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The effects of electron beam irradiation on the properties of ethylene propylene diene monomer (EPDM)/butyl rubber composites in presence of a polyfunctional monomer were investigated by means of differential scanning calorimetry (DSC), thermal analysis, scanning electron microscopy (SEM), attenuated total reflection absorption infrared spectroscopy (ATR-IR), and mechanical and surface energy measurements. The samples were exposed over a wide range of irradiation doses (20–150 kGy). The EPDM matrix was modified with butyl rubber, chlorobutyl rubber, and bromobutyl rubber. The gel content and crosslink density were found to increase with the electron beam irradiation dose. The values of the hardness and modulus increased gradually with the irradiation dose, while the tensile strength and elongation at break decreased with increasing irradiation dose. The EPDM/butyl rubber composites presented a higher thermal stability compared to the initial EPDM sample. The incorporation of butyl rubbers into the EPDM matrix led to an increase in material hydrophobicity. A similar trend was observed when the irradiation dose increased. The greatest change in the surface free energy and the contact angles occurs at an irradiation dose of 20 kGy. The Charlesby–Pinner plots prove the tendency to crosslinking as the irradiation dose increases. [ABSTRACT FROM AUTHOR]

Abstract: With the aim of develop new materials for active food packaging, composites of low-density polyethylene (LDPE) with chitosan (CS) or chitosan sodium montmorillonite clay nanocomposites (CSnano), with or without Irganox 1076 commercial synthetic antioxidant or vitamin E (VE) as natural antioxidant were prepared by melt processing. The obtained materials have been characterized by processing behavior, mechanical and thermal properties, positive groups determination, atomic force microscopy and standard tests to assess antimicrobial and antioxidant activities. The compositions assuring insignificant decrease in mechanical and thermal properties were selected as LDPE/3CSnano/VE and LDPE/6CSnano/VE. It has been shown the chitosan imparts antimicrobial properties to LDPE films while the vitamin E increased the oxidation induction period, especially for materials containing chitosan nanocomposites. The incorporation of both chitosan nanocomposites and vitamin E in polyethylene gave films with good antimicrobial and thermal properties because of significant increase of charge surface and important changes in surface topology and antimicrobial activity because of a synergistic effect. The nanocomposites cannot only passively protect the food against environmental factors, but they may enhance shelf life of food products. [Copyright &y& Elsevier]

This study was focused on the synthesis and characterization of some ion exchange resins based on acrylic copolymers, and the composite formation by CaCO 3 by carbonate diffusion protocol. The resins were deeply investigated in terms of chemical composition (anionic, cationic, amphoteric) and crosslinker content, by: swelling degree, ion-exchange capacity, volume variation, charge density, size. FTIR-ATR spectroscopy demonstrated the presence of the functional group in the acrylic copolymers, with the formation of functionalized acrylic ion exchange resins. The materials surface morphology was evidenced using scanning electron microscopy. X-ray diffraction showed that CaCO 3 polymorphism depends on the chemical structure of the used ionic exchange resins. Some of the obtained resins and their composites with CaCO 3 were tested as sorbents for small organic molecules, such as dyes (neutral red, NR and bromocresol green, BCG) and antibiotics (tetracycline hydrochloride, TCH). While the maximum sorption capacity for BCG and NR dyes is similar (2.247 mg/g and 2.288 mg/g, respectively), but depends on the sorbent's functional groups, all the investigated samples showed a significantly higher sorption capacity for TCH, up to 50.25 mg/g. The maximum TCH release profile was improved by CaCO 3 crystallization, suggesting that the composite samples could efficiently be used as drug delivering systems. The design the resins properties by varying the precursor crosslinker content (3 and 8%) and applying a broad range of functionalization pathways was followed, by introducing weak acid, weak amino (aminolysis with ethylenediamine, triethylenetetramine or 4-dimethylaminobenzaldehyde) or zwitterionic groups. The synthesis of CaCO 3 composite materials was also followed, applying an in-situ crystallization method, based on the ammonium diffusion in desiccator. The capacity of the synthesized resins to interact with different small organic molecules, such as dyes or antibiotics, was also shown. [Display omitted] • Design the resins properties by varying the precursor crosslinker content 3 and 8%. • Ion exchanger copolymers with weak acid, weak amino or zwitterionic groups. • Synthesis of CaCO 3 composite materials by in-situ diffusion crystallization method. • The ion exchanger beads capacity to interact with different dyes or antibiotics. [ABSTRACT FROM AUTHOR]