Crystallites orientation of isotactic polypropylene prepared by low elongation was studied by means of X-ray diffraction analysis.
The diagonal orientation of c-axes of crystallites to the stretching direction were observed at initial stage of elongation and the final orientation of c-axes was parallel to the stretching direction.
When the orientation of c-axes of crystallites were parallel to the stretching direction, diffraction patterns for a smectic modification was observed on the equator of X-ray photographs, and when the orientation of c-axes of crystallites were diagonal to the stretching direction, the smectic modification disappeared and a hexagonal modification appeared.
It was found that, right- and left-hand helices are alternately situated in the monoclinicand hexagonal transformations, whereas the arrangement of two sorts of helices are at randomin the smectic transformation.
The appearance of a hexagonal form in monoclinic polypropylene prepared by cold stretching shows that chain-folds in crystallites do not untied, and the appearance of a smectic form is due to the reformation of untied chain-folds.
From these results, the following conclusions seem to be deduced:
1) The diagonal c-axes of most of the crystallites to the stretching direction are observed at initial state of elongation and in this case the hexagonal modification is derived from a part of crystallites.
2) At final state of elongation, the parallel orientation of c-axes of polycarbonate crystallite was observed, or the chain-fold of crystallite disappeared. The fiber prepared at final state of elongation consists of a smectic and amonoclinic modificatio.

View full abstract

Homogeneous polymerization of AN in dimethyl-sulfoxide (DMSO) catalyzed by ammoniumpersulphate was studied. Polymerization mechanism was considered to be the redox system between persulphate/DMSO as follows:
The apparent rate of polymerization was shown to be _??_The each constant of chain transfer at 30°C was calculated, which was shown to be A′=20, C_m=1.5times;10^-4 and C_s=4.7times;10^-5. Activation energy for redox polymerization was about 18.5kcal/mol.

View full abstract

The molecular weight distribution of polycarbonate was investigated. The samples were fractionated by the successive precipitation method using methylene chloride as the solvent and n-heptane as the precipitant and the molecular weights were determined from the intrinsic viscosities.
Under the standard conditions bisphenol A and phosgene were reacted in the emulsion state. The two peaks in the molecular weight distribution curve, however, found in the case of the sample which were reacted in non-emulsifing solution.
The M_w/Mn, values of the standard samples were about 1.2. The width of the molecular weight distribution of the sample prepared by the interfacial polycondensation was narrower than that of the polymer prepared by the melt method. Owing to the degradation of polycarbonate in methylene chloride-methyl alcohol solution, methyl alcohol was unsuitable to the precipitant for the successive precipitation fractionation.

View full abstract

For the purpose of studying the curing process of epoxy resin, the gelation time in the reaction of Epon 828 with amines in benzene-ethyl alcohol 1:1 (in volume) solution under various conditions were measured. The gelation time changed according to the number of the reactive hydrogen atom of amino-group and the reactivity of amine, but the apparent activation energies of gelation using primary amines and secondary amines (for example, ethylenediamine, diethylenetriamine) were about the same value, 12-13kcal/mol. In the case of the tertiary amines (for example, triethylamine, diethylaminopropylamine), the activation energies of gelation became higher in value as a result of different reaction (polymerization by opening the epoxy group with tertiary amine as catalyst).
Furthermore, the influences of the concentration of reactant, fillers and composition of mixtureof amines on gelation were studied, and the relations between gelation time and these factors were found to agree with that derived from the theoretical consideration.

View full abstract

The hardening reaction after gelation in the reaction of Epon 828 with p, p′-diaminodiphenylmethane was studied by examining the solubility of product in dioxane and the factors which influenced the insolubilization reaction.
The following results were obtained:
(1) In excess of amine, the time when it became insoluble in dioxane (gelation time) tended to become shorter than in the case of the reaction in equivalent mole ratio, but the rate of insolubilization after gelation was reduced.
(2) Moisture and silicagel had an effect for reducing the gelation time.
(3) The insolubilization reaction after gelation occurred not only in soluble parts, but also among soluble and insoluble parts under controlled reaction conditions.

