Polyurethane (PU) foams are widely used as sound-absorbing materials in automobile interiors because of their light weight and shaping ability. In this study, the morphology, sound absorption coefficient, and thermomechanical properties of PU foams with cyclopentane as a co-blowing agent and melamine particles as fillers were analyzed. The addition of cyclopentane and melamine particles affected the viscosity of the polyol system and the interfacial compatibility between the fillers and the PU matrix, resulting in cavity and pore structures. However, when excessive amounts of cyclopentane were added, the viscosity decreased significantly, which weakened the cavity walls and led to a decrease in sound absorption performance. It was further confirmed that the sound absorption performance decreased owing to particle agglomeration when excess melamine particles were added. Through a morphological analysis, the cavity/pore size and open porosity were found to be strongly related to the sound absorption coefficient.

폴리우레탄(PU) 폼은 가볍고 성형이 용이하여 자동차 내부의 흡음재와 시트재로 널리 사용된다. 본 연구에서는 보조 발포제로 싸이클로펜테인을 사용하고, 필러로 멜라민 입자를 첨가한 PU 폼의 형태학적 구조, 흡음계수, 열기계적 특성을 분석하였다. 싸이클로펜테인과 멜라민 입자의 첨가는 폴리올 시스템의 점도와 필러와 폴리우레탄 메트릭스(PU matrix) 간의 계면 상호작용에 영향을 주어 공동(cavity) 및 기공(pore) 구조 형성에 영향을 주었다. 하지만 싸이클로펜테인을 과도하게 첨가할 경우 점도가 크게 감소하여 공동 벽이 약화되었고, 이로 인해 흡음성능이 저하되었다. 또한 멜라민 입자를 과량 첨가했을 때 입자 응집이 발생하여 흡음 성능이 감소하는 것도 확인되었다. 형태학 분석을 통해 공동/기공 크기 및 개방 기공률(open porosity)이 흡음계수와 밀접한 관련이 있음을 확인했다.

Keywords: melamine particle, morphology, NCO conversion, polyurethane, cyclopentane.

This study was supported by the Basic Study and Interdisciplinary R&D Foundation Fund of the University of Seoul (2025) for Jung Hyeun Kim. This research was also supported by the Post-Plastic Specialized Graduate Program through the Korea Environmental Industry & Technology Institute (KEITI), funded by the Ministry of Environment (MOE) for Insung Ree.

The authors declare that there is no conflict of interest.