摘要:

AbstractThe polymerization ofN‐vinylcarbazole at 60°C in benzene has been initiated with azoisobutyronitrile, benzoyl peroxide, and their mixtures. The kinetics indicate that the azonitrile and the peroxide promote polymerizations of fundamentally different types. The resulting polymers have been examined by gel‐permeation chromatography. The polymer produced with benzoyl peroxide contains a small amount of a high molecular weight fraction which, from the point of view of end groups, resembles the polymer made by use of the azonitrile. It is concluded that benzoyl peroxide in this system gives rise to two types of polymerization which occur simultaneo

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140801

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe radiation‐induced grafting of acrylonitrile, 4‐vinylpyridine, and styrene was carried out by both radical and ionic mechanisms. Grafted polymers with equal percentages of graft were obtained by the radical and ionic propagation of the grafted chains. The molecular weight of homopolymers has been determined. The thermomechanical properties of the graft polymers were investigated. The yield temperatures for the graft polymers obtained by ionic propagation of the grafted chains is higher than that of graft polymers obtained by a radical mechanism. This is attributed to the higher molecular weight of the grafted chains obtained by the radiation‐induced grafting by the ionic mechanism. The radiation‐induced grafting of polyacrylonitrile increases significantly the thermal stability of polyethylene. The differential thermal analysis shows no marked differences in properties of the p

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140802

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractSwelling in chloroform resulted in delamination of surface‐hydroxylated styrene‐butadiene‐styrene block copolymers, with the formation of three fractions: crosslinked gel, reacted sol, and unreacted chloroform‐soluble material. From the relative weights of these fractions, the depth of penetration of the reaction and the shape of the reaction front were determined. The weight of the gel fraction gave directly an estimate of the depth of penetration, λxwhich decreased with increasing film thickness. This was attributed to the increased amount of reacted polymer being noncrosslinked material (sol) in the interior compared to the 100% crosslinked nature of the surface region and to a reduction in the penetration of the reaction front resulting from the effect of stress transfer in lowering the permeation rate of peracetic acid. Comparison of the depth of penetration estimates λxand λsdetermined from the weight of the unreacted polymer demonstrated that, for the conditions used, the reaction front is quite broad. (For example, at 40°C, in 71% acetic acid for 80 min, the fully crosslinked portion is 15 μm thick and the partially reacted region extends for another 8.5 μm.) The combined influences of the increase in penetration of the reactants in the polymer and the relief of stress secondary to this increase in penetration were reflected in the time dependence of the depths of penetra

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140803

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe degradation of blends of PVA and PMMA in the form of films cast from a common solution of the polymers has been studied by TVA, TG, and EGA (evolved gas analysis) for acetic acid. Volatile degradation products have been characterized by spectroscopic and GLC techniques. Molecular weight, spectral and thermal stability changes in PMMA extracted from partially degraded blends have been examined. These blends behave in a closely analogous manner to PVC‐PMMA blends already investigated. The results suggest that the PMMA component of the heterogeneous blends is modified in two ways: (1) in a destabilization reaction series initiated by attack of acetate radicals generated in the PVA phase which migrate into the PMMA phase, and (2) in a stabilization reaction involving conversion of ester side groups to acid and subsequently to anhydride ring structures which act as blocking points for depolymerization. The rate of acetic acid production in the blend is less than in PVA degraded alone. The mechanism of degradation of PVA is reconsidered in the light of these result

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140804

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractA series of compounds, mostly derivatives ofN,N′‐diphenyloxamide, used as inhibitors of copper‐catalyzed oxidation in polyolefins has been reacted with cupric salts. The resultant copper–inhibitor complexes have been characterized as insoluble, polymeric solids, and their catalytic reactivities in the oxidation of low‐density polyethylene were measured at 100°C. The maximum rates of oxidation are first‐order in surface area, and some very general trends in structure and reactivity can be drawn from these data. Reasons for the relative effectiveness of various copper deactivators in polyolefin oxidation are brief

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140805

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe sequential carbenium ion block copolymerization of ethyl vinyl ether (EVE) and isobutyl vinyl ether (IBVE) withN‐vinylcarbazole (NVC) is described. Requisite conditions for the successful application of the sequential synthesis technique to these systems were established: (1) the use of stable carbocation initiator salts (e.g., Ph3CSbCl6) which lead to essentially terminationless polymerizations; (2) low solvent‐to‐monomer ratios in order to suppress any possible chain transfer to methylene dichloride molecules; (3) high ratios of initiator to monomer which create a pseudo‐“living” system. The block products (PEVE‐b‐PNVC and PIBVE‐b‐PNVC) were isolated by precipitation and extraction. The intrinsic viscosities of these products displ

