Influence of Sepiolite Addition Methods and Contents on Physical Properties of Natural Rubber Composites

Abstract

The influence of sepiolite loadings (1-10 phr) and sepiolite addition procedures (mill and latex mixing approaches) on properties improvement of natural rubber composites was investigated. The viscosity, curing behavior, and tensile test were used to assess the property changes whereas the rubber-filler interactions was confirmed by using stress relaxation, swelling, Mooney-Rivlin and rheological methods. It was found that the characteristics of rubber composites influenced by both mixing methods and filler contents. Comparing between two different mixing methods, the slower stress relaxation rate and less swelling capability were achieved from mill mixing technique. This method also lowered the strain where the upturn of stress was occurred as suggested by Mooney-Rivlin plot. The greater properties enhancement of composites was obtained from milling method because of the better rubber-filler interactions, probably as a result of the nature of filler used. The greatest tensile strength improvement was achieved at 1 phr sepiolite loading where the smallest damping characteristics (tan ????) indicating the highest elastic behavior were obtained as revealed by rheological measurements. The simplicity of production and shortened step of milling procedure would be more favorable than the latex mixing approach for fabrication sepiolite filled rubber composites.

Influence of different vulcanizing agents on structures and properties of sepiolite-filled natural rubber composites

“…This is an alternative approach to evaluating the rubber-filler interaction. Moreover, strong interaction between filler particles and rubber chains usually retarded the stress relaxation rate [7,33]. Figure 5 shows that all composite samples showed a linearly decreasing trend of stress over time.…”

“…However, the mechanical properties, i.e., tensile and curing properties, were not reported. Recently, Hayeemasae et al [7] have investigated the effect of sepiolite addition procedures (mill and latex mixing approaches) on the properties of the NR/sepiolite composites. They have discovered that the conventional milling method improved composite properties due to better rubber-filler interactions attributed to the nature of sepiolite, which does not swell in water like other types of clay.…”

“…Twodimensional (2D) SAXS images were background corrected and then integrated to obtain the scattering intensity (I) as a function of the scattering vector (q). The q is defined as Equation ( 7): (7) where λ is the wavelength and 2θ is the scattering angle.…”

“…Various types of filler have been applied in rubber composites, with carbon black and silica being the most widely used fillers in the rubber industries [1,2]. Recently, the use of sepiolite as filler in rubber composites has been the subject of research due to the unique structure of sepiolite, allowing for the enhancement of mechanical, thermal, and barrier performance of composites [5][6][7]. Sepiolite, a naturally occurring material, is a hydrous magnesium silicate with the conceptual unit cell formula of Si 12 Mg 8 O 30 (OH,F) 4 •(H 2 O) 4 •8H 2 O.…”