Melt blown process applications

Nonwoven fabrics account for more PP usage than any other single fiber application. There are three types of nonwoven fabrics thermobonded, from staple fibers spunbonded and melt-blown. The spunbonded and melt-blown processes are discussed below. The fabrics from each process differ from each other in properties and appearance, and often combinations of two types are used together. Spunbonded fabrics are strong, whereas melt-blown fabrics are soft and have high bulk. 

The fibers formed in the melt-blown process are very fine and allow for the production of lightweight uniform fabrics that are soft but not strong. Fabrics from fine melt-blown fibers can be used in medical applications because they... 

The principal advantage of the melt-blown process is that it can make fine filaments and produce very light weight fabrics with excellent uniformity. The result is a soft fabric with excellent barrier properties, meaning effective filtration characteristics and resistance to penetration by aqueous liquids. This property is vital in medical applications as concerns on blood-borne diseases increase. 

Biodegradable thermoplastics, like PHB and PLA, can be processed by conventional thermoplastic processing technologies, such as extrusion, injection molding, melt spinning, blowing film, and melt blown, for a wide range of application as enviromnentally friendly materials and for medical applications. 

PBS is a typical thermoplastic and can be processed via various methods, such as extrusion, injection molding, film blowing, fiber spinning, and thermoforming. It has been reported that PBS can be processed into melt-blown, multifilament, monofilament, nonwoven, flat and split yarn, injection-molded products, film, paper laminate, sheet, and tape for applications in the textile and plastic industries. 

In addition, REX processing was used to chemically modify PLA via an alcoholysis mechanism for blown film applications. In this case, intensive alcoholysis reactions from a diol solution or from functionalized alcohol promoted by titanium tetrapropoxide were carried out to tune the PLA chain length and rheology. It was found that under certain alcoholysis conditions, the resulting PLA blends were suitable for melt-blown non-woven processing. 

PVDF copolymers at <1000 ppm in typical blown film applications is effective in reducing melt fracture and allowing increased extrusion rates Chemical resistance to bleaching agents and other paper mill process chemicals... 

The PLA polymers are processed using conventional spunbond or melt blown techniques. The plies of the nonwovens can either be hot calendered, needle punched, hydroentangled, or chemical bonded. They are intended for disposable hygiene, agriculture, and medical applications such as diapers. 

These materials are produced in a single manufacturing line, combining spun-bonded fabric and melt blown production processes. The composite can outperform the individual components in a number of areas and can offer unique new properties. Applications include hygiene, construction and medical industries [15]. 

There are two parts in this chapter. In part 1 (section 8.3), the above-mentioned models, i.e. the ANN model and statistical model are used to predict the fiber diameter of melt blown nonwoven fabrics from the processing parameters. The results are expected to give an indication of the relative roles of these models in predicting the fiber diameter of melt blown nonwoven fabrics. In part 2 (section 8.4), to meet the demand of establishing small-scaled ANN models, an input variable selection method was developed to help model the structure-property relations of nonwoven fabrics for filtration application. The structural parameters were selected by utilizing this method. The ANN models of structure-property relations of nonwovens were established. This section will establish a reasonably good ANN model that can generalize well and consider more structural parameters as the model inputs. 

The mechanisms described above tell us how heat travels in systems, but we are also interested in its rate of transfer. The most common way to describe the heat transfer rate is through the use of thermal conductivity coefficients, which define how quickly heat will travel per unit length (or area for convection processes). Every material has a characteristic thermal conductivity coefficient. Metals have high thermal conductivities, while polymers generally exhibit low thermal conductivities. One interesting application of thermal conductivity is the utilization of calcium carbonate in blown film processing. Calcium carbonate is added to a polyethylene resin to increase the heat transfer rate from the melt to the air surrounding the bubble. Without the calcium carbonate, the resin cools much more slowly and production rates are decreased. 

Very few studies have been performed investigating the effect of branching on the extensional rheological properties of polystyrenes. Such investigations can be valuable because many of the fabrication operations associated with commercial applications of polystyrene include operations in which the polystyrene melt undergoes an extensional deformation. Some examples are extruded foam sheet, blown film, oriented (tentered) sheet, and thermoforming. The types of deformations associated with these processing operations are best described as... 

Profile, pipe, blown-film, and wire-coating dies are examples of dies generally constructed of hot-rolled steel for low-pressure melt applications. The high-pressure dies can be made of certain steels such as 4140 steel. Chrome plating is generally apphed to the flow surfaces, particularly when processing certain plastics such as EVA. Stainless steel is used for any die subject to corrosion. The steel... 

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