**5. References**

262 Thermoplastic Elastomers

strong and bright future is forecasted for this technology. The scope and utility of this technology will increase and meltblowing will become a major technique in nonwoven technology. The application of speciality polymer structures will no doubt offer new nonwoven materials unobtainable by other competitive technologies. (Dahiya et al., 2004) In this chapter the results of a study regarding the investigations of the effect of die air pressure, extruder pressure, collector drum speed, and collector vacuum on the physical properties, namely thickness, basis weight, air permeability, fiber diameter and tensile

The results have shown that thickness of polypropylene meltblown nonwovens were effected mostly by the drum speed and the collector vacuum. An increase in the drum speed and an increase in the vacuum caused a decrease in the thickness. Thicker surfaces were

The basis weight of the polypropylene meltblown nonwovens were mostly influenced by the die air pressure, collector drum speed and collector vacuum. The basis weight increased gradually with decreasing collector drum speed and increased with increasing die air pressure. The collector vacuum had a significant effect on basis weight; when the vacuum increased the basis weight also increased. The effect of extruder pressure on the basis weight

Air permeability is an important property for meltblown nonwovens, that effect their performance in many applications especially in filtration. The air permeability property of the meltblown nonwovens were influenced by the die air pressure, the collector drum speed, the collector vacuum and extruder pressure. The air permeability increased with increasing die air pressure, collector drum speed and decreasing vacuum. The air

Fibre diameter of meltblown nonwovens is a very important parameter for such applications as filtration and cleaning. Fibre diameter was effected by the collector vacuum and the extruder pressure. The die air pressure did not have a significant effect on the fibre diameter. The fibre diameter slightly increased, when the collector vacuum increased from 15% to 30%, but it did not change significantly with an increase in the collector vacuum from 30% to 60%. The fibre diameter of the meltblown nonwovens investigated in this study

Breaking load and elongation were significantly influenced by the collector drum speed, collector vacuum, die air pressure and extruder pressure in production direction. The extruder pressure did not appear to be a significant factor for the tensile properties in the width direction. The breaking load results in production direction were slightly higher and therefore the elongation results were slightly lower than the results in the width direction. This is because orientation of the fibres were more towards the production direction around the collector drum and therefore the strength were more enhanced in this direction. The breaking load increased with increasing die air pressure both in the production and the width directions, due to the increase in basis weight and thickness. The elongation decreased with increasing die air pressure in the production direction, due to incresing breaking load. In the width direction this trend was not valid; increasing pressure caused an increase in the elongation in this direction. For both of the directions as a general trend the

properties of polypropylene meltblown nonwoven webs were presented.

obtained with lower collector drum speeds and lover vacuum values.

permeability decreased with the increasing extruder pressure.

were not affected by the extruder pressure.

was not statistically significant.

	- < http://ojs.cnr.ncsu.edu/index.php/JTATM/article/viewFile/342/275>

**13** 

*Brazil* 

*University of Campinas* 

**Thermoplastic Extrusion in Food Processing** 

Extrusion cooking was first introduced in food and feed processing in the late 1950s. Since then, the systems involved have grown in popularity, efficiency and flexibility. Extrusion cooking technology is most used for cereal and protein processing in the food industry and is closely related to the pet food and feed sectors. In the last decade, the development of extruders has evolved to yield sophisticated products, new flavour generation,

Thermoplastic extrusion is considered a HTST (High-Temperature, Short-Time) process in the food industry, and it permits, with little or no modification of the basic equipments and appropriate process control, the production of a great variety of food and feed products (Camire et al., 1990; Chang et al., 2001; El-Dash, 1981). This technique has been widely used with raw materials such as corn, wheat, rice and, especially in recent years, with soy (Chang

Depending on the raw materials and of the characteristics desired for the final product, extruders operate with low, medium or high shear; however, thermoplastic extruders are used for high shear. As examples, pasta and processed meat products are produced with low shear (cold extrusion); meat analogues and some pet foods are produced with medium shear; and expanded snack products, breakfast cereals and textured vegetable proteins are

For Fellows (2000), the two main factors that influence the characteristics of extruded products are: raw material characteristics and operational conditions of the extruder. As main characteristics of the raw material, the following can be highlighted: type of material, moisture content, physical state, chemical composition (quantity and type of starch, proteins, fats and sugars) and pH of the material. The operational parameters that can be pointed out as important are: temperature, pressure, die diameter and shear force, with the latter being influenced by the internal design of the extruder and by its length; as well as

Guy (2001) and Stanley (1986) relate the following advantages to the thermoplastic extrusion process: versatility, low costs, high production yields, good quality products and no

**1. Introduction** 

encapsulation and sterilisation.

et al., 2001; Kadan & Pepperman, 2002).

screw geometry and rotation speed.

effluents.

produced with high shear (thermoplastic extrusion).

Caroline Joy Steel, Maria Gabriela Vernaza Leoro, Marcio Schmiele,

Reinaldo Eduardo Ferreira and Yoon Kil Chang

*Textile Research Journal*, Vol. 73, No.1, January 2003, pp. 15-21, DOI: 10.1177/004051750307300103

[9] Dahiya A.; Kamath, M. G. & Hegde, R. R. (2004). Meltblown Technology, In: *The Official Website of the University of Tennessee*, 21.11.2011, Available from: http://web.utk.edu/~mse/Textiles/Melt%20Blown%20Technology.htm
