Highly drawn poly (ethylene terephthalate) (PET) films were crystallized in air at Ta=130-180°C for one hour. These films (named O. S.) shrunk freely by heating in air at Tc=200, 220 and 230°C for 30min. and the changes in x (degree of crystallinity), _??_ (Scherrer's size of crystallite), L (long period), f (X-ray orientation degree), l (length of film) and S (thermal shrinkage) were traced. Plotting these parameters against ΔTr=Tc-Ta, changes in temperature causing films to contract, the following results were obtained: (1) Relation between S(Tc) and ΔTr, was approximately linear (Fig. 5). (2) The rate of increment of x, _??_, L was nearly proportional to ΔTr (Fig. 4, Fig. 7-9 and Fig. 13). (3) The rate of decrement of n=1/_??_ and the rate of increment of r=(L-_??_) was also nearly proportional to ΔTr, (Fig. 11 and Fig. 18). The results of (1) and (2) showed that the higher the degree of crystallinity of O. S., the lower the amount of shrinkage decreased. Assuming the structure of the annealed PET film as the two-phase model of alternating crystalline and non-crystalline regions, the results of (2) and (3) indicated that thicknesses of each lamellar and inter-lamellar regions (_??_ and r) increased on contraction thermally, whereas the numbers of layers of lamellae (n) in the drawn direction of film became smaller. These contractive behaviors seemed to be reasonable compared with the temperature ranges of crystallite-recrystallization into lamellae of PET films2).
When the setting between the top of the metallic or model wire and the plain plate and the depth from the top of wire to the bottom of groove are changed respectively, the friction factor λ of wire is obtained by measuring the drop in pressure at different values of velocities of the air in a given length of a very thin rectangular tube in the same manner as mentioned in the previous report.1) From the relationships between the drop in pressure ΔP in a given length of the tube and the mean velocity of the air _??_ and those between λ and Re for laminor flow (Re<1000), the following results are obtained: 1) When the setting is changed, the drop in pressure at a mean velocity is maximum in the minimum setting between the top of wire and the plain plate. 2) When the depth from the top of wire to the bottom of groove is changed, the drop in pressure increases with decreasing the depth of groove even in the constant setting. Moreover, in the relation between λ and Re expressed as λ=K/Re, the higher value of K is obtained in case of the shallower groove. From these results mentioned above, the effective carding action can be expected pneumatically between the plain plate and the metallic wire by minimizing the setting and by using the wire having the shallowest groove.
The effect of orientation of nuclei on the stress-induced crystallization of polyethylene is discussed. Changes of stress and birefringence during elongation and subsequent relaxation process have been measured at molten state and slightly crystallized state for low density polyethylene. The behavior of stress and birefringence in both process for molten polymer were shown to be consistent with Kuhn-Grun's theoretical equation. The film, being quenched after elongation, had preferred a-axis orientation. The behavior of stress and birefringence during elongation for partially crystallized polymer have not coincided with rubber elastic theory because of the contribution of orientation of spherulitic nuclei in the melt, but these were shown to accord with rubber-like behavior in the relaxation process. These film had preferred b-axis orientation to the stress direction. Dependence of crystal orientation on elongation temperature and cooling condition have been investigated for low density polyethylene and high density polyethylene. The film, elongated from partially crystallized state, had the mixture of preferred a- and b- axis orientation to the stress direction. It is considered that characteristic crystal orientation is achieved with stress-induced crystallization of molten polymer and with ordered crystallization starting from the oriented spherulitic nuclei.
In order to investigate the effects of glycerol on the properties of water, the proton magnetic resonance of water-glycerol mixture has been determined in the absence and presence of electrolytes. By adding glycerol into water, significant downfield shift was observed. This result suggests that glycerol would promote the intermolecular hydrogen-bonding of water. The upfield shift of water proton resonance on the addition of structure breakers, KCI, KBr and KI, of which the structure-breaking ability increases in that order, was found to be more prominent in the presence of higher glycerol content. This effect was remarkable for the electrolytes which are well known as the effective structure breakers to water. These results suggest that glycerol apparently promotes the structure breaking effects of the electrolytes. The apparent increases of the structure breaking effects of these electrolytes are explained in terms of the promotions of intermolecular hydrogen-bonding in water caused by glycerol.
Graft copolymerization of acrylonitrile (M1) with various vinyl monomers (M2) onto cellulose were carried out in an aqueous medium using ceric salt as an initiator. The effects of M2 monomers on the conversion and the alternating tendency of copolymers obtained were examined. Total conversion was greatly enhanced by the presence of cellulose and decreased in the order of methyl acrylate (MA), ethyl acrylate (EA), methyl methacrylate (MMA), butyl acrylate (BA), vinyl acetate (VAc) and styrene (St). The above coincides with the order of the solubility of monomers in water. Per cent grafting and grafting efficiency increased with the AN content in the feed. The monomer reactivity ratios r1 and r2 of grafted and ungrafted copolymers obtained by the copolymerization in the presence and in the absence of cellulose were determined by using the Fineman-Ross method. Alternating tendency of copolymers obtained by the copolymerization of AN with M2 monomers decreases with the e value in M2 monomers and alternating tendency of the grafted copolymers is higher than that in the absence of cellulose. From these results, it is supposed that the formation of cellulose-AN (M1) complex brings about the increase in electron accepting ability, and uncomplexed M2 monomer functions as a donor to the cellulose-AN complex. As a result, a donor-acceptor complex is generated, and the graft copolymerization is initiated.
Piperazine polyamide homologs were prepared by melt polycondensation of piperazine or 2-methyl piperazine or 2, 5-dimethyl piperazine with adipic acid or suberic acid or sebacic acid. The melting points of the polymers decreases, whereas, the glass transition points increases by methylsubstitution of piperazine ring. The densities of the polymers decreases and the moisture regains increase by methyl-substitution of piperazine ring. Methyl-substituted piperazine polyamides have relatively high moisture regain, which probably is due to the higher electro-negativity of carbonyl group and the loose packing of polymer chain.