Samples rubber

Several other examples of modified mobile phases are given in Figs. 13.58 and 13.59 using 90/5/5 TEIF/MeOH/ACN and 95/5 chloroform/w-butylamine for the SEC analysis of poloxamer and nitrile-butadiene rubber samples, respectively. 

Since ozone attack on rubber is essentially a surface phenomenon, the test methods involve exposure of the rubber samples under static and/or dynamic strain, in a closed chamber at a constant temperature, to an atmosphere containing a given concentration of ozone. Cured test pieces are examined periodically for cracking. 

The authors are thankful to Dr. P. Sadhukhan (Bridgestone/Firestone Research, Akron, OH) for different rubber samples Dr. T. Medintseva (the Semenov s Instimte of Chemical Physics, Moscow, Russia) for TPV samples Dr. N. Dutta (University of South Australia, Adelaide, Australia) for the samples of SEBS filled with oil Dr. Z. Petrovich (Kansas Polymer Research Center, Pittsburg State University, Pittsburg, KA) for PU samples, and NIST/ATP Award 70NANB4H3055 for financial support. 

FIGURE 22.1 Transmission electron microscopy (TEM) micrograph of a carbon black network obtained from an ultrathin cut of a filled rubber sample. 

Stress and Energy Distribution in Rubber Samples Sliding... 

An abrasion experiment is carried out by sliding a rubber sample over a given distance and determining the volume loss by some suitable method, usually by determining the difference in weight before and after. It is always assumed that the abraded volume is proportional to the distance covered between measurements, which is reasonable if the sharpness of the track remains constant. Hence, the abraded volume is always referred to unit distance covered. This basic quantity depends on the pressure between the sliding surfaces, the temperamre, speed, and the topography of the track, such as sharpness and coarseness of the asperities. 

Being cut from tires, the rubber samples in this work cannot always be studied using standard test procedures. The specific techniques used to measure rubber aging have been described in detail elsewhere and are summarized below [2]. The same techniques have been used to evaluate rubber aging in both field and the laboratory oven-aging studies. For reference. Figure 34.2 shows a diagram of the internal components of a radial-ply tire. 

Principles and Characteristics A first step in additive analysis is the identification of the matrix. In this respect the objective for most polymer analyses for R D purposes is merely the definition of the most appropriate extraction conditions (solvent choice), whereas in rubber or coatings analysis usually the simultaneous characterisation of the polymeric components and the additives is at stake. In fact, one of the most basic tests to carry out on a rubber sample is to determine the base polymer. Figure 2.1 shows the broad variety of additive containing polymeric matrices. 

In principle, any type of sample can be analysed by SEC provided that it can be solubilised and that there are no enthalpic interactions between sample and packing material. By definition then, this technique cannot be carried out on vulcanisates and even unvulcanised fully compounded rubber samples can present problems due to filler-rubber interactions. The primary use of SEC is to determine the whole MWD of polymers and the various averages (number, viscosity, weight, z-average) based on a calibration curve and to allow qualitative comparisons of different samples. Many commercial polymers have a broad MWD leading to strong peak overlap in the chromatography of complex multicomponent systems. 

Conventional XRF analysis uses calibration by regression, which is quite feasible for known matrices. Both single and multi-element standards are in use, prepared for example by vacuum evaporation of elements or compounds on a thin Mylar film. Comparing the X-ray intensities of the sample with those of a standard, allows quantitative analysis. Depending on the degree of similarity between sample and standard, a small or large correction for matrix effects is required. Calibration standards and samples must be carefully prepared standards must be checked frequently because of polymer degradation from continued exposure to X-rays. For trace-element determination, a standard very close in composition to the sample is required. This may be a certified reference material or a sample analysed by a primary technique (e.g. NAA). Standard reference material for rubber samples is not commercially available. Use can also be made of an internal standard,... 

The deterioration of the physical properties of rubber products when exposed to service conditions also the controlled exposure of rubber samples to a variety of deteriorating influences in the evaluation of antioxidants and antiozonants. See Accelerated Ageing. 

