Effect of dextran and enzymatically decomposed dextran on the sucrose crystal shape

2019 ◽  
pp. 588-596
Author(s):  
Karin Abraham ◽  
Henriette Brykczynski ◽  
E.S.J. Rudolph-Flöter ◽  
Karl Schlumbach ◽  
A. Schäfer ◽  
...  

The effect of dextran’s molecular mass distribution on the sucrose crystal shape was key to this study. Therefore, sucrose crystals were produced by evaporating crystallization experiments using synthetic thick juices in the form of pure sugar syrups containing high (T2000) and low (T40) molecular mass dextran fractions as well as enzymatically decomposed dextran. The combined analysis of molecular mass distributions by size exclusion chromatography and sucrose crystal shapes by static image analysis were used to identify the least harmful reaction products resulting from the enzymatic decomposition of dextran. The combined evaluation of two shape parameters, circularity and width-to-length ratio, has shown that three different shape modifications can be related to the presence of dextran, namely cube-shaped crystals, elongated needle-shaped crystals and agglomerates. In the main, the data indicated that high T2000 contents and generally all T40 dextran contents led to an increased occurrence of agglomerated and occasionally elongated crystals. The latter was especially found for high T2000 dextran contents. In contrast, low T2000 dextran contents predominantly increased the amount of cube-like crystals. The enzymatic decomposition of dextran resulted in a gradual reduction of the molecular mass. It was shown that an insufficient decomposition to broadly distributed low molecular mass dextran fragments, which are realistic to assume for technical cane and beet juices, still dramatically affected the sucrose crystal shape. Once dextran was decomposed to molecules with molecular masses of less than 5 kDa, no dextran-related effects on the sucrose crystal shape were found.

A study has been made into electrification of linear flexible-chain polymers extruded through metal and dielectric ducts. Most of the work concerns 1,4-polybutadienes prepared by anionic polymerization, with different molecular masses and molecular mass distributions. A pre-requisite for intense static electrification is the relaxation transition of the polymer from fluid into forced high-elastic state in which the polymer slides over the duct wall surface. The relation between electrification of polymers and their molecular mass, molecular-mass distribution, temperature, sliding velocity, and the duct length has been established. Electrification of polybutadiene in dielectric ducts and the effect of the chemical nature of polymers on their static electrification were also examined.


1986 ◽  
Vol 58 (12) ◽  
pp. 2403-2408 ◽  
Author(s):  
Keith D. Bartle ◽  
Derek G. Mills ◽  
Michael J. Mulligan ◽  
Ifeanyi O. Amaechina ◽  
Norman. Taylor

2004 ◽  
Vol 18 (3) ◽  
pp. 778-788 ◽  
Author(s):  
Fatma Karaca ◽  
Carlos A. Islas ◽  
Marcos Millan ◽  
Mahtab Behrouzi ◽  
Trevor J. Morgan ◽  
...  

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 424
Author(s):  
Kristina L. Goranova ◽  
Anne Kathrine Kattenhøj Sloth Overgaard ◽  
Ivan Gitsov

This paper reports the creation of hydroxyapatite/polyester nanografts by “graft-from” polymerization of d,l-lactide with [Ca5(OH)(PO4)3]2 as the initiator and tin(II)-2-ethylhexanoate as the catalyst. Model polymerizations were performed with cyclooctanol as initiator to confirm the grafting on the surface of the hydroxyapatite nanocrystals. Polymers with the highest molecular mass (Mn) between 4250 Da (cyclooctanol) and 6100 Da (hydroxyapatite) were produced. In both cases the molecular mass distributions of the polymers formed were monomodal. The materials obtained were characterized by size-exclusion chromatography, NMR and FT-IR spectroscopy, and thermal methods. Their suitability as additives for commercial bone cement (Simplex P Speedset, Stryker Orthopaedics) has been confirmed by thermal analysis techniques and mechanical testing. The results obtained show that addition of the hydroxyapatite/ polyester nanografts improved both thermal and mechanical properties of the bone cement.


Sign in / Sign up

Export Citation Format

Share Document