Spunlaced Flax/Polypropylene Nonwoven as Auto Interior Material: Acoustical and Fogging Performance

This paper reported a study on acoustical and fogging properties of a spunlaced flax/polypropylene nonwoven. This nonwoven was carded and crosslapped with a 50/50 blend ratio by weight. The spunlacing process was carried out on an AquaJet spunlace line with two different settings of water pressure. The spunlaced nonwoven was thermally bonded using a panel press. Acoustical and fogging properties of the spunlaced nonwoven in both felt and panel form were evaluated in accordance with the industrial standards of Alpha Cabin, ASTM, and DIN. For the spunlaced flax/polypropylene nonwoven felts (before hot-pressing), the both impedance tube test and Alpha Cabin test indicated that the sound absorption coefficient approached to 1.0 with increase of sound frequency; for the spunlaced flax/polypropylene nonwoven panels (after hot-pressing), the sound absorption coefficient was always below 0.3 within the whole testing range of sound frequency. The sound insulation test performed by the impedance tube instrument revealed that the spunlaced flax/polypropylene nonwoven panels behaved as a typical isotropic thin panel with the resonance frequencies of 366 Hz and 354 Hz and the coincidence frequencies of 3576 Hz and 3762 Hz corresponding to two different machine settings for the spunlacing process. The fogging test result showed that the spunlacing process had a complicated influence on the nonwoven fogging property. High-pressure water jetting not only helped reduce fogging emission by the removal of impurity particles but also helped increase fogging emission by the increase of total nonwoven surface area.