聚丙烯熔喷非织造材料电晕驻极处理研究

利用电晕驻极技术处理聚丙烯熔喷非织造材料,讨论了驻极电压、驻极时间以及两电极之间距离等工艺参数对滤料性能的影响,研究了驻极处理后聚丙烯过滤材料表面形貌结构的变化。结果表明:经过驻极处理后,聚丙烯熔喷非织造材料纤维表面略现粗糙;随着驻极电压和时间的增加,材料表面静电电位呈现逐渐增加后下降的趋势,随着电极距离的增加,材料表面静电电位逐渐下降;驻极处理后,聚丙烯熔喷材料的过滤效率显著提高,但透气性未发生显著变化;在存储过程中,驻极聚丙烯过滤材料的表面电位在初期迅速衰减,以后变化趋缓。     

高性能聚丙烯熔喷布驻极母粒的制备与应用研究

对聚丙烯熔喷布及聚丙烯熔喷布用驻极母粒制备方法进行了介绍,针对现有驻极母粒制备方法的不足,对不同的主驻极剂材料、辅助驻极材料以及其之间的协同作用、制备工艺等展开了研究,通过以熔喷聚丙烯、柔顺剂、主驻极剂、辅驻极剂、成核剂、抗氧剂为原料,工艺要求主驻极剂均匀分散于辅驻极剂中,主驻极剂与辅驻极剂之间产生协同效应,获得性能良好的驻极母粒产品。在聚丙烯熔喷布喷丝过程,加入的驻极母粒产品,可以有效提高熔喷布表面电荷,通过测试熔喷布过滤效率,通过加入本方法制备的驻极母粒,细菌过滤效率（BFE）大于95%,聚丙烯熔喷布的综合过滤效率、抗热衰的性能、柔韧性得到大幅度提升。     

不同驻极方式下聚丙烯熔喷非织造布的过滤性能

研究了容尘试验前后电驻极、水驻极聚丙烯熔喷非织造布的形貌特征,探讨了在不同试验条件下两种驻极方式的熔喷布对盐性气溶胶颗粒物的过滤效率、气流阻力、透气性等指标的影响。结果表明:相比于电驻极熔喷布,水驻极熔喷布的内部纤维更细、孔隙更多、透气性更好,在同一气体流速下,过滤效率更高、气流阻力更低;随流速增加,两种熔喷布的过滤效率下降,其中水驻极熔喷布下降较少,对应的气流阻力较低;随叠加层数的增加,两种熔喷布的过滤效率和气流阻力同时增大,相同叠加层数下,水驻极熔喷布的气流阻力更低;容尘试验后,过滤效率可达100%,水驻极熔喷布的气流阻力更低,透气性更好。由此可见,相比于电驻极方式,水驻极是一种更优的驻极方式。     

纳米电气石/聚丙烯驻极熔喷非织造布的研制

研制了一种纳米电气石改性驻极体熔喷聚丙烯非织造布母粒,并采用电晕放电法制备出纳米电气石/聚丙烯驻极熔喷非织造布。探讨了纳米电气石在聚丙烯树脂中的分散状况及改性母粒的流变性能,同时对非织造布力学性能、表面电荷密度和过滤性能进行了测试。结果表明:电气石能较好地分散在聚丙烯树脂中;加入特种电气石之后,纤网的机械性能有所下降;驻极体熔喷非织造布的驻极效果大大改善,其表面电荷密度、过滤性能均有明显提高。     

高效驻极聚丙烯熔喷专用料的制备与研究

通过化学降解聚丙烯(PP)、添加特殊处理的纳米驻极剂并复配粉体分散剂,"一步法"制备高效驻极PP熔喷专用料.借助扫描电子显微镜、高温凝胶色谱、自动滤料检测等测试方法,研究了PP熔喷专用料主要物性与熔喷布过滤性的影响因素.结果表明:该材料性能满足GB/T 30923-2014要求,且具有长效高过滤性,熔喷布工艺得到了优化...     

