Liquid nucleating additives for improving thermal insulating properties and mechanical strength of polyisocyanurate foams |
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Authors: | Min Jung Kang Youn Hee Kim Gun Pyo Park Mi Sun Han Woo Nyon Kim and Sang Do Park |
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Affiliation: | (1) Department of Chemical and Biological Engineering, Korea University, Anam-dong, Seoul, 136-713, Korea;(2) Korea Institute of Energy Research, Yuseong-gu, Daejeon, 305-343, Korea; |
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Abstract: | The effects of liquid-type nucleating silane additives on the cell structure, mechanical strength, and thermal insulating
properties of the polyisocyanurate (PIR) foams have been studied. The PIR foams synthesized with hexamethyldisilazane (HMDS)
as a silane additive showed the smaller average cell size and lower thermal conductivity than those of the PIR foams prepared
with the hexamethyldisiloxane, dimethoxydimethylsilane, and hexadecyltrimethoxysilane. When HMDS was added, average cell size
of the PIR foam was becoming smaller due to lower surface tension of the polyol solution, thereby the nucleation rate and
number of bubbles produced were increased and then the cell size becomes smaller. The additives likely act as nucleating agents
during the formation of PIR foams. The smaller cell size appears to be one of the major reasons for the improvement of thermal
insulation properties and mechanical properties of the PIR foams. From the results of cell size, thermal conductivity, and
mechanical strength of the PIR foams, it is suggested that the HMDS may be the efficient liquid-type additive for the reduction
of cell size and improvement of the thermal insulation property of the PIR foams. |
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