Rubber measurement

C. J. Carman We did try to look at the bound rubber. It turns out that there still is too much motion in such rubber to get cross polarization. You can see it by bound rubber measurements. On the time scale of this experiment it does not contribute to the spectrum. 

The dynamic response of polydimethylsiloxane (PDMS) reinforced with fused silica with and without surface treatment has been discussed in terms of interactions between the filler and polymer [54]. Since bound rubber measurements showed that PDMS chains were strongly attached to the silica surface, agglomeration due to direct contact between silica aggregates was considered an unlikely explanation for the marked increase in storage modulus seen with increasing filler content at low strains. Instead three types of flller-polymer-flller association were proposed which would cause agglomeration, as depicted in Fig. 15. 

Figure 2 shows the variation with time of the amount of grafted rubber measured on the basis of the amount of n-heptane-extractable rubber at 60 °C. The behavior is asymptotic, and for ethylene-propylene copolymers the yield of grafted rubber never exceeds 60%. 

ASTM D3768-03 BS 903 PA38 Standard practice for rubber-measurement of dimensions Methods for determination of dimensions of test pieces and products for test purposes... 

Fig. 9. H cramps spectra of Si-rubber measured under the same conditions, with the centre of the observed frequency changed in increments of 500 Hz.

Reichenbach and Eckelmann (152) were able to establish several generalizations regarding the storage modulus of filled, uncured rubbers. They found a linear dependence between the storage moduli of the filled and unfilled rubbers measured at corresponding frequencies, i.e.,... 

Figure 1. Young s modulus vs. temperature for polybutadiene rubbers —Measured on apparatus...

D 5099—Standard test methods for rubber- Measurement of processing properties using capillary rheometry. Annual Book of ASTM Standards. Vol. 09.01. 1996. p. 804. 

ISO 3417—Rubber—Measurement of vulcanization characteristics with the o.scillating disc curemeter (1991). 

Because bound rubber measures elastomer adsorption onto filler surface, it is highly dependent on filler loading, specific surface, and strucfure, which are parameters that can be measured independently (Meissner, 1974). However, at given loading and carbon black surface area and structure, it has been demonstrated that bound rubber is also dependent on carbon black surface energy (Wolff et ah, 1993). 

Fig. 16. Crystallisation of natural rubber measured by the volume decrease.

Bound Rubber. The filler network is clearly evidenced by bound rubber measurements [115-117]. Bound rubber is a very specific measurement done on green mixes it consists of determining the part of rubber that can not be extracted by a good solvent [118]. A small part of rubber, previously weighted. 

Bound rubber. From bound rubber measurements, it was suggested a weaker rubber-hller interaction for NR/CNT composite compared to the NR/ CB composites, due to the weak adhesion between inner and outer CNT layers (that allows them to slip) and to the weak adhesion between outer layers and the rubber. The increase in mechanical properties of the nanocomposites was explained with the high aspect ratio of CNT. 

In the scientific literature, nuclear magnetic resonance (NMR)," bound rubber measurements and glass transition (Tg) determination through calorimetric analysis are preferentially adopted for investigating the filler-rubber interaction, whereas microscopic analysis is in particular selected for assessing filler distribution and dispersion and for depicting the nature of the filler network. ... 

I. Valvassori, A. Zambelli, A. Copolymers of ethylene, higher a-olefins, and monocyclomonool-efins or aUcyl derivatives thereof. U.S. Patent 3,505,301 (Montecatini Edison S.p.A.), April 7, 1970. (b) Zambelli, A. Tosi, C. Sacchi, C. Polymerization of propylene to syndiotactic polymer. VI. Monomer insertion. Macromolecules 1972, 5, 649-654. (c) LocateUi, R Immirzi, A. Zambelli, A. Palumbo, R. Maglio, G. Orientation of propylene units in polypropylene and ethylene/propylene copolymers. Makromol. Chem. 1975,176, 1121-1128. (d) Carman, C. J. Harrington, R. A. Wilkes, C. E. Monomer sequence distribution in ethylene-propylene rubber measured by C NMR. 3. Use of reaction probability mode. Macromolecules 1977, 10, 536-544. (e) Zucchini, U. Dall Occo, T. Resconi, L. Ziegler-Natta catalysis for the polyolefin industry Present status and perspectives. Indian... 

How fast the process of interdiffusion takes place may be measured from the diffusion coefficients (D) of rubbers measured as a function of their MW. For typical industrial polymers with a MW of 200 - 300 x 10, D is 10 - 13 cm /s. With this value of D it is estimated that within one second after contact is achieved an rubber chain would interdiffuse about 45 A - enough for substantial interpenetration. 

Fig. 1. Temperature dependence of the spin-lattice relaxation time (Tj), the rotating frame relaxation time (T,, ), and the spin-spin relaxation time (T ) for natural rubber. Measured at a radio frequency of 30 MHz and amplitude of 10 gauss (ref 9)...

Fig. 15. Dependence of Tj on temperature and pressure in natural rubber, measured at...

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