聚丙烯熔喷非织造材料的空气过滤效果研究

以含粉尘粒径为0.3~10.0μm的空气为尘源,测定了纤维直径为1~5μm,面密度为20.7~54.0g/m2的聚丙烯(PP)熔喷非织造材料对空气的过滤效率,研究了材料的纤维直径、面密度及电晕驻极处理对其过滤效率的影响。结果表明:随着PP非织造材料纤维直径的减小及面密度的增加,材料的过滤效率提高;纤维直径和面密度对过滤效率的影响在一定范围内具有互补性;驻极处理可有效提高PP非织造材料的过滤效率,当粉尘粒径为0.3μm时,经驻极处理后过滤效率从85.6%提高到96.2%。     

密度梯度复合滤料的结构与过滤性能研究

以聚丙烯(PP)纺粘布(简称纺粘布)为支撑层、PP熔喷布(简称熔喷布)为中间滤层、静电纺聚乳酸纳米纤维布(简称电纺布)为表面滤层,制备三级密度梯度结构复合滤料(简称三级梯度滤料),以纺黏布和熔喷布制得二级密度梯度结构复合滤料(简称二级梯度滤料),借助自动滤料测试仪等研究了滤料的结构和性能。结果表明:纺粘布、熔喷布和电纺布的纤维平均直径分别为19.58,2.89,0.71μm,平均孔径分别为76.80,12.02,2.52μm;在纤维层单位面积质量相近的情况下,随着纤维平均直径变小,滤料平均孔径变小,纤维直径和滤料平均孔径的变动幅度基本一致。三级梯度滤料的平均孔径为2.12μm,孔径分布为0.89~4.40μm;与二级梯度滤料相比,三级梯度滤料孔径范围变窄,平均孔径下降了80.5%,在气体流量为32L/min时,对空气动力学质量中值直径为0.26μm的NaCl气溶胶的过滤效率达到99.2%,过滤效率提高了66.7%,三级梯度滤料综合过滤性能得到明显提升;密度梯度滤料的阻力具有加和效应,约等于各纤维层阻力之和,密度梯度滤料的过滤效率不具有加和效应,主要取决于过滤效率最高的纤维层。     

口罩用聚丙烯熔喷非织造布过滤性能的研究

采用盐性气溶胶颗粒对聚丙烯(PP)熔喷非织造布进行容尘实验,研究了不同气体流量、滤料层数、过滤时间对PP熔喷非织造布过滤特性的影响。结果表明:对于单层熔喷非织造布,气体流量为30 L/min时,初始阻力为37.4 Pa,初始过滤效率为97.86%;气体流量为85 L/min时,初始阻力为112.2 Pa,初始过滤效率为90.69%;随着气体流量的增加,PP熔喷非织造布的过滤效率呈现近似线性下降的趋势,而过滤阻力则呈现线性增长的趋势;当气体流量为30,85 L/min,采样时间为4 s时,随着叠加层数的增加,其过滤效率的差异越来越小,过滤阻力差异越来越大,呈现不同的增长趋势;对于单层熔喷非织造布,随着过滤时间的增加,过滤效率和阻力增加,但过滤效率的增长趋势呈先急后缓,而过滤阻力则呈先缓后急的趋势。     

熔喷聚丙烯原料性能及加工工艺研究

分析了聚丙烯(PP)熔喷专用料的结构与性能,研究熔喷料的分子量及分子量分布、熔体质量流动速率、熔融结晶、灰分及挥发分性能对工艺的影响。通过熔喷短纤纺丝制备不同克重的熔喷布,考察熔喷布的力学性能、过滤效果、阻力性能,建立原料、设备、工艺之间的影响关系。结果表明:氢调法和降解法PP熔喷专用料具有适宜的熔体质量流动速率、良好的热稳定性和力学性能,熔体质量流动速率分别为1 570 g/10min和1 560 g/10min,分子量分布指数分别为3.3和2.54,灰分分别为0.005%和0.02%;制备的熔喷布纤维直径在2～3μm, 25 g重熔喷布32 L/min流量下的盐性过滤效率可达到99%以上,气体阻力30 Pa左右,40 g重熔喷布在95 L/min流量下油性过滤效率可达到97%以上,具有很好的过滤效果,可满足口罩、空气过滤等领域的性能需求。     

非织造布

20022280熔喷法:增加熔流速率及其特点Noynear犷N.;Chemieal Fibers International,200(,,50(5),p .442一444(英)BOrealis Polymers生产三个级别的造粒用于聚丙烯熔喷布的生产。造粒比粉状和球粒状聚丙烯提供更好的流变性控制和稳定作用以及更好的均匀性。因为它不含外来拼料,处理容易且安全。较好控制熔体弹性,较好混和有色MB和消除对分离简化和改善加工的要求。MFR级别越高,纤维越细,孔洞尺寸越小,耗能越低,产率越高,铺网越柔软,卫生产品抗渗透性越高和过滤织物的效率越好。(张桂水)熔喷法纺粘布聚丙烯过滤织物 20022281用于液体和…     

Electrostatic Capture Efficiency Enhancement of Polypropylene Electret Filters with Barium Titanate

This study reports on the effects of BaTiO₃—a high dielectric constant additive—addition on charging and filtration properties of meltblown polypropylene (PP) electret filters. Since electrostatic capture efficiency of electret filters is mainly dependent on electrical forces, surface potential and aerosol filtration properties were analyzed and compared. Due to quasi-permanent nature of electret property, stability of charging and filtration performance was also investigated via following an isothermal charge decay procedure. Addition of BaTiO₃ did not alter fiber morphology significantly. Particularly, the stability of electrostatic filtration performance was found to be promising with the addition of BaTiO₃. Possible microstructural changes after addition of BaTiO₃ were investigated via wide angle X-ray diffraction. Changes in crystal structure of PP upon addition of BaTiO₃ did not deteriorate electrostatic properties.

Copyright 2015 American Association for Aerosol Research     

熔喷聚丙烯驻极体过滤材料对医用消毒剂的耐受性研究

熔喷聚丙烯驻极体过滤材料由于具有特殊的静电过滤机理,而显现出低流阻、高效率等优点,尤其是所具有的除尘、灭菌多功能的特点,使其成为了医用防护口罩的最佳用材。在特殊环境下的驻极体电荷稳定性是需要深入了解的关键问题。本文在前期工作的基础上,采用浸泡方法研究了材料在医用消毒剂作用下的过滤效率稳定性。结果表明:经双氧水、苯酚、戊二醛、含氯消毒剂、硼酸、甲醛、过氧乙酸和消毒酒精等医用消毒剂浸泡后,其过滤效率几乎不会衰减。但材料用洗洁精和洗衣粉清洗时,其过滤性能下降较大。因此,熔喷聚丙烯驻极体过滤材料在医用环境中使用具备良好的稳定性,可作为医用防护口罩的首选材料。但建议作为一次性呼吸防护用品使用。     

Dust Collection by a Fiber Bundle Electret Filter in an MVAC System

Electret filters are composed of thin, electrically charged fibers that are often utilized in industrial fields that require high collection efficiency with low flow resistance. A bundle-type electret filter in the Mechanical Ventilation and Air-Conditioning (MVAC) system of a Metro-subway was characterized in this study. The particle penetration and pressure drop parameters were examined under a filtration velocity ranging from 0.5 to 2.5 m/s. Particle penetration increased significantly in the early stages of filtration, but then became steady. The filter quality, which is a useful index of the filtration performance incorporating pressure drop and filtration efficiency, was evaluated for the test filters. The fiber bundle filter demonstrated a higher filter quality than the mechanical filter or the general panel-type electret filter with a small drop in pressure even at a high filtration velocity. In addition, the three dimensional structure and high electrostatic charge of the fiber bundle filter would enable a long retention time and constant level of pressure drop throughout the filtration.     

Experimental Study on Charge Decay of Electret Filter Due to Organic Solvent Exposure

The electret filter is a potential component to remove airborne particles due to its high collection efficiency and low pressure drop. However, its filtration performance is gradually decreased by exposure to organic solvents, which limits the application of electret filters. The effect of ethanol exposure on the filtration performance of polypropylene electret filters was investigated experimentally to clarify the charge decay phenomenon in this study. Experimental results revealed that filter performance is strongly dependent upon the challenged mass and existing state of an ethanol solvent. The filter performance was drastically degraded by exposure to ethanol droplets generated from a solution with ethanol concentrations above 30%; however, it was maintained during exposure to ethanol vapors. This tendency was also seen in the surface potentials of the exposed filter media. In addition, we found that the critical challenging amount of ethanol droplets was in the vicinity of 0.045 g/cm² to neutralize a tested electret filter in this study.

Copyright 2015 American Association for Aerosol Research     

Study on correlation of filtration performance and charge behavior and crystalline structure for melt‐blown polypropylene electret fabrics

Melt‐blown polypropylene (PP) electret fabrics are widely used as air filter media due to the specific mechanism of electrostatic filtering. In this article, two additives, stearate and modified rosin, are doped to PP fabrics during melt‐blown process. The filtration performance of doped PP gets improved greatly, with filtration efficiency increased by 6% at room temperature but its temperature stability promoted dramatically. As a result, the filtration efficiency of doped PP still remains above 95% of its initial, whereas that of non‐doped PP only remains 58% at 110°C. By XRD characterization the structure modification is observed after doping. The crystallinity increases from 14.17% to 22.64% and 29.62%, respectively. Meanwhile, the crystallite has a smaller size, respectively, 89Å and 86Å as compared to 107Å for non‐doping in the direction vertical to lattice plane (110). This demonstrates that additive doping can give rise to larger crystallinity and more fine‐grained crystallite. Therefore, doped PP improves its charge storage behavior ascribing to expanding interface between crystallite and amorphous region and then enlarging charge trap density. Furthermore, the effect of additive doping on electret charge storage behavior is investigated by short‐circuit TSD, and the filtration performance can be explained relevantly with TSD. A charge storage profile is also adopted to illustrate that the space charge captured by charge traps is in the form of space‐charge dipole with the rigidity of crystallite. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42807.     

Structure and performance of electroblown PVDF-based nanofibrous electret filters

Poly(vinylidene fluoride) (PVDF)-based nanofibrous mats were produced via electrically assisted solution blowing (electroblowing). Morphology and filtration properties of the nanofibrous mats were investigated as a function of polymer concentration and applied voltage. The average fiber diameter was reduced from 727 ± 366 nm to 408 ± 143 nm and from 424 ± 233 nm to 328 ± 105 nm, using 16 wt% and 12 wt% concentrations, respectively, with an increase of electric voltage from 0 to 30 kV. In addition, the pore size of the mats produced from 12 wt% concentration decreases with the increase of electric voltage. Results showed that electroblown mats possess high filtration properties and performance. Enhancement of mechanical capturing efficiency is attributed to the reduction in fiber diameter and pore size. The enhancement of electrostatic capturing efficiency is thought to be from the improved electret property of the mats, which eliminates the need for a second step to polarize nanofibrous mats. As a result, both mechanical and electrostatic capture efficiency of the mats is enhanced compared to solution blown PVDF mats. The emerging electret property might be due to the accumulation of the electrostatic charges at high voltage and the enhanced polarized β phase, which is the result of the high drawing ratio applied to the polymer jet during the spinning process.     

Desalination by electret technology

A purification process of making use of electret technology for efficient but cost effective deionization was discussed in this paper. Douglas MacGregor claimed that PTFE electret works as a means of ions separation for desalination due to the polarization of an electrolyte and ions migration under a permanent electrostatic field generated by a pair of electrets with opposite polarities. The electrostatic field attracts counter-ions to the charged solid surface, and thus generates a purified effluent in the mainstream. Theoretical and experimental analyses were made to investigate the practicality of desalination by electret technology. It is found that MacGregor's design is meaningful only for a dilute electrolyte or a system with very high surface charge density because the number of the counter-ions attracted to the surface is limited and cannot exceed that of the surface charges at the electret.     

Electret characteristics of melt-blown polylactic acid fabrics for air filtration application

Polylactic acid (PLA) is a biodegradable and biocompatible polymer. Melt-blown PLA electret fabrics have become attractive materials for air filter applications. Its filtration performance mainly depends on the electrostatic effect originating from electrets. How to improve their electret behavior and then to enhance their filtration efficiency has always been challenging. In this article, three melt-blown PLA fabrics with different morphological or crystal structure are made from different process conditions or ingredient. The electrets are formed by means of corona charging technology. Their crystalline and morphological structure was analyzed, and filtration performance was measured. Their charge-trapping feature was studied by thermal stimulating discharge technology. The results proved that the air filtration efficiency of three melt-blown samples improved a lot when electrets were formed. Different crystalline structures of PLA fabrics will result in differences in their electret charge-trapping feature. The PLA fabrics with semi-crystalline characteristics display a regular charge-trapped level distribution and amorphous structure hints the diversity of charge-trapped levels. The deference in filtration resistance is mainly ascribed to the different fiber diameters and their distributions. More narrow distribution of fiber diameter leads to more compact fabrics and to higher filtration resistance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48309.     

Characterization of filter media prepared from aligned nanofibers for fine dust screen

Nanofibers for fine dust filters of four structures (random, aligned, orthogonal, and nanofiber net) were prepared by electrospinning method using polymers such as PAN and PA6. While conventional electret filters experienced deterioration problems in fine dust(PM_1.0) capture as its surface charge decayed, the electrospun nanofibers prepared contributed to the removal capacity. The filters from aligned fibers showed high quality factors ( q _F : filter performance indicator) and filtration efficiency from 22 to 50% depending on particle size than simple electret media at a face velocity of 15.92 cm/s. The fiber structure of nanofiber net (NFN) presented almost absolute collection efficiency, particularly on dust particles smaller than 300 nm. Furthermore, the composite filters which are composed both of a commercial electret mask filters and nanofiber nets effectively enhanced the overall filtration efficiency by 59.46%, resulting in more than 99% for PM_1.0. Consequently, electrospun polymer nanofibers offer a promising plausible mask filter material with air permeability. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48166.