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140806

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe polymerizations of 4‐methyl‐1‐pentene(4M1P), 4‐methyl‐2‐pentene (4M2P), 2‐methyl‐2‐pentene (2M2P), and 2‐methyl‐1‐pentene (2M1P) with Ziegler‐Natta catalyst have been investigated. Both 4M1P and 4M2P were found to polymerize with TiCl3–(C2H5)Al catalyst to give high molecular weight poly(4M1P), while 2M2P and 2M1P did not give polymers with 4M1P units. However, when the polymerizations of 2M1P and 2M2P were carried out with ternary catalyst systems, TiCl3–(C2H5)AlCl–(PPh3)2PdCl2and TiCl3–(C2H5)AlCl–Ni(SCN)2polymers with 4M1P units were obtained in low yield. It was concluded that these four methylpentenes could polymerize with the monomer‐isomerization polymerization mechanism to poly(4M1P). The results of the observed isomer distribution of methylpentenes recovered, and the rate of polymerization of four methylpentenes suggest that the isomerization from 2M1P to 4M1P with the above ternary catalyst systems might proceed via a di

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140807

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe synthesis of a number of ring‐substituted phenyl isopropenyl ketones and their polymerization with styrene is reported. The ultraviolet absorption spectra of the polymers are analogous to those of ring‐substituted acetophenones and valerophenones. The quantum yields of the Norrish type II photoreaction were estimated in 1,2‐dichloroethane solution at 364 nm by automatic viscometry. These quantum yields are comparable to those of substituted butyrophenones and valerophenones, in that relatively high quantum yields were obtained for the unsubstituted andp‐chloro‐substituted compounds with low yields forp‐amino andp‐hydroxy compounds. Thep‐nitro‐substituted compound gives no type II reaction, presumably because the excitation becomes localized on the nitro groups which photolyzes by a mechanism which does not involve chain scission. The implications of these studies on possible applications to photoimag

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140808

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractTetrabenzyltitanium (B4Ti), tribenzyltitanium chloride (B3TiCl), tetra(p‐methylbenzyl)titanium (R4Ti) and tri(p‐methylbenzyl)titanium chloride (R3TiCl) have been used as catalysts for ethylene and propylene polymerization activated by AlEt2Cl. B4Ti‐AIEt2Cl in solution polymerizes ethylene readily but its activity decays rapidly. B4Ti was also supported on Cab‐O‐Sil, Alon C, and Mg(OH)Cl. The last support was found to give catalyst with longest lifetime with a rate of polymerization,Rp= 7.0 g/hr‐mmole Ti‐atm ethylene.14CO counting techniques gave 1.13 × 10−3mole of propagating center per mole of B4Ti; the rate constant of propagation,kp= 540 l./mole‐sec. None of the tetravalent titanium compounds polymerize propylene in solution. However, when supported on Mg(OH)Cl, Cab‐O‐Sil, Alon C, Cab‐O‐Ti, and charcoal, they all polymerize propylene. In this work the supports were characterized by various techniques, including the paramagnetic probe method, to determine the concentration and nature of surface hydroxyls. Those factors controlling the rate and stereospecificity of propylene polymerization were investigated. The system B3TiCl–Mg(OH)Cl–AlEt2Cl is the most active withRp= 2.89 g/hr‐mmole Ti‐atm propylene. The concentration of propagation center is 0.9 × 10−3mole per mole of B3TiCl;kp= 32 l./mole‐sec. This catalyst gave only about 70% stereoregular polymer. Diethyl ether is found to raise stereospecificity to 100%, but there is a concommittent tenfold decrease of activity. Other interesting catalyst systems are: (π‐C5H5)TiMe3–Mg(OH)Cl–AlEt2Cl (1.56, 89.5); (π‐C5H5)TiMe2–Mg(OH)Cl–AlEt2Cl (0.075, 94.5); and (π‐C5H5)TiMe3–Alon C–Al‐Et2Cl (0.08,97.2), where the first number in the parenthesis isRpin g/mmole Ti‐hr‐atm and the second entry corresponds to percentage yield of stereoregular polypropylene. Hafnocene and ti

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140809

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY

摘要:

AbstractThe interaction of poly(vinylpyrrolidone) (PVP) with variousp‐X‐substituted phenols (X = CH3O, CH3, C2H5, H, Cl, Br, and NO2) in aqueous solution was investigated by means of equilibrium dialysis at 30°C. By applying the Klotz equation for the results obtained, the bonding constantsKbetween PVP andp‐substituted phenols were determined. It was found that theKvalues were approximately correlated with the Hammett σ values ofp‐substituents in phenols, indicating that the bonding forces due to electrostatic and hydrogen‐bonding interactions were significant, and they increased with increasing electron‐withdrawing nature of the substituents. Therefore, in addition to the hydrophobic interaction which has been accepted, it was assumed that the above interaction forces also played an important role in the interactions between PVP andp‐substituted phenols in a

ISSN:0360-6376    

DOI:10.1002/pol.1976.170140810

出版商:John Wiley&Sons, Inc.    

年代:1976

数据来源: WILEY