Cis-Trans Isomerization of Natural Rubber under the Influence of Organo-Aluminum Compounds and Titanium Tetrachloride

1959 ◽  
Vol 32 (4) ◽  
pp. 1036-1038 ◽  
Author(s):  
B. A. Dolgoplosk ◽  
E. N. Kropacheva ◽  
K. V. Nelson
Keyword(s):  
Natural Rubber ◽  
Ultraviolet Light ◽  
Titanium Tetrachloride ◽  
Chemical Properties ◽  
Regular Structure ◽  
Polymer Chains ◽  
Polymerization Process ◽  
Aluminum Compounds ◽  
Physical And Chemical ◽  
First Time

Abstract Ziegler catalysts have become of prime importance for synthesis of polymers with regular structure, particularly cis-polyisoprene. The disruption of the structure of the chain by the formation of trans units was, until now, connected only with the influence of the physical and chemical properties of the catalyst on the nature of the addition of the diene monomers during the polymerization process. In the present work it is shown that destruction of regularity of structure can be caused by isomerization of cis units in complete polymer chains into trans units under the influence of the compounds used for initiating the polymerization process. Attempts to isomerize natural rubber by means of ultraviolet light and iodine did not give the expected effect. Ferri established for the first time that under the influence of zinc chloride and titanium tetrachloride natural rubber undergoes changes accompanied by disappearence of crystallization on stretching as shown by x-ray structure analysis. On the basis of these results the authors presumed that under the influence of these agents isomerization of cis units to trans units occurs in the natural rubber chain. The isomerization of cis-1,4 units to trans units in polybutadiene by means of ultraviolet light in the presence of organic bromine or sulfur compounds was first accomplished and proved by Golub. The formation of trans units in natural rubber under similar conditions was not observed. The study of the isomerizing effect of TiCl4 and organo-aluminum compounds was conducted by us on solutions of milled natural rubber (NK) in benzene in sealed glass ampoules. The benzene used was dried and distilled over sodium. All work was conducted in an atmosphere of dry argon. Unsaturation and microstructure of the chain was determined on each sample. The study of microstructure of polyisoprenes was carried out by means of infrared spectra, the relative content of the different configurations of the polymer chain being determined by the absorption in the 800–1000 cm−1 region. The method previously developed by one of us was used for this purpose.

scholarly journals Assessment of Graphene Oxide and Nanoclay Based Hybrid Filler in Chlorobutyl-Natural Rubber Blend for Advanced Gas Barrier Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1098
Author(s):  
Jibin Keloth Paduvilan ◽  
Prajitha Velayudhan ◽  
Ashin Amanulla ◽  
Hanna Joseph Maria ◽  
Allisson Saiter-Fourcin ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Carbon Black ◽  
Natural Rubber ◽  
Gas Permeability ◽  
Chemical Properties ◽  
Barrier Properties ◽  
Hybrid Filler ◽  
Physical And Chemical ◽  
Chlorobutyl Rubber ◽  
And Chemical Properties

Nanomaterials have engaged response from the scientific world in recent decades due to their exceptional physical and chemical properties counter to their bulk. They have been widely used in a polymer matrix to improve mechanical, thermal, barrier, electronic and chemical properties. In rubber nanocomposites, nanofillers dispersion and the interfacial adhesion between polymer and fillers influences the composites factual properties. In the present work, a comparison of the hybrid effects of carbon black with two different nanofillers (graphene oxide and nanoclay) was studied. The 70/30 composition of chlorobutyl rubber/natural rubber elastomer blend was taken as per the blend composition optimized from our previous studies. The hybrid effects of graphene oxide and nanoclay in dispersing the nanofillers were studied mainly by analyzing nanocomposite barrier properties. The results confirm that the combined effect of carbon black with graphene oxide and nanoclay could create hybrid effects in decreasing the gas permeability. The prepared nanocomposites which partially replace the expensive chlorobutyl rubber can be used for tyre inner liner application. Additionally, the reduction in the amount of carbon black in the nanocomposite can be an added advantage of considering the environmental and economic factors.

STUDY OF AMINO ACID MODIFIERS IN GUAYULE NATURAL RUBBER

2015 ◽  
Vol 88 (2) ◽  
pp. 310-323 ◽  
Author(s):  
Colleen McMahan ◽  
Dhondup Lhamo
Keyword(s):  
Amino Acids ◽  
Natural Rubber ◽  
Oxidative Stability ◽  
Chemical Properties ◽  
The United States ◽  
Thermal Oxidative Stability ◽  
Green Strength ◽  
Strain Induced Crystallization ◽  
New Perspective ◽  
Physical And Chemical

