摘要:

Pepsin was immobilized on BIOZAN R (Hercules) with dicyclohexylcarbodiimide as activator. The reaction product obtained has a protein content of 35–110 mg/g of polymer and a proteolytic activity between 20.85–28.75 μmol tyrosine/L·min·g of polymer). The coupling reaction rate is maximum under the following conditions: pepsin/BIOZAN R ratio = 0.52 g/g, DCCI/BIOZAN R ratio = 0.2 g/g, pH = 3.4, reaction time = 4 h.

ISSN:0022-233X    

DOI:10.1080/00222338608063415

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

9-Fluorenyl (FMA) and 9-phenyl-9-fluorenyl methacrylates (PFMA) were prepared from methacryloyl chloride with 9-fluorenol and from silver methacrylate with 9-phenyl-9-fluorenyl chloride, respectively. The polymerizations of FMA and PFMA were studied by using α,α′-azobisisobutyronitrile (AIBN), n-butyllithium (n-BuLi), and n-BuLi-(−)-sparteine (Sp) complex in toluene and tetrahydrofuran (THF). Only PFMA polymers obtained with the n-BuLi-Sp complex showed a specific rotation ([α]D21−3 to −16° in THF).

ISSN:0022-233X    

DOI:10.1080/00222338608063416

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Ceiling temperatures (Tc) and reactivities of N-phenylmethacrylamide (PMAm) and o-substituted PMAm's in free-radical polymerization and the thermal stability of the polymers obtained were investigated. Although PMAm and o-substituted analogs gave the same Tc, 123°C at 0.64 mol/L in N,N-dimethylformamide, that of 2,6-dimethyl-PMAm was found to be as low as 65°C. These findings are interpreted in terms of steric hindrance as a consequence of the bulkiness of the 2- and 6-substituents and of the rigid and planar structure expected for the polymers. In copolymerization with styrene, the o-monosubstituted PMAm's were estimated to be more reactive than PMAm by a factor of about 3 except for o-phenyl-PMAm. The enhanced reactivity of the PMAm with a relatively small o-substituent is explained by ground-state strain of the monomer tending toward a planar structure. 2,6-Dimethyl-PMAm and o-phenyl-PMAm showed lower and slightly higher reactivities than PMAm, respectively, probably due to the blocking effect of these substituents against the approaching polymer radical. Enhancement of thermal degradation owing to the substitution was confirmed by means of thermogravimetric analyses of the polymers. The polymers from the 2,6-dimethyl-substituted and the o-monosubstituted PMAm' exhibited similar maximum-degradation-rate temperatures.

ISSN:0022-233X    

DOI:10.1080/00222338608063417

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Polyhydrazides and polyamides were prepared from hydrazine, piperazine, or substituted piperazines and muconic or α,α′ -dimethylmuconic acid chlorides by interfacial and solution polymerization. Low-temperature solution polymerization was preferred for polyhydrazides, and the interfacial technique for the piperazides. Polymers of dimethylmuconic acid exhibited better properties than those of muconic acid, e.g., molecular weight, film strength, and solubility. Optical properties, such as transparency, color, refractive index, and birefringence, were also determined and compared to aromatic polyamides and hydrazides.

ISSN:0022-233X    

DOI:10.1080/00222338608063418

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Ultrasonic (70 W, 20 kHz) solution (2%) degradations of poly(alkyl methacrylates) have been carried out in toluene at 27°C and in tetrahydrofuran (THF) at -20°C. Mwand Mnof all polymers (before and after sonification) were computed from GPC. Irrespective of the alkyl substituent, Mwdecreased rapidly at first and then slowly approached limiting values. All Mw/Mnratios were in the vicinity of 1.5 at the limiting chain lengths. For identical Mn, the rate constants k were (4.2 ± 2.0) × 10−6min−1in toluene at 27°C and (5.4 ± 2.0) × 10−6min−1in THF at -20°C. For poly(isopropyl methacrylate) and poly(octadecyl methacrylate) with higher, but identical, Mn,0, k values were higher ((9.0 ± 1.0) × 10−6min−1at 27°C and (18.0 ± 1.5) × 10−6min−1at -20°C). This suggests that Mn,0and not the bulk size of the alkyl substituents is the factor that determines the rate of degradation. Lowering of the temperature accelerates degradation due primarily to lower chain mobility of poly-(alkyl methacrylates) and enhanced cavitation. The average number of chain scissions ([(Mn)0/(Mn)t] - 1) calculated from component degradation data are much higher than those obtained with overall Mn,tvalues.

ISSN:0022-233X    

DOI:10.1080/00222338608063419

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

N-Acryloyl-L-valine (ALV) was found to yield polymer microspheres when it was polymerized with a radical initiator in acetophenone. The resulting microspheres showed thermochromism in aromatic solvents such as benzonitrile, methyl benzoate, and acetophenone. Graft copolymerization of benzyl methacrylate (BzMA) onto poly(ALV) microspheres was carried out in benzonitrile by using the photoreaction of carboxyl groups in poly (ALV) with Pb(OAc)4. The grafting efficiency was not very high (15–28%). Methyl methacrylate as the second monomer gave a higher grafting efficiency (56%) although the polymer yield was considerably lower. The resulting graft copolymer was characterized by IR spectroscopy and thermogravimetry. The grafted poly (ALV) microspheres were well dispersed in benzene. A benzene solution of grafted poly(ALV) microspheres and homopoly(BzMA) gave a film with finely dispersed poly (ALV) microspheres.

ISSN:0022-233X    

DOI:10.1080/00222338608063420

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Osmotic pressure measurements of aqueous solutions of cellulose acetate phthalate (CAP) were carried out with the help of a highspeed membrane osmometer. The value of the osmotic coefficient, g, for different concentrations of CAP, as well as at different degree of neutralization for various concentrations, were estimated. The effect of concentration and degree of neutralization on the value of g were investigated. The experimental results were also treated in the light of Oosawa' theory.

ISSN:0022-233X    

DOI:10.1080/00222338608063421

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This article deals with the kinetics of ionic polymerization with instantaneous initiation and spontaneous termination. The set of kinetic differential equations was solved rigorously by means of nonsteady-state analysis. Even though the expressions of the molecular size distribution function and other molecular parameters include an exponential integral function, all the molecular parameters can easily be computed numerically. Thus, this work is significant for controlling and regulating the relevant polymerizations.

ISSN:0022-233X    

DOI:10.1080/00222338608063422

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The effect of impurity termination on molecular size distribution for anionic polymerization with instantaneous initiation is discussed. In order to derive rigorous expressions for the molecular size distribution function and other molecular parameters, this paper follows a mathematical procedure which has proved to be useful for the theoretical treatment of the kinetics of polymerizations in the previous parts of this series. The variation of all molecular parameters with the extent of polymerization is illustrated.

ISSN:0022-233X    

DOI:10.1080/00222338608063423

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The kinetics of vinyl acetate polymerization in the presence of allyl chloride were studied by a dilatometric method. The retardation of the rate of polymerization was explained in terms of degradative chain transfer to allyl chloride. Analysis of the polymerization rate data indicates that a relatively large proportion of the allyl chloride transfer radicals is reactive toward initiation.

ISSN:0022-233X    

DOI:10.1080/00222338608063424

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor