Jānis Zicāns

Bionanocomposites poly(ϵ-caprolactone)/organomodified Moroccan beidellite clay prepared by in situ ring opening polymerization: Characterizations and properties

ABSTRACT In this study, a series of poly(ϵ-caprolactone) (PCL)/clay bionanocomposites were prepared via in situ ring opening polymerization (ROP) of ϵ-caprolactone catalyzed by titanium butoxide. The natural Moroccan clay beidellite (BDT), used as nanocharge, was organomodified with cetyltrimethylammonium bromide, CTA, to obtain the organically modified 3CTA-BDT (3 = CTA/BDT equivalent feed ratio). Characteristics of the final nanocomposites are investigated by FTIR, SEC, XRD, SEM, TGA, DSC, optical tensiometry, thermal conductivity and water vapor sorption analysis. The intercalated/exfoliated morphologies, revealed by XRD and SEM analyses, confirm uniform dispersion of the nanoclay within the PCL matrix. Thermal stability of all the nanocomposites is improved by the addition of 3CTA-BDT clay compared to pure PCL polymer. The DSC data show that the addition of 3CTA-BDT particles promotes an increase in the disorder of the crystalline phase, which reduces the crystallinity degree. The hydrophobicity of Polymer/clay compatibility was analyzed by studying surface polarity degree of samples by contact angle measurements. Thermal conductivity and water vapor sorption was also discussed. The permeability (P), the sorption coefficient (S) and the diffusion coefficient (D), showed a significant decrease with increasing 3CTA-BDT loading.

Mechanical and Heat Shrinkable Properties of Electron Beam Irradiated Polypropylene With Bisphenol A Dimethacrylate Crosslinker

Abstract Radiation crosslinking of polyolefins has gained interest for the development of advanced heat-shrinkable materials. Propylene homopolymer (PP1), polypropylene-polyethylene block copolymers (PP2, PP3) and their mixtures with 3 wt.% of bisphenol A dimethacrylate (BPDMA) crosslinking agent were irradiated with 25–150 kGy of accelerated electrons and were compared for aforementioned purpose. The studied mechanical properties indicated increased elongation in the presence of BPDMA that was contributed to the crosslinked moieties of PP and the crosslinking agent. The shrinkage stresses were comparable to that of polyethylene based heat-shrinkable material.