This article reviews the noise absorption capacity of thermally bonded nonwovens in the range of audible frequencies (125-2500 Hz). First, we focus on the effects of the properties of the fibers, which constitute nonwovens, on the sound absorption properties, and then we consider the web orientation angle of nonwovens. We also investigate a composite model of the sound absorption properties of nonwovens, including the surface roughness and panel vibration. We have used an impedance tube interferometer, which provides the normal incidence sound absorption coefficient of materials, for the determination of the noise absorption properties of nonwovens produced under different conditions. The noise absorption capacity of nonwovens depends primarily on the thickness and surface characteristics of specimens, but the effects of the fiber contents are only marginal. Interestingly, when there is a panel in front of nonwovens, the noise absorption capacity increases significantly at low and medium frequencies (250 -1000 Hz).

The goal of this research was to determine the fiber and web properties of melt-blown (MB) thermoplastic polyurethane (TPU) polymer as dependent on the MB processing conditions. The relationships between the MB fiber properties and the MB process conditions, such as the die-to-collector distance and the velocity of the MB TPU fiber in the spin line, were measured and estimated on the basis of the air velocity and air temperature, respectively. Consequently, this study provided fundamental guidelines of heat, air flow, and distance conditions of the MB process for the production of commercially acceptable MB TPU nonwovens. More specifically, the essential insight into the MB process was fundamentally valid for the MB TPU process; however, the inherent heat sensitivity of the TPU polymer brought more complexity at fiber and web formation than the conventional polyolefin MB process.

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We herein report the effects of plasticizer content (1–5 wt %) on the structure, non‐isothermal crystallization kinetics, thermal stability, and rheological property of a new type of multicomponent polyarylate (PAR). Fourier transform infrared spectra reveal the presence of a specific interaction between plasticizer and PAR chains, indicating the good dispersion of the plasticizer at the molecular level. The plasticizer influences on the non‐isothermal crystallization behavior of the PAR in two different ways: a mobility enhancer of PAR chains and an impurity to the crystallization of PAR. The melt‐crystallization temperature (Tmc) and enthalpy (ΔHmc) of the plasticized PARs at cooling runs are higher than those of the neat PAR, which is owing to the enhanced mobility of PAR chains by the plasticizer. On the other hand, the non‐isothermal crystallization rates at different cooling rates of 5–40 °C/min are slower for the PARs with higher plasticizer contents, which is due to the impurity effect of the plasticizer on the melt‐crystallization of PARs. Although the PARs with 1–5 wt % plasticizer have lowered thermal decomposition temperatures, compared to the neat PAR, they are thermally stable up to ∼400 °C. The complex melt viscosity of PAR with only 1 wt % plasticizer is far lower than that of the neat PAR. Overall, it is found that only 1 wt % plasticizer is quite effective to facilitate the melt‐processibility and to increase the crystallinity of PAR. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45704.

In this study, a series of thermotropic liquid crystalline polyester (TLCP)-based blends containing 1–30 wt% poly(ethylene-co-glycidyl methacrylate) (PEGMA) were fabricated by masterbatch-assisted melt-compounding. The scanning electron microscopy (SEM) images showed a uniformly dispersed microfibrillar structure for the TLCP component in cryogenically-fractured blends, without any phase-separated domains. The FT-IR spectra showed that the carbonyl stretching bands of TLCP/PEGMA blends shifted to higher wavenumbers, suggesting the presence of specific interactions and/or grafting reactions between carboxyl/hydroxyl groups of TLCP and glycidyl methacrylate groups of PEGMA. Accordingly, the melting and crystallization temperatures of the PEGMA component in the blends were greatly lowered compared to the TLCP component. The thermal decomposition peak temperatures of the PEGMA and TLCP components in the blends were characterized as higher than those of neat PEGMA and neat TLCP, respectively. From the rheological data collected at 300 °C, the shear moduli and complex viscosities for the blend with 30 wt% PEGMA were found to be much higher than those of neat PEGMA, which supports the existence of PEGMA-g-TLCP formed during the melt-compounding. The dynamic mechanical thermal analysis (DMA) analyses demonstrated that the storage moduli of the blends decreased slightly with the PEGMA content up to 3 wt%, increased at the PEGMA content of 5 wt%, and decreased again at PEGMA contents above 7 wt%. The maximum storage moduli for the blend with 5 wt% PEGMA are interpreted to be due to the reinforcing effect of PEGMA-g-TLCP copolymers.