Die-to-collector Distance Research Articles

A novel investigations on medical and non-medical mask performance with influence of marine waste microplastics (polypropylene)

The entire human race is struggling with the spread of COVID-19. Worldwide, the wearing of face masks is indispensable to prevent such spread. Despite numerous studies reporting on the fabrication of face masks and surgical masks to reduce spread and thus human deaths, this novel work is considered the marine waste of microplastics, namely Polypropylene (PP) polymer, used to fabricate non-woven fabric masks through the melt-blown process. This experimental work aims to maximize the mask's quality and minimize its fabrication cost by optimizing the melt-blown process parameters and using microplastics. The melt-blown process was used to make masks. Parameters such as extruder temperature, hot air temperature, melt flow rate, and die-to-collector distance (DCD) were investigated as independent variables. The quality of the mask was investigated in terms of bacterial filtration efficiency (BFE), particle filtration efficiency (PFE), and differential pressure. The Taguchi L16 orthogonal array and Taguchi analysis were employed for experimental design and statistical optimization, respectively. The results reveal that the higher BFE and PFE are recorded at 96.7 % and 98.6 %, respectively. The surface morphological investigation on different layers ensured the fine and uniform porosity of the layers and exhibited minimum breath resistance (a low differential pressure of 0.00152 kPa/cm2). Hence the chemically treated marine waste microplastics improved the masks' performance.

The effect of process parameters on the properties of elastic melt blown nonwovens: Air pressure and DCD

AbstractAn elastic masterbatch and elastic melt blown nonwovens are prepared based successively on styrene‐ethylene/butylene‐styrene (SEBS) and polypropylene (PP) blend. The phase separation morphology, rheological properties and crystal structure of the elastic masterbatch are investigated. The results show that a compatible and stable structure is obtained in molten SEBS and PP blend with excellent mobility in the temperature range of 210–230°C. The crystallization of PP slows down resulting in a finer structure due to the restriction of the SEBS network structure with rarely change of crystalline structure. The relationship between process parameters and properties of the elastic nonwoven is also studied in detail. Air pressure and die to collector distance (DCD) have discernible effects on fiber diameter and bonding between fibers, further influencing the performances of nonwovens including porosity, tensile strength and elastic recovery. Elastic recovery is shown to be significantly more affected by DCD than by air pressure.

Microfiber shedding from nonwoven materials including wipes and meltblown nonwovens in air and water environments.

Nonwoven products are widely used in disposable products, such as wipes, diapers, and masks. Microfibers shed from these products in the aquatic and air environment have not been fully described. In the present study, 15 commercial single-use nonwoven products (wipes) and 16 meltblown nonwoven materials produced in a pilot plant were investigated regarding their microfiber generation in aquatic and air environments and compared to selected textile materials and paper tissue materials. Microfibers shed in water were studied using a Launder Ometer equipment (1–65 mg of microfibers per gram material), and microfibers shed in air were evaluated using a dusting testing machine that shakes a piece of the nonwoven back and forth (~ 4 mg of microfibers per gram material). The raw materials and bonding technologies affected the microfiber generation both in water and air conditions. When the commercial nonwovens contained less natural cellulosic fibers, less microfibers were generated. Bonding with hydroentangling and/or double bonding by two different bonding methods could improve the resistance to microfiber generation. Meltblown nonwoven fabrics generated fewer microfibers compared to the other commercial nonwovens studied here, and the manufacturing factors, such as DCD (die-to-collector distance) and air flow rate, affected the tendency of microfiber generation. The results suggest that it is possible to control the tendency of microfiber shedding through the choice of operating parameters during nonwoven manufacturing processes.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-022-20053-z.

Process–Structure–Property relationship of roping in meltblown nonwovens

For applications such as face masks and medical gowns, defects can pose a threat to the reliability of protective materials. Roping, the entanglement of two or more fibers in a nonwoven, can cause a decrease in pore size uniformity, filtration efficiency, and barrier properties in meltblown nonwovens. In this work, a novel measurement methodology for roping was developed utilizing SEM images, ImageJ software, and statistical analysis with R. The study analyzed 16 different meltblown nonwovens with two different die tips with a 1550 MFR polypropylene, utilizing a full factorial design with 4 factors at 2 levels. A model was developed for the mitigation of roping, and it was determined that the interactions of capillary density with air flow and air flow with die-to-collector distance (DCD) had the greatest impact on the formation of roping in meltblown nonwovens. The fundamental learnings of the effects of the process parameters on roping formation could be applied to industrial applications such as face masks to tailor the balance between filtration efficiency and air permeability. The linear model could be directly applied to applications such as HEPA (High Efficiency Particulate Air) and ULPA (Ultra Low Particulate Air) filters, for operating room and clean room filters, in which nonuniformity and loss of surface area critical to performance, and thus the mitigation of roping would be beneficial.

