Graft Polymers Derived from Natural Rubber

1956 ◽  
Vol 29 (1) ◽  
pp. 99-105 ◽  
Author(s):  
G. F. Bloomfield ◽  
F. M. Merrett ◽  
F. J. Popham ◽  
P. Mc L. Swift
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Methyl Methacrylate ◽  
Transfer Reaction ◽  
Polymer Chains ◽  
Vinyl Monomers ◽  
Grafted Polymer ◽  
Polymeric Chains ◽  
Graft Polymers ◽  
Direct Growth

Abstract Graft polymers result when vinyl monomers are polymerized in the presence of natural rubber, either in solution or as latex, and some of the polymeric chains become attached to the rubber molecules. The properties of the natural rubber can be widely modified according to the nature and the amount of the grafted polymer. The polymer-modified natural rubber appears to be produced by direct growth of polymer chains on to rubber molecules rather than by a transfer reaction involving the rubber. Graft polymers of styrene and methyl methacrylate with natural rubber can be compounded and cured to give light-colored articles of good tensile strength, and rubber-methyl methacrylate graft polymers have outstanding flex-cracking and fatigue resistance.

Mechanochemical Devulcanization of Vulcanized Gum Natural Rubber

2005 ◽  
Vol 21 (3) ◽  
pp. 183-199
Author(s):  
G.K. Jana ◽  
C.K. Das
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Natural Rubber ◽  
Three Dimensional ◽  
Elongation At Break ◽  
Tear Strength ◽  
Vulcanized Rubber ◽  
Dimensional Network ◽  
Polymeric Chains ◽  
Cure Time

De-vulcanization of vulcanized elastomers represents a great challenge because of their three-dimensional network structure. Sulfur-cured gum natural rubbers containing three different sulfur/accelerator ratios were de-vulcanized by thio-acids. The process was carried out at 90 °C for 10 minutes in an open two-roll cracker-cum-mixing mill. Two concentrations of de-vulcanizing agent were tried in order to study the cleavage of the sulfidic bonds. The mechanical properties of the re-vulcanized rubber (like tensile strength, modulus, tear strength and elongation at break) were improved with increasing concentrations of de-vulcanizing agent, because the crosslink density increased. A decrease in scorch time and in optimum cure time and an increase in the state of cure were observed when vulcanized rubber was treated with high amounts of de-vulcanizing agent. The temperature of onset of degradation was also increased with increasing concentration of thio-acid. DMA analysis revealed that the storage modulus increased on re-vulcanization. From IR spectroscopy it was observed that oxidation of the main polymeric chains did not occur at the time of high temperature milling. Over 80% retention of the original mechanical properties (like tensile strength, modulus, tear strength and elongation at break) of the vulcanized natural rubber was achieved by this mechanochemical process.

Aeration of Natural Rubber Latex. II. Graft Polymerization of Vinyl Monomers with Aerated Latex Rubber

1958 ◽  
Vol 31 (3) ◽  
pp. 430-435 ◽  
Author(s):  
B. C. Sekhar
Keyword(s):  
Natural Rubber ◽  
Methyl Methacrylate ◽  
Graft Polymerization ◽  
Natural Rubber Latex ◽  
Gel Strength ◽  
Vinyl Monomers ◽  
Polymer Content ◽  
Rubber Latex ◽  
Film Forming ◽  
Vinyl Polymer

Abstract The peroxidic groups produced on the rubber hydrocarbon when oxygen is absorbed by ammonia-preserved latex are capable of initiating the graft polymerization of methyl methacrylate and other vinyl monomers, in the presence of suitable reducing agents. The products so formed contain only small proportions of unbound homopolymer. In the latex state, the products have a much higher wet gel strength and better film forming properties than materials of the same total vinyl polymer content prepared by other methods.

Graft Polymers with Preset Molecular Configurations

1958 ◽  
Vol 31 (4) ◽  
pp. 829-837
Author(s):  
F. M. Merrett
Keyword(s):  
Solid State ◽  
Natural Rubber ◽  
Methyl Methacrylate ◽  
Physical Properties ◽  
Polymethyl Methacrylate ◽  
Side Chains ◽  
Technological Properties ◽  
Graft Polymers

Abstract The concept of “tailor-made” macromolecules when applied to graft polymers implies an effective correlation between the chemical and physical properties of the component parts and the technological properties of the resultant whole. Earlier experiments have indicated that, for a given graft macromolecule of natural rubber and polymethyl methacrylate, one extreme physical configuration could readily be effected in solution, viz., with the rubber trunk chains collapsed and the methyl methacrylate side chains extended. The complementary configuration—rubber chains extended and the methyl methacrylate chains collapsed—seemed equally easy of achievement. If these configurations could be carried through to the solid state then comparison of the properties of the dry rubbers would provide one such correlation between established physical configurations and resultant technological properties. The evidence for these definite configurations is briefly described below followed by preparative methods for bulk quantities of the dry rubbers and the evaluation of their technological properties.