ABSTRACT Guayule, a desert shrub indigenous to the United States, is under development as a source of natural rubber that can be used in place of petroleum-based rubber or Hevea rubber. In natural rubbers, physical and chemical properties can be strongly affected by nonrubber constituents, typically proteins and lipids, present in the material, depending on the plant species and postharvest processing. Hevea natural rubber typically contains high levels of nonrubber constituents that contribute to thermal-oxidative stability, cure acceleration, and especially strain-induced crystallization. The latter has been attributed to compound properties that render Hevea natural rubber uniquely suited for the most demanding rubber applications (e.g., aircraft tires). Hevea proteins are susceptible to hydrolysis, releasing free amino acids into the latex, which can affect rubber and compound properties. Here, low-protein guayule latex was blended with a series of amino acids varying in chemical structure. Bulk viscosity was reduced, thermal-oxidative stability was improved, and cure rate was influenced by the addition of amino acids. Generally, gel formation, green strength, and tensile strength were not affected. The results introduce a new perspective for amino acids as biobased rubber compound additives and provide insights into naturally occurring nonrubber constituents' interaction with natural rubber polymers.

scholarly journals A Study of Zooplankton Community in Dukan Lake, Kurdistan Region-Iraq, with a New Record of Craspedacusta sowerbii Lankester (1880) Medusa (Cnidaria: Hydrozoa)

2017 ◽  
Vol 14 (4) ◽  
pp. 735-741 ◽  
Author(s):  
Baghdad Science Journal
Keyword(s):  
Similarity Index ◽  
Chemical Properties ◽  
Zooplankton Community ◽  
Ion Concentration ◽  
Hydrogen Ion Concentration ◽  
Alkaline Side ◽  
Physical And Chemical ◽  
First Time ◽  
Jaccard's Similarity Index ◽  
And Chemical Properties

A study of Zooplankton community has been carried out at four selected sites on Dukan Lake. Samples of water and zooplankton were collected monthly for the period from July 2015 to February 2016. Some physical and chemical properties of water were studied and the results showed that the air temperature were ranged from 0 to 36.16 °C, water temperature ranged from 2.83 to 34.66 °C, hydrogen ion concentration of studied sites were found to lie in alkaline side, it was ranged between 6.87 to 8.57, electrical conductivity ranged from 190.79 to 850.08 µs.cm­¹, turbidity ranged from 0.9-7.7 NTU, and dissolved oxygen from 3.3 to 6.8 mg.l-¹ while BOD5 were ranged from 0.53 to 34.66 mg.l-¹. Concerning to the zooplankton, 37 species were identified which belonged to Cladocera (48.38%), Copepod (43.28%), Rotifera (8.23%), Targigrada (0.08%) and Cnidaria (0.1%). The medusa of Craspedacusta sowerbii Lankester (1880) was recorded for the first time in Iraq. Regarding to zooplankton community, rotifer were ranged between 0 to 690.91 ind.m-3, Copepoda from 54.55 to 5927.27 ind.m-3 and Cladocera ranged from 18.18 to 6072.73 ind.m-3. According to Shanon-Weiner index, species diversity for zooplankton invertebrates was ranged from 0.325 to 1.091 bits/ind. Jaccard’s similarity index showed that the highest similarity was recorded between site (1) and site (4) with 40.74%.

EFFECT OF PROTEIN ADDITION ON PROPERTIES OF GUAYULE NATURAL RUBBER

2017 ◽  
Vol 90 (2) ◽  
pp. 387-404 ◽  
Author(s):  
Dhondup Lhamo ◽  
Colleen McMahan
Keyword(s):  
Amino Acids ◽  
Natural Rubber ◽  
Oxidative Stability ◽  
Chemical Properties ◽  
Green Strength ◽  
Truck Tires ◽  
Oxidative Resistance ◽  
Strain Induced Crystallization ◽  
General Protein ◽  
Physical And Chemical

ABSTRACT Parthenium argentatum, commonly known as guayule, is a desert shrub cultivated as a domestic source of natural rubber in the semi-arid southwestern United States. Guayule natural rubber (GR) may be used to replace petroleum-based rubber or in place of Hevea natural rubber (NR), but substitution must take into consideration differences in physical and chemical properties. Currently, Hevea NR is required in tire applications, especially aircraft and truck tires, because of its high oxidative resistance, rapid cure rate, and exceptional stress–strain response. These outstanding features are attributed to the presence of nonrubber constituents, mainly proteins and lipids, which cause the rubber to gel, and they contribute to strain-induced crystallization. In contrast, GR is low in proteins and is thus deprived of some attributes of Hevea. Addition of amino acids and proteins to guayule could potentially improve performance and thereby widen the range of applications for use. In a previous study, amino acids blended with GR latex improved thermo-oxidative stability, served as plasticizers and cure accelerators, and enhanced green strength slightly, but tensile strength was not improved. Here, a series of bio-based commercial proteins (gelatin, soy, albumin, casein, zein, gliadin, and gluten) were added to GR as a latex blend. In general, protein addition reduced bulk viscosity and improved thermo-oxidative stability. The gel content and green strength of the polymer–protein blends were increased, with the exception of gliadin, but not to levels observed for Hevea. Effects on vulcanization and mechanical properties in compounds were surprisingly influenced by the choice of antioxidants used. Our results demonstrate the potential of proteins as bio-based rubber compounding additives.

