Maleic acid grafting on low density polyethylene

Abstract

Grafting of maleic acid (MAc) on low density polyethylene (LDPE) was carried out using γ‐irradiation technique. Preactivation method was used for grafting and a maximum grafting of 2.4% was obtained. Grafted polymer(LDPE‐g‐MAc) was characterized by chemical method, Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermo‐Gravimetric Analysis (TGA), Melt Flow Index (MFI), Tensile Property Measurement, Particle Size Analysis, and Hot Stage Optical Microscopy. Presence of carbonyl peak of high intensity, high acid value, and low melt flow index value confirmed grafting of MAc on LDPE. A marginal change in thermal and mechanical properties of LDPE was observed after grafting. Change in crystallization behavior of LDPE has been noticed after grafting. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2802–2807, 2004

Investigation of Poly(vinyl pyrrolidone) in methanol by dynamic light scattering and viscosity techniques

“…The same behavior was shown for a solution of the PVP in water and that was explained by the change of the conformation which had occured as a result of the rotational freedom around -C-C-single bonds within the PVP molecule in moderately dilute solution [10,11]. Further more, vinyl polymers contain methylene units in their main chain as the spacer, which would relieve steric repulsion between the side chain substituents and the chain becomes a less-flexible polymer [12].…”

“…3 shows an anomalous behavior (rapid viscosity upswing This would be indicative of molecular break-down and/or conformational change to a more compact shape, as observed by O. Melad in the case of PVP in DMF [23] and by M. Singh et. al in the case of PVP in water [10,11]. This behavior could be attributed to the smaller structural changes of PVP in methanol, and to the rotational freedom around -C -C-single bonds within monomer units in dilute solution, which results in conformational changes [10,11].…”

“…al in the case of PVP in water [10,11]. This behavior could be attributed to the smaller structural changes of PVP in methanol, and to the rotational freedom around -C -C-single bonds within monomer units in dilute solution, which results in conformational changes [10,11]. In fact the most important polymerpolymer interaction is the thermodynamic interaction which includes the intramolecular excluded volume effect, resulting in an expansion of the coil in solution and the intermolecular excluded volume effect, resulting in contraction of the coil [23,24].…”

“…We note that the temperature don't change the MHS exponent a; may be the range of chosen temperature is weak. The rotational freedom of PVP monomer units around -C-C-single bonds can provide a less-flexible chain [10,11,15]. We have tried to adjust our curve, by the second-order least-squares regression [13].…”

“…2 is somewhat accentuated by the high molecular weight sample. A macromolecule can adopt many different conformations by rotation over the covalent single bonds that form the chain skeleton [11]. In most circumstances, the inter-conversion from one to another conformation is very easy, and the polymer changes among the allowed conformations.…”