摘要:

AbstractThe mass spectral characteristics of poly(2,6‐dimethyl‐1,4‐phenylene ether), its monomer (2,6‐xylenol), and its dimer (3,5‐dimethyl‐4‐hydroxyphenyl 2,6‐xylyl ether) have been determined. The monomer and dimer show peaks for the molecular ions (122; 242 amu) and degradation patterns similar to those ofo‐methylaryl ethers. Loss of methyl and cleavage of the ether with transfer of ano‐methyl hydrogen are observed. Metastable transitions are recorded corresponding to a loss of 15 from 122 and 56 from 107 amu (xylenol) and of 151 from 242 and 40 from 104 amu (ether). The polymer volatilizes readily at 380–400°C. (TGA shows rapid weight loss at 400°C) and gives sets of peaks at (N× 120) ± 14 up to 1080 (N= 9). The principal peak is at (N× 120) + 2, calibrated against PFA, and this is attributed to an ion of a volatilized oligomer. The oligomer is either present as such, is formed in a degradation process involving an ether redistribution, or is formed in a hydrogen transfer process in t

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090111

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractThe use ofN,N,N′,N′‐tetramethylethylenediamine (TMEDA) is known to enhance the metallation of capability of butyllithium. It has been found that this TMEDA–BuLi reagent smoothly metallates olefins in high yields at 50°C in less than 4 hr by replacement of allylic hydrogen. This reaction has been applied to unsaturated polymers such as polybutadiene and polyisoprene. The resulting products have lithium atoms scattered along the chain. The amount of lithium on the chain can be varied over wide limits. Each lithium atom on the chain can act as a site for grafting or adding functional groups to the base polymer. Thus, this method allows the preparation of polymers having controlled amounts of branching as well as the introduction of functional groups into the polymer. Through the use of this metallation technique, polymers containing styrene and butadience grafts are specifically reported. In addition, polymers containing hydroxyl or carboxyl groups along the backbone are prepared by using this t

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090112

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractThe three‐dimensional polymerization of the system glycol monomethacrylate–glycol dimethacrylates–solvents has been studied. The kinetic dependences thus obtained were interpreted in terms of the dependence of rate constants of the individual reactions on the properties of the medium used. The three‐dimensional polymer formed was characterized in the range from medium to the highest conv

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090113

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractAn NMR method for determining the distribution of acetyl groups in cellulose acetates was developed. Treatment of cellulose acetates with acetyl‐d3chloride gave products having simple spectra which could be analyzed quantitatively to give the distribution of acetyl groups in the original sample. The method was applied to studying (1) the hydrolysis of cellulose triacetate with ammonia, (2) the acetylation of cellulose acetate with acetyl chloride, and (3) the acetylation of cellulose acetate with acetic anhydrid

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090114

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

Abstractcis‐ andtrans‐1‐Ethoxy‐1,3‐butadienes were polymerized by a variety of cationic agents in various solvents at −78°C. Thetransether, which is the more stable isomer, was found to have greater polymerizability than thecisether. Thetransmonomer gave polymers predominantly of thetrans‐1,4 type, whereas thecismonomer showed a tendency toward the formation of polymers having the microstructure of the 1,2 type. It was concluded that, in thecisether, the carbon atom which is the most vulnerable to the attack of carbonium ions is the one at the 2‐position, whereas, in the case of thetransisomer, the terminal 4‐carbon is the most reactive center. The conclusion was confirmed from the results of acetal addition reaction catalyzed by boron trifluoride etherate. The marked contrast in the mode of reaction of the two isomeric ethers toward carbonium ions was interpreted in terms of the difference in the degree of bonding in th

