摘要:

AbstractCalculations of the polymer molecular weight distribution are carried out using a model of emulsion polymerization, which fundamentally derives from the early work of HARKINS, and which, in its general features, is to‐day accepted. The distributions are actually presented as functions of the kinetic chain lifetime and time of reaction, although, under certain assumptions set out in the following work, the lifetime is directly proportional to the molecular weigh

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460101

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractCalculations of the particle size number distribution resulting from emulsion polymerization have been carried out for a model of the system used previously by the authors. The sum of the lifetimes of the growing molecules which a particle has contained, is used as the measure of its size. The resulting curves indicate an increase in the breadth of the distribution with increasing time.

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460102

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractOptically active poly(L‐α‐hydroxyisovalerate) and poly(L‐α‐hydroxyisocaproate) were prepared by the ring‐opening polymerization of the corresponding glycolides, and their physical properties were studied.The polymerization conditions to obtain polymers with high molecular weight and high optical purity were al

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460103

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractOptically active oligo(L‐α‐hydroxyisovalerates), Z[OCH(iso‐C3H7)CO]nOCH3(Z = CH3CO, (I‐n), Z = CHCl2CO (II‐n), and Z = H (III‐n); n = 1–5), were synthesized. The synthesis of I‐n was carried out by the condensation ofL‐α‐acetoxyisovaleroyl chloride with III‐(n−1). III‐(n−1), in turn, were prepared by a stepwise method which involved the condensation ofL‐α‐dichloroacetoxyisovaleroyl chloride with III‐(n−2) followed by removal of the terminal dichlo

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460104

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractIt was found that isoprene polymerizes quickly at 20°C in presence of iodine, but only if it is submitted to a pressure of 14,000 bar. Several elements particularly such as the constance of the microstructure (76% 1.4transaddition) lead to the assumption of radical mechanism. The polymerization is very sensitive to pressure, especially in the propagation step

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460105

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe tickening of lamellar crystals occurring during isothermal crystallization has been explained as the result of molecular fractionation induced by crystallization. The feasibility of this theory is confirmed by the analysis of the DSC melting curves of a Marlex 50 polymer as a function of the crystallization time. The melting curves are recorded for meltcrystallized samples and solution grown crystals. In contrast with the crystallization from melt, the melting peak for solution grown crystals remains practically at a constant temperature, in the range of the crystallization time studied. Obviously, this corresponds to the observed constant fold period. This molecular fractionation theory is compared with the one of HOFFMANNand PETERLIN.

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460106

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

Abstract1.5‐Diphenyl‐3‐(p‐vinylphenyl)‐verdazyl (vinyl verdazyl) was anionically polymerized withn‐butyllithium or sodium naphthalene as initiator yielding a dark green polymer of a molecular weight ofca.2800. The metal salt of the verdazyl monomer is assumed to be an intermediate compound during the polymerization; the reaction product of the salt with benzyl bromide, benzyl verdazyl, was isolated. Poly(vinyl verdazyl) and its copolymers with styrene and methyl methacrylate showed a strong ESR signal corresponding to up to 63% radi

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460107

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractCationic cyclopolymerizations of 1.1′‐divinylferrocene with LEWIS acids and alkylaluminum catalysts were performed under various conditions. The cyclization constant rc(the ratio of rate constants of the intramolecular cyclization and the intermolecular propagation) was determined by applying the equation previously empolyed for cyclopolymerizations ofo‐divinylbenzene. The rcvalue (0°C, CH2Cl2) was approximately 1 mole/l. with BF3OEt2, SnCl4, and TiCl4, but increased to 1.8 to 2.8 mole/l. with aluminum‐containing catalysts. It also increased (from 0.67 to 1.49 mole/l.) with increasing polarity of polymerization solvents. The intramolecular cyclization was shown to possess an activation energy higher than that of the intermolecular propagation by 1.2 to 1.5 kcal/mole (AlEtCl2/C6H5CH2Cl, CH2Cl2). These data were interpreted as follows: the intramolecular cyclization of the growing carbonium ion pair becomes more favorable, as the tightness of the ion pair decreases, because of the increase in reactivity. Thermal behaviors of several polymers were examined by differential scanning calorimetry and thermogravimetric analysis, and it was suggested that extensive crosslinking occurred in the molten polymer at abo

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460108

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe general form of the variation of In [η] with temperature which results from the excluded‐volume theories of FLORY, KURATA‐STOCKMAYER‐ROIG, PTITSYN, and FIXMAN, is examined. On the basis of these theories a new analysis of ln [η]TversusT data is presented, which enables both d ln 〈r2〉0/dT and the Ψ‐temperature to be evaluated. The procedure has been applied to polytetrahydrofuran in a large number of solvents, and the applicability of excluded‐volume theories to these syst

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460109

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractCopolymerizations ofl‐ anddl‐menthyl vinyl ethers were carried out with BF3O(C2H5)2, Al(C2H5)2Cl or SnCl4as catalyst. The yield and the mol. wt. of the polymers decreased as thed‐monomer content in the feed monomer mixtures increased. The optical rotation changed linearly with the monomer composition, suggesting no preference of one of the monomers to the other did take place in the polymerization. The optical rotatory dispersions of all the polymers were expressed with DRUDEequation, and COTTONeffect was not obs

ISSN:0025-116X    

DOI:10.1002/macp.1971.021460110

出版商:Hüthig&Wepf Verlag    

年代:1971

数据来源: WILEY