摘要:

The acid-catalyzed reaction of dialdehyde starch with diethylene glycol and polyethylene oxide-400 under anhydrous conditions was studied as a new approach to the preparation of graft polymers of polyalkylene oxides on starch, the attachment of the side chains being through acetal linkages. The reaction was carried out in DMF in the presence of p-toluene sulfonic acid. It was found that increasing the reaction temperature, the diol concentration, or the reaction time led to an increase in the degree of grafting, as seen from the decrease in the dicarbonyl content of the products. Fusible graft polymers, soluble in water and in organic solvents, were obtained.

ISSN:0022-233X    

DOI:10.1080/00222337008060990

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Degree of branching in PVC as a function of its temperature of polymerization has been determined by the catalytic hydrogenation (LiAlH4) of the polymer followed by IR measurements. The samples used were prepared at 55, 90, 130, and 160°C. A branching calibration curve (ACH3/ACH2vs CH3/CH2) was established for linear hydrocarbons, and was found to follow the relation, ACH3/ACH2= 20(CH3/CH2). This equation was used to characterize the branching indices of PVC samples studied. Branching values in units of 100(CH3/CH2) were as follows: 55°C (1.92), 90°C (1.95), 130°C (2.61), and 160°C (2.96). These results are in agreement with the theoretical prediction that the degree of branching in PVC should decrease with the lowering of its temperature of polymerization because the energy of activation for the propagation step is smaller than that for chain the transfer step.

ISSN:0022-233X    

DOI:10.1080/00222337008060991

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A new mechanism for separation in gel permeation chromatography (CPC) or gel filtration has been developed based upon the postulate that flow occurs through the gel phase. On the basis of the hydrodynamic nature of the separation mechanism, the new nameHydrodynamic Fractionationis proposed. A theory has been formulated for the case of equal pore size in the gel phase and equal sized spaces between the beads. This theory predicts the elution volume vs molecular weight curve. The flow-rate dependence of the separation peaks is investigated.

ISSN:0022-233X    

DOI:10.1080/00222337008060992

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The nuclear magnetic resonance spectra of packed beds containing the cation exchanger Dowex 50W-X8 in water vary with counter ion. Chemical shifts for water protons internal to the resin bead are in the order H+(lowest frequency) » Zn2+≊ Cd2+≤ Pb2+≊ Mg2+≤ Ag+≤ Ca2+≊ Tl+≊ NEt+4≊ Ba2+≊ Li+≊ NMe4+≊ Sr2+≤ NH4+≤ Rb+≊ K+≊ Na+≊ NBu4+. The concentrated electrolyte model of ion-exchange resins is substantiated by generally good agreement between 1) chemical shifts/g equiv./kg for cations in aqueous solutions referred to NH4+and 2) chemical shifts/g equiv./kg for resin forms referred to NH4+form resin.

ISSN:0022-233X    

DOI:10.1080/00222337008060993

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/00222337008060994

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

ISSN:0022-233X    

DOI:10.1080/00222337008060995

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

This is a scanned image of the original Editorial Board page(s) for this issue.

ISSN:0022-233X    

DOI:10.1080/00222337008060979

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor