Local Uniaxial Order in a Grafted Polymer Melt via Deuterium NMR

1995 ◽  
Vol 75 (11) ◽  
pp. 2140-2143 ◽  
Author(s):  
M. Zeghal ◽  
P. Auroy ◽  
B. Deloche
1997 ◽  
Vol 56 (5) ◽  
pp. 5603-5614 ◽  
Author(s):  
M. Zeghal ◽  
B. Deloche ◽  
P.-A. Albouy ◽  
P. Auroy

1992 ◽  
Vol 25 (18) ◽  
pp. 4569-4574 ◽  
Author(s):  
G. T. Pickett ◽  
T. A. Witten
Keyword(s):  

Author(s):  
A. C. Reimschuessel ◽  
V. Kramer

Staining techniques can be used for either the identification of different polymers or for the differentiation of specific morphological domains within a given polymer. To reveal morphological features in nylon 6, we choose a technique based upon diffusion of the staining agent into accessible regions of the polymer.When a crystallizable polymer - such as nylon 6 - is cooled from the melt, lamellae form by chainfolding of the crystallizing long chain macromolecules. The regions between adjacent lamellae represent the less ordered amorphous domains into which stain can diffuse. In this process the lamellae will be “outlined” by the dense stain, giving rise to contrast comparable to that obtained by “negative” staining techniques.If the cooling of the polymer melt proceeds relatively slowly - as in molding operations - the lamellae are usually arranged in a radial manner. This morphology is referred to as spherulitic.


2014 ◽  
Vol 35 (1) ◽  
pp. 121-135 ◽  
Author(s):  
Tomasz Rydzkowski ◽  
Iwona Michalska-Pożoga

Abstract The paper presents the summary of research on polymer melt particle motion trajectories in a disc zone of a screw-disk extruder. We analysed two models of its structure, different in levels of taken simplifications. The analysis includes computer simulations of material particle flow and results of experimental tests to determine the properties of the resultant extrudate. Analysis of the results shows that the motion of melt in the disk zone of a screw-disk extruder is a superposition of pressure and dragged streams. The observed trajectories of polymer particles and relations of mechanical properties and elongation of the molecular chain proved the presence of a stretching effect on polymer molecular chains.


Author(s):  
Felipe Oliveira Basso ◽  
Paulo Zdanski ◽  
Diego Beppler ◽  
Miguel Vaz Jr.

1993 ◽  
Vol 8 (4) ◽  
pp. 328-334
Author(s):  
T. Kegasawa ◽  
J. L. White
Keyword(s):  

2020 ◽  
Vol 16 (9) ◽  
pp. 1404-1410
Author(s):  
Rishabha Malviya

Background: In the previous study, investigators have synthesized acrylamide grafted and carboxymethylated derivatives of neem gum and evaluated their potential in the formulation of nanoparticles. In continuation of previous work, authors have evaluated neem gum polysaccharide (NGP), acrylamide grafted neem gum polysaccharide (NGP-g-Am) and carboxymethylated neem gum polysaccharide (CMNGP) as binding agent in the tablet dosage form. Methods: Diclofenac sodium was used as a model drug while microcrystalline cellulose and talc were used as excipient in the preparation of granules employing wet granulation technique. NGP, NGP-g-Am and CMNGP were utilized as binding agent in the preparation of granules. Prepared granules were characterized for various pre-compression and post-compression parameters. Results and Discussion: Binding agents were used in the concentration of 4-24%w/w. NGP incorporated granules showed more bulk density and lower values of tapped density, Carr’s index, bulkiness, Hausner’s ratio and angle of repose as compared to NGP-g-Am consisting granules. NGP-g-Am consisting tablets showed more hardness and zero friability as compared to NGP based tablets. Drug content was found lower for the tablets having grafted polymer in place of NGP. CMNGP were also utilized to prepare granules but granules were not be able to compress keeping all the compacting parameters same as used in the case of NGP and NGP-g-Am consisting granules. NGP and NGP-g-Am were able to sustain drug release up to 6 and 8 h, respectively. Conclusion: It can be concluded that NGP-g-Am induces better properties when used as a binder in the tablet formulation than native polymer, while CMNGP cannot be utilized as a binding agent in the preparation of a tablet.


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