Polymerization of Vinyl Monomers in Rubber Latexes

1960 ◽  
Vol 33 (3) ◽  
pp. 825-833 ◽  
Author(s):  
P. W. Allen ◽  
C. L. M. Bell ◽  
E. G. Cockbain
Keyword(s):  
Natural Rubber ◽  
Methyl Methacrylate ◽  
Kinetic Study ◽  
Graft Copolymers ◽  
Natural Rubber Latex ◽  
Kinetic Studies ◽  
Vinyl Monomers ◽  
Rubber Latex

Abstract In recent years numerous workers have reported on the polymerization of vinyl monomers, in the presence of polymers, in which graft copolymers and/or homopolymers are formed. Kinetic studies of such reactions have been relatively few, however, particularly for systems involving polymer latexes rather than solutions. In the present paper a kinetic study of the polymerization of styrene, methyl methacrylate, and homologous methacrylic esters in natural rubber latex is reported, and certain abnormal features of the polymerizations are discussed.

Structural Features of Buna-S. Relation to Physical Properties

1945 ◽  
Vol 18 (1) ◽  
pp. 41-61
Author(s):  
A. R. Kemp ◽  
W. G. Straitiff
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Physical Properties ◽  
Structural Features ◽  
Polymer Chains ◽  
Polymerization Reaction ◽  
Gel Structure ◽  
Gutta Percha ◽  
Cross Linkage

Abstract The low tensile strength of Buna-S gum stocks is generally believed to be due to failure to obtain effective cross-linkage as the result of vulcanization with sulfur and accelerators. Combined with this is the complete absence of crystallization of Buna-S on stretching which, in the case of natural rubber, reinforces and strengthens the vulcanized gel structure. The absence of crystallization in Buna-S can be explained on the basis of nonsymmetry along the polymer chains. Strictly speaking, Buna-S is not a true polymer, for ozonolysis shows that the styrene units are not spaced evenly in the chain but are grouped together in some locations. Ozonolysis also has proved the presence of vinyl groups attached to the chain, resulting from the polymerization of butadiene in the 1,2 instead of the 1,4 position. These vinyl groups must be unevenly spaced along the chain, and mixed trans and cis isomers must be present. Figure 1 illustrates the chemical units present in Buna-S, rubber, and gutta-percha hydrocarbons. In a Buna-S copolymer containing 24.5 per cent of styrene, there are six butadiene to one styrene units. It appears that about one butadiene in five polymerizes in the 1,2 position in the chain. It should be emphasized that, in Buna-S, ozonolysis has shown that no regular order exists in the location of A, B, and C units in the polymer. An entire lack of symmetry in the positioning of these units in the chain would be expected in view of the nature of the polymerization reaction.

Strength of Amorphous and of Crystallizing Rubberlike Polymers

1946 ◽  
Vol 19 (1) ◽  
pp. 42-45 ◽  
Author(s):  
A. P. Aleksandrov ◽  
J. S. Lazurkin
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Methyl Methacrylate ◽  
Butyl Rubber ◽  
Chemical Compositions ◽  
Butadiene Rubber ◽  
Linear Polymers ◽  
Elastic State ◽  
Natural Rubber Vulcanizates ◽  
Isoprene Rubber

Abstract The strengths of unloaded vulcanizates and the action of active fillers differ greatly according to the types of elastomers from which they are derived. These differences are not connected directly with the chemical compositions of the elastomers. Thus, for example, vulcanizates of natural rubber and synthetic isoprene rubber differ in strength in the ratio 10–15 to 1, whereas vulcanizates of Butyl rubber and of polychloroprene are very similar to natural rubber vulcanizates with respect to tensile strength. These differences in tensile strength cannot be ascribed directly to differences in structure of the chains, linear or branched; linear polymers of styrene and of methyl methacrylate “vulcanized” by small admixtures of butadiene-benzene or dimethacrylate-ethyleneglycol have, in the elastic state, tensile strengths which are just as low as those of unloaded vulcanizates of sodium-butadiene rubber or of isoprene rubber. The differences in tensile strength must, accordingly, be looked for in the different macroscopic properties of these polymers.

Tensile Strength of Protein-free Natural Rubber and its Vulcanizate Soaked in Water

2020 ◽  
Vol 93 (9) ◽  
pp. 293-299
Author(s):  
Luu Thanh HUYEN ◽  
Chen Ao RAN ◽  
Yoshimasa YAMAMOTO ◽  
Seiichi KAWAHARA
Keyword(s):  
Tensile Strength ◽  
Natural Rubber
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