View full abstract

In the study about gelation of epoxy resin with amines, it was found that following equations were applicable to curing processes, (a) epoxy resin with amine mixtures and (b) epoxy resin containing the reactive diluent (monofunctional epoxy compounds) with amine hardener.
(a)(5ρ+1)q2=n
(b)λ{(1+2λ-3λ²)q₂²+2(λ-1)q₂^3/2+6q₂}=n
n=(initial epoxy group)/(initial amino group)
q₂=the extent of converted primary amine to tertiary amine
ρ=(the reacted amino group of the tetrafunctional amine)/(the total reacted amino group)
λ=(the reacted epoxy group of diepoxy compound)/(the total reacted epoxy group)
From this relationship and the reaction rate formula, the relative gelation time at various n, ρ, and λ were calculated and coincided with the observed value.

View full abstract

Polyvinyl alcohol (average DP 1590, C=O and COOH content 0.015 and 0.030mol% based on the monomeric unit) was oxidized by H₂0₂ in acidic solution at pH2.5. The polymer showed no depression in DP. However, when the H₂0₂ treated polymer was heated in alkaline solution, decrease of DP was observed.
On the other hand, when the polyvinyl alcohol was oxidized by H₂0₂ in alkaline solution, remarkable decrease of DP was observed, but further decrease of DP of the polymer could not be seen by heating it in alkaline solution. It was also found that acetylacetone gave 2 moles of acetic acid by the oxidation with H₂0₂ in aqueous Na OH solution. These facts suggest that the degradation of the polymer with the oxidation in alkaline solution proceeded as follows:
The total COOH group produced by the oxidation was given by [COOH]_tot=2a_c+c+s-a_ob, where a_c, c, s and a_oi were the C=O group produced in the main chain of the polymer by oxidation, C=O and COOH contents of the original polymer and the observed C=0 group of the product, respectively. The a_c, was calculated by 1/P_A′=a_c/100+1/1590, where P_A′ was the average DP of the degraded polymer. The [COOH]_tot showed a good agreement with the observed value, which increased linearly with the total C=O content (a_t=2a_c+0.015) of the resulting polymer. The apparent activation energies of the oxidation of C=O to COOH and of the degradation of polymer by the reaction were 2.3 and 9.2kcal/mol, respectively.

View full abstract

The method of determination of the butoxy groups of butylated methylolmelamine resins was investigated.
Butanol and formaldehyde obtained from the hydrolyzed resins with phosphoric acid were distilled and collected into water. The distillate was treated with alkaline silver oxide to remove formaldehyde. Then the butanol in distillate was determined colorimetrically by using p-dimethylarninobenzaldehyde-conc. H₂SO₄.

View full abstract

A modified method for the iodometric determination of methylol group in butylated methylolmelaminewas established. In the method, dioxane is used as a solvent which prevents the precipitation of resins during analysis and thus makes the accurate analysis possible.
The composition of butylated methylolmelamine can be determined by combining this method with the colorimetric determination of butanol and the hydrolysis of resins by phosphoric acid.

View full abstract

Styrene, para-and ortho-chlorostyrene were polymerized by SnCl₄-CCl₈COOH at 30°C. The relative reactivities of monomers and growing ions were estimated by copolymerization and chain transfer reaction to toluene, respectively. The reactivities of monomers and growing ions were found to be in the order of styrene>o-chlorostyrene>p-chlorostyrene and o-chlorostyrene>p-chlorostyrene>styrene, respectively. The chlorostyrenes, which have smaller reactivities of monomers than styrene, have larger reactivities of growing ions than styrene, similarly to the tendency found in radical polymerization. The relationships between the reactivities of the two isomers of chlorostyrenes, however, were opposite to this tendency.
The reactivities of monomers in monomer transfer reaction were found to be in the order of styrene>o-chlorostyrene>p-chlorostyrene.
These experimental facts were discussed in correlation with the electrostatic and the steric effects of chlorine atom.

View full abstract

Polymerization of styrene derivatives with a nucleophilic substituent such as para-methylstyrene, ortho-methoxystyrene and para-methoxystyrene were carried out using SnCl₄·CCl₃COOH catalyst at 30°C, and the effects of substituent to the reactivity of monomer and carbonium ion produced from the monomer were investigated. Taking into account the results in chlorostyrene polymerization together, the relationships log R_M versus Brown's σ⁺ and log R_I versus σ⁺ were plotted for four para -substituted styrenes (p-Cl, p-H, p-CH₃ and p -CH₃O), where R _M is the reciprocal of the monomer reactivity ratio γ ₁, in the copolymerization of styrene derivative (M₁) and styrene (M²), and R_I is k γ₁/kγ ₂, that is, the ratio of chain transfer constant to toluene of styrene derivative (M₁) against that of styrene (M₂). From the former relationship the p-value was found to be-1.8, and +2.1 of ρ-value was obtained from the latter. Thus, the larger the nucleophilic character of the substituent is, the larger the reactivity of monomer is and the smaller the reactivity of carbonium ion is.
The steric effect of substituent, the effect of the alteration of the catalyst into BF₃ ·O (C₂H₅) ₂and the mechanism of monomer transfer reaction in these styrene derivatives were also discussed.

