Photoconductive properties of chemically pure poly-N-vinylcarbazole film specimen which was polymerized without using initiator were investigated. The photoconductivity cell used were “Surface cell” and “Sandwich cell”.
The resistance of the specimen in the dark was 1.9×10¹⁵ ohm cm at room temperature and the thermal activation energies for conduction in the dark and under the light were 0.66eV and 0.14 eV respectively. Almost linear relations were obtained between the light intensity and the photocurrent, and a larger value of photocurrent was observed when the illuminated electrode was positive. The dry air increased photocurrents of the surface cell. These behaviours suggested that the charge carriers in this polymer were positive holes rather than electrons.

View full abstract

Effects of cooling, melting temperature and melting time on the sample of PET, melted in vacuum, were investigated by measuring the thermal expansion, specific heat and differential thermal analysis. The anomalous thermal expansion on heating, as suggested by K. Ueberreiter and his co-workers was found in the vicinity of 200°C for both variously quenched and slowly cooled PET samples. The results obtained from specific heat measurement and differential thermal analysis show a slight thermal change at the temperature range where the anomalous thermal expansion occurred. This anomalous thermal expansion may be explained by the thickening of the folded chain crystal due to the sliding diffusion suggested by Hirai and his co-workers.

View full abstract

The thermal dimensional changes of PVA crystallites were studied by X-ray diffraction method from room temperature to about 200°C. The crystallites expanded anisotropically with the increase in temperature; the expansion coefficient in the direction of a axis was much larger than that of c axis, and that of b axis (molecular direction) was somewhat negative at higher temperature. The thermal expansion coefficient of the crystallites changes discontinuously at about 120°C. This characteristic temperature could be considered as the second-order transition point of PVA crystallites. It was concluded, considering the results of X-ray diffraction and the change of specific heat that this transition of PVA crystallite is of very mild kind. As the temperature coefficient of β(angle between a and c axis) was estimated to take negative value, PVA crystallites may approach to orthorohmbic with the increase in temperature.

View full abstract

A simple statistical thermodynamic treatment of the dependence of lateral order in molecular arrangement on temperature for the crystallite of polyether type polymer -{-A-(B) _b-} _n-is put forward in this paper: this treatment is analogous to the elementary theory of orderdisorder transformation for a binary alloy. The degree of lateral order (f_p) is given by following equation, _??_
where b is the number of atomic group B in a repeating unit, l is the dimension of a segment moving along the direction of chain axis in the crystallite, Δεr is the difference in bond energy between ordered and disordered arrangements for a pair of repeating units, k is Boltzmann constant and T is absolute temperature.
The heat of fusion of polyether type polymer (ΔH_f) is given by following equation, where f_p is the degree of lateral order in molecular arrangement calculated from above equation at the melting point (T_m) and ΔH_AA, ΔH_BB and ΔH_AB are the heats of fusion for A-A, B-B and A-B bonds repectively, _??_
The heats of fusion of polyethers of polymethyleneoxide series calculated by this equation are in good agreement with measured values.

View full abstract

For the purpose of investigating the oxidation reaction at high temperature of the radiationcured thylene-propylenec opolymers, c hemicals tress relaxation measurementw as performed. As the results, it was found that this type of elastomer was scissioned at the crosslink site preferably, in contrast with the radiation-cured natural rubber which was usually scissioned within the molecular chain randomly. From the intermittent stress relaxation measurements, it was observed that the amounts of cross-linkingb y oxidation decreased with the increase of the initial crosslink density.