Fluffy Polypropylene–Polyethylene glycol fabrics with branched micro- and nanofibrous structures for rapid liquid transport

A high liquid-transportation capability is required for high-performance moisture-functional wound-dressing fabrics. However, simultaneously accelerating liquid wetting and penetration aspects remains challenging. Herein, we fabricated a fluffy polypropylene–polyethylene glycol (PP-PEG) fabric with branched micro- and nanofiber via an environmentally friendly and cost-effective melt-blowing technique. The introduction of incompatible PEG reduced the viscosity of the PP melt and decreased the dimension of fibers; thus, a branched micro- and nanofibrous structure was obtained. By incorporating the amount of 15 wt% PEG, the water content of the outer face increased from 70.3% to 270.6%. A fluffy structure in the fabric's thickness direction was achieved by tailoring the die-to-collector distance (DCD) during the melt-blowing process. The porosity increased from 87.1% to 90.1% with the DCD increased from 10 cm to 30 cm, which achieved a vertical penetration velocity of 7.02 cm/s at the water head of 90 mm. Moreover, micro- and nanofibrous morphology with the excellent mechanical properties and fine hydrolytic stability could enhance the water retention capacity that maintain the humidity of a microenvironment. This branched fluffy fabric with fast water-transportation capability is expected to be used in hygienic and medical fabric.

Melt blown polypropylene nanofiber template for homogenous pore channels monoliths

Monoliths are an important technology for filtration, liquid chromatography, and protein purification. A template commonly uses to produce porous monolith. However, it is a challenge to produce a monolith with a homogenous porous structure due to the arrangements of pores within the monolith are often uneven and sometimes closed, causing pressure to accumulate and increase within the monolith which reduce the efficiency of the monoliths. Therefore, an appropriate template is needed to produce a monolith with homogenous porous structure. Nanofiber is a potential alternative as a template due to its high porosity and interconnectivity. Therefore, this research aimed to investigate the potential of polypropylene melt blown nanofiber fabricated at various operating condition to fabricate monolith by assessing the monolith morphology. Nanofibers templates were produced using a melt blowing technique at various motor speeds, air pressures, and die-to-collector distance (DCD) between 30 and 50 Hz, 0.30 and 0.50 Mpa, and 20 and 50 cm respectively, design by Response Surface Methodology. The nanofibers were characterized for its morphology and melting point using scanning electron microscope (SEM) and molten point analysis instrument respectively. The findings show that the polypropylene nanofiber diameter was in the range of 3.58 to 11.00 x 103 nm. Meanwhile, melting point obtained were in the range of 121.0 to 128.8 °C. Subsequently macropores monoliths were successfully fabricated at 0.45 Mpa air pressure, 40 Hz motor speed and 60.23 cm die-to-collector distance. It can be concluded that, melt blown polypropylene nanofiber can be potentially applied as a template for monolith fabrication.

Modeling Polymer Crystallization Kinetics in the Meltblowing Process

A novel model of the crystallization process in meltblowing process is proposed and implemented in numerical simulations. The spinline crystallization is studied using numerical solutions of the system of coupled quasi-one-dimensional equations describing the dynamics of multiple polymer jets moving in the surrounding high-speed air. Cooling, crystallization, and solidification accompany three-dimensional motion of polymer jets resulting in their vigorous stretching by the air flux including the aerodynamically driven bending/flapping. The numerical solutions predict distribution of the degree of crystallinity in polymer jets in flight, as well as in the laydown formed on the collecting screen, with the three-dimensional structure of the laydown being fully reconstructed. The effect of the collector screen temperature, die-to-collector distance (DCD), and the activation energy of the viscous flow in the polymer melt on the laydown features is studied in detail.