View full abstract

The effects of γ-irradiation on the PVC plasticized with tricresyl phosphate and phenyl dicresyl phosphate were investigated. Visual damage of the specimens was very small and their tensile strength showed no detectable decrease up to the dose of 7.7×10⁷r. The degree of polymerization of PVC extracted from the irradiated samples showed slight increase at the early stage of exposure, but afterwards no appreciable change was observed. The molecular weight distribution curves of decomposed PVC also varied slightly from that of original PVC. These results lead to the conclusion that phosphate type plasticizers protect PVC effectively against the decomposition by gamma;-irradiation.

View full abstract

The effect of γ-irradiation on PVC plasticized with di 2-ethylhexyl sebacate and epoxysafloweroil was studied. Visual damage of the specimens at various dose levels was rather slight and tensile strength and elongation of specimen underwent almost no diminution up to 7.7×10⁷r dosages. The degree of polymerization of PVC extracted from the irradiated samples showed no appreciable change, and gel-formation due to the crosslinking of PVC was not observed. The epoxysafloweroil seemed to attach to PVC when polymer radicals were produced by γ-rays and the increase of polymer weight was observed.

View full abstract

The effects of γ-irradiation on PVC plasticized with various amounts of di 2-ethylhexylphthalate (DOP) were studied in detail. Colour change of specimen was depressed strongly by the addition of DOP. The variation of chlorine content of PVC extracted from each specimen was rather small and gel formation was observed only at the two samples which contained no or small amounts of DOP at 5×10⁷ r dose. At the same dose the soluble parts of the above gel containing PVC exhibited a drastic increase in degree of polymerization due to crosslinking of molecule. It is obvious, therefore, that DOP exerts a protective effect upon the decomposition of PVC by γ-rays.

View full abstract

The plasticized polyvinyl chloride containing various amounts of epoxysaflower oil (ESO) was found to have an excellent mechanical strength, a low volatility and a low water absorption capacity, and so it is concluded that ESO can be used as a primary plasticizer as satisfactorily as di-2-ethylhexyl phthalate. Heat stability of PVC was markedly improved by the addition of small amount of ESO. Not only the decomposition coloring but also crosslinking of PVC were markedly retarded as compared with the case of DOP. The variation of Huggins' constant k′ of the soluble fraction was not appreciable in both cases.

View full abstract

Methyl ester of polyacrylic acid was partially saponified to the same degree (30-40mol%) in acetone-water mixtures of various compositions using NaOH as a catalyst. The obtained samples may be assumed to differ from each other in the distribution of COOH groups along the polymer chain. The samples in which COOH groups were assumed to be locally distributed along the chain had lower viscosity, higher pK-value and higher resaponification rate by alkali in aqueous solutions than those in which COOH groups were assumed to be separately distributed. As the next series of the experiments, polyvinyl alcohol was partially acetalized to the same degree (23mol%) with glyoxylic acid in solution and film states. The obtained samples differ from each other in the distribution of COOH groups, but they showed practically no difference in the viscosity and potentiometric titration behavior in aqueous solutions. Some discussions were given for these results.

View full abstract

Deacetylation of polyvinyl acetate was carried out in methanol with several acids or bases as catalyst, and the effect of added solvents on the reaction rate was studied. By adding a few portion of water the reaction rate was not affected with base catalysts, but with acid catalysts remarkably decreased. In cases with acid catalysts, both of the initial rate and the autocatalytic effect were decreased by addition of water, and addition of acetic acid and N, Ndimethyl formamide also remarkably decreased the reaction rate. Some discussions were given for the results, and the following conclusion was deduced that decreasing of the reaction rate should be mainly due to the change of acidity function of the reaction medium by addition of polar solvents.

View full abstract