Estimation, from Swelling, of the Structural Contribution of Chemical Reactions to the Vulcanization of Natural Rubber. Part II. Estimation of Equilibrium Degree of Swelling

1964 ◽  
Vol 37 (2) ◽  
pp. 571-575 ◽  
Author(s):  
Bryan Ellis ◽  
G. N. Welding
Keyword(s):  
Natural Rubber ◽  
Chemical Reactions ◽  
Volume Fraction ◽  
Equilibrium Degree ◽  
Degree Of Swelling ◽  
Rubber Part ◽  
Structural Contribution

Abstract An investigation has been made of the measurement of degree of swelling of vulcanizates and the estimation of υτ, the volume fraction of polymer in a vulcanizate swollen to equilibrium. Methods have been established for dealing with a volatile swelling liquid, allowing for small percentages of nonpolymer in the vulcanizates, testing for diffusion equilibrium and correcting for swelling increment. The resulting values of υτ are suitable for use as described in the preceding Part I.

Estimation, from Swelling, of the Structural Contribution of Chemical Reactions to the Vulcanization of Natural Rubber. Part I. General Method

1964 ◽  
Vol 37 (2) ◽  
pp. 563-570 ◽  
Author(s):  
Bryan Ellis ◽  
G. N. Welding
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Chemical Reactions ◽  
Network Structure ◽  
Reference Data ◽  
Direct Method ◽  
High Elasticity ◽  
Rubber Part ◽  
Structural Contribution ◽  
General Method

Abstract A procedure is described for estimating indirectly the contribution of vulcanization reactions to the build-up of network structure. This method is useful with technically important vulcanizing systems for which no direct method of estimation has been found. Errors of the theory of high elasticity are avoided by using published results, such as those of Moore and Watson of direct chemical estimates obtained with a special vulcanizing system that is chemically well understood. Reliance on the theories of end correction and swelling is also avoided by using published experimental relations. The method is applicable to any linear primary polymer of arbitrary molecular weight and any suitable swelling liquid, for which the required reference data have been obtained.

Estimation, from Swelling, of the Structural Contribution of Chemical Reactions to the Vulcanization of Natural Rubber. Part III. Restricted Method

1964 ◽  
Vol 37 (2) ◽  
pp. 576-582 ◽  
Author(s):  
R. M. Russell ◽  
D. A. Smith ◽  
G. N. Welding
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
Volume Fraction ◽  
Direct Method ◽  
Previous Method ◽  
Equilibrium Volume ◽  
Rubber Part ◽  
Structural Contribution ◽  
Large Correction ◽  
Equilibrium Volume Fraction

Abstract A method is described whereby the structural contribution of vulcanizing reactions may be estimated graphically from measurements of the equilibrium volume fraction of rubber in a vulcanizate swollen in n-decanc at 25.0°. Use is made of the data of Moore and Watson represented in the form of a relation between (ρMc−1)vulc and υτ. The method is applicable with technically important vulcanizing systems for which no direct method of estimation is available, and is simpler than the previous method (Part I). The method is limited to natural rubber of fixed primary molecular weight, but the limitation avoids a large correction for free ends of chains. Suitable experimental techniques are described.

Thermoplastic Natural Rubber of Co-Polyamide: Effect of Blend Ratios on Mechanical, Swelling, Dynamic and Morphological Properties

2013 ◽  
Vol 844 ◽  
pp. 89-92
Author(s):  
Boripat Sripornsawat ◽  
Azizon Kaesaman ◽  
Charoen Nakason
Keyword(s):  
Natural Rubber ◽  
Dynamic Properties ◽  
Complex Viscosity ◽  
Continuous Phase ◽  
Morphological Properties ◽  
Elongation At Break ◽  
Degree Of Swelling ◽  
Tan Δ ◽  
Thermoplastic Natural Rubber ◽  
Blend Ratios

