Study On Preparation And Performance Of High-performance Melt Differential Ultrafine Fiber Sound-absorbing Cotton

With the acceleration of urbanization,the problem of noise pollution has become more and more serious,and the slow attenuation of noise in the low and middle frequency range is more likely to cause chronic damage to people's bodies.At present,porous materials widely used.Its high-frequency sound absorption performance is good,but it hardly absorbs sound in lower frequency.Ultrafine fibers with high specific surface area provide the possibility for effective absorption of lower frequency noise.At present,almost all ultra-fine sound-absorbing fibers are prepared by solution electrospinning technology.In this paper,the green and rapid preparation of PP and PLA ultrafine fibers are realized through melt differential electrospinning technology,and they are combined with the widely used PET sound-absorbing cotton on the market.The sound absorption properties of ultrafine fiber sound-absorbing cotton and composite sound-absorbing materials are studied.PP/PEG ultrafine fibers are prepared by melt differential electrospinning device,and then processed by folding,cutting,cold pressing and other steps to be processed into PP/PEG Ultrafine fiber sound-absorbing cotton,and systematically analyzed the influence of fiber diameter,thickness and cavity for sound absorption.Results show diameter is 1.8 ?m,resonance frequency is 376 Hz with coefficient 0.82,NRC is 0.52.Average coefficient is 0.55 with the excellent ability for 200?400 Hz.The sample retains the sound absorption advantage in high frequency.By applying a cavity behind the ultrafine fiber cotton,its low-frequency sound absorption performance is further improved.When the cavity depth is 40 mm,the resonance frequency is 235 Hz,the sound absorption coefficient is 0.93,NRC is 0.57,and the average sound absorption coefficient is 0.88 from 200 to 300 Hz.In order to take advantage of the space cost advantage of ultrafine fibers,PP/PET composite sound-absorbing material is prepared by compounding PP ultrafine fiber film on PET sound-absorbing cotton,and systematically studied diameter,spinning-time,structure and cavity for sound absorption.PP ultrafine fiber film can significantly increase the sound absorption coefficient of PET;spinning time is the biggest factor affecting the sound absorption.When the spinning time is 15 min,the sound absorption coefficient at 3395 Hz near 1,and the increase in spinning time enhances the resonance of composite materials and sound waves;refinement improves sound absorption coefficient in middle frequency and the smallest fiber can absorb middle sound;the cavity becomes deeper to improve the lower frequency sound absorption,but high frequency sound absorption becomes worse.Finally,the research ideas of PP/PET composite materials are applied to the more green and environmentally friendly PLA materials,combined with the melt differential electrospinning technology to prepare PLA/PET composite materials.The results show that the sound absorption performance of PLA is better than PP,diameter can improve the mid-frequency sound absorption.The smallest fiber diameter has the best sound absorption.when frequency above 1575 Hz,the sound absorption coefficient is over 0.5;the spinning time has the most obvious increase sound absorption coefficient.When the spinning time is 15 minutes,the sound absorption coefficient at 3000 Hz is close to 1;the composite structure significantly change the final sound absorption performance,and the sound wave first contacts the PLA ultrafine fiber with best sound absorption effect,but weakens the effect on high frequency;the deeper cavity,the better sound absorption in lower frequencies.When depth is 45mm,sound absorption in middle frequency is excellent.In summary,the ultrafine fiber cotton have excellent sound absorption in lower frequency,and retains high frequency advantage,and can significantly reduce space waste.In the case of similar thickness,the sound absorption performance of the single-component sound-absorbing cotton prepared by folding ultrafine fibers for many times is much higher than that of the composite of ultrafine fibers in the form of a film with traditional porous sound-absorbing materials in the low and middle frequency range,but this puts forward higher requirements for the production efficiency of ultrafine fibers.Sound absorption and noise reduction products used to improve the quality of people's lives must be green and environmentally friendly.While having excellent sound absorption performance in a wide frequency range,they should save space as much as possible.The research content of this paper is the new application of melt electrospinning technology in the field of sound absorption and noise reduction,which provides ideas for the rapid preparation of green high-performance sound-absorbing cotton.