View full abstract

In order to reinvestigate the intermittent stress relaxation measurement method which has been used to measure the quantity of the crosslinkings formed in the structure of rubber networks, some experiments were carried out. The simultaneous measurement of continuous and intermittent relaxation method (SMCIR method) was applied to natural rubber and EPR vulcanizates. It is superior to the usual method, being capable of determing the crosslinking formed in the elongated state, and also obtaining the continuous and the intermittent relaxation curves for the same sample. We proposed a method for obtaining the stress in the intermittent relaxation by extrapolation as follows: f=klog (Δt) +b

View full abstract

The transition polymerization of crotonamide by basic catalyst was studied. It was found that poly-β-aminobutyric acid was obtained from crotonamide in relatively high yield by using potassium t-butoxide or sodium t-butoxide as catalyst in pyridine or chlorobenzene.
The initial reaction may be represented as follows; CH₈CH=CHCONH₂+t-BuOM→t-BuOH+CH₈CH=CHCONHM where M: potassium or sodium.
Then, the transition polymerization occurs, and the polymer which has an olefinic end group is obtained. A reaction rate equation of polymerization of crotonamide in pyridine using potassium t-butoxide as a catalyst is expressed as follows;
In [monomer] ₀/[monomer] =k_c [catalyst](time)
where [monomer] ₀: the initial concentration of monomer., k_e: the rate constant.
The apparent activation energy is 10.8 kcal/mol.

View full abstract

Polyvinyl alcohol (PVA) and some low molecular weight polyhydric alcohols were acetalized with various aldehydes (acet-, propion- and n-butyr-aldehyde) in water, using acid catalysts (hydrochloric acid, methanesulfonic acid and toluenesulfonic acid), and the effects of addition of sodium chloride on the initial rate of the reactions were investigated. Sodium chloride (0-0.7M) generally accelerated acetalization of polyhydric alcohols, and the order of the acceleration effects was PVA>pentaerythritol>1, 3-butanediol>1, 3-propanediol. For example, by addition of 0.7 M sodium chloride the acetalization rate of PVA increased nearly twice. The acceleration effect was nearly independent on the reaction temperature (5-70°C) in the case of the PVA, but increased with decreasing reaction temperature in the cases of the other alcohols. In the cases of the any alcohol the acceleration effect was nearly independent on concentration ([OH] =0.05-0.20M) of the alcohol and the kind and concentration (N/200 and N/10) of catalysts. Hydrolysis of ethyl acetate under the similar conditions was accelerated only slightly by addition of sodium chloride.

View full abstract

The polymerization and copolymerization of 2-methyl-N-vinyl imidazole (MVI) and 2-phenyl-N-vinyl imidazole (PVI) are described. MVI and PVI were easily polymerized with free radical initiators to give linear polyelectrolytes. No polymer could be obtained with typical cationic, anionic or Ziegler type catalysts presumably because of relatively high basicity of the imidazole.
The photo-polymerization of MVI at low temperature gave high molecular weight polymer but, in case of PVI, no polymer was obtained. The reactivity ratios in the copolymerization of MVI with St or MMA, and of PVI with MMA, have been determined and the Q and e values were caluculated as follows;
for St (1)-MVI (2) r₁=8.97, r₂=0.069; Q₂=0.19, e₂=-1.49
for MMA (1)-MVI (2) r₁=3.48, r₂=0.003; Q₂=0.10, e₂=-1.73
for MMA (1)-PVI (2) r₁=3.50, r₂=0.006; Q₂=0.34, e₂=-1.58
In view of the UV spectra of imidazole derivatives, and their copolymerization parameters, it seems reasonable to assume that the vinyl group in N-vinyl imidazole is conjugated mainly with N atom adjacent to the vinyl group.

