Search results for "Crystallinitie"
showing 2 items of 2 documents
Crystallinity of block copolymer controlled by cyclodextrin
2018
We report a differential scanning calorimetry study to investigate the effect of cyclodextrins (CD) on the crystallinity of a copolymer. Tetronics was selected as copolymer with star-like shape formed by four polyethylene oxide flanked by four polypropylene oxide blocks linked to ethylenediamine central group. The use of CD with different cavity size was exploited for a block selective inclusion. A model for supramolecular association was considered for a quantitative description of the enthalpy data. The polymer chain incorporation into the CD cavity generates a loss of crystallinity. The stoichiometry of the CD/copolymer aggregates can be tuned by changing the CD cavity size. The investig…
Preparation of pH sensitive poly(vinilydenefluoride) porous membranes by grafting of acrylic acid assisted by supercritical carbon dioxide
2012
Free radical grafting of acrylic acid (AA) on poly(vinilydenefluoride) (PVDF) porous membranes was studied at 65°C using supercritical carbon dioxide (scCO 2) as a solvent and delivery agent. The process was initiated by the thermal decomposition of benzoylperoxide (BPO). Spectroscopic analyses confirmed the presence of poly(AA) chains linked to treated membranes. The mass fraction of grafted AA increased with grafting time and BPO concentration while it decreased when the density of the fluid phase was enhanced. A not-monotonic trend was obtained when the effect of the initial AA concentration was studied. The grafting process was accompanied by a reduction of the crystallinity of the PVDF…