Maleated natural rubber (MNR) was synthesized and formulated to prepare thermoplastic natural rubber (TPNR) by blending with co-polyamide (COPA). It was found that 100% modulus, tensile strength, elongation at break, hardness and degree of swelling increased with increasing proportion of COPA. However, degree of swelling and tension set value decreased which reflects enhancing of rubber elasticity. Dynamic properties were also determined by a rotor less oscillating shear rheometer (Rheo Tech MDpt). It was found that increasing proportion of MNR caused increasing of storage modulus and complex viscosity but decreasing tan δ value. Morphological properties were also determined by SEM technique. It was found that the MNR/COPA simple blends with the proportion of rubber 40, 50 and 60 wt% exhibited the co-continuous phase structures.

Shock-Induced Chemical Reactions in Multi-Functional Structural Energetic Intermetallic Nanocomposite Mixtures

Aerospace ◽  
2005 ◽  
Author(s):  
V. Narayanan ◽  
X. Lu ◽  
S. Hanagud
Keyword(s):  
Metal Oxides ◽  
Chemical Reactions ◽  
Energetic Materials ◽  
Thermal Loading ◽  
Volume Fraction ◽  
Irreversible Thermodynamics ◽  
Irreversible Processes ◽  
Finite Difference Schemes ◽  
Dual Functional ◽  
Metal Metal

Shock induced chemical reactions of intermetallics or mixtures of metal and metal-oxides are also used to synthesize new materials with unique phases and microstructures. These materials are also of significant interest to the energetics community because of the significant amount of heat energy released during chemical reactions when subjected to shock and/or thermal loading. Binary energetic materials are classified into two categories— metal/metal oxides and intermetallics. When these materials are synthesized at a nano level with binders and other structural reinforcements, the strength of the resulting mixture increases. Thus, these materials can be used as dual-functional binary energetic structural materials. In this paper, we study the shock-induced chemical reactions of intermetallic mixtures of nickel and aluminum of varying volume fractions of the constituents. The chemical reaction between nickel and aluminum produces different products based on the volume fraction of the starting nickel and aluminum. These chemical reactions along with the transition state are modeled at the continuum level. In this paper, the intermetallic mixture is impact loaded and the subsequent shock process and associated irreversible processes such as void collapse and chemical reactions are modeled in the framework of non-equilibrium thermodynamics. Extended irreversible thermodynamics (EIT) is used to describe the fluxes in this system and account for the associated irreversible processes. Numerical simulations of the intermetallic mixture are carried out using finite difference schemes.

Mechanism of Rubber Vulcanization with Sulfur

1938 ◽  
Vol 11 (1) ◽  
pp. 107-130
Author(s):  
W. K. Lewis ◽  
Lombard Squires ◽  
Robert D. Nutting
Keyword(s):  
Natural Rubber ◽  
Temperature Coefficient ◽  
Chemical Reactions ◽  
Chemical Reaction ◽  
Reaction Rate ◽  
Complex Behavior ◽  
Double Bonds ◽  
Irreversible Reaction ◽  
Sulfur Addition

Abstract THAT vulcanization of rubber with sulfur always involves a chemical reaction consisting in the addition of sulfur to the double bonds of the rubber molecule has been conclusively established (18, 28). The facts indicate that this addition of sulfur to rubber is an irreversible reaction (31). The temperature coefficient of the reaction is high, increasing about 2.65 fold per 10° C. at ordinary curing temperatures (31). Furthermore, the reaction is apparently exothermic (4, 24). It is noteworthy that catalysts are apparently necessary, since synthetic rubbers prepared from pure materials add sulfur slowly, if at all. The proteins and perhaps the resins in natural rubber undoubtedly serve as accelerators. The curves for combined sulfur vs. time of cure for typical mixes are shown in Figures 1 and 2. Figure 1 is taken from the data of Kratz and Flower (16); the composition and temperature of cure for this mix are shown in Cranor's Table I (9). Figure 2, curve 1, is from Table I of Eaton and Day (10), and curve 2 from data obtained in this laboratory (27, Table I). Superficial inspection of these curves shows extraordinary divergence of type. Figure 1 is a typical fadeaway curve, characteristic of most chemical reactions, where the reaction rate decreases with decreasing concentration of the reacting materials. Curve 1, Figure 2, is an entirely different type, where the rate of sulfur addition is constant until nearly 70 per cent of the initial sulfur has reacted. Curve 2, Figure 2, shows even more complex behavior. Again the rate is constant in the initial portions of the cure. However, following this period, the rate increases markedly but later falls off, approaching zero, to give an S-shaped eurve.

