Poly-O-benzyl-L-serine (PBLS) was synthesized as a model compound related to silk sericin and the molecular structure was investigated by infrared spectrometry, X-ray diffractometry and differential scanning calorimetry (DSC). Close similarity was observed between PBLS and silk sericin in crystalline structure, molecular conformation and thermal property. Infrared spectra indicated that as-polymerized PBLS exhibited anti-parallel beta structure, which mainly observed with random coil structure in silk sericin. PBLS prepared by casting with dichloroacetic acid solution at 50°C, was fibrous crystal with beta structure. Amount of anti-parallel beta structure of silk sericin surrounding the silk brins was considered to increase by the drawing and spinning motion of silkworm. The results of PBLS supported the bundle-type model in order to describe the molecular structure of silk sericin.

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The coagulation reaction in the PGA fiber spun from the spinning dope of the conc. poly(sodium-L-glutamate) (PSLG) aqueous solution was studied using acid solutions as a coagulant.
Solutions in most of inorganic and a few organic acids were found to be effective for the preparation of fibers and films of PGA. When the spinning dope adding a slight amount of pH-indicater (Congo Red) was extruded into the acid solution, a blue layer was formed from the surface of the filament. The diffusion rate of H⁺ was estimated by measuring the growth rate of the blue layer. The desolvation rate from the extruded filament was determined by measuring the changes in the degree of swelling; (the weight of coagulated gel/the weight of polymer). The results obtained were expressed as a function of the coagulation time, concentration and temperature of the HCl, H₂SO₄ and H₃ PO₄ solutions.

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A conc. aqueous solution of poly (sodium-L-glutamate) (PSLG) was spun in an aqueous phosphoric acid solution as a coagulant. The coagulation parameters, such as the concentration, temperature and length of the coagulation bath, were discussed in relation to the chain conformation, crystal-type and mechanical properties of the resulting fibers.
The fibers in good quality were obtained by the spinning under the optimum conditions; the concentration ranging from 30 to 50%, temperature 20 to 30°C and length of the coagulation bath 0.25m to lm. The molecular chains of fibers were found to be extended and formed β-type crystals. These crystals were highly oriented along the fiber axis. The conformation of PGA molecules changed from the α-helix to the β-structure at temperatures above 70°C. Therefore, it is preferable to be carried out the wet-spinning at temperatures below 70°C.

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A gel chromatographic investigation has been made for the binding of Cu²⁺, Pb²⁺. Zn²⁺ and Cd²⁺ to soluble derivatives of high sulfur component of wool, namely, S-carboxylkeratin (K-COOH), S-β-aminoethylkeratin (K-NH₂) and keratose (K-SO₃H). A Sephadex G-25 gel column was used with 0.05 M acetate buffer in a pH range of 4.5-6.5 as eluent. The binding parameters and the numbers of the binding sites for the complex formation were evaluated by a procedure described by Klotz et al. The selectivity of the binding sites was examined by competitive binding experiments carried out for binary mixtures of the metal ions. The results indicate that (i) the binding parameters depend strongly on the type of the keratin derivatives; (ii) the carboxyl groups introduced act as binding sites for the divalent metal ions; (iii) the amino groups do not act as binding sites for Pb²⁺, Zn²⁺ and Cd²⁺ but act as strong binding sites for Cu²⁺ (iv) the binding data for Pb²⁺, Zn²⁺ and Cd²⁺ are analysed in terms of a single kind of binding sites for respective cations, while those for Cu²⁺ are analysed in terms of two kinds of independent binding sites with high and low binding constants; and (v) competition between Cu²⁺and Pb²⁺ takes place for the low affinity sites but not for the high affinity sites.

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Six types of heat resistant synthetic electrical insulating papers (A-insulating papers), which belong to thermal H-class, named A-Board, GA-Paper, A-Tissue, A-Mica Paper and A-Mica, were developed to meet various requirements. They were made of pulp like materials such as fibrids and fibres made from aromatic polyamide, fribrids and glass fiberes or mica platelets.
These A-insulating papers have following characteristics and end-use areas.
1) A-Board, designed for the electrical insulating board of special A-class rolling stock transformer for the electric trains of the Nationwide New Line of Japanese National Railway, has high physical and electrical properties, excellent moldability and uniformity in density and thickness. It is also suitable for the insulating board of dry type transformers.
2) GA-Board, composed of fibrids and super fine glass fibres, is characterized by its easy varnish and oil impregnability, punching quality and high dimensional stability. It is used as the insulation board for dry type transformers.
3) GA-Paper, composed of fibrids and super fine glass fibres, is characterized by its good varnish impregnability and holdability and high dimensional stability. It is suitable for a substitute for electrical insulating asbesto sheet and the good layer insulation sheet for rotating machines.
4) A-Tissue, thin leaf insulating paper made of only aromatic polyamide fibrids, is characterized by its very high dielectric strength and high flexibility. It is suitable for the wrapping tape for a wire insulation.
5) A-Mica Paper, flexible mica sheet combined mica platelets with a few wt.% of fibrids, has good handling quality, because fibrids grasp and hold firmly mica platelets. So it is used as very good basic material of mica paper tapes as insulation for high voltage rotating machines.
6) A-Mica, laminate paper thermally bonded without any adhesives A-Mica Paper and aromatic polyamide paper (backing) into a single sheet by hot calender, has excellent electrical properties and corona resistance due to high mica content and uniformity. It is adopted as the good insulating sheet for high voltage rotating machines.

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