A Comparison of Reduced-NAD Preparations from Four Commercial Sources

1968 ◽  
Vol 14 (8) ◽  
pp. 754-763 ◽  
Author(s):  
R B McComb ◽  
Royal J Gay
Keyword(s):  
Ultraviolet Light ◽  
Light Absorption ◽  
Phosphorus Content ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Ldh Isoenzymes ◽  
Activity Measurements ◽  
Commercial Sources ◽  
Physical And Chemical ◽  
And Chemical Properties

Abstract The physical and chemical properties of several commercial sources of reduced NAD were examined. Properties compared included physical appearance, sodium and phosphorus content, ultraviolet light absorption at 260 and 340 nm, and relative rates of oxidation with two human LDH isoenzymes. Major differences between individual preparations were noted with respect to physical and chemical properties, as well as in the activity measurements. The commercial reduced-NAD preparations most rapidly oxidized by LDH were white, free-flowing substances with 260 nm:340 nm absorbance (A260:A340) ratios below 2.45. Detectable amounts of an LDH inhibitor were found in all preparations examined. A strong LDH inhibitor, which had the same properties as the inhibitor present in commercial reduced NAD, was isolated by column chromatography. This LDH inhibitor was found to produce the same degree of inhibition toward four LDH isoenzymes.

Effect of silver nanoparticles on human primary keratinocytes

2013 ◽  
Vol 394 (1) ◽  
pp. 113-123 ◽  
Author(s):  
Radoslaw Szmyd ◽  
Anna Grazyna Goralczyk ◽  
Lukasz Skalniak ◽  
Agnieszka Cierniak ◽  
Barbara Lipert ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Chemical Properties ◽  
Wound Dressings ◽  
Epidermal Keratinocytes ◽  
Primary Keratinocytes ◽  
Human Epidermal Keratinocytes ◽  
Normal Human ◽  
Physical And Chemical ◽  
First Time ◽  
Human Primary Keratinocytes

Abstract Silver nanoparticles (AgNPs) have many biological applications in biomedicine, biotechnology and other life sciences. Depending on the size, shape and the type of carrier, AgNPs demonstrate different physical and chemical properties. AgNPs have strong antimicrobial, antiviral and antifungal activity, thus they are used extensively in a range of medical settings, particularly in wound dressings but also in cosmetics. This study was undertaken to examine the potential toxic effects of 15 nm polyvinylpyrrolidone-coated AgNPs on primary normal human epidermal keratinocytes (NHEK). Cells were treated with different concentrations of AgNPs and then cell viability, metabolic activity and other biological and biochemical aspects of keratinocytes functioning were studied. We observed that AgNPs decrease keratinocyte viability, metabolism and also proliferatory and migratory potential of these cells. Moreover, longer exposure resulted in activation of caspase 3/7 and DNA damage. Our studies show for the first time, that AgNPs may present possible danger for primary keratinocytes, concerning activation of genotoxic and cytotoxic processes depending on the concentration.

Sila-Pharmaka, 9. Mitt. [1] Darstellung und Eigenschaften potentiell curarewirksamer Silicium-Verbindungen, I / Sila-Drugs, 9th Communication [1] Preparation and Properties of Silicon Compounds with Potential Curare-Like Activity, I

1978 ◽  
Vol 33 (4) ◽  
pp. 412-416 ◽  
Author(s):  
Reinhold Tacke ◽  
Roland Niedner
Keyword(s):  
Mass Spectroscopy ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Organosilicon Compounds ◽  
Silicon Compounds ◽  
H Nmr ◽  
Toxicological Data ◽  
Physical And Chemical ◽  
First Time ◽  
And Chemical Properties

Abstract Organosilicon compounds 8, 9 and 10 with potential curare-like action and their precursors 5, 6 and 7 were synthesized for the first time. 5−10 were characterized by their physical and chemical properties, and their structures were confirmed by analyses, 1 H NMR and mass spectroscopy (only for 5−7). The pharmacological and toxicological data of 8, 9 and 10 are reported.

