**3.3 Air permeability**

252 Thermoplastic Elastomers

Table 7 and Figure 2 showed that the basis weight increased gradually with decreasing collector drum speed. The highest values were obtained with 10 ft/min collector drum speed as 239,769 g/m2 on average and the lowest values were obtained with 30 ft/min

As it can be seen in Figure 2 and Table 8, basis weight increased also with increasing die air pressure. The highest values were obtained with 8 psi as 322,711 g/m2, whereas the lowest

> 8 45 322,711 Sig. 1,000 1,000 1,000

Table 8. Student-Newman-Keuls test results related with the effect of the die air pressure on

Student-Newman-Keuls tests have also shown that the collector vacuum had a significant effect on basis weight and also that when the vacuum increased the weight also increased. So the highest values were obtained with 60% vacuum as 220,720 g/m and the lowest values were obtained with 15% vacuum as 171,902 g/m as it can be seen in Table 9 and Figure 2.

> 60 45 220,720 Sig. 1,000 1,000 1,000

Table 9. Student-Newman-Kleus test results related with the effect of the collector vacuum

**Correlations Extruder** 

Sig. (2-tailed) ,080

The results of the 2-Tailed Pearson Correlation test applied to see the relationship between the extruder pressure and the basis weight were given in Table 10. The results showed that

Table 10. 2-Tailed Pearson Correlation test results related with the effect of extruder

**Subset 1 2 3**

**Subset 1 2 3** 

Pearson Correlation 1 ,151 Sig. (2-tailed) ,080 N 135 135

Pearson Correlation ,151 1

N 135 135

**Pressure Weight** 

collector drum speed as 137,033 g/m2 on average.

**Pressure (psi) N**

**Die Air** 

Alpha = 0,05

**Collector Vacuum** 

Alpha = 0,05

**Extruder Pressure (psi)**

**Weight (g/m)**

pressure on to the basis weight

**(%) N**

15 45 171,902

30 45 175,004

to the basis weight

on to the basis weight

values were obtained with 6 psi pressure as 31,411 g/m2.

6 45 31,411

7 45 213,504

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 are mostly effected by the die air pressure, the collector drum speed, the collector vacuum and extruder pressure. The results obtained from air permeability results were presented in Figure 3.

Fig. 3. Air permeability values of polypropylene meltblown nonwovens

As it can be seen in Table 11, the die air pressure had a significant effect on the air permeability of the polypropylene meltblown nonwovens. Table 11 and Figure 3 showed that the air permeability increased with increasing die air pressure. It can be also said that the air permeability was effected by the weight of the sample and it increased by decreasing weight. The highest results were obtained with 6 psi as 347,065 g/m2/l, whereas the lowest values were obtained with 8 psi as 275,444 g/m2/l.


Alpha = 0,05

Table 11. Student-Newman-Kleus test results related with the effect of the die air pressure on to the air permeability

Investigation of the Production Parameters and

**3.4 Fibre diameter** 

Physical Characteristics of Polypropylene Meltblown Nonwovens 255

significant, evet though it was not very strong considering the value. It can be commented that there was a negative correlation of 17,4% between the extruder pressure and the air

Fibre diameter of meltblown nonwovens plays a critical role in some physical properties of the meltblown nonwovens, as it determines the surface area, which is a very important parameter for such applications as filtration and cleaning. Better filtration and cleaning performances are achieved with smaller fibre diameter, due to the increased surface are. Fibre diameter was effected by the collector vacuum and the extruder pressure. Figure 4 showed the fibre diameter properties of polypropylene meltblown nonwovens. In this study

permeability. The air permeability decreased with the increasing extruder pressure.

meltblown nonwovens with fibre diameter of 5-9 m were achieved.

Fig. 4. Fibre diameter values of polypropylene meltblown nonwovens

**Die Air** 

Alpha = 0,05.

on to the air fibre diameter

As it can be seen in Table 15, results of the statistical analysis have shown that the die air pressure did not have a significant effect on the fibre diameter. It is also possible that the

> 6 45 6,944 8 45 7,224 7 45 7,235 Sig. ,055

Table 15. Student-Newman-Kleus test results related with the effect of the die air pressure

**Subset 1** 

effect was not clear since the die air pressure values were very close to each other.

**Pressure N** 

Figure 3 and Table 12 show that, the air permeability increased with increasing collector drum speed. This result was thought to be related to the decrease in thickness and basis weight. The highest results were obtained with 30 ft/min as 452,267 g/m2/l, whereas the lowest values were obtained with 10 ft/min as 184,122 g/m2/l.


Table 12. Student-Newman-Kleus test results related with the effect of the collector drum speed on to the air permeability

Regarding the effect of the collector vacuum on the air permeability, it can be said that the air permeability increased with decreasing vacuum. This can be due to the increase in the basis weight with increasing vacuum. The highest results were obtained with 15% as 382,156 g/m2/l, whereas the lowest values were obtained with 60% as 255,689 g/m2/l.

The results of the statistical subgroup analysis about the effect of the collector vacuum on the air permeability were presented in Table 13.


Table 13. Student-Newman-Kleus test results related with the effect of the collector drum speed on to the air permeability


Table 14. 2-Tailed Pearson Correlation test results related with the effect of the extruder pressure on to the air permeability

Table 14 shows the correlation test results regarding the effect of the extruder pressure on the air permeability. As it can be seen in the table, the correlation was found to be statistically significant, evet though it was not very strong considering the value. It can be commented that there was a negative correlation of 17,4% between the extruder pressure and the air permeability. The air permeability decreased with the increasing extruder pressure.
