Natural rubber microscopy properties

Nukaga, H., Fujinami, S., Watabe, H., Nakajima, K., and Nishi, T., Evaluation of mechanical properties of carbon black reinforced natural rubber by atomic force microscopy, J. Soc. Rubber Ind. Jpn., 79, 509-515 (2006). 

Mondragon et al. [250] used unmodified and modified natural mbber latex (uNRL and mNRL) to prepare thermoplastic starch/natural rubber/montmorillonite type clay (TPS/NR/Na+-MMT) nanocomposites by twin-screw extrusion. Transmission electron microscopy showed that clay nanoparticles were preferentially intercalated into the mbber phase. Elastic modulus and tensile strength of TPS/NR blends were dramatically improved as a result of mbber modification. Properties of blends were almost unaffected by the dispersion of the clay except for the TPS/ mNR blend loading 2 % MMT. This was attributed to the exfoliation of the MMT. 

Miyata and Yamaoka [152] used scanning probe microscopy to determine the microscale friction force of silicone-treated polymer film surfaces. Polyurethane acrylates cured by an electron beam were used as polymer films. The microscale friction obtained by scanning probe microscopy was compared with macroscale data, such as surface free energy as determined by the Owens-Wendt method and the macroscale friction coefficient determined by the ASTM method. These comparisons showed a good linear relationship between the surface free energy and friction force, which was insensitive to the nature of polymer specimens or to silicone treatment methods. Good linearity was also observed between the macroscale and microscale friction force. It was concluded that scanning probe microscopy could be a powerful tool in this field of polymer science. Evrard et al. [153] reported coefficient of friction measurements for nitrile rubber. Frictional properties of polyacetals, polyesters, polyacrylics [63], reinforced and unreinforced polyamides, and polyethylene terephthalate [52] have also been studied. 

The effect is examined of tetramethyl thiuram disulphide (TMTD) on the heat ageing and oxidation of clay-filled NR, with reference to the plasticity retention index of NR, using thermal analysis and scanning electron microscopy test methods. The results showed that heat and oxygen resistant properties could be obtained when the clay-filled natural rubber compound was cured by semi-effective or effective curing systems, with 1.5 phr or 3.0 phr of TMTD. 3 refs. 

In rubber-modified polystyrenes, the rubber is dispersed in the polystyrene matrix in the form of discrete particles. The two-phase nature of rubber-modified polystyrene was first suggested by Buchdahl and Nielsen [47] based on data on dynamic mechanical properties obtained with a torsion pendulum. The existence of two prominent loss peaks led to this conclusion, one at low temperatures which is due to the a relaxation of the rubber (e.g. 193 K for polybutadiene) and one at high temperatures which is due to the a relaxation of the matrix (e.g. 373 K for polystyrene). Later, microscopy provided proof of the existence of the rubber phase as a discrete dispersed phase in polystyrene [48]. 

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