Graft polymers prepared by catalytic chain transfer polymerization (CCTP) and applied as solvent-borne dispersants for carbon black dispersions of high solid

In this article, a series of graft polymer dispersants were conveniently prepared by the grafting through method, among which the macromonomer was synthesized with one-pot through CCTP technology. Rheology and transmission electron microscopy (TEM) were utilized to study the influence of amide content on the carbon black (CB) dispersing ability of these polymers in xylene. When the tertiary amino groups on the backbone were partly quaternized, the apparent viscosity of the obtained CB suspensions decreased remarkably and the flocculation of the CB particles are effectively suppressed. TEM observations showed that the CB particles were well dispersed by the quaternized dispersant. It could be concluded that the graft polymers with a certain amount of quaternized amino groups (20 wt.%) are an efficient dispersants of CB in organic solvent.

Influence of amide content on the crystal structure of chitin

The crystalline structure of chitin and chitosan was investigated by X-ray diffraction (XRD). Chitosan filaments were prepared using a saturated solution of calcium chloride dihydrate in methanol (CaCl2-MeOH) as a mild solvent and the study focused on the interaction between the degree of acetylation (DA) and crystallinity. There were pronounced differences in the XRD patterns for specimens with DA values between 44.2% and 52.2%. We suggest that the crystalline structure changes from an anhydrous-type chitosan to an α-chitin type without any additives. CaCl2-MeOH is a good solvent for chitin and a poor solvent for chitosan and we found that it can regulate the distribution of N-acetyl glucosamine and glucosamine between amorphous and crystalline regions.

Chemical differences between thyrotropin isohormones

Amide determinations have been carried out, with a newly developed g.l.c. method, on thyrotropin hormones prepared by isoelectric focusing. The observed differences in amide content fully account for the differences in the electrochemical properties of the isohormones.