Development of membranes by radiation grafting of acrylamide into polyethylene films: Characterization and thermal investigations

Abstract

Polyethylene-g-polyacrylamide membranes were prepared by graft polymerization of acrylamide into polyethylene films by preirradiation technique. The characterization and thermal behavior of membranes with different degrees of grafting were evaluated by density, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry measurements. Grafting led to considerable changes in the structure of polyethylene membranes. The density of the polyethylene film increased wtih the increase in the degree of grafting, although the increase beyond 100% grafting was less pronounced than at lower graft levels. The heat of fusion and the crystallinity of polyethylene decreased with the increase in the degree of grafting. The decrease in crystallinity is because of the cumulative effect of the dilution of inherent crystallinity by the incorporation of amorphous polyacrylamide grafts within the noncrystalline region of polyethylene (dilution effect) and partial disruption of the crystallites (crystal defects). X-ray diffraction measurements also revealed a decrease in the crystallinity in grafted films. Membranes behaved as a two-component system where polyethylene and polyacrylamide components underwent independent degradation irrespective of the graft levels. In general, the thermal stability of polyethylene in membranes was markedly improved by the grafting of acrylamide monomer as evident from the initial decomposition temperature increasing from 311°C for virgin PE to 390°C in grafted membranes.

Development of membranes by radiation grafting of acrylamide into polyethylene films: Properties and metal ion separation

“…Probably, the structure of the membranes developed in our system is more amenable to water uptake due to the sharp decrease in the crystallinity by grafting. 25 As a result, large amorphous volumes may be available for water penetration within the membrane. …”

“…The crystalline structure of the membranes is disrupted significantly and a highly amorphous structure develops at the high graft levels of 590%. 25 The loss of crystallinity makes the matrix highly permeable, which may be a favorable factor in the accessibility of mercury ions to the amide groups within the membrane. Bicak et al also reported that acrylamide-grafted cellulose acts as a very effective sorbent for the removal of mercury ions and a mercury loading capacity of 3.55 mmol/g was achieved.…”

“…Recently, we carried out the grafting of acrylamide into polyethylene films to develop membranes for the separation of toxic metals from textile waste water. [22][23][24][25] These membranes undergo considerable changes in the surface morphology as well as in the bulk structure as a function of the grafted polyacrylamide component. 24,25 Membranes undergo considerable deterioration in the crystalline structure and have very little crystallinity at higher graft levels.…”

“…[22][23][24][25] These membranes undergo considerable changes in the surface morphology as well as in the bulk structure as a function of the grafted polyacrylamide component. 24,25 Membranes undergo considerable deterioration in the crystalline structure and have very little crystallinity at higher graft levels. In the present study, the physical properties, such as swelling characteristics and electric resistance as well as mercury binding, of these radiation-grafted polyethyleneg-polyacrylamide membranes with different degrees of grafting were investigated.…”

Design of modified plastic surfaces for antimicrobial applications: Impact of ionizing radiation on the physical and mechanical properties of polypropylene

“…These changes may be in terms of the crystallinity, mechanical behavior and thermal stability depending on the compatibility of the grafted component with the backbone matrix (Krupa and Luyt, 2001). The grafted material may behave as the bicomponent system as observed in FEP-g-polystyrene system (Gupta and Scherer, 1993) or else, it may undergo multi-step degradation pattern as evident from the TGA (thermogravimetric analysis) pattern of polyethyleneg-polyacrylamide films (Gupta and Anjum, 2001). The surface confinement of the grafts leaves behind a large fraction of the polymer bulk intact so that mechanical properties of the modified PP are expected to be significantly retained.…”