Resistance to extension of a cut or tear in a rubber sample. See Tear Strength. 

A name given to a vulcanised rubber sample or product particularly where the shape or form of the rubber is not required to be specified. Vulcanisation... 

An apparatus which demonstrates the Gough-Joule effect. It comprises a pendulum adjusted so that a rubber sample is under stretch. Heat from a lamp causes the rubber to contract and swing the pendulum. This pulls the rubber into a shaded section where it extends and moves the pendulum back to the original position, whereupon the cycle is repeated. 

Figure 5. Effect of temperature on the flammability of ethylene-acrylic rubber samples.

Turner and coworkers111 118 119 used specially purified rubber samples and irradiated them in the absence of air. They found the yield of the physical cross-linking to decrease with the dose the initial yield is G = 3.5. However, the yield of chemical cross-linking was found to be 1.3. 

The nontreated rubber samples began losmg the initial friction coefficient value during this test after 0.5 h... 

Place the IPG strip face down onto the stacking gel, about 5 mM apart of the cathode paper bridge. Place silicone rubber sample applicators for molar mass marker proteins at one or both sides of the IPG strip. 

The nature of the acrylic gel is obviously quite different from that of the natural rubber. Sample A had the same measureahle gel in both sedimentation and filtration through 5 pore filters. 

After disposal of the NG from the rubber sample bottle, the bottle shall be cleansed thoroughly with acetone, flushed during about 3 mins under direct flow of tap w, rinsed with distd w and dried... 

Sample 1, Old Formulation of Bromolutyl Siliconized Rubber Sample 2, New Formulation of Bromolutyl Siliconized Rubber Sample 3, New Formulation of Chlorolutyl Siliconized Rubber... 

Jenke [73] studied the extractabihty of aniline, diphenylguanidine, dedenzyl-amine, and triisopropanolamine from a synthetic polyisoprene rubber similar to the material used in pharmaceutical applications. Rubber samples were autoclaved (121 °C) in contact with water or NaCl 0.9% solution for lh.Table 33 presents the concentration of each compound in solution after the extraction procedure using 2g rubber material. Extraction profiles ranged between 1.64 and 3.73 mg/L, with the exception of diphenylguanidine, whose extraction yield reached 11.76 mg/L. 

Delaunay-Bertoncini, N., van der Wielen, F. W. M., De Voogt, P., Erlandsson, B., and Schoenmakers, P. J. (2004), Analysis of low-molar-mass materials in commercial rubber samples by Soxhlet and headspace extractions followed by GC-MS analysis, /. Pharm. Biomed. Anal, 35,1059-1073. 

Relative ranking of crosslink densities - The apparent crosslink density was determined by swelling the rubber samples in toluene as solvent. The vulcanized samples of 20 x 20 mm2 size were cut from a 2 mm sheet and immersed in 100 mL of toluene at room temperature for 72 h [51]. The solvent was renewed after 24 h. The sample was removed, blotted quickly with filter paper, and weighed. The samples were collected and left for 24 h in vacuo at 105°C to evaporate the solvent. The swelling value Q, defined as grams of toluene per gram of rubber hydrocarbon, was calculated as ... 

For example, the volume change of an acrylonitrile-butadiene rubber (NBR)40 sample at X = 2 relative to the volume of its undeformed state was about 5 x 10 4, and the values for the other vulcanizates were less than this. We therefore assumed that the use of Eqs. (34) and (35) is warranted for the computation of dW/dlt for our rubber samples, except at very small deformations for which// < 3.02. In most cases, stress relaxation was allowed to proceed at given stretch ratios and 1- and 10-min isochronal stress values were taken for the calculations. 

K. Fukuma, T. Akagj, ami K. Kitai for their cooperation in experimental work. Japan Synthetic Rubber Company supplied the rubber samples used, and Mitsubishi-Monsanto Chemicals Company supported part of this research, to which their thanks are also due. 

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