摘要:

AbstractOzone resistance and high flex life are some of the important features of elastomers needed in the rubber industry. EPDM, a terpolymer of ethylene, propylene, and small amounts of a nonconjugated diene, has a saturated carbon‐carbon backbone and therefore shows excellent resistance to ozone and aging, and good flex properties. However, butyl rubber (1IR) has a small amount of unsaturation in its carbon‐carbon backbone and consequently does not exhibit as good ozone resistance and aging characteristics as EPDM. We discovered a family of new rubbers named HexsynTM, which were synthesized by copolymerizing higher α‐olefins (C4‐C10) with a mixture of 4‐methyl‐ and 5‐methyl‐1,4‐hexadienes. One outstanding Hexsyn™ rubber is a copolymer of 4‐hexene and the 5‐methyl‐1,4‐hexadiene. This copolymer uniquely combines the useful properties of EPDM and butyl. Outstanding features are excellent flex life, excellent ozone resistance, good compression set resistance, and high damping.Due to its excellent flex life, HexsynTM((hexene copolymer) has been found useful in fabricating experimental pumping diaphragms of air‐driven artificial hearts of calves and also for left ventricle assist devices. This rubber has found application as a flexing element in artificial finger joints for dam

ISSN:0360-8905    

DOI:10.1002/polc.5070740114

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractA polymeric analogue of crystal violet in which the triarylmethane moiety is pendent from a polyester backbone has been examined as a sensitizer for photoconductivity in poly‐N‐vinyicarbazole. In both positive and negative surface charging modes, the dark decay rates increase linearly with sensitizer concentration, but are lower than those for monomeric crystal violet sensitization. The photodecay rates, in both modes, show optimal concentration dependence and are higher than those for monomeric crystal vio

ISSN:0360-8905    

DOI:10.1002/polc.5070740115

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractWe have carried out an in‐depth study of the alkali metal ion binding characteristics of a model ionophoric macromolecule, poly(4′‐vinylbenzo 18‐crown‐6), P18C6. Ion selective electrode potentiometry has been utilized to determine stability constants for complexstion of K+, Na+, and Cs+to P18C6 in methanol/water (80/20)w. Our results show that (he intrinsic binding constants, Kn, of P18C6 towards K+C1−and Na+Cl−are identical to that of the monomeric analog, benzo‐18‐crown‐6.In the absence of supporting electrolyte, the apparent binding constant of benzo‐18‐crown‐6 is greater than (hat of P18C6. At low tonic strength the binding of K+to P18C6 depends strongly on the fraction of crown moieties bound. P18C6 binds K+C1−and Na+Cl−with a stoichiometry of 2 mol of crown per mole of M+. This binding, however, is not sandwich mode. The binding of K+Cl−, K+NO3and K+ClO4−to P18C6 in methanol/water differs significantly, withKN(K+ClO4−1 being nearly an order of magnitude greater thanKN(K+Cl−). Cs+is bound to P1SC6 with a stoichiometry of ∼3 mol of crown per mole of Cs+, and the ion is bou

ISSN:0360-8905    

DOI:10.1002/polc.5070740116

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThree novel main‐chain polyarninimides were prepared containing rigid and/or flexible groups within the backbone. The polymer precursors were initially synthesized from bis‐dimethylhydrazides and dihalides at room temperature through the Menschulkin reaction, which yielded hydrazinium ionenes. In a similar fashion, low molecular weight model compounds were also prepared in order to confirm the structures of the ionene polymers. It was found that the ionenes were totally, or at least partially, converted o the aminimide form in the presence of water alone, while the model cationic compounds required a strong base before conversion to their corresponding aminimides. These new polymers were characterized by (heir infrared and NMK spectra, as well as dilute solution viscosity. Preliminary solution properties indicate that the hydrazinium form of the polymers behave as poly electrolytes, whereas the aminimide form behaves as a neutral poly

ISSN:0360-8905    

DOI:10.1002/polc.5070740117

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe primary carbenium salt 9‐anihranylmethyl hexafluorophosphate is characterized by1H‐ and13C‐NMR spectroscopy. The results show that in the temperature range −60°‐15°C the initiator exists as a classical carbenium ion and a protonated anthracenium ion. At higher temperatures the reactions of self‐alkylation and disproportionation proceed, giving bianthracenes, hydroanthracenes, and other dimer forms.The polymerization of α‐methylstyrene andp‐methoxystyrene, initiated by 9‐anthranylmethyl hexafluorophosphate, is investigated. The mechanism of initiation, the stereochemical configuration, and the end groups of the polymer c

