The Synergistic Effect of Natural Rubber on the Crystallization of Lithium Poly(Isoprene)S (Coral Rubber)

1972 ◽  
Vol 45 (5) ◽  
pp. 1303-1314 ◽  
Author(s):  
M. J. Brock ◽  
Marjorie J. Hackathorn
Keyword(s):  
Synergistic Effect ◽  
Natural Rubber ◽  
Silver Nitrate ◽  
Induction Period ◽  
Volume Change ◽  
Crystallization Rate ◽  
Similar Species ◽  
Retarding Effect ◽  
Seeding Effect ◽  
Crystallizable Polymer

Abstract The influence of silver nitrate on the crystallization of poly(isoprene)s has been demonstrated as well as the synergistic effect of natural rubber on the crystallization of lithium catalyzed poly(isoprene). This synergism does not appear to be a “seeding” effect in the strictly definitive sense, since no seed crystals are actually added. In this case a better description of this effect might be cocrystallization where nucleation is promoted by the addition of a quantity of a highly regular similar species. Actually there is a good probability that the nucleating crystals themselves contain segments of the synthetic poly(isoprene). This conclusion is supported by the data shown in Figure 6 for a 50/50 mixture of natural rubber and a noncrystallizable Alfin polymer. The dilato meter curve for this mixture indicates that the 50 per cent non-crystallizable polymer has a slight retarding effect on the induction period for the crystallization of the natural rubber but the crystallization rate of the natural rubber in the 50/50 mixture is quite rapid up to the total volume change expected for natural rubber portion of the mixture. However, in the presence of 50 per cent of a crystallizable lithium poly(isoprene) (also shown in Figure 6), the crystallization rate of this mixture is much slower due to co crystallization. The proposed change from head-tail cis-1,4 addition to tail-head cis-4,1 addition whenever a 3,4 unit is introduced into the polymer chain seems to explain the experimental crystallinity data obtained in these studies. In addition, it raises some questions about the polymerization mechanisms involved and resulting from the orientation of a 3,4 unit being added to the growing end of a polydienyl chain.

Induction period of the crystallization of silver nitrate solutions in ethylene glycol

1991 ◽  
Vol 56 (10) ◽  
pp. 2142-2147
Author(s):  
Ivo Sláma
Keyword(s):  
Ethylene Glycol ◽  
Silver Nitrate ◽  
Induction Period ◽  
Glass Forming Ability ◽  
Transformation Theory ◽  
Concentration Region ◽  
Glass Forming ◽  
Temperature Transformation ◽  
Silver Nitrate Solutions ◽  
Nitrate Solutions

The dependence of the induction period of crystallization on supercooling was examined for the silver nitrate-ethylene glycol system over the concentration region of silver nitrate lome fraction of 0 to 0.12. Addition of AgNO3 to ethylene glycol was found to increase considerably the critical induction period of crystallization, although to a lesser extent than Ca(NO3)2, CaCl2, ZnCl2, LiCl and LiNO3 do. The effect of these salts on the critical induction period of crystallization in dimethylsulfoxide, dimethylformamide, dimethylacetamide and methanol was compared in terms of the solvent-rich composition limit of the glass-forming ability. By using the TTT(Time-Temperature-Transformation) theory, it has been deduced that the effect of the salts on the critical induction period of crystallization of ethylene glycol is probably due to the different dependences of viscosity on their concentration in ethylene glyco in the supercooling region.

Phenothiazine as an Antifatigue Agent for Natural Rubber, Synthetic Polyisoprene and SBR

1965 ◽  
Vol 38 (3) ◽  
pp. 661-665
Author(s):  
Z. N. Tarasova ◽  
I. I. Eitingon ◽  
L. G. Senatorskaya ◽  
T. V. Fedorova ◽  
B. A. Dogadkin
Keyword(s):  
Mechanical Properties ◽  
Synergistic Effect ◽  
Natural Rubber ◽  
Thermal Oxidation ◽  
Fatigue Resistance

Abstract Phenothiazine has no effect on vulcanization of rubber or standard mechanical properties of the vulcanizates. Phenothiazine considerably increases fatigue resistance of vulcanizates of the rubbers studied, under different fatigue conditions. Under the effect of thermal oxidation and repeated deformation phenothiazine or its conversion products combine with the vulcanizate. The phenothiazine does not combine when subjected only to heating. When used with certain inhibitors of oxidation phenothiazine has a synergistic effect.

