摘要:

Macroreticular cation exchangers can be prepared by polymerizing sulfonated phenols with formaldehyde under acidic conditions. The resins are highly porous with large surface areas. Their properties compare well with those based on styrene and divinylbenzene copolymers.

ISSN:0022-233X    

DOI:10.1080/00222337808069408

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Thermal degradation of PVC treated with alkylaluminum compounds has been studied. Four PVC samples of different molecular weights have been treated with Me3Al, and Et3A1, and the dehydrochlorination rates of the polymers were determined at 190 and 220°C under a nitrogen atmosphere. The alkylaluminum-treated low molecular weight samples show marked increase in thermal stability, i. e., slower rate of dehydrochlorination right from the beginning of degradation, whereas with the higher molecular weight samples stabilization becomes pronounced only after a few percent of dehydrochlorination. The color of R3Al-treated samples was much lighter (yellowish) than those of controls (dark brown) at 1% HCl loss. The average polyene sequence lengths formed during the early stages of dehydrochlorination are found to be much shorter with RsAl-treated PVC than with virgin samples. It appears as though polyene sequences which arose by zipping- initiation from allylic and/or tertiary chlorine sites are longer than those which form by random initiation along the chain. The autocatalytic (i. e., HC1-catalyzed) dehydrochlorination observed with virgin PVC disappears after treatment with R3A1. The HCl-catalyzed dehydrochlorination is minimized when thin films are used instead of powdery samples, which may be due to higher rates of HC1 diffusion through thin films. Autocatalysis of dehydrochlorination is affected by the concentrations of double bonds and HCl and the length of polyene sequences. Interaction between polyenes and HC1 by hydrogen transfer may lead to the re-initiation of unzipping, thus lengthening the polyene sequences.

ISSN:0022-233X    

DOI:10.1080/00222337808069409

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Thermal decompositions of polyisoprene, poly(p-isopropyl α-methylstyrene) (PPIPαMS), and poly(isoprene/p-isopropyl α-methylstyrene) (sample M-32) were carried out at various temperatures in the range 200–340° C in a differential thermo-gravimetric apparatus. The undecomposed polymers as well as their decomposed residues were analyzed by gel-permeation chromatography (GPC), infrared spectroscopy (IR), and nuclear magnetic resonance (NMR). Based on the changes observed in the distribution of molecular weights, depolymerization is the predominant step in the decomposition of PPIPAMS and polymer M-32, whereas random scissions predominate in the case of polyisoprene. The combined data of GPC, IR, and NMR indicate that only interchain reactions leading to the formation of cyclized products are present in the decomposition of polyisoprene while interchain as well as intrachain reactions are operative in the case of polymer M-32.

ISSN:0022-233X    

DOI:10.1080/00222337808069410

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The polymerization of vinyl monomer initiated by an aqueous solution of sodium polystyrenesulfonate (PSS-Na) was carried out at 85°C. Methyl methacrylate (MMA) and styrene were polymerized, while acrylonitrile was not. The rate of polymerization of MMA decreased with the increase of the degree of polymerization of PSS-Na. However, the polymerization was not initiated by sodium ethyl benzenesulfonate which was a unit molecule of PSS-Na. The polymerization proved to be a radical reaction. The polymerization was considered to commence with the formation of hydrophobic areas with PSS-Na in the aqueous phase. MMA is incorporated into these areas, and there the polymerization is initiated and proceeds. The hydrophobic areas were assumed to be similar to the micelles formed by anionic detergents such as sodium alkylbenzene sulfonate. An initiation mechanism is proposed.

ISSN:0022-233X    

DOI:10.1080/00222337808069411

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Vinyl mercaptobenzazoles [thiazole (VMBT), oxazole (VMBO), and imidazole (VMBI)] were prepared through dehydrochlorination of the respective β-chloroethyl mercaptobenzazoles. These monomers were found to undergo vinyl polymerization in the presence of light or radical initiator, α,α'-azobisisobutyonitrile, to give relatively high molecular weight homopolymers. From the results of radical copolymerizations of these monomers with various monomers, the copolymerization parameters were determined as follows: VMBT(M2): r1styrene(M1): r1= 2.12 ± 0.09, r2= 0.336 ± 0.028, Q2= 0.75, ez= −1.38; VMBO(M2)-styrene(M1): r1= 2.61 ± 0.13, r2= 0.274 ± 0.03, Q2= 0.61, e2= −1.38; VBMI(M2)-styrene(M1) r1=4.0, r2= 0.2, Q2= 0.37, e2= −1.17. The polymerization reactivities of these monomers obtained from these parameters were compared with those of other vinyl sulfide monomers and discussed.

ISSN:0022-233X    

DOI:10.1080/00222337808069412

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A kinetic study of radical polymerization of vinyl mercaptobenzothiazole (VMBT) with α,α′-azobisisobutyonitrile (AIBN) at 60°C was carried out. The rate of polymerization (Rp) was found to be expressed by the rate equation: Rp= k[AIBN]0.5[VMBT]1.0, indicating that the polymerization of this monomer proceeds via an ordinary radical mechanism. The apparent activation energy for overall polymerization was calculated to be 20.9 kcal/mole. Moreover, this monomer was copolymerized with methyl methacrylate, acrylonitrile, vinyl acetate, phenyl vinyl sulfide, maleic anhydride, and fumaronitrile at 60°C. From the results obtained, the copolymerization parameters were determined and discussed.

ISSN:0022-233X    

DOI:10.1080/00222337808069413

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The kinetics of the copolymerization of methyl methacrylate and maleic anhydride was investigated in benzenic solutions at 60 and 70° C and in bulk at 60°C. The microstructure of the copolymers was determined by1H-NMR and IR spectrophotometry. In benzene solutions the mechanism of copolymerization involves the participation of an associative species between both comonomers. In bulk a terminal model is sufficient to explain all the results.

ISSN:0022-233X    

DOI:10.1080/00222337808069414

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Poly(ethyl acrylate) has been grafted onto Himachali wool in an aqueous medium by using ceric ammonium nitrate (CAN) as redox initiator. Copolymerization was studied at five different temperatures: 40, 45, 50, 55, and 60°C. Maximum grafting occurred at 45°C. Nitric acid was found to catalyze the graft copolymerization reactions. Percentage and efficiency of grafting were found to be dependent upon concentrations of CAN (initiator) and of monomer. Percentage of grafting has been determined as function of time, and from the slope of percent grafting versus time plot, the initial rate of graft copolymerization (R) has been determined.

ISSN:0022-233X    

DOI:10.1080/00222337808069415

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

The polymerization of methyl methacrylate (MMA) initiated by the system lysozyme, copper(II) chloride, and water was carried out. The effect of the amount of each component on the conversion of MMA was studied. The polymerization proceeded through a radical mechanism. Urea, known to be a denaturing agent for protein, was able to promote the polymerization. On addition of urea, it was found that the following three reactions took place: (1) promotion of the polymerization of MMA with lysozyme, Cu(II) ion, and water by the unfolding of the third structure of lysozyme, (2) polymerization initiated by urea and Cu(II) ion, (3) polymerization initiated by the S-S bonds of lysozyme and urea.

ISSN:0022-233X    

DOI:10.1080/00222337808069416

出版商:Taylor & Francis Group    

年代:1978

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:10.1080/00222337808069407

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor