Jung Nam Im

Effects of binder fibers and bonding processes on PET hollow fiber nonwovens for automotive cushion materials

In this study, nonwoven fabrics were developed for the replacement of polyurethane foams in car interiors, in particular, cushioning materials for car seats. Polyethylene terephthalate (PET) hollow fibers and two types of bicomponent binder fibers were used to manufacture automotive nonwovens by carding processes and then post-bonding processes, such as needle punching or thermal bonding. The physical and mechanical properties of nonwovens were thoroughly investigated with respect to the effects of binder fibers and bonding processes. The tensile strength and elongation for nonwovens were found to be significantly improved by combined needle punching and thermal bonding processes. In addition, the nonwoven cushioning materials were characterized in terms of hardness, support factors, and compressive and ball rebound resilience. The nonwovens showed greater hardness than the flexible PU foam. However, support factors over 2.8 for the nonwovens indicated improved seating comfort, along with better seating characteristics of greater resilience and air permeability in comparison with the PU foam.

Manufacturing and analyses of wet-laid nonwoven consisting of carboxymethyl cellulose fibers

Carboxymethyl cellulose (CMC) is a cellulose derivative having water-soluble property, biodegradability, and biocompatibility. It has been used in various medical applications as forms of gel, film, membrane, or powder. In this study, composite CMC nonwovens were produced, by a wet-laid nonwoven process, to improve the wet strength of carboxymethyl cellulose nonwovens. Followed by preparing the CMC fibers from cotton fiber, the composite CMC nonwovens composed of CMC fibers and PE/PP bicomponent fibers were manufactured by using 85/15 % v/v of ethanol/water solution as a dispersion medium. Structural analyses of CMC fibers, such as XRD, TGA, FT-IR, and degree of substitution indicated that CMC fibers were successfully produced. The wet strength of CMC nonwoven was dramatically increased by blending with the PE/PP fibers without sacrificing the key properties for wound dressing materials such as liquid absorption, gel blocking and liquid retention. It is expected that the composite CMC nonwovens will be a good candidate for wound dressing materials for mild exudate condition.

Study on the effects of reaction conditions on carboxymethyl cellulose nonwoven manufactured by wet-laid process

Carboxymethyl cellulose (CMC) has been used in medical area by virtue of their high water absorption property, bio-degradability, and biocompatibility. It has been mainly used as forms of gel, powder, and film due to the limitation in processability on textile structures, especially nonwoven. In this study we demonstrated wet-laid nonwoven process for viscose rayon and carboxymethylation to produce CMC nonwoven. The effects of process conditions, such as reaction time and amount of monochloroacetic acid (MCA) in carboxymethylation, were investigated in terms of the degree of substitution (DS), morphological properties and mechanical properties of the CMC nonwoven. Molar ratio of MCA to cellulose and etherification time played important roles in determining characteristics of CMC nonwoven. As DS increased, strength was improved while elongation decreased. Gel blocking behavior of CMC nonwoven with higher DS indicated the applicability of CMC nonwoven as wound dressing and adhesion prevention materials.

Preparation and characterization of calcium carboxymethyl cellulose/chitosan blend nonwovens for hemostatic agents:

Wet-laid blend nonwovens of calcium carboxymethyl cellulose fibers and chitosan powder were prepared as a new efficacious hemostatic agent, and their water absorption behavior, rupture strength in the dry and wet states, blood clotting properties, calcium ion release behavior, and cytotoxicity were investigated. The calcium carboxymethyl cellulose and chitosan nonwovens lost their structural integrity in the wet state due to water absorption and subsequent gelation, whereas the calcium carboxymethyl cellulose/chitosan blend nonwovens maintained their structural integrity. The formation of polyelectrolyte complexes between calcium carboxymethyl cellulose and chitosan after the absorption of water is believed to have contributed to the structural integrity in the wet state. In the in vitro blood clotting tests, the calcium carboxymethyl cellulose/chitosan blend nonwovens immediately absorbed blood and exhibited efficacious blood clotting characteristics. The calcium carboxymethyl cellulose/chitosan blend nonwovens were not cytotoxic. Considering both the structural stability in the wet state and blood clotting performance, calcium carboxymethyl cellulose/chitosan (7/3 w/w) blend nonwoven was found to be the most effective hemostatic agent of those assessed in this study, and has good potential for commercial application.

Structure and liquid handling properties of water-insoluble carboxymethyl cellulose foam

A sodium carboxymethyl cellulose (Na-CMC) foam was obtained by lyophilization of aqueous Na-CMC solution and chemically treated with citric acid in order to control the water-solubility and liquid handling properties. The objective of this study was to prepare the water-insoluble CMC (H-CMC) foams and to investigate the liquid handling properties and their applicability to wound management materials. The chemical structure was analyzed by FT-IR, ICP, TGA, and XRD. The structural analyses revealed that the substitution of sodium atom in Na-CMC to hydrogen atom during the acid treatment resulted in more hydrogen bonding in the molecular structure. Acid concentration and treatment time influenced liquid handling properties of the foam. The increase in the amount of acid and treatment time decreased the liquid absorption capacities of the H-CMC foams. The expansion ratio and the liquid handling properties of compressed foam were affected by the compression temperature. The expansion ratio and the liquid absorption capacity decreased above 80 ℃ of compression temperature. The cytotoxicity test result confirmed the cell viability of extracted solution. This approach for controlling the shape stability and liquid handling properties by acid treatment of Na-CMC foam is expected to find useful applications in the development of novel moisture wound dressing materials.

Isothermal crystallization behavior of PAR/PBT composite prepared by island-in-a-sea fiber method

The PAR fiber reinforced PBT composite was manufactured using the PAR/PBT island-in-a-sea fiber. The isothermal crystallization kinetics of the PAR/PBT composite and the neat PBT resin were investigated in the temperature range of 187–199 °C. To calculate the Avrami parameters for analyzing the crystallization behavior, crystallization peaks were measured and analyzed in terms of the crystallization temperature and the inclusion of the PAR fiber. The crystallization rate of the PBT is faster than that of the PAR/PBT composite from the analysis of their relative crystallinity. Consequently, it is considered that the PAR fiber interrupted the crystal nucleation and growth of the PBT matrix. It can be confirmed with the crystallization half time and the crystalline morphologies at the chosen isothermal temperatures.

Composite Nonwoven of Meltblown/Electrospun Polyurethane

Transdermal drug delivery system has various merits compared to oral drug delivery system. Polyurethane nonwovens have been attracted as backing materials for patch and wound dressing, as they have superior stretchability and breathablility to films. The previous works on thermoplastic polyurethane nonwovens were mainly focused on the effects of meltblow processing parameters rather than pore, through which the infection can be occurred. It is critical to reduce the pore size without sacrificing the air permeability. In this study, we developed polyurethane composite nonwovens by combining the meltblowing and electrospinning processes. The composite nonwoven showed less than of mean pore diameter with maintaining the air permeability. The load-elongation curve showed excellent adhesion between the meltblown and the electrospun layers even at large elongation. The excellent pore properties and stretchability of the composite nonwoven can be very useful for patch backing materials.

Liquid handling properties of hollow viscose rayon/super absorbent fibers nonwovens for reusable incontinence products

To develop reusable incontinence products, blend nonwovens of hollow viscose rayon (HVR) and super absorbent fibers (SAFs) were prepared using a needle-punching process and their liquid handling properties, such as the fluid absorption capacity, fluid retention capacity, fluid absorption under load, moisture evaporation rate, and repeated water absorption were investigated. As the SAF content in the HVR/SAF blend nonwovens was increased, the fluid absorption capacity, fluid retention capacity, and fluid absorption under load increased, whereas the moisture evaporation rate decreased. SAF had a more significant effect on fluid retention than fluid absorption. In the case of HVR/SAF(8/2) and HVR/SAF(7/3), more than 100 % of the fluid absorption capacity was retained even after 5 cycles of repeated water absorption tests. Overall, the HVR/SAF blend nonwovens are good candidates for reusable incontinence products.

Characterization of Mechanical and Flammability Properties of Nonwoven Fabrics Containing Polyethylene Terephthalate and Polylactic Acid Hollow Fibers

Abstract: The purpose of this study is to develop a lightweight and environmentally friendly nonwoven fabric to sub-stitute polyurethane (PU) foams in automotive interiors. Two types of hollow fibers-polyethylene terephthalate (PET)hollow fiber and polylactic acid (PLA) hollow fiber-and bicomponent binder fibers were used to manufacture the non-woven fabrics for seat cushions by carding, needle punching, thermal bonding, and air through bonding processes. Theideal characteristics required for automotive seat cushions were evaluated, and the significant changes with the struc-tural components were analyzed. The nonwoven fabrics showed better air permeability, compressional resilience, ballrebound resilience, and non-flammability in comparison with PU foams. The characteristics were affected by the man-ufacturing processes. Keywords: nonwoven, PET hollow fiber, PLA hollow fiber, PU foam, automotive seat 1. 서 론 1970년대부터 최근에 이르기까지 자동차산업에서는 자동차의 연비개선과 환경오염의 주원인인 배기가스 저감을목적으로 부품의 일체화, 단순화, 소재의 최적화 등 차량구조 설계와 경량 소재 사용 등으로 차량의 경량화가 추진되고 있다. 자동차 1대당 섬유소재의 양은 1990년대 20kg,2006년에는 28kg, 2010년 약 35kg 정도로 그 사용량이 증가하고 있으며, 최근 금속 차체를 섬유강화복합재료로 대체하려는 연구가 완성단계에 이르고 있어 자동차에서의 섬유사용량 및 이에 따른 경량화는 비약적인 증가세가 예상된다. 자동차 내장재로 사용되는 산업용섬유 중에서 특히부직포 소재는 경량성, 원가절감, 흡·차음 등의 성능향상,성형 및 몰딩기능, 외관의 다양화가 가능하다는 장점을 가지며 자동차 헤드라이너, 대쉬보드, 실내 매트, 도어트림,트렁크 내장재 등에 다양하게 적용되고 있다[1-3]. 차량 경량화와 함께 소비자의 요구가 다양화되고 고급화됨에 따라자동차의 실내·외 정숙성과 주행시 안정감, 쾌적성을 확보하기 위해, 소음과 진동을 제어·차단하는 이른바 NVH(noise, vibration, harshness)에 관한 연구도 활발히 진행되고 있는 실정이다[4-6]. 자동차 및 수송기기용 시트의 쿠션재로는 PU foam이 가장 많이 사용되고 있다. 그러나 PU foam은 사용 중 지속적으로 VOCs를 배출하며 재생 및 재활용이 어렵고 연소시 독성 가스를 배출하는 등 많은 문제점을 가지고 있다.특히, 일본에서는 자동차내의 VOCs로 인한 질환을 SickCar 증후군이라 명명하며 자동차업계, 부품 및 재료업체가협력으로 VOCs 문제에 대응책을 마련하고 있는 실정이다[7,8]. 따라서 본 연구에서는 PU foam을 대체할 수 있는 친환경 부직포 쿠션재의 적용성 연구를 수행하고자 하였다. 중공섬유는 섬유의 내부가 비어 있는 형태로 비중공섬유에 비해 가볍고 중공부분에 채워진 공기로 인하여 보온성,흡음성 등이 뛰어나다는 장점이 있다. 뿐만 아니라 굽힘강성과 반발탄성이 일반섬유에 비해 상대적으로 우수하여 구김이나 압축에 대한 회복성도 크다고 알려져 있다[9-11].따라서 본 연구에서는 자동차 시트용 쿠션재의 친환경 및경량화를 목적으로 재활용 또는 생분해가 가능한 2종의 중

Prediction and Interpretation of Hydraulic Permeability for Nonwoven Fabrics Considering Hypothetical 2-D Layer

The permeability defined by Darcy’s law indicates the degree of ability that a fluid can flow through nonwoven media under a differential pressure in laminar flow. The permeability generally indicates the specific permeability or absolute permeability. On the other hand, if the fluid is water, the permeability indicates the hydraulic conductivity or permeability coefficient. The permeability is one of the important properties for nonwoven media and a prediction of the permeability acts as a bridge between the manufacturing technology and performance requirements. Because capillary channel theory aims to make the flow of fluid easier and more understandable, many models are based on capillary channel theory. On the other hand, the theory has a limitation in that it is unsuitable for high porosity media. In this study, a very thin downstream layer, which was suggested by Lifshutz [9], was introduced to derive a prediction model of hydraulic permeability. Needle-punched and spunbonded nonwoven fabrics with various basis weights were used in the cross-plain water permeability test. From this ‘thin layer’ model, reasonable agreement between the predicted and experimental results was obtained.