Elastomer Structures and ‘Cold Crystallization’

1979 ◽  
Vol 52 (1) ◽  
pp. 207-212 ◽  
Author(s):  
M. Bruzzone ◽  
E. Sorta
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Melting Point ◽  
Natural Rubber ◽  
Crystallization Rate ◽  
Cold Crystallization ◽  
Structural Defects ◽  
Strain Induced Crystallization ◽  
Induced Crystallization

Abstract In a great number of applications an ideal elastomer should satisfy, to a certain extent, both of the following requirements: (1) nearly instantaneous crystallization upon application of strain (strain induced crystallization) and (2) slow or no crystallization when cooled at the temperature of maximum crystallization rate (cold induced crystallization). A noteworthy case of (2) is elastomer crystallization in a strained state. The connection between the points (1) and (2) has not been clearly understood up to now, but it is known that some crystallizable elastomers fulfil the requirements of both (1) and (2) better than others. From an experimental point of view, cold induced crystallization kinetics are substantially easier to measure than those of very fast strain induced crystallization. The phenomenon of cold induced crystallization in natural rubber, NR, has been known since the very beginning of elastomer technology and the tendency of natural rubber to crystallize by cooling has been overcome by crosslinking it with sulphur (vulcanization) without impairing its ability to crystallize by stretching (Goodyear, 1836). The synthesis of cis-polyisoprenes (IR) and cis-polybutadiene (BR) of different microstructural purity (different cis content) gave the possibility of changing the crystallization rate. It has also been reported that the very fast cold crystallization of trans-polypentenamer (TPA) could be reduced by lowering the trans content. The same fact had been observed earlier for trans-polychloroprene. There is a general agreement in postulating that the reduction of the crystallization rate, obtained either by cross-linking or by chain regularity reduction, can be linked with the lowering of the melting point. In both cases the low level of structural defects introduced in the chains does not affect the glass transition temperature in such a way as to vary the crystallization rate. The aim of this paper is to emphasize the importance of the variations of the glass transition temperature and melting point on the elastomeric cold crystallization rate and the way these may be used in planning new elastomer structures.

Low-volume-change, dendrite-free lithium metal anodes enabled by lithophilic 3D matrix with LiF-enriched surface

2019 ◽  
Vol 7 (11) ◽  
pp. 6090-6098 ◽  
Author(s):  
Yangyang Feng ◽  
Chaofan Zhang ◽  
Bing Li ◽  
Shizhao Xiong ◽  
Jiangxuan Song
Keyword(s):  
Synergistic Effect ◽  
Volume Change ◽  
Three Dimensional ◽  
Lithium Metal ◽  
Metal Anode ◽  
3D Matrix ◽  
Lithium Metal Anodes ◽  
Li Metal Anode ◽  
Low Volume ◽  
Novel Concept

We report a novel concept for a stable Li metal anode via the synergistic effect of a three-dimensional skeleton and stable artificial SEI.

scholarly journals Synergistic effect by high specific surface area carbon black as secondary filler in silica reinforced natural rubber tire tread compounds

2020 ◽  
Vol 81 ◽  
pp. 106173 ◽  
Author(s):  
Suppachai Sattayanurak ◽  
Kannika Sahakaro ◽  
Wisut Kaewsakul ◽  
Wilma K. Dierkes ◽  
Louis A.E.M. Reuvekamp ◽  
...  
Keyword(s):  
Carbon Black ◽  
Synergistic Effect ◽  
Natural Rubber ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
Rubber Tire

Role of interfacial interaction on the crystallization behavior and melting characteristics of PP/Nano-CaCO3 composites modified with different compatibilizers

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Yuhai Wang ◽  
Hao Shen ◽  
Gu Li ◽  
Kancheng Mai
Keyword(s):  
Synergistic Effect ◽  
Heterogeneous Nucleation ◽  
Crystallization Temperature ◽  
Crystallization Behavior ◽  
Crystallization Rate ◽  
Interfacial Interaction ◽  
Scanning Calorimetry ◽  
Polar Groups ◽  
Melting Characteristics

AbstractPP/nano-CaCO3 composites with different interfacial interaction were prepared by addition of compatibilizers with the same polar groups but different backbones. The non-isothermal and isothermal crystallization behavior of PP/nano- CaCO3 composites was investigated using differential scanning calorimetry (DSC). The results indicated that the interfacial interaction between PP and nano-CaCO3 increased the crystallization temperature and crystallization rate of PP due to the heterogeneous nucleation of nano-CaCO3. The interfacial interaction between nano- CaCO3 and compatibilizer further increased the crystallization temperature and crystallization rate of PP and induced the formation of β-crystal of PP due to the synergistic effect of heterogeneous nucleation between nano-CaCO3 and compatibilizer. This synergistic effect of heterogeneous nucleation between nano- CaCO3 and compatibilizer depended on the interfacial interaction between compatibilizer and PP matrix. The increased compatibility between compatibilizer and PP matrix favoured the heterogeneous nucleation between nano-CaCO3 and compatibilizer

scholarly journals Synergistic effect of graphene oxide and boron-nitrogen structure on flame retardancy of natural rubber/IFR composites