scholarly journals Mechanisms of deformation in crystallizable natural rubber. Part 2: Quantitative calorimetric analysis

Polymer ◽  
2013 ◽  
Vol 54 (11) ◽  
pp. 2727-2736 ◽  
Author(s):  
J.R. Samaca Martinez ◽  
J.-B. Le Cam ◽  
X. Balandraud ◽  
E. Toussaint ◽  
J. Caillard
Keyword(s):  
Natural Rubber ◽  
Calorimetric Analysis ◽  
Rubber Part ◽  
Mechanisms Of Deformation

scholarly journals Shear Flow Induced Alignment of Carbon Nanotubes in Natural Rubber

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Yan He ◽  
Zhifang Cao ◽  
Lianxiang Ma
Keyword(s):  
Carbon Nanotubes ◽  
Natural Rubber ◽  
Volume Fraction ◽  
Mechanical Analysis ◽  
Multiwalled Carbon ◽  
Variable Volume ◽  
Transmission Electron ◽  
Aligned Carbon Nanotubes ◽  
Rubber Composite ◽  
Spectroscopy Studies

A new procedure for the fabrication of natural rubber composite with aligned carbon nanotubes is provided in this study. The two-step approach is based on (i) the preparation of mixture latex of natural rubber, multiwalled carbon nanotubes, and other components and (ii) the orientation of carbon nanotubes by a flow field. Rubber composite sheets filled with variable volume fraction of aligned carbon nanotubes were fabricated and then confirmed by transmission electron microscopy and Raman spectroscopy studies. An obvious increase in thermal conductivity has been obtained after the alignment of carbon nanotubes. The dynamic mechanical analysis was carried out in a tear mode for the composite.

Vulcanization Reactions in Butyl Rubber. Action of Dinitroso, Dioxime, and Related Compounds

1946 ◽  
Vol 19 (4) ◽  
pp. 900-914 ◽  
Author(s):  
John Rehner ◽  
Paul J. Flory
Keyword(s):  
Natural Rubber ◽  
Chemical Reactions ◽  
Active Agent ◽  
Butyl Rubber ◽  
Nitroso Compounds ◽  
Cross Linking ◽  
Oxidizing Agent ◽  
Nitroso Group ◽  
Oxidizing Agents ◽  
Related Compounds

Abstract Experiments have been carried out to determine the chemical reactions that occur when Butyl rubber is vulcanized by quinone dioxime or related compounds. Observations have been made of the reactions of these substances with simple olefins, and of the effect of oxidizing agents on the dioxime-type of vulcanization of Butyl in solution. The theory is proposed that, in the vulcanization of Butyl by quinone dioxime or its esters, in presence of oxidizing agents, the active agent is p-dinitrosobenzene formed by oxidation of the dioxime. Chemical reactions are suggested for the subsequent cross-linking or vulcanizing steps, and the results of confirmatory experiments are presented. p-Dinitrosobenzene and other polynitroso compounds are active vulcanizing agents for Butyl, natural rubber, Buna-S, Buna-N, and Neoprene, and do not require the addition of an oxidizing agent. It is suggested that vulcanization of natural rubber by polynitro compounds involves their reduction to corresponding nitroso compounds as the first step, and that the nitroso group adds to rubber to produce cross-linkages.

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