As a part of the current study on decrease of the solubility of gypsum fiber, preparation of gypsum hemihydrate fiber incorporating phosphate ion and the decrease of its solubility were reported in our previous paper. Studies were made to investigate decrease of the solubility of gypsum fibers by substitution of Ca²⁺_??_Sr²⁺, simultaneous substitutions of Ca ²⁺_??_Sr²⁺ and SO₄^2-_??_HPO₄^2- into the hemihydrate fiber. Characteristics of solid solutions were investigated by means of X-ray diffraction, thermal analysis (TG-DTA), scanning electron microscopic observation and dissolution test.
The incorporation of strontium ion in the hemihydrate fiber by the aqueous reaction in CaCl₂-SrCl₂-H₂SO₄-CH₃OH system at 80°C was synthesized by adding a H₂SO₄-CH₃OH solution into a CaCl₂-SrCl₂ solution. Changes in lattice constants caused by the substitution of Ca²⁺_??_Sr²⁺ in the hexagonal hemihydrate fiber were found by X-ray diffraction. The upper limit of the incorporation was 33 mol per cent (Sr²⁺/Ca²⁺mol ratio 0.5). This finding was also supported from data of TG-DTA and scanning electron microscopic observation. The solid solution had an aspect ratio of about 350 (diameter 0.2μm, length 70μm). However, the decrease of the solubility of strontium ion-incorporated hemihydrate fiber did not improved against that of phosphate ion-incorporated hemihydrate fiber reported by a previous paper.
Whereas simultaneous substitutions of both Ca²⁺_??_Sr²⁺ (Sr²⁺/Ca²⁺mol ratio 0.1) and SO₄^2-_??_HPO₄^2- (HPO₄^2-/SO₄^2-mol ratio 0.15) into hemihydrate fiber were attempted by the aqueous reaction in CaSO₄-SrCl₂-Na₂HPO₄-CH₃OH system at 65°C. The solid solution was formulated as Ca_0.9 Sr_0.1 (SO₄) _0.85 (HPO₄) _0.15·1/2H₂O and had a high flexibile fiber as an aspect ratio of about 200 (diameter 0.3μm, length 60μm). Its solubility after dipping in water for 24 h decreased to about 1/30 against that of gypsum dihydrate.

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Spherical cobalt hydrogenphosphate hydrate was synthesized at the early stage of the liquid reaction in CoCl₂-H₃PO₄-KOH-H₂O system at 96°C and properties of the spherulite were investigated by means of thermal analysis (TG-DTA), chemical analysis, X-ray diffraction and paper-chromatographic analysis.
The composition of the spherulite was showed as CoHPO₄·2H₂O from chemical analysis. Its dehydration process was chemically formurated as follows; CoHPO₄·2H₂O<100°C→CoHPO₄·H₂O>220°C→CoHPO₄>290°C→Amorphous phase>590°C→α-Co₂P₂O₇
Also formation of diphosphate group at about 100°C and triphosphate group at 350°C-550°C were detected by paper chromatographic analysis so that the condensation and dehydration proceeded simultaneously. The diphydrate which contained zeolitic water was converted into CoHPO₄·XH₂O under saturated vapour steam at 25°C and Co₃ (PO₄) ₂·4H₂O under formulated water at 96°C. Its hydrothermal process was chemically formurated as follows; CoHPO₄·2H₂O200°C→Co₃ (PO₄) ₂·2H₂O250°C→CO₃ (PO₄) ₂·H₂O350°C→Co₃ (PO₄) ₂.

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A series of composites were prepared with natural zeolite and phenolic resin, and the effect of another additional fillers such as glass-and linter pulp fibers on the properties of the composites was examined.
By the addition of the glass fiber to the composites, the improvement of the following properties was observed in proportion to its concentration; mechanical properties such as tensile-, bending-, and charpy impact strength, thermal stability, insulating resistance and water absorption properties.
While the addition of the linter pulp fiber to the composites decreased these physical properties. This is presumably ascribed to its heterogeneous distribution in the composites during processing and its hydrophilic properties.

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