ISSN:0360-8905    

DOI:10.1002/polc.5070740118

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

Abstract2‐Vinyllhiolane‐1,1‐dioxide (Ia) and 2‐vinylthiane‐1,1‐dioxide(Ib) have been prepared and polymerized with free radical initiators to obtain poly(sulfonyl‐hex‐2‐enylene) (IIa) and poly(sulfonyl‐hept‐2‐enyIene‐co‐2‐vinylthiane‐1,1‐dioxide) (IIb), respectively, via a ring‐opening mechanism. Structures of the polymers are supported by infrared and1H‐NMR spectroscopy. Poly(sulfonyl‐hex‐2‐enylene) was insoluble in ordinary organic solvents, but soluble in concentrated sulfuric acid or trifluoroacetic acid, and was white amorphous powder, softening at 168°C. Degradation occurred at 294°C under N2. Ia copolymerized with certain vinyl monomers, such as ethyl acrylate, but its copolymerization behavior was

ISSN:0360-8905    

DOI:10.1002/polc.5070740119

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractFive vinylcatechol precursors have been synthesized by either alcohol dehydration or Wittig coupling techniques. Dehydration of the appropriatesec‐phenethyl alcohol is the most efficient synthetic approach: the following monomers (yields) are reported: 5‐vinyl‐1,3‐benzodioxole, I (63%); 3,4‐dimethoxystyrene, II (45%); 2,3‐dimethoxystyrene, III (85%);6‐vinyl‐1,4‐benzodioxane.IV(65%); and4‐vinyl‐l,3‐benzodioxole, V(50%). The monomers can be converted by free‐radical techniques to polymers with molecular weights up to 95,000. Monomers I, II, IV, and V polymerized in the presence of stannic chloride; monomers I, III, and IV yielded polymers upon treatment with butyllithium. With the exception of poly IV, the blocking groups can be removed by treatment with boron trichloride followed by methanolysis to liberate poly(3‐vinyl‐ or 4‐vinylcatechol). Suprisingly, the stability of the catechol polymers depends upon the substituent distribution; poly(3‐vinylcatechol) is more stable than any polycatechol previously reported. It is soluble in methanol, autooxidizes very slowly, but can be oxidized by ceric ammonium nitrate

ISSN:0360-8905    

DOI:10.1002/polc.5070740120

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractTwo new methods of predicting free radical polymerizability of allyl monomers have been developed. MINDO/3 calculations of eigenvalues for the C—H bond a to the atlyl substituent allow comparison of relative bond strengths. Monomers known to undergo degradative chain transfer display more positive eigenvalues correlating with weaker α‐C—H bonds. Polymerizable monomers have more negative eigenvalues and stronger α‐C—H bonds. The latter possess strongly polarized or protonated substituents not capable of resonance stabilization of a chain‐terminating allyl radical. The inductive effect of such substituents on the13C NMR peaks of the vinyl carbons is the basis for the empirical spectroscopic method. Allyl compounds display β‐carbon peaks farther downfield than the γ‐carbon peaks. Polymerizable monomers generally have β peaks shifted upfield and γ peaks shifted downfield from those of poor monomers. This effect brings the two peaks closer together in the spectrum. Thus, the smaller the Δδ value (δβ− δγ), the more likely the monomer is to polymerize well. Monomers with intermediate eigenvalues or Δδ values may polymerize with difficulty or only under special conditions. Combined use of the theoretical and empirical techniques can allow prediction of inherent polymerizability and can facilitate evaluation of reaction media most

ISSN:0360-8905    

DOI:10.1002/polc.5070740121

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractThe stereoisomeric configurations of poly(2,5‐tetraliydrofurandiyl), 1, and poly(2,3‐tetrahydrofurandiyl), 2, have been investigated by conformational analysis. Similar results were obtained for 1 and 2, Threodiisotactic (tit) and erythrodisyndiotactic (est) configurations could form low energy helical conformations, whereas erythrodiisotactic (eit) and threodisyndiotactic (tst) configurations generally formed low energy linear conformations. Helical conformations of I placed oxygen atoms at the interior of the helices, but helical conformations of 2 placed oxygen atoms more toward the periphery. The results of ion‐binding experiments are interpreted in terms of the results of conformational analysis. Ion‐binding experiments are consistent with the suggestion that configurations that can form low energy, helical conformations with oxygen atoms at the interior of the helices could bind cations efficiently. Configurations that can form only low energy linear conformations, or that form helices with oxygen atoms toward the periphery of the helices, should be inefficient in binding

ISSN:0360-8905    

DOI:10.1002/polc.5070740122

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY

摘要:

AbstractEquilibrium phase studies were carried out on the ternary system of polystyrene‐poly butadiene‐toluene at 23°C and 1 atm. Narrow and broad molecular weight distribution (MWD) samples of polystyrene and polybutadiene were employed, and their binodal curves were established. Expressions were derived to calculate X2i values for both monodisperse (narrow MWD) and polydisperse polymers. Typical interaction parameters determined from (lie experimental data are presented. It is concluded that monodisperse expressions can be used for polydisperse polymers using the number‐average molecular

ISSN:0360-8905    

DOI:10.1002/polc.5070740123

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1986

数据来源: WILEY