Polyurethane Foam-Clay Nanocomposites: Nanoclays as Cell Openers

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• 作者：G. Harikrishnan ; T. Umasankar Patro ; D. V. Khakhar
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2006
• 出版时间：October 11, 2006
• 年：2006
• 卷：45
• 期：21
• 页码：7126 - 7134
• 全文大小：569K
• 年卷期：v.45,no.21(October 11, 2006)
• ISSN：1520-5045

文摘

Flexible and rigid polyurethane (PU) foam nanocomposites were synthesized using unmodified and organicallymodified montmorillonite clays. X-ray diffraction and transmission electron microscopy studies showed that,while the unmodified clays were intercalated, the modified clays were exfoliated in the foams produced. Thecell morphology of the foams was investigated by environmental scanning electron microscopy. The fractionof open cells (defined as the cells in which the foam lamellae are all ruptured) in the foam is an importantparameter governing many properties, such as the degree of softness in the case of flexible foams anddimensional stability for both rigid and flexible foams. The open cell content in PU-clay foamednanocomposites was investigated. It was found that clays act as efficient cell openers in both rigid and flexiblefoams and a greater fraction of open cells was obtained with increasing clay concentration. Modified clayswere found to be more efficient cell openers than the unmodified clay. The degree of softness of flexiblefoam was increased and the dimensional stability of both rigid and flexible foams was improved, with clayaddition. The thermal conductivity and compressive strength of the rigid foams were not significantly affectedby clay addition. The kinetics of the foaming process with different clays was investigated. The polymerizationand the foaming reactions were found to be affected in different ways for the modified and unmodified clays.Comparison with chemical cell openers in the case of flexible foams indicated that clays could be a goodalternative.