摘要:

AbstractEthyl α‐hydroxymethylacrylate (EHMA) was synthesized and homopolymerized in bulk and in solution. The poly(EHMA) is readily soluble in alcohol, acetone, tetrahydrofuran, and methylene chloride at room temperature. Intramolecular lactone formation occurred when poly(EHMA) was heated to 180–230°C. The kinetics of EHMA homopolymerization was investigated in ethyl acetate, using α,α′‐azobisisobutylonitrile as an initiator. The rate of polymerizationRpwas expressed byRp=k[AIBN]0.50[EHMA]1.4and the overall activation energy was calculated as 71.9 kJ/mol. Kinetic constants for EHMA polymerization were obtained as follows:kp/k t1= 0.17L0.9mol−0.9s−0.5; 2fkd= 1.5 × 10−5s−1. The relative reactivity ratios of EHMA(M2) copolymerization with styrene (r1= 0.472,r2= 0.564) in ethyl acetate were obtained. Applying theQ‐escheme led toQ=

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270301

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe microstructure of polyphosphites and polyphosphates obtained by the ring‐opening polymerization of asymmetrically substituted 5‐membered cyclic phosphites was studied. It has been established, using31P NMR, that 4‐substituted 2‐hydro‐2‐oxo‐1,3,2‐dioxaphospholanes underwent polymerization giving polymers with head‐to‐tail dyads as well as head‐to‐head and tail‐to‐tail structures. Analyses of31P NMR spectra of racemic and optically active poly(2‐hydro‐4‐methyl‐2‐oxo‐1,3,2‐dioxaphospholane) and model compounds estimated the statistical mode of ring scission of cyclic phosphites. Similar results were obtained for the polymerization of 4‐acetoxymethyl‐2‐hydro‐2‐oxo‐1,3,2‐dioxaphospholane, which provided the simplest mode

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270302

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe copolyester composed of 60 mol%p‐hydroxybenzoic acid and 40 mol% ethylene terephthalate has been studied extensively by earlier workers. However, some confusion exists particularly with respect to the nature of the thermal transitions and the possible presence of additional phases. In the present study we have examined this copolyester and found that it is possible to separate the material into soluble and insoluble fractions with significantly different ratios ofp‐hydroxybenzoic acid to ethylene terephthalate. In fact, the soluble PET‐rich fraction is blocky in nature, while the PHBA‐rich fraction is more random. The multiple thermal transitions can now be readily interpreted in terms of a heterogeneous composition which tends to segregate and phase s

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270303

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractA solution of AlCl3in CH2Cl2prepared in advance was used 18 days after the mixing of the components as an initiation system in the polymerization of isobutylene performed in CH2Cl2in the temperature range between −10 and −20°C. The1H‐NMR analysis of polyisobutylene (PIB) samples synthesized to low and high conversion showed that it is the initiation reaction and not the transfer reaction to dichloromethane that is responsible for the CH2Cl endgroup in the polymer chain. In case of the transfer to monomer formation of PIB with internal terminal unsaturation [PIBCHC(CH3)2] is preferred to external unsaturation [PIBCH2(CH3)CCH2]. The solutions of AlCl3in CH2Cl2showed an absorption band

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270304

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractPlasma polymerization of ethylene glycol monomethylether (EGMME) was investigated by elemental analysis, infrared spectroscopy, and ESCA. The surface and permeation properties for the formed polymers were discussed. EGMME was plasma‐polymerized to yield films. The films contained a large amount of oxygen‐containing groups such as hydroxy, carbonyl, carboxylate ester, and ether groups. The formation of polymers having hydroxy groups was favorable in plasma polymerization at lowW/FMvalues. Their surface energy was high (63.2–57 dyn/cm) and decreased with increasing theW/FMvalue. The plasma‐polymers from EGMME had slightly high water‐vapor permeability and low oxygen and nitrogen permeabilities. The plasma‐polymers, conclusively, are characterized to have high selectivity in water‐vap

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270305

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractPolymerization of vinyl acetate initiated by β‐picoliniump‐chlorophenacylide was carried out at 30, 35, and 40°C, using conventional dilatometric technique. The initiator and the monomer exponent values were 0.80 ± 0.15 and unity, respectively. The polymerization was inhibited in the presence of hydroquinone, but was favored by nonpolar solvent and polymerization temperature. The energy of activation was 90.3 KJ mol−1. An average value ofk p2/ktfor the present system was found to be 0.37 × 10−2. The results are explained in terms of a radical mode of polymerization with degradative initiator transfer; the principal mode of termination, however, wa

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270306

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe CCD (chemical composition distribution) of poly(styrene‐co‐ethyl methacrylate) has been determined by thin layer chromatography/flame ionization detection (TLC/FID). It appeared that a mixture of five reference copolymers obtained by solution polymerization each having a narrow CCD, could be separated in five distinct peaks, provided a modified spotting procedure and a concentration gradient elution technique were applied. All copolymers prepared by solution polymerization could be successfully characterized. Copolymers obtained by emulsion techniques using nonionic or anionic surfactants containing oxyethylene groups, or in the absence of chain length modifier behaved anomalously and appeared to have spurious CCD's. Also the average composition calculated from these CCD's did not agree with the average composition determined by1H‐NMR. This anomalous behaviour disappeared when using sodium lauryl sulfate as surfactant or when applying a chain length modifier (n‐dodecyl mercaptan) during the preparation of the polymer. Several possibilities have been proposed in order to explain these phenomena. The most probable explanation seems to be reaction of a growing polymer chain with surfactant molecules resulting in a quasi‐terpolymer. This polymer containing highly polar oxyethylene groups, remains strongly adsorbed on the silica surface during elution, thus disturbing the separatio

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270307

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractEthylene–propylene random copolymers bearing grafted succinic anhydride functions have been reacted with an α,ω‐hydroxyl telechelic polybutadiene to obtain elastomeric interpolymer complexes. A kinetic study has been carried out by infrared techniques to study the influence of the addition of catalyst, stoichiometry, and temperature on the degree of monoesterification rea

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270308

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractIn the bulk polymerization of three isomeric diallyl phthalates, diallyl phthalate (DAP), diallyl isophthalate, and diallyl terephthalate (DAT), no difference in the actual gel point was substantially observed. This interesting gelation behavior is discussed in terms of the correlation between gelation and the difference in cyclization modes, and the difference in reactivity between the uncyclized and cyclized radicals for crosslinking; the nonconsecutive addition in DAT polymerization led to a delayed gelation and the cyclized radical in DAP polymerization showed an enhanced reactivity for crosslinking.

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270309

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractCopolymers of styrene and vinyl acetate were synthesized electrochemically. The reaction system was composed of methylene chloride as the solvent, and a quaternary ammonium salt as the electrolyte. The reactions were run in a divided cell and the influence of current strength, reaction time, and temperature on the yield, molecular weight, and chemical composition of the resulting copolymers was investigated. It was found that the polymer chains were composed mainly of styrene units.

ISSN:0887-624X    

DOI:10.1002/pola.1989.080270310

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY