Research On Cryogenic Insulation Materialand Their Properties

With the popularization and application of cryogenic insulation technology, it put forward higher requirements on the performance of thermal insulation container, especially for small latent heat of vaporization of cryogenic liquids, such as liquid nitrogen, liquid hydrogen etc. In order to improve the low-temperature liquid storage efficiency, reduce the heat loss of cryogenic liquid in the process of storage and transmission, it is necessary to improve the performance of thermal insulation material. Glass fiber paper is a widely used thermal insulation material on cryogenic insulation, it’s generally used as a interval material in the vacuum multilayer insulation,glass fiber insulating paper plays an important role in the heat insulation effect on the multilayer insulation structure.In this article, fiber morphology of glass wool on different beating degree and paper properties are analyzed firstly. secondly, the dispersion properties of glass wool fibers were studied, and then the porous filler were added to glass woo paper and the influence of filler on the performance of the paper was studied. Finally, the cryogenic insulation papers were made by mixing chopped strand glass fiber with glass wool of different beating degree.Through the research on the fiber morphology and paper properties of glass wool with different beating degree, we can conclude that the average fiber length increased with the beating degree of glass wool increased. When the beating degree increased over 39°SR, the fiber length was not affected seriously. The fiber coarseness increased and then decreased with the beating degree increased. When the beating degree increased to 39°SR, the fiber coarseness increased to the highest. The fiber kink and bend ratio decreasedwith the fiber beating degree increased. When the beating degree of glass wool fiber increased from 29°SR to 39°SR, the tightness of paper increased quickly, then flattened out. The paper porosity decreased but the tensile strength increased. The thermal conductivity of the paper decreased then increased with the fiber beating degree increasing, and it got to the lowest0.015 W·(m·K)-1 when the beating degree of glass wool increased to 39°SR.It’s difficult to disperse the glass wool fiber in water, so the dispersion was researched in this paper, and the best dispersion was obtained when the pulp concentration was 0.4%, and the defibering time was 4min. The dispersion performance of glass wool improved by adding dispersant APAM 、 CMC and(Na PO3)6. For dispersant CMC and(Na PO3)6, the best dosage was 0.2%~0.3%(for dry pulp), and for APMP, the best dosage was0.3%~0.4%. Compared with other two dispersants, when the dosage of(Na PO3)6 was less than 0.3%, the glass wool gained best dispersion performance.The properties of paper by adding different porous filler was studied,the results showed that the effect of adding porous filler on paper air permeability was obvious. It can significantly improve the air permeability of the sheet only by adding 10% fillers. The air permeability reached to a maximum when the filler addition amount was 25%, and the air permeability by adding filler B was larger than that by adding filler A. The thermal conductivity of glass wool insulation paper was first decreased and then increased with the filler was added. The thermal conductivity by adding filler A was smaller than that by adding filler B. When filler A addition amount was 20%, the thermal conductivity of the sheet was the minimum,and when filler B addition amount was 25%, the thermal conductivity of the sheet was the minimum.The influence of the content of glass wool fiber on the properties of paper was extensively studied by varying the ratio of glass wool. According to the result, the porosity of paper decreased with the increase of content of glass wool, when the content of glass wool was higher than 50%, the downward trend of porosity became slower, the tensile strength of paper increased with the increase of content of glass wool, and the thermalconductivity of paper decreased with the increase of content of glass wool.When the content of glass wool was above 70% and the beating degree was less than 33°SR, beating degree had a significant influence on the thermal conductivity of paper, and the beating degree increase continously, the influence on the thermal conductivity of paper was not obvious.