Study on structure and property of PP/TPU melt-blown nonwovens

This work studied the feasibility of the melt-blown nonwovens which were made by blending thermoplastic polyurethane (TPU) with polypropylene (PP). Firstly, PP/TPU-blending pellets with different PP and TPU weight ratios were prepared through extrusion process, and then PP/TPU hybrid nonwovens were fabricated by the melt-blowing method. SEM observation showed that the single fiber in the nonwovens formed a sea-island structure in which TPU served as the ‘island’ phase and PP served as the ‘sea’ phase. The compatibility of the two phases was poor. Furthermore, the influence of die to collector distance (DCD) on the structure and properties of PP/TPU melt-blown nonwovens, including fiber diameter, thickness, surface density, and tensile strength, was analyzed. The results showed that PP/TPU melt-blown nonwovens exhibited excellent mechanical properties, they are soft, elastic, and have a certain tensile strength.

Microstructural analysis of melt-blown nonwoven fabric by X-ray micro computed tomography

The structures of melt-blown nonwoven fabric, including the fiber volume fraction and fiber orientation, are decided by the melt-blowing conditions, such as the die-to-collector distance (DCD), air suction and air flow rate. In this study, the effects of these melt-blowing conditions on the structure of melt-blown fabric was investigated by X-ray micro computed tomography with a resolution of 1 µm/voxel and a measurement area of 1 mm2. The structural profile along the thickness direction of the fabric was also analyzed. Obtained averages of fiber diameter and basis weight were almost identical to the results of scanning electron microscopy measurements and tests following the standard of International Organization for Standardization. Samples produced with insufficient air suction showed larger deviation of basis weight on the 1 mm2 scale compared with those produced with sufficient air suction. The fiber volume fraction changed steeply around the fabric surface, which was attributed to surface roughness. Insufficient DCD increased the fiber diameter and surface roughness, and decreased the thickness of the fabric. The fiber volume fraction gradually decreased from the collector side to the die side for fabrics with sufficient DCD. The fibers were oriented along the machine direction rather than the cross-machine direction for all layers and samples, and orientation profiles corresponded to the zero-span tensile strength of corresponding samples.

Structure and mechanical properties of polyethylene melt blown nonwovens

Purpose Recently, the usage of melt blown products in many areas has increased. In melt blown process, generally polymers have been used. There are a variety of polymers. Characteristics of melt blown nonwovens have changed significantly depending on the polymer type. Also, there are several parameters such as die temperature, die-to-collector distance (DCD), air pressure, etc. that modify the nonwovens in melt blown process. The purpose of this paper is to investigate the effect of these parameters on the characteristics of nonwovens made up of polyethylene (PE). Design/methodology/approach In the melt blown process, two die temperatures, three different die air pressures and three different DCDs were used. In total, 18 samples were produced. On produced samples, thickness, tear and tensile strengths, fiber diameter, basis weight tests were done. Also SEM observations were obtained. Findings It was observed that parameters studied have a significant effect on characteristics of the produced nonwoven. Fiber diameter, basis weight and strength decrease by depending on factors. Also, it was observed that temperature has an effect, but slight. This work shows that higher temperatures should be studied. Finer and uniform fiber diameter is obtained with an increase in air pressure. Research limitations/implications PE is becoming increasingly important in nonwovens due to its lower melting point for processing and softer feel in nonwoven products. Practical implications Although the use of PE in polymer-laid nonwovens, especially as bicomponent fibers, has been growing in recent years, there are limited data on their processability and performance. In this context, with the availability of relatively higher melt flow rate PE, understanding the processability and structure and properties of the melt blown PE is very helpful in designing and developing the right products. This research was conducted to evaluate the processability of the PE resin using a typical PP melt blowing pilot line and to determine the structure and properties of the formed webs. Originality/value PE has superior properties such as excellent chemical resistance, good fatigue, wear resistance and higher impact strength. Also, PE provides good resistance to organic solvents, degreasing agents and electrolytic attack. PE has lower working temperatures than polypropylene, is light in weight, resistant to staining and has low moisture absorption rates. Thus, this study provides important contributions to the area since there are no data reported about the effect of various processing parameters on the structure and properties of PE melt blown nonwovens.

하이드로 대전에 의한 의료용 멜트블로운 부직포 마스크 여과재의 제조

Abstract: In this study, a melt-blown nonwoven filter for medical masks was manufactured using an online hydrocharging system. The effects of basis weight (gsm) and die to collector distance (DCD) on the breathing resistanceand filtration efficiency were investigated. Hydro charging of the nonwoven web seemed to improve the filtering effi-ciency. However, it did not affect breathing resistance. It was demonstrated that the breathing resistance and filtrationefficiency increased with increasing gsm but decreased with increasing DCD. With a DCD of 19 cm, when the gsmincreased from 20 to 50 gsm, breathing resistance increased from 5.14 to 8.33 mmH 2 O and filtration efficiencyincreased from 81.39 to 94.98%. With a basis weight of 25 gsm, when the DCD increased from 15 to 25 cm, breath-ing resistance decreased from 7.38 to 4.27 mmH 2 O and filtration efficiency decreased from 89.56 to 68.28%. In addi-tion, it was demonstrated using stability tests that the hydro charging effect lasted for 13 weeks.Keywords: melt-blown nonwoven, hydro charging, medical mask, filtration efficiency, breathing resistance

Physical and thermal characterization of polylactic acid meltblown nonwovens

ABSTRACTA series of polylactic acid (PLA) nonwovens were prepared by the melt blowing process using micro and nano dies. The nonwovens were characterized for structural, thermal, and mechanical properties. These properties varied with the type of die, airflow, and die to collector distance (DCD). The mean pore size for PLA microfiber ranged between 1.82 and 10.48 micrometers, and nanofiber nonwovens ranged between 452 and 818 nanometers. The tensile modulus and strength of PLA nonwovens increased with airflow at a given DCD, but decreased with increased DCD for a given airflow. Thermograms from calorimetry showed microfiber mats had a larger composition of beta‐form crystals than the nanofiber mats. The results showed that a wide range of nonwovens can easily be generated with properties tailored to the specific application. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40593.

Meltblown nanofiber media for enhanced quality factor

Nanofibers definitely hold great advantage and promise in filtration as they have very high specific surface area, which ensures greater probability of capturing the particles and hence, the filtration efficiency of the nanofiber filter media is high. Electrospun nanofibers are prohibitively expensive due to extremely low production rate. With recent advances in melt blowing technology, nanofibers could be produced at production rate few orders of magnitude higher than that of conventional single syringe electrospinning and hence, quite cost effective. Influence of air pressure and die to collector distance (DCD) were studied on the number average fiber diameter for the nanofibers as well as the performance properties of the nonwoven webs, each factor at three discrete levels. The nanofibers were as fine as 260 nm. A very encouraging observation of the study is very high values of quality factor observed for nanofiber nonwoven filter media. In order to compare the filtration efficiency of different nanofiber nonwoven media samples with different basis weight, a novel term of specific filtration efficiency is proposed and was found that the specific filtration efficiency with the increase in DCD or air pressure.

멜트블로운 부직포의 후가공 공정에 의한 흡음재의 제조와 특성

For sound absorption and sound insulation in automobile industry, the sound absorption materials based on meltblown nonwovens were prepared by SMS (spunbond-meltblown-spunbond) technique. And the sound absorption coefficient () of the meltblown nonwoven, produced with isotatic-polypropylene(PP), was examined for the various processing conditions such as die-to-collector distance(DCD), nonwoven weight(GSM), and air suction conditions. The meltblown nonwoven for sound absorption materials was composed of bulky microfiber web, increasing with increases in weight and DCD. The sound absorption coefficient() was excellent as a sound absorption materials of PAD type composed of SMS(spunbond-meltblownspunbond) nonwovens.

Polyether Based Thermoplastic Polyurethane Melt Blown Nonwovens

A series of melt blown samples were produced from three hardness grades of ether based thermoplastic polyurethane elastomers (TPU). The fabrics were tested to investigate their structure-property relationship in a melt blown process. Solution viscosities of the web were only 20–26% of there original values indicating a large loss in polymer molecular weight during melt blowing. Fiber diameter distributions measured on melt blown samples were found comparable to those made with more conventional polymers. The fiber orientation distribution functions (ODF) suggest slight fiber orientation in machine direction. Tensile and elongation properties depended on die-to-collector distance (DCD), polymer hardness and fiber ODF. A strong relationship between the tensile strength and die-to-collector distance was identified and attributed to reduced interfiber adhesion in the web with increasing DCD. The reduction in adhesion was attributed to greater extents of solidification before reaching the forming belt for longer DCDs. This paper is the first in a series relating the influence of the melt blowing process parameters on the polymer properties and the nonwoven fabric properties for block thermoplastic elastomers.

