tecoflex loses approximately 10% of its molecular weight (both Mn and Mw) after 3 months and restored its initial value within 6 months of its functioning as a graft. Mechanical testing demonstrates a 30% reduction in the tensile strength after 3 months in VG and a 10% increase after 6 months. The stability and mechanical properties of polyurethane-based VGs demonstrate their utility for the reconstitution of damaged arteries.

scholarly journals Sintered Structural Steels Containing Mn, Cr And Mo – The Summary of the Investigations

2016 ◽  
Vol 16 (2) ◽  
pp. 59-85
Author(s):  
Maciej Sulowski
Keyword(s):  
Mechanical Properties ◽  
Chemical Composition ◽  
Sintered Material ◽  
Structural Steels ◽  
Processing Conditions ◽  
Alloying Element ◽  
Sintering Atmosphere ◽  
Sintered Steels ◽  
Method Of Production ◽  
Better Than

AbstractThe paper is presented the development and method of production of modern, Ni-free sintered structural steels which contain carbide forming alloying elements (Cr) with high affinity for oxygen (Cr, Mn) and the much smaller additive of an expensive alloying element (Mo), enabling the production of structural sintered steels in commercial belt furnaces, using safe sintering atmospheres. The investigations reported deal with the analysis of microstructure and mechanical properties of these sintered structural steels produced in different processing conditions, especially modification of chemical composition of sintering atmosphere and also the connections between the microstructure of sintered material and its mechanical properties. This analysis was done to propose the appropriate chemical composition of sintered Ni-free steels with properties which are comparable or even better than those of sintered structural steels containing rich and carcinogenic nickel. The investigations of PM Mn- Cr-Mo steels were preceded by those on Mn steels.

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