2020 ◽  
Vol 13 (8) ◽  
pp. 6274-6284 ◽  
Author(s):  
Na Wang ◽  
Hao Liu ◽  
Jing Zhang ◽  
Miao Zhang ◽  
Qinghong Fang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Synergistic Effect ◽  
Natural Rubber ◽  
Flame Retardancy ◽  
Boron Nitrogen

Synergistic effect of multi walled carbon nanotubes and reduced graphene oxides in natural rubber for sensing application

Soft Matter ◽  
2013 ◽  
Vol 9 (43) ◽  
pp. 10343 ◽  
Author(s):  
Deepalekshmi Ponnamma ◽  
Kishor Kumar Sadasivuni ◽  
Michael Strankowski ◽  
Qipeng Guo ◽  
Sabu Thomas
Keyword(s):  
Carbon Nanotubes ◽  
Synergistic Effect ◽  
Natural Rubber ◽  
Graphene Oxides ◽  
Reduced Graphene ◽  
Multi Walled Carbon Nanotubes ◽  
Sensing Application ◽  
Reduced Graphene Oxides ◽  
Walled Carbon Nanotubes

Origin of Characteristic Properties of Natural Rubber—Synergistic Effect of Fatty Acids on Crystallization of cis-1,4-Polyisoprene: II, Mixed and Esterified Fatty Acids in Natural Rubber

1996 ◽  
Vol 69 (4) ◽  
pp. 608-614 ◽  
Author(s):  
Naoyuki Nishiyama ◽  
Seiichi Kawahara ◽  
Takashi Kakubo ◽  
Eng Aik Hwee ◽  
Yasuyuki Tanaka
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Natural Rubber ◽  
Free Fatty Acids ◽  
Crystallization Rate ◽  
Chain Fatty Acid ◽  
Long Chain Fatty Acid ◽  
Esterified Fatty Acids ◽  
Deproteinized Natural Rubber ◽  
Long Chain

Abstract Crystallization behavior of deproteinized natural rubber at −25°C was investigated by dilatometry in connection with the effect of long-chain fatty acid groups, esterified to the rubber chain, as well as free fatty acids and their esters. The overall crystallization rate decreased after removal of the acetone-extractable free fatty acids and their esters, while it increased significantly when the fatty acid groups esterified to natural rubber molecule were removed by transesterification with sodium methoxide. Both the acetone-extracted and transesterified rubbers showed a significant increase in the overall crystallization rate after the addition of 1 wt % stearic acid. The crystallization of acetone-extracted rubber was accelerated by the addition of 1 wt % methyl linoleate, a plasticizer of natural rubber, whereas it was suppressed in the case of transesterified rubber in which the esterified fatty acid groups were removed completely. The fatty acid groups esterified to natural rubber molecule gave rise to the accelerated crystallization of the rubber in conjunction with free fatty acids and their esters.

Heats of Reaction of Natural Rubber with Sulfur

1970 ◽  
Vol 43 (6) ◽  
pp. 1275-1293 ◽  
Author(s):  
N. Bekkedahl ◽  
J. J. Weeks
Keyword(s):  
Hydrogen Sulfide ◽  
Standard Deviation ◽  
Natural Rubber ◽  
Volume Change ◽  
Side Reaction ◽  
Enthalpy Change ◽  
Heat Of Reaction ◽  
Use Of Data ◽  
Heats Of Reaction

Abstract An adiabatic copper calorimeter was used to determine the heats of vulcanization of pale crepe natural rubber with sulfur for mixtures varying in composition from 0 to 32 per cent added sulfur. The side reaction that produces hydrogen sulfide was avoided by using reaction temperatures near 155° C. Heats of reaction at 25° C and at 155° C are reported. The enthalpy change at 25° C for compounds containing up to about 18 per cent sulfur is given in joules per gram of vulcanizate by the equation, ΔH25=−21.1·S with a standard deviation of 11 J/g. Here S is the percentage of combined sulfur. Above 18 per cent sulfur the heat of reaction at 25° C remains approximately constant at 380 ± 8 J/g. A comparison is made between the heat of vulcanization and the volume change on vulcanization, both as functions of combined sulfur, by making use of data in the literature.

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