Influence of Processing Conditions on Melt Blown Web Structure: Part 1 – DCD

We begin an effort to quantitatively measure the influence of processing conditions on the detailed structure of commercial polypropylene melt blown (MB) webs. In this paper, we report the influence of die-to-collector distance (DCD) on fiber entanglement, fiber orientation and pore structure in webs. This enabled us to quantify the influence of DCD on web structure as well as achieve greater understanding of the commercial MB process.

Meltblown Structures Formed by a Robotic and Meltblowing Integrated System: Impact of Process Parameters on Pore Size

Our earlier studies have evaluated the effect of meltblowing process parameters on fiber diameter and orientation distribution. This paper deals with parametric studies evaluating the effect of polymer throughput, attenuating air pressure, take-up speed of the web, fiber stream approach angle, and die-to-collector distance (DCD) on pore sizes and their distribution in meltblown nonwoven webs. Pore sizes and their cumulative frequency are determined by an automated perm porometer. Under the conditions explored, the average pore size of meltblown fabrics decreases significantly when the attenuating air pressure increases. Pore size decreases significantly when the take-up speed of the web increases. As expected, an increase in the polymer throughput increases the average pore size. Increasing the DCD initially decreases, then increases pore size. confirming the existence of different "zones" in the space between the die and collector. An increase in the fiber stream approach angle initially decreases, then significantly increases pore size in the web.

Meltblown Structures Formed by a Robotic and Meltblowing Integrated System: Impact of Process Parameters on Fiber Orientation and Diameter Distribution

In a previous publication, we described a novel system that forms three-dimensional (3D) structures on 3D molds and two-dimensional (2D) structures on a rotating drum through proper integration of a laboratory scale meltblown unit with a small die and a six-axis robot. In this paper, we investigate the impact of take-up speed. die-to-collector distance (DCD). polymer throughput rate. and attenuating air pressure on the fiber orien tation and diameter distribution of 2D structures formed by the system. We introduce a new parameter, the fiber stream approach angle, which can be precisely controlled by the robot, and discuss its impact on the meltblown structure. In the experimental range studied, fiber orientation and diameter distribution are significantly impacted by the parameters. Among these parameters. the fiber stream approach angle shows the highest effect on fiber orientation distribution.

Study of Meltblown Structures Formed by Robotic and Meltblowing Integrated System: Impact of Process Parameters on Fiber Orientation

A novel system that forms two-dimensional (2D) structures on a rotating drum and three-dimensional (3D) structures on 3D molds through proper integration of a laboratory scale meltblown unit with a small die and six-axis robot is briefly described. The system advantages over traditional systems are demonstrated. Parametric studies evaluating the effect of take-up speed, die-to-collector-distance (DCD), polymer throughput rate, and attenuating air pressure on the fiber orientation distribution functions (ODFs) of 2D structures formed by the system are reported. An additional new parameter termed “fiber-stream approach-angle” is introduced and its impact on the ODF of 2D structures is also reported. Under the experimental range studied, the ODFs were significantly impacted by the parameters studied. The fiber-stream approach angle showed the highest impact, among the parameter studied, on the ODF.

Application of neural networks to meltblown process control

Process modeling is essential for the control of optimization and an on-line prediction is very useful for process monitoring and quality control. Up to now, no satisfactory methods have been found to model an industrial meltblown process since it is of highly dimensional and nonlinear complexity. In this article, back-propagation neural networks (BPNNs) were investigated for modeling the meltblown process and on-line predicting the product specifications such as fiber diameter and web thickness. The feasibility of this application was successfully demonstrated by agreement of the prediction results from the BPNN to the actual measurements of a practical case. The network inputs included extruder temperature, die temperature, melt flow rate, air temperature at die, air pressure at die, and die-to-collector distance (DCD). The output of the fiber diameter was obtained by neural computing. The network training was based on 160 sets of the training samples and the trained network was tested with 70 sets of test samples which were different from the training data. This research is preliminary and of industrial significance and especially valuable for the optimal control of advanced meltblown processes.