View full abstract

The gel-effect of radiation induced polymerization of styrene in viscous systems was investigated kinetically under the existence of radiation cross-linked polystyrenes of different degree of swelling, linear polystyrenes of different degree of polymerization and ethylbenzene. Air free samples were irradiated by gamma-rays at the dose rate of 7.0×10³ r/hr, at 30°C.
Observed acceleration of the rate of polymerization did not depend on the degree of crosslinking nor the degree of polymerization of polystyrene, but depended on the concentration of polystyrene. Ethylbenzene, however, caused no acceleration in the rate.
Consequently, the kinetics of gamma-ray induced polymerization of styrene at higher conversions could be investigated by adding cross-linked polystyrene to styrene monomer.
When styrene was polymerized in the presence of cross-linked polystyrene, the rate of polymerization, the degree of polymerization, the grafting ratio and the grafting efficiency largely increased beyond the conversion value of 35% simultaneously. These phenomena can be considered to be closely related with each other.
It is assumed that the concentration of polymer radicals is led to non-steady state in the presence of polystyrene.
This assumption was showed reasonable by applying the equation proposed by G. M. Burnett and G. L. Duncan.

View full abstract

Wood cellulose was irradiated by γ-rays of Co-60 and neutron in atomic pile. The degree of polymerization, copper number and residual amount of acid hydrolysis of irradiated cellulose were measured. Using corresponding dose basing on the decomposition of polymethylmethacrylate, irradiation effects by γ-rays and neutron flux were compared. No difference was observed on decereasing of molecular weight. However irradiation damage on cellulose crystal was found more remarkable in atomic pile and this result was explained as the effect of fast neutron.

View full abstract

The copolymers of monomethyl maleate or monobutyl maleate and styrene, contain maleic anhydride unit. The molar fractions of maleic anhydride unit in the copolymers decrease with increasing the amounts of methyl alcohol in reaction mixtures. The amounts of methyl alcohol in reaction mixtures affect moreover the molar fractions of styrene in the copolymers and the rate of copolymerization.

View full abstract

The monomer reactivity ratios for the copolymerization of diallyl benzenephosphonate (DABP) and methyl methacrylate (MMA) or styrene (St), respectively, have been measured at 70°C.
MMA-DABP, r₁=22.96, r₂=0.135
St-DABP, r₂=28.97, r₂=0.027
DABP is less active for copolymerization with MMA or St, but DABP is more active than that of other allylic compounds.
Viscosity have been measured for some copolymers and these values are found to depend on the phosphonate contents in the monomer mixtures.
The infrared spectra data of copolymers seems to indicate that DABP monomer propagates by a cyclic polymerization mechanism.

View full abstract

Graft-polymerization of acrylonitrile on to the ozonized polyethylene film was studied. High density and low density polyethylenes were used. A little ozonization was enough to induce a graft polymerization. In this case, only a small quantity of infrared absorbance of carbonyl groups was observed. Low density polyethylene gave much more graft polymer than high density one. Activation energy of the graft-polymerization calculated from the initial polymerization rate was 21-22 kcal/mol in both polyethylenes. Activity of the graft-polymerization degraded gradually with the elapse of time. Quantity of the homopolymer was remarkable than that of the case of γ-ray oxidation or thermal oxidation grafting.

View full abstract

The graft copolymerization of vinyl chloride to high and low density polyethylenes has been achieved by the irradiation of the polymers in the monomer vapor. Even at high degree of grafting, this method produces very little homopolymer. Influence of several parameters such as dose rate (0.1×10⁵-2.7×10⁵r/hr), vapor pressure of the monomer (282-2110mmHg), reaction temperature (0-60°C), film thickness (0.02-0.6mm), on the kinetics of the reaction has been studied. The results are as follows.
a) The influence of dose rate on the rate of grafting can be expressed by the empirical equation V∝I^a, in which a has a value 0.8-0.9 in the range of dose rate between 1×10⁴ and 1×10⁵r/hr.
b) The relation between vapor pressure of the monomer and the rate of grafting can be expressed by the equationlicc V∝P^β, in which β has a value 1.5-1.8 depending on the crystallinity of polyethylene and the thickness of the film.
c) The initial rate of grafting decreases with increase of temperature.
d) Since the grafting occurs favorably in the amorphous region, the rate of grafting of low density polyethylene is higher than that of high density polyethylene. The distribution of graft concentration across the section was also discussed.

View full abstract