Nonwoven fabric/spacer fabric/polyurethane foam composites: Physical and mechanical evaluations

et al. 2018

Materials

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This study proposes multifunctional, fabric-reinforced composites (MFRCs) based on a bionic design, which are prepared by two-step foaming and a combination of different fabric constructs. MFRCs are evaluated in terms of sound absorption, compression resistance, electromagnetic interference shielding effectiveness (EMI SE), and drop impact, thereby examining the effects of fabric structures. The test results indicate that the enhanced composites have superiority functions when combined with carbon fabric in the upper layer and spacer fabric in the lower layer. They have maximum compression resistance, which is 116.9 kPa at a strain of 60%, and their compression strength is increased by 135.9% compared with the control specimen. As a result of the fabric structure on the cell morphology, the maximum resonance peak shifts toward high frequency when using spacer fabric as the intermediate layer. The average sound absorption coefficient is above 0.7 at 1000–4000 Hz. The reinforced composites possessed EMI SE of 50 dB at 2 GHz; an attenuation rate of 99.999% was obtained, suggesting a good practical application value. Furthermore, the cushioning effect of the MFRCs improved significantly, and the maximum dynamic contact force during the impact process was reduced by 57.28% compared with composites without any fabric structure. The resulting MFRCs are expected to be used as sound absorbent security walls, machinery equipment, and packaging for commercial EMI shielding applications in the future.

Section: Introductionmentioning

confidence: 99%

Multifunctional, Polyurethane-Based Foam Composites Reinforced by a Fabric Structure: Preparation, Mechanical, Acoustic, and EMI Shielding Properties

et al. 2018

Materials

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“…Isocyanate and a small amount of water content react to form a small amount of CO 2 , which facilitates the formation and an even morphology of cells. Increasing water content results in a great volume of CO 2 , which in turn accelerates the foam expansion rate and generates a large size of cells [20]. As a result, the cells have a larger size and uneven morphology.…”

Section: Resultsmentioning

confidence: 99%

Study on preparation, sound absorption, and electromagnetic shielding effectiveness of rigid foam composites

Peng

Jnl of Sandwich Structures & Materials

et al. 2018

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This study aims to propose and obtain rigid foam composites that have features of good sound absorption and electromagnetic shielding effectiveness. Polyether polyol, isocyanate, and distilled water are used to form rigid foams. The hot pressed low-melting-point polyester nonwoven fabrics with an area density of 200 g/m2 are combined with polyester aluminum foil, thereby forming the panels. The cell structure, compression stress, tensile properties, thermal conductivity, sound absorption, and electromagnetic shielding effectiveness of the rigid foam composites are evaluated in order to examine the influence of the amount of water content (0, 0.1, 0.2, 0.3, and 0.4 wt%). The test results show that using 0.1 wt% of water content provides the rigid foam composites with a maximum foam density of 0.16 g/cm3, an average cell size of 0.36 mm, the maximum tensile stress of 2.84 MPa, a good thermal insulation performance, an optimal sound coefficient of 0.92, and an optimal electromagnetic shielding effectiveness of above 40 dB.

“…Pan et al prepared the nonwoven fabric/spacer fabric/PU foam sandwiches with features of strong mechanical strength, sound absorption, and fire retardant. The resulting products could be applied as building construction and electromagnetic shielding materials . Many studies on the compression performance of PU foam have been conducted .…”

Section: Introductionmentioning

confidence: 99%

Sound absorption and compressive property of PU foam‐filled composite sandwiches: Effects of needle‐punched fabric structure, porous structure, and fabric‐foam interface

Zhang

Polymers for Advanced Techs

et al. 2019

The flexible polyurethane (PU) foam-filled composite sandwiches are constructed using three types of needle-punched fabrics (upper layer), PU foam (core layer), and nylon (bottom layer). Different contents of deionized water were used to adjust the pore size and bulk density of PU foam by free-foaming. Effects of needlepunched fabric components, cell structure, and fabric-foam interface on sound absorption and compressive property of the composite sandwiches were investigated. Fabric-foam interface contributes to improve high-frequency sound absorption efficiency. When containing 0.5 wt% water in the core and nylon-glass grid needle-punched composite fabric (NPUN-G) in the upper face, the composite sandwiches exhibited optimal sound absorption of 0.78 at low frequency of 450 Hz, and optimal compressive strength of 14.4 kPa. Combination of needle-punched composite fabric improved the sound absorption coefficient and compressive strength, as high as 223% and 121%, respectively, compared with pure PU foam. This study provided an important basis for the preparation of high-strength composite sandwiches with low-frequency sound absorption.