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Showing 3 results for Carbon Black
Effect of Carbon Black on morphological and mechanical properties of rubber foams produced by a single-step method

Volume 1, Issue 1 (12-2017)
Abstract
In this research, closed-cell natural rubber foams were produced using a single-step compression molding. The effect of carbon black content on morphology, physical and mechanical properties of the foams were examined. Results showed that in this methodology, the foam density was independent of reinforcement percentage, which is a unique characteristic of single-step foams that contrasts with other previous observations. The study of curing behavior of foam compounds showed that the carbon black increasing from 0 to 30 phr increased the crosslink density (CLD) from 6.5 to 8.3*10-5 mol/cm3, the cure rate from 16.1 to 23.2 (%/min) and the ultimate torque from 5.8 to 10.4 Nm, while, reduced curing time from 9.2 to 5.8 min. The scanning electron microscope (SEM) results showed that the reinforcement acted as a nucleation agent increasing the cell density from 8 N/cm3 to 140 N/cm3 and reducing the cell size from 579µm to 255µm. The increase of reinforcing content in the produced foams reduced the cells size and enhanced the properties of the rubber matrix. Accordingly, the modulus and hardness of the foams were increased by  0.8MPa and 40 shore A, respectively. Results of sound absorption and reflection showed that the rubber foam reflects the sound waves more than 90% and absorbs waves about 10%.
Toner production by in situ emulsion polymerization: Investigation of the effect of reaction temperature and stirrer speed

Volume 6, Issue 1 (6-2022)
Abstract 
Abstract

Research subject: In recent years, toner-based printers have found many applications for ease of use, economical, high speed and quality. Therefore, many attempts have been made to produce toner by various methods such as suspension polymerization and emulsion aggregation. But in all these methods, despite the proper color properties and particle size, the reaction conversion is low.
Research approach: In the present study, in situ emulsion polymerization method based on styrene and butyl acrylate monomers in the presence of carbon black has been used to produce toner with a conversion above 75%. In this regard, the effect of polymerization reaction temperature and stirrer speed on conversion at different times, particle size and particle size distribution, thermal and color properties of the final product were investigated. Color measurement was performed to evaluate the color characteristics. Also, the microstructure of the synthesized toners was evaluated using scanning electron microscopy.
Main results: The results show that in situ emulsion polymerization method while having the proper conversion of the reaction in the range of 75-90% is well able to create the suitable color characteristics and particle size distribution for the toner. All toners produced had a particle size distribution and a spherical shape that was unaffected by the reaction temperature and stirrer speed. By increasing the polymerization temperature from 70℃ to 80℃, resulted in a higher conversion, but the increase in stirrer speed had a dual effect on the conversion. Sticking of spherical particles with each other was observed by increasing the temperature to 90℃. The sudden addition of a monomers to the reaction media and using batch process resulted in the observation of two glass transition temperatures. This type of toner synthesis can be a guide for future research to produce toner with the highest conversion.

Modified self-consistent micromechanics approach to the prediction of the stress-strain behavior of elastomeric nanocomposite using incremental theory
Mohamad Karimi Dona, Bijan Mohammadi, Fathollah Taheri-Behrooz,
Volume 23, Issue 8 (8-2023)
Abstract
In the present research, classic micromechanical methods and their application as constitutive models in conjugation with incremental theory were developed. Using the modified Eshelby model, the Eigen strain concept in polymeric composite, and a modified form of self-consistent model the elastic properties of nanocomposites were predicted. Also, the stress-strain behavior of elastomer nanocomposites was calculated and validated by the experimentally determined ones. The results showed that the new model can predict the stress-strain behavior of elastomer nanocomposite at different particle volume fractions.
 
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