Polyethylene single-crystal mats deformed by hot pressing were annealed in air at temperatures between 100°C and 130°C for 1 hour. The changes of heat of fusion and melting point with increasing annealing temperature have been investigated by differential scanning calorimeter.
The annealing behavior of compressed mats has been found to differ from that of drawn mats. For compressed mats it was observed that the heat of fusion passes through a maximum at an annealing temperature of 120°C and melting point shows no detectable change on annealing up to 115°C whereas it increases drastically at higher temperature over 120°C.
Experimental results were interpreted in terms of two mechanisms, i.e., the contraction of unit cell dimension and the thickening of lamella, each dominating below and above an annealing temperature of 120°C respectively.

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Previously, it was reported that a remarkable tendency of fibrillation of poly(p-phenyleneterephthalamide) (PPT) fiber on its deformation was related to the pillar-shaped microfibrillar structure and that this tendency may lead to poorer fatigue resistance compared with other synthetic fibers when it was used as a reinforcement for rubber.
We found that these problems could be solved by copolymerization of PPT to the extent that the spinning dope of the copolymers showed optical anisotropy.
The fine structure of such copolymer fibers was studied by the wide and small angle X-ray scattering and the birefringence measurement.
The following results were obtained.
1) Copolymer fiber have the extended chain structure similar to PPT fiber, and the tenacity of copolymer fiber is same as that of PPT fiber.
2) Diaminocomonomer unit (NN'-bisaminobenzoilethylene diamine or piperazine) of copolymer fiber is forced to be included in crystals of PPT, and a crystal of copolymer fiber becomes more paracrystalline than that of PPT fiber. Therefore the cross section of copolymer fiber is more uniform than that of PPT fiber and the pillar-shaped microfibrillar structure found in PPT fiber disappears in copolymer fiber.
3) Such modification of fine structure leads to the improvement of mechanical propertiess of PPT fiber, such as increased elongation-at-break, knot tenacity and knot elongation.

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The effect of the nitrogen pressure up to 61kg/cm² on the thermal properties of silk fibroin was studied. Differential thermal analysis (DTA) run was taken at the heating rate of 10°C/min. The DTA curve of a silk fibroin thread showed a single endothermic peak at ca. 319°C under the pressure of 1.0kg/cm² This peak is due to the thermal decomposition of the silk fibroin. The peak was splitted into two and the lower main peak temperature was shifted to lower temperature with the increasing pressure. Under the pressure of 61kg/cm², the DTA curve of a silk fibroin showed an initial endothermic peak at 300°C and second endothermic peak at 326°C. The lower endothermic peak temperature agreed well with the single peak temperature obtained for the specimen contracted by immerging the original specimen in aqueous LiBr solution (70%) at 25°C. The birefringence of the specimen decreased down to 46% of the original silk fibroin. On the other hand, the silk fibroin hydrolyzed by aqueous HCl solution showed an endothermic peak at ca. 320°C. This temperature agreed with the higher endothermic peak temperature.
The temperature at which the decomposition began was shifted to lower temperature with increasing the pressure of nitrogen. It was also found that a drastic shrinkage of the silk fibroin thread occurred in a temperature range of 300 to 330°C, accompanying a conformational change from β to random coil. From these results, it may be concluded that the endothermic peak appeared at around 300°C is attributed to the thermal decomposition of the amorphous β structure of silk fibroin and that the endothermic peak at 326°C is due to the decomposition of silk fibroin with the crystalline β structure.

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Heat-treatment effects of the Loeb type cellulose acetate membranes were studied. With the heat-treatment temperature, the permeability of the volume flux driven by the ΔP decreased; the permeability of the volume flux driven by (ΔP-Δπ) increased; the selectivity of the volume flux driven by ΔP and reflection coefficient increased: hence the selectivity of the membrane was improved by the heat-treatment. The volume fraction of the cellulose acetate in the swollen Loeb type cellulose acetate membrane increased with the heat-treatment temperature. The relations between the volume fraction and the membrane constants, permeability and selectivity, were approximately linear.
The glass transition temperature of the Loeb type cellulose acetate membrane exists at 74°C. Heat treatment at this temperature induces a large compaction of the dense layer of the Loeb type membrane which is observed by the transmission electron micrograph.
The heat of fusion of freeze-dried Loeb type cellulose acetate membrane was not changed with heat-treatment temperature, suggesting that the crystallinity of Loeb type cellulose acetate membrane do not increase by heat-treatment.
These experimental results indicate that the heat-treatment gives rise to the reorganization and compaction of non-crystalline region of membrane.

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Infrared absorption and dynamic loss tangent (tan δ) measurements were made on poly(ethylene terephthalate) to study the microstructure of the amorphous part which induced Case II swelling. Unoriented films crystallized by various methods including annealing to attain a wide variety of crystallinity were used as samples.
Case II swelling was independent of the amount of regular folding. It was inferred that the microstructure contains a large amount of ethylene glycol residue in trans conformation and is included in well-formed spherulites. The α_a absorption in tan δ behavior, which is related to the microbrownian motion of chain segments in amorphous region, indicates that the texture may consist of the chain segments of highly elastic character.

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Gas chromatography of the mixture of sorbitol and various O-methylsorbitols prepared from partially O-methylated cellulose by acid hydrolysis followed by reduction with NaBH₄, was carried out on OV-7 column by the linear temperature-programmed method after the mixture being converted to trifluoroacetyl (TFA), acetyl (Ac) and trimethylsilyl (TMS) derivatives. The Kováts retention indices were determined as well as retention times and retention temperatures for TFA, Ac and TMS derivatives of the eight components, which were sorbitol and seven kinds of O-methyl-sorbitols in the mixture.
The correlation between the chemical structures and the retention indices for each derivative of the eight components was studied on an assumption of the additive contribution of each structural unit to the retention index. It was concluded that the chemical structures had the intimate relation to the retention indices for the three kinds of derivatives of various O-methylsorbitols.

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The effect of the interaction between sodium dodecyl sulfate (SDS) and polyvinyl alcohol (PVA) on soil deposition of polyester fibers in a carbon black containing bath is investigated.
The amount of SDS bound to PVA having different acetate residue content (0.6_??_21.5mol%) is measured by means of equilibrium dialysis. The amount positively depends on the concentration of SDS and the acetate residue content of PVA. While, the degree of soil deposition on polyester fibers also increases with the acetate residue content of PVA. Thus, the binding of SDS onto PVA reduces the anti-soil-deposition effect of PVA.
It is considered that PVA-SDS complex which behaves as an anionic polymer in the soiling bath becomes difficult to adhere to the negatively charged carbon black particle, resulting in the increased degree of soil deposition on polyester fibers.

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