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090115

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractThe bulk polymerization of acrylonitrile with azobisisobutyronitrile as initiator and FeCl3as terminator was studied at 60°C. It was found that the reaction proceeds like solution polymerization and does not exhibit the familiar autoacceleration found in bulk polymerizations. It was concluded that a steady‐state condition of growing radical chains exists. Initial rates, to approximately 3% conversion, were measured dilatometrically and were found to be proportional to the ratio of the initiator to terminator concentration, where this ratio is smaller than 3 : 1 and are due to the predominance of the FeCl3monoradical termination mechanism. On increasing the ratio of initiator to FeCl3, the usual biradical termination mechanism becomes important as well. Assuming that the ratio of propagation constant to termination constant in this work is similar to the knwon ratio in DMF solution, a monomer “effective” concentration in the bulk of about 20% of the nominal concentration of pure acrylonitrile (14.38 mole/l. at 60°C) can be calculated. This result is interpreted by a molecular mechanism for the bulk polymerization of acrylo

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090116

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractHigh conversions of oligomeric silazanes that are not volatile at 200°C/0.1 mm are obtained when hexamethylcyclotrisilazane or octamethylcyclotetrasilazane is heated with a molar deficiency of dichlorodimethylsilane at 175°C. The oligomers, which show moderate solvolytic stability, contain disilazane, trisilylamine, and cyclodisilazane units. They are structurally similar to materials that have been prepared by others from hexamethylcyclotrisilazane and ammonium bromide. When the oligomers are treated with ammonia and heated to 325°C, evidence can be found in their spectra for the presence of oligocyclodisilazane structur

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090117

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractThe synthesis of linear polyimides by the addition of dicarboxylic acids to dinitriles has been investigated. Adipic, suberic,m‐ andp‐phenylenediacetic, isophthalic, andp‐cyanobenzoic acids as well as adiponitrile,m‐ andp‐phenylenediacetonitrile, and isophthalonitrile were studied. Fairly favorable results, low molecular weight polymers only, were obtained in the reaction ofp‐phenylenediacetic acid withp‐phenylenediacetonitrile. The formation of polyimides seems to be restricted by the solubilities of the reactants and products as well as by the pKvalues of the starting dicarboxylic acid and of the acid wh

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090118

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractThe α to γ transition that occurs in nylon 6 upon iodine treatment was investigated by infrared spectroscopy, differential thermal analysis, and x‐ray diffraction techniques. Thin films of nylon (0.2 mil) were treated in either iodine–potassium iodide aqueous solution or in iodine vapor. Very short treatment times, in the order of 30 sec, were found to effect the transition when a solution 0.5Mwith respect to iodine was used. The infrared spectra of the iodine nylon complexes formed from either the α‐ or γ‐nylon 6 treated in vapor or dissolved iodine were all similar. This is an indication that molecular iodine is the active species in forming the complex. The temperature of the washing solution used to remove the iodine from the nylon determines whether an α‐nylon 6 or γ‐nylon 6 is obtained from the complex after washing. Nylon 6 plaque surfaces and thin films are similar in their behavior towards the iodine treatment. The γ‐nylon 6 is a stable modification at all temperatures below its melting point. The conversion of the γ form back to the α modification can occur only if the hydrogen bonding is severely affected, e.g., by phenol treatment, iodine treatment, melting, etc. Infrared spectroscopy provided no evidence for an α–γ transition in nylon 6 on heating the sample continuously through its melting point. The shapes of the melting peaks in the above two modifications of nylon 6 were sufficiently different to provide a means of identifying

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090119

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY

摘要:

AbstractThe utilization of OF2, for chain extension of polyperfluoropolyenes, insertion of functional groups into the polymer structure and addition copolymerization with perfluorodiene is described. The results of reactions of OF2and polyperfluoro‐1,2‐ and ‐1,4‐butadiene indicate that conditions can be selected either to extend the polymer chain or to insert acyl fluoride groups into the polymer structure. Ambient and higher temperatures favor insertion of acyl fluoride groups. At 0°C chain extension occurs without introduction of acyl fluoride groups. Preliminary results on the novel synthesis of perfluoroalkylene oxide polymer by addition copolymerization of perfluorobutadiene and OF2is also

ISSN:0449-296X    

DOI:10.1002/pol.1971.150090120

出版商:John Wiley&Sons, Inc.    

年代:1971

数据来源: WILEY