摘要:

A cation-exchange resin (a crosslinked polymer carrying carboxyl groups) was used as a model compound for carbon black, and the grafting of several polymers to the resin was investigated. Reaction of acyl chloride groups that had been placed on the ion-exchange resin with polymers having hydroxyl or amino groups, such as polypropylene glycol, polyethylene glycol, polybutadiene glycol, polyvinyl alcohol, silicone diol, silicone diamine, and polyethyleneimine, resulted in grafting to the ion-exchange resin. In further experiments, primary amino groups were placed on the cation-exchange resin by reaction of acyl chloride groups with ethylenediamine. It was found that ring-opening polymerization of γmethylL-glutamateN-carboxyanhydride is initiated by the amino groups on the resin, and polypeptide was grafted from the cation-exchange resin. Therefore, the reactivity of carboxyl groups on the resin was found to be similar to that on carbon black. However, carboxyl groups on the resin failed to initiate the cationic polymerization of vinyl monomers, in contrast to those on carbon black. This suggested that the acidity of carboxyl groups on carbon black is greater than on the cation-exchange resin.

ISSN:0022-233X    

DOI:10.1080/10601328808055083

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The graft copolymerization of butyl acrylate (BA) onto gelatin with ceric ammonium nitrate (CAN) as redox initiator in an aqueous medium has been studied. The products were characterized by IR. The effects of various reaction parameters, including reaction time and temperature, concentrations of gelatin, monomer, initiator, and nitric acid, on the percentage of grafting, the grafting efficiency, and the rate of graft copolymerization were studied systematically. The influences of some inorganic salts, organic additives, and the emulsifier were also investigated. The disappearing rate of Ce(IV) during the period of reaction was observed. The activation energy of graft copolymerization, homo-polymerization, and total polymerization were calculated. The reaction mechanism is discussed, and rate equations of the reaction are proposed.

ISSN:0022-233X    

DOI:10.1080/10601328808055084

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Block polymerization of methyl methacrylate initiated with monohalo-terminated polystyrene/manganese carbonyl systems were investigated. The rate of polymerization was lower than that of the trihalo-terminated polystyrenelmanganese carbonyl system. The molecular weight of the block copolymers obtained was independent of the conversion. To define the polymerization mechanism, 1-bromobutane was employed as a model compound for monohalo-terminated polystyrene. Polymerization kinetics followed a modified rate equation based on the Michaelis-Menten mechanism. The molecular weight of the block co-polymer could be regulated by varying the ratio of monohalo-terminated polymer to methyl methacrylate. Graft polymerization of methyl methacrylate initiated with chloromethylstyrene-styrene copolymer/ manganese carbonyl was also carried out. The polymerization behavior was strongly affected by the concentration of manganese carbonyl. Characterization of graft copolymers by GPC and halogen analysis showed that the number of grafting points per backbone polymer molecule increased when the concentration of manganese carbonyl was raised, but that the branches became shorter.

ISSN:0022-233X    

DOI:10.1080/10601328808055085

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The polymer of 1- 3-O[(R)1-(L-alanyl-D-isoglutamyl carbonyl)ethyl] α-D-glucopyranos-6-O-carbonyl ethylene was synthesized as a acryloyl type polymer by fixing theD-glucose analog (GADP) ofN-acetylmuramyl-L-alanyl-D-isoglutamine (MDP), which is the minimum required structure responsible for the immunoadjuvant activity of bacterial cell-wall peptidoglycan.N- [2-(1,2-O-Isopropylidene-6-O-acryloyl-α-D-glucofuranos-3-Oyl)-(R)-propionyl] -L-alanyl-D-isoglutamine benzyl ester (6) was prepared as a key monomer in the synthesis. The homopolymerization of 6 and the copolymerization of 6 with hydrophobic acryloyl monomers were carried out in benzene at 60°C by using 2,2′-azobisisobutyronitrile as a radical initiator to give homopolymer 7 and copolymer 10, respectively. Removal of isopropylidene and benzyl protecting groups from 7, 10 and 8, 11 was carried out by acid treatment with trifluoroacetic acid/water (6:1 v/v) and by catalytic hydrogenolysis with palladium carbon, respectively, to afford the homopolymer 9 and the copolymer 12.

ISSN:0022-233X    

DOI:10.1080/10601328808055086

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

1,1′-Dihydroxyethyl-2,2′-biimidazole has been used as a copolymerizing monomer with the diglycidyl ether of bisphenol A in the preparation of biimidazole-containing epoxy polymers. Polymerization reactions were studied in bulk, with and without catalyst, and inN,N-dimethylforma-mide and anisole solvents, with and without catalyst. FT-IR and NMR spectra, molecular weight, thermal and solubility characteristics were obtained. Polymers isolated as amorphous light brown solids were found to be only sparingly soluble in THF or in highly polar nitrogen-containing solvents (DMF, NMP, pyridine). These materials exhibited molecular weights up to 37 000 for SnC14-catalyzed polymerization carried out in DMF. A glass-transition temperature of 391°C was observed for polymers obtained under uncatalyzed solventless conditions. The glass transition temperature was 373°C for product obtained under SnC14-catalyzed, solventless conditions. Thermogravimetric analysis in air of polymers obtained under varying solvent and catalyst conditions showed less than 25% weight loss below 330°C and greater than 75% weight loss above 400°C.

ISSN:0022-233X    

DOI:10.1080/10601328808055087

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Transparent, electrically conductive composite films were obtained by vapor-phase polymerization of pyrrole into a poly(vinyl chloride) (PVC) matrix containing FeCl3. The effects of water and of organic solvents on the polymerization were investigated. It was found that the conductance of the films increases in the presence of both water vapor and of good solvents or swelling agents for PVC. The conductivity of the films rises with reaction time and so does the rate of increase with higher FeCl3concentration. The production of HCl was monitored by two methods, the precipitation of AgCl in an aqueous solution of silver nitrate and the increase in conductance of an aliquot of distilled water which had been placed into the reaction chamber. On the basis of our experimental results, we propose a reaction mechanism that explains the observed increase of conductance with time. A universal kinetic formula has been derived which relates the increase of electrical conductance to other parameters characterizing the boundary conditions of the polymerization.

ISSN:0022-233X    

DOI:10.1080/10601328808055088

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The reaction kinetics of atactic polypropylene (APP) in bulk with dicumyl peroxide (DCP) as a radical generator have been studied by means of thermal differential analysis. Hydrogen abstraction from APP by cumyl radicals gives (polypropylen)yl radicals which undergo transfer to DCP, chain scission, disproportionation, and crosslinking, as well as reaction with cumyl radicals. Chain scission is shown to be the faster and crosslinking the slower of these two processes, even at temperatures of 473 K and above. Activation parameters are determined, and an analysis of the different processes is made on their basis.

ISSN:0022-233X    

DOI:10.1080/10601328808055089

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The number of particles formed in batch emulsion polymerization over wide ranges of emulsifier and initiator concentration has been investigated by computer simulation with a mathematical model developed in a previous paper. The influence of particle coagulation is also considered. The results show that, at low emulsifier concentration, the steady-state particle numberNsis governed by homogeneous nucleation so thatNsincreases slowly with increasing emulsifier concentration [S]. In this range,Nsincreases with increasing monomer polarity. The steep rise inNswith emulsifier concentration after [S] exceeds a critical value suggests a transition from homogeneous nucleation domination to micelle nucleation. The slope of theNsvs [S] relationship increases as the particle coagulation rate constantKfincreases. The powerxin the empirical relationshipNs≊ [S]xdecreases with increasing polarity of monomer in this region. At very high micelle concentration, insufficient radical generation and the increasing tendency for particle coagulation causeN2to be less dependent on emulsifier concentration. These phenomena have been reviewed by Vanderhoff and confirmed by the experimental data presented by Sutterlin. The particle number increases with increasing initiator concentration [I] when [S] is above the CMC. As [I] continues to increase, however,Nsbecomes relatively constant. Experimental data for styrene, butyl acrylate, and methyl acrylate from the literature are compared with the model predictions. Agreement between the theoretical predictions and the experimental data is evident over a wide range of emulsifier and initiator concentrations.

ISSN:0022-233X    

DOI:10.1080/10601328808055090

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Methyl acrylate was grafted onto dissolving pulp by ceric ion in aqueous sulfuric acid under oxygen-free argon. At a low Ce(IV) concentration (up to 1 mmol/L), the rate of polymerization (Rp) is proportional to [Ce]0.5[MA]1[cellulose]1. At higher concentrations of cericion (1–20 mmol/L),Rpis proportional to [Ce]0[M]1.5[cellulose]1. The mechanism of grafting is consistent with a kinetic scheme involving initiation by primary radicals and termination by growing polymer radicals. Above 20 mmol/L of ceric salt, the data are consistent with the linear termination mode.

ISSN:0022-233X    

DOI:10.1080/10601328808055091

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The polymerization of some kinds of vinyl monomer was found to occur in aqueous solutions of poly(ethylene glycol) diglycolic acid (PEG Acid) or sodium poly(ethylene glycol) diglycolate (PEG Acid Na) through radical mechanisms without any further initiator, as a so-called “uncatalyzed polymerization.” Although the initiating radical species for PEG Acid was determined to be the same as that for PEG Acid Na by means of the spin-trapping technique, the initiating ability of PEG Acid was higher than that of PEG Acid Na. These results are assumed to be attributable to the difference in the initiation mechanisms of the two systems and in the incorporating abilities of monomer into the hydrophobic areas formed by PEG Acid and PEG Acid Na.

ISSN:0022-233X    

DOI:10.1080/10601328808055092

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor