The effect of molecular weight on the viscoelastic performance of an advanced polymer (LaRC-SI) was investigated through the use of creep compliance tests. Testing consisted of short-term isothermal creep and recovery with the creep segments performed under constant load. The tests were conducted at three temperatures below the glass transition temperature of each material with different molec...

a new model based on a combination of the polymeric multigrain and multilayer models has been developed to predict the polymerization rate, particle growth, morphology, effective parameters on broadening of the molecular weight distribution, number and weight average of the molecular weight, isotacticity index and bulk density of polymer. mathematical correlations and the kinetics used in this ...

We introduce a single molecular analysis technique for the evaluation of molecular weight distributions of polyelectrolyte solutions by measuring translocation times of sodium polystyrenesulfonate (NaPSS) chains in a mixture passing through an α-hemolysin protein nanopore. The ionic current through an α-hemolysin nanopore is partially blocked transiently when the pore is occupied by a polymer c...

Aseries of water dispersible polyurethanes containing carboxylate anion as the hydrophilic pendant group were prepared from toluene diisocyanate (TDI), 1,4butanediol (1,4-BDO), dimethylol propionic acid (DMPA) and different molecular weight of polytetramethylene glycol (PTMG). IR Spectroscopy was used to check the end of polymerization reaction and characterization of polymer.The effect of PTMG...

Porcine intestinal mucosal heparin induced aggregation of platelets in citrated platelet-rich plasma and enhanced platelet aggregation and serotonin secretion induced by other agents. This action of heparin was blocked by substances that elevate platelet cyclic AMP and by EDTA but not by inhibitors of platelet cyclooxygenase. The effect was not inhibited by apyrase or by N-amylthio-5'-AMP and t...

cofactor required for ristocetin. Fractionation of heparin yielded preparations that varied in molecular weight and, within a given molecular weight fraction, in affinity for antithrombin III. Fractions of high molecular weight (average 20,000) were more reactive with platelets than were fractions of low molecular weight (7,000). Anticoagulant activity did not parallel the platelet reactivity o...

Periploca sepium Bunge (Chinese silk vine) is a woody climbing vine belonging to the family Asclepiadaceae. It originally comes from Northwest China. Periploca resembles the Para-rubber tree, Hevea brasiliensis, regarding a similar body plan to produce a milky exudate containing rubber latex. The Periploca plant was assessed as a rubber-producing plant by rubber structure elucidation and its mo...

Five different molecular weight phenolphthalein poly(aryl ether ketone) (PEK-C) fractions in CHCl3 were studied by static and dynamic laser light scattering (LLS). The dynamic LLS revealed that the PEK-C samples contain some large polymer clusters. These large clusters can be removed by filtering the solution with a 0.1-μm filter. We found that the persistence length of PEK-C in CHCl3 at 25 °C ...

A new method was developed for production of low molecular weight chitosan, in which high molecular weight chitosan was treated with dilute sulfuric acid at 120°C. Chitosan was dissolved in the acid solution in a few minutes, and as depolymerized to low molecular weight chitosan by longer times. Low molecular weight chitosan was recovered from the acid by cooling down the solution and increasin...