Accelerators such as tetramethylthiuram disulfide (TMTD) are responsible for releasing nitrosamines, considered carcinogenic by international organizations. Tetrabenzylthiuram disulfide (TBzTD) and zinc dibenzyldithiocarbamate (ZBEC) are indicated as substituents of TMTD for not releasing noxious nitrosamines. Thus, the objective of this work was to compare the use of TMTD, TBzTD, and ZBEC accelerators in the production of isobutylene-isoprene rubber compounds. It was evaluated the effect of TBzTD/mercaptobenzothiazole and ZBEC/ N-cyclohexyl-2-benzothiazolesulfenamide pairs in the rheological properties and the first pair achieved better results. Subsequently, it was evaluated compounds containing TBzTD and ZBEC accelerators separately. The experimental design data of the obtained maximum torque were correlated by an interpolation method (thin-plate spline interpolation method). Physical-mechanical and thermodynamic measurements showed a decrease in the mechanical properties of TBzTD and ZBEC compounds. Thermogravimetric analysis did not indicate thermal differences between the compounds, Fourier transform infrared and swelling degree analyses corroborated the difference found in the crosslink densities of the compounds.

Polyhydroxybutyrate and chitosan have been studied as materials for drug delivery systems (DDSs) due to their biodegradability and biocompatibility. The aim of this work was to produce amphiphilic polyhydroxybutyrate/chitosan matrices that form porous structures (scaffolds) after swelling in water and arnica extract. The matrices were analyzed by TGA, SEM, XDR, DSC, and FTIR. Thin plate spline interpolation method (TPSIM) was used to predict the swelling of the matrices generating three‐dimensional data fitted, showing the influence of time and concentration variables on both fluids absorption. Polyhydroxybutyrate/chitosan samples containing 60 wt % (weight percent) of chitosan formed a porous structure as they were submitted to arnica loading, and the obtained device was able to deliver arnica in physiological medium. Thus, the produced matrices have a strong potential to perform both as scaffolds and DDS © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47838.

Polymers such as the biocompatible polyhydroxybutyrate (PHB) and the polysaccharide chitosan (Chi), a pH-sensitive polymer, have been studied for drug delivery applications and scaffolds production. In this work, matrices of PHB and Chi were produced by compression molding (S PHB-Chi) and loaded with a broad-spectrum biocide chlorhexidine (CHX) (S PHB-Chi-CHX). The matrices were analyzed by scanning electron microscope (SEM). The S PHB-Chi capacity to absorb and deliver CHX was evaluated by UV-Vis. The antibacterial activity of the samples against S. aureus, P. aeruginosa and E. coli (most common pathogens that cause infection in several body sites) was evaluated using the disk-agar diffusion method. The CHX release results were fitted by the Power Law model. The results suggested that the morphology and the CHX delivery profile were directly related to the Chi amount in the samples and also showed that the S PHB-Chi-CHX is able to inhibit the microorganism proliferation, constituting it as a potential candidate for oral applications.

In recent years, tissue engineering has been developing methodologies to potentialize the regeneration of injured tissues, such as using biomaterials to obtain scaffolds performing the controlled release of drugs. The polymers polyhydroxy butyrate (PHB) and chitosan (CHI) have been used in the production of matrices applied to scaffold production. This study aims to produce and evaluate matrices containing different proportions of PHB and CHI using the compression molding technique. These matrices can form scaffolds after drug incorporation of Hamamelis virginiana (HV).  In order to predict the swelling of the matrices, the Thin Plate Spline Interpolation method (TPSIM) was used to generate three-dimensional data fitted, showing the influence of time and concentration variables on drug absorption. Results show that the percentage of CHI in the samples determines the swelling degree of the matrices. According to scanning electron microscopy analyses, increasing this polymer's quantity modifies the matrix's morphology, making it more heterogeneous. The sample with 50% by weight composition of CHI showed better-swelling results and samples loaded with HV demonstrated drug release ability. Thus, the obtained matrices have great potential to work as scaffolds and drug delivery systems, and therefore, they are promising products for application in tissue engineering.

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