Cis-Trans Isomerization of Natural Rubber under the Influence of Hydrogen Chloride or Ethylaluminum Dichloride

1960 ◽  
Vol 33 (4) ◽  
pp. 985-987 ◽  
Author(s):  
I. I. Boldyreva ◽  
B. A. Dolgoplosk ◽  
E. N. Kropacjeva ◽  
K. V. Nel'son
Keyword(s):  
Natural Rubber ◽  
Hydrogen Chloride ◽  
Benzene Solution ◽  
Polymer Chains ◽  
Trans Content ◽  
Aluminum Compounds ◽  
Cis And Trans ◽  
Chloride Activity ◽  
Made In

Abstract We have established earlier that organo-aluminum compounds, and titanium tetrachloride, bring about the isomerization of the cis-isoprene units in natural rubber into the trans. The isomerization process, as influenced by the above materials, proceeds at appreciable velocity even at room temperature. The present communication reports the results of investigating the cis-trans isomerism of natural rubber as influenced by hydrogen chloride and ethylaluminum dichloride. The isomerizing action of hydrogen chloride upon unsaturated acids and stilbene was dislosed earlier in a series of papers. We investigated the action of dry hydrogen chloride and ethylaluminum dichloride on benzene solutions of natural rubber under the conditions described earlier. Hydrogen chloride was introduced in the form of a saturated benzene solution. In investigating the hydrogen chloride activity, each polymer sample was examined for unsaturation, chlorine content of the polymer chains and microstructure. The latter was characterized with the aid of infrared absorption spectra. As in the previous report, quantitative determination of the cis and trans content was made in the 840 cm−1 region, where the intensity and contour are substantially dissimilar for natural rubber and guttapercha. Furthermore, an additional inspection was made qualitatively in other regions of the IR spectrum (1100–1150 cm−1 and 1300–1330 cm−1), the feasibility of utilizing the 1300–1330 cm−1 region having been reported in a recent publication by Golub, who investigated the isomerization of natural rubber and guttapercha under the influence of selenium at temperatures of 180–220°.

scholarly journals New Nanocomposite Derivatives From Thiadiazole Polymers /Silica Synthesis and Characterization using Free Radical Polymerization

2019 ◽  
Vol 32 (1) ◽  
pp. 27 ◽  
Author(s):  
Nasir Sadoon Abid ◽  
Maha T. Sultan ◽  
Jumbad H. Tomma
Keyword(s):  
Free Radical ◽  
Silica Nanoparticles ◽  
Radical Polymerization ◽  
Chemical Properties ◽  
Free Radical Polymerization ◽  
Polymer Chains ◽  
X Ray ◽  
Silica Nanocomposites ◽  
Ft Ir ◽  
Physical And Chemical

A new class of thiadiazole /silica nanocomposites with chemical bonds between thiadiazole monomers and modified nanosilica surface were synthesized by free radical polymerization. Presence silica nanoparticles in the structure of  nanocomposite showed effectively improve the physical and chemical properties of Producing polymers. A nanocomposite material with feature properties comparison with their polymers, The structure and morphology of the synthesis materials were investigated by FT-IR spectrum which display preparation new thiadiazole compounds and polymerization monomers. FT-IR showed disappeared double bond (C=C) of monomers, due to produce long chains of thiadiazole polymers and nanocomposite. X-ray diffraction gave idea about crystalline structure of nanoparticles and nanocomposite , X-ray showed that silica nanoparticles have high intensity at 18000 , due to nanoscale of particles which allowed for particles aggregation together. While nanocomposite show low intensity due to reacted thiadaizole polymer chains with silica nanoparticles surface. The distribution of nanoparticles had characterized by Atomic forces microscopy AFM. AFM results shown roughness in the surfaces of nanocomposites C1 and C2, comparison with silica nanoparticles which gave smooth surface. The roughness attributed to reaction between functionalized surface of silica nanoparticles and chains of thiadaizole polymers, which led to change in size particles distribution and surface of particles that refer to nanocomposite.    

scholarly journals STUDY OF COMPOSITION, PHYSICAL AND CHEMICAL PROPERTIES AND BIOLOGICAL ACTIVITY OF POLYSACCHARIDE COMPLEX OF ARCTIUM LAPPA LEAVES

2017 ◽  
Vol 25 (1) ◽  
pp. 42-48
Author(s):  
I A. Sychev ◽  
D G. Kokina
Keyword(s):  
Chemical Properties ◽  
Erythrocyte Membranes ◽  
Physical And Chemical Properties ◽  
Qualitative Composition ◽  
Arctium Lappa ◽  
Polysaccharide Complex ◽  
Healthy Donors ◽  
Physical And Chemical ◽  
First Time ◽  
And Chemical Properties

A method of isolation of polysaccharide complex from the leaves of Burdock (Arctium lappa L.) is described in the article. For the first time the qualitative composition of this complex was determined, belonging to the group of heteroglycans. Some of physical and chemical properties of polysaccharide complex were studied. It is shown that polysaccharide complex increases catalase activity and peroxide resistance of the erythrocyte membranes of healthy donors. The study found that polysaccharide complex of Burdock improves physical performance of test animals.

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