Carlos Henrique Scuracchio

Crosslinking Kinetics of Blends of Ethylene Vinyl Acetate and Ground Tire Rubber

The copolymer ethylene vinyl acetate (EVA) and blends of EVA and ground tire rubber (GTR) with different compositions are prepared in the presence and absence of dicumyl peroxide (DCP) as a crosslinking agent. The crosslinking kinetics is investigated through oscillatory disc rheometry (ODR) and differential scanning calorimetry (DSC). The crosslinking kinetics is found to be dependent on the amount of GTR in the EVA/GTR blends; the partially crosslinked GTR phase acts as a physical barrier, slowing down the EVA crosslinking rate. Furthermore, activation energies (Ea) and reaction order (n) values suggest that the crosslinking reactions are not restricted to the EVA bulk, but can also occur to some extent at the EVA/GTR interface.

Development of artificial muscles based on electroactive ionomeric polymer-metal composites.

This work contextualizes the research of materials that can be applied as artificial muscles. The main motivation of this research is the importance of the development of mechatronic systems for the replacement of traditional devices of actuation and motion based on rotational electrical motors by other devices that reproduce biological muscle movements. Electroactive polymers (EAPs) are materials that respond to electric stimuli with shape and/or dimension changes, and accomplish movements that are smooth enough to mimic biological muscles. Among EAPs, the ionomeric polymer-metal composites (IPMCs) are an interesting alternative to biomimetic devices due to large displacements when submitted to low applied voltage. This article presents a brief review of IPMCs, a sample preparation procedure, and some electromechanical experimental results. We also discuss the applicability of this technology in medical devices and as artificial muscles.

The Role of Carbon Black on Devulcanization of Natural Rubber by Microwaves

One of the greatest problems of the modern society is the recycling of vulcanized elastomers, like tires and industrial rejects. This work studies one of the techniques of devulcanization of natural rubber (NR), the devulcanization by microwaves, as well as the influence of the amount of carbon black on this process through devulcanization of the NR with controlled composition on it. The samples were analyzed by Soxhlet extraction and some important correlations could be made based on its results and also by the final temperature of the samples just after the time of exposure to microwaves. The results highlighted that the increase of the temperature is responsible for the occurrence of devulcanization, which is dependent on both the amount of carbon black present in the rubber and the time of exposure to microwaves. These factors can influence its degree of devulcanization, since they are important for the absorption of energy by the material.

Blends of ground tire rubber devulcanized by microwaves/HDPE - Part A: influence of devulcanization process

The main objective of this work is the study of the influence of microwaves devulcanization of the elastomeric phase on dynamically revulcanized blends based on Ground Tire Rubber (GTR)/High Density Polyethylene (HDPE). The devulcanization of the GTR was performed in a system comprised of a conventional microwave oven adapted with a motorized stirring at a constant microwaves power and at various exposure times. The influence of the devulcanization process on the final properties of the blends was evaluated in terms of mechanical, viscoelastic, thermal and rheological properties. The morphology was also studied.

Vulcanization behavior of NBR with organically modified clay

The rheometric measurements were used to study the kinetics of vulcanization of the nanocomposites nitrile butadiene rubber (NBR)/organically modified montmorillonite in different concentrations. The presence of clay has modified the rheometric properties of rubber. However the E a values were not significantly modified with the presence of nanofiller.

Desvulcanização do resíduo de terpolímero de etileno-propileno-dieno (EPDM-r) por micro-ondas

Vulcanized elastomers are materials commonly used in several applications, such as automotive and footwear industries. In this study, scraps of ethylene-propylene-diene terpolymer (EPDM-r) from the automotive industry were exposed to microwaves during different periods (2-5 min). After devulcanization, the samples were characterized by gel content, differential scanning calorimetry (DSC) and activation energy of degradation (Ea) determined by thermogravimetric analysis (TGA). The degradation behavior of EPDM-r was consistent with the literature. The gel content analysis showed that the EPDM-r was devulcanized only at 5 minutes of exposure to the microwaves. DSC analysis demonstrated no significant changes in the samples, and the Ea results confirmed that the additives found in the composition of the EPDM-r affect the efficiency of the regeneration method.

The use of atomic force microscopy as an important technique to analyze the dispersion of nanometric fillers and morphology in nanocomposites and polymer blends based on elastomers

AFM has been recognized as one of the most powerful tools for the analysis of surface morphologies because it creates three-dimensional images at angstrom and nano scale. This technique has been exhaustively used in the analyses of dispersion of nanometric components in nanocomposites and in polymer blends, because of the easiness of sample preparation and lower equipment maintenance costs compared to electron microscopy. In this review, contributions using AFM are described, with emphasis on the dispersion of nanofillers in polymeric matrices. It is aimed to show the importance of technical analysis for nanocomposites and polymer blends based on elastomers.

Blends of ground tire rubber devulcanized by microwaves/HDPE - Part B: influence of clay addition

The main objective of this work is to study the influence of clay addition on dynamically revulcanized blends of Ground Tire Rubber (GTR)/High Density Polyethylene (HDPE). GTR was previously devulcanized in a system comprised of a conventional microwave oven adapted with a motorized stirring, with a fixed microwave power and at various exposure times. The influence of clay addition on the final properties of the blends was evaluated in terms of mechanical, viscoelastic, thermal and rheological properties, with morphology being also analyzed. The results depict that the clay can modify the rheological behavior of the GTR phase, in addition to the thermal and mechanical properties of some blends.