During the last decades, nonwoven textiles have become widely used in the medical field due to their ease of use and due to the recent increase in the importance given to hygiene. In this study, doublelayer nonwoven structures were developed in order to be used under the orthopedic bandages and plaster casts which are widely used in the fracture treatment. The aim of this development is to give more comfort and ease in use to the wearer. Viscose and polypropylene were used as raw materials and doublelayer nonwoven structures were produced by using meltblown and needling methods. Air permeability, thickness, bending rigidity, basis weight and moisture transport (MMT) tests were applied to the doublelayered nonwovens. The results have shown that; doublelayer nonwoven structures which can be used in the fracture treatment are good candidates to be replaced by cotton pads since they provide better comfort to the user.
Keywords: Double layered nonwovenS; Meltblown; Needle punching; Medical textiles; Orthopedic bandages
PE: Polyethylene; PET: Polyethylene Terephthalate; PBT: Polybutylene Terephthalate; PS: Polystyrene; PA: Polyamide; MMT: Moisture Transport Properties
There are three types of surfaces commonly used under the orthopedic bandages and plaster casts. These products are used to improve the comfort of the patient by minimizing the risk of abrasion and irritation due to friction.These products:
The surfaces, which are already being used in hospitals under the plaster casts have secveral drawbacks such as:
In order to provide a more comfortable and healthy treatment process for the patients in consideration of all these negativities, non-woven surface structures were produced using polypropylene and viscone raw materials by meltblown and needling methods and these surfaces were combined in different combinations using needling technique. Double layered support structures were formed.
Use of nonwoven surfaces has increased during the last decades. One of the reasons for their wide range of applications is that nonwovens can be easily produced. Besides, they are advantageous to be used due to their price compliance, barrier properties and increased activities.
Orthopedic cushion bandages are used for the purpose of filling and in order to prevent the discomfort due to the orthopedic (plaster) casts and pressure bandages. Orthopedic cushion bandages are produced by using nonwovens such as polyurethane foam, polyester, polypropylene fibers or different mixtures of synthetic and natural fibers. Bandages with nonwoven structure are roughened by gently needling in order to provide the bulkiness and porous structure. In this way, comfort features can be positively developed [1].
These materials are applied right under the compression bandage/plaster cast. They have a cushion role to the appropriate body unit and ensure that bandages/plaster casts do not harm the skin and/or lead to irritations. Furthermore, they also ensure the balanced distribution of the pressure on either the leg or the arm which were put in a plaster cast. These materials can be used as two or three layers in recessed portions and bone spurs of the skin in order to have a better cushion effect [2].
In this study, doublelayered nonwoven structures were designed and developed in order to use them in the inner surface of orthopedic plaster casts and bandages instead of cotton. In the current study, polypropylene and viscose were used as a raw material in the production of doublelayer surfaces which were produced in order to provide the sufficient thickness and performance features. In this study, moisture transfer properties and some physical features (air permeability, thickness, bending rigidity, basis weight) of samples were tested and the results were evaluated statistically.
In this study, the production phase had 3 stages, namely; the production of polypropylene meltblown layers of 3 different basis weight, the production of viscose needle punched layers with 2 different basis weights each and combination of these layers with each other.
Meltblowing is a single stage process which leads the thermoplastic resins to be melted in an extruder and then to be sprayed from the nozzles onto a cylinder to cool down and form a surface with the help of high velocity air [3]. The solidified fibers create the nonwoven surface as a result of being randomly oriented on the collecting cylinder. Fibers are pretty interlaced due to the turbulence created by the air flow. A vacuum, which is in the collector, generally pulls back the hot air [4].
Advantages
Some other polymers (such as polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyamide (PA) can also be used in the meltblown process [5]. However, in our study, we preferred to use 1100 MFR polypropylene as a raw material due to its advantages such as cost saving, robustness, low melting temperature, low density, high strength [6].
Due to structure which is produced by the hydrophobic polypropylene granules, the moisture is released from the skin of the user passes from the pores to the hydrophilic surface in the part which contacts the hydrophobic user.
In our study, 3 surfaces in different weights were obtained by changing the rotational speed of the collector drum. Meltblown experimental plan is shown in Table 1.
Production Parameter |
M1 |
M2 |
M3 |
Air temperature [oF] |
390 |
390 |
390 |
Die metal temparature [oF] |
370 |
370 |
370 |
Extruder speed [%] |
20 |
20 |
20 |
Output [%] |
360 |
360 |
360 |
Die to collector distance [cm] |
100 |
100 |
100 |
Collector drum speed [ft/min] |
20 |
40 |
60 |
Basis weight [g/m2] |
95 |
54 |
38 |
Table 1: Production parameters of meltblown process are given in the table below.
Viscose fibres were used as a raw material while producing surfaces by using needling method. The reason of using viscose is that its hydrophility is higher compared to cotton. Furthermore, surfaces which are produced with viscose fibers are comfortable [7]. Thus, viscose fiber is preferred in our study due to their outstanding features.
In the production stage, viscose needle punched nonwovens of two different thickness were produced. Thin viscose surfaces (Nv1), thick viscose surfaces (Nv2). Then meltblown, needle punched layers were combined with each other according to the experimental plan shown in Table 2.
Sample Number |
1 |
2 |
3 |
4 |
5 |
6 |
Combination of Meltblown and Needle punching |
M1+Nv1 |
M1+Nv2 |
M2+ Nv1 |
M2+ Nv2 |
M3+ Nv1 |
M3+ Nv2 |
Table 2: Combinations of the doublelayer structures.
Air permeability, thickness, bending rigidity, basis weight and moisture transport properties (MMT) tests were conducted to combinations of the doublelayer structures. There is standard in all tests except for moisture transport properties (MMT). Test standards shown in Table 3.
Test |
Air Permeability |
Thickness |
Bending Rigidity |
Basis wWeight |
Moisture Transport Properties (MMT) |
Standard |
TS 391 EN |
TS 7128 EN ISO 5084 |
ASTM |
TS EN ISO 29073-1 |
- |
Table 3: Standards of tests applied to the doublelayer structures.
The results of air permeability, basis weight, moisture transport properties (MMT), thickness, bending rigidity tests and related evaluations are given below.
Air permeability
According to air permeability results obtained by using meltblown-needling methods, the lowest air permeability values were obtained when methods were applied to meltblown M1 (95g/m2) surface, higher values were obtained from the combinations with M2 surface (54g/m2) and the highest values were obtained when combinations were applied to M3 surface (38g/m2). This difference was due to the meltblown surface structure. M1 was a heavier, thicker and more voluminous structure whereas this rate decreased towards M3 surface.
When air permeability results were examined on the needling surfaces, results were observed on the surfaces with low basis weight (Nvi) and on the surfaces with high basis weight (Nvk) with lower values.
Air permeability measurements of meltblown-needling combinations can be seen in Figure 1.
Thickness
It is clear that the surface forming the difference in the thickness results is the needling surface. Meltblown-needling combination samples with fine viscose needled surfaces had lower thickness values compared to samples with thick viscose needled surfaces. Thickness measurements of meltblown-needling combinations can be seen in Table 4.
Combination of Meltblown and Needling |
Thickness Results (mm) |
M1+Nv1 |
2,627 |
M2+Nv1 |
2,517 |
M3+Nv1 |
2,533 |
M1+Nv2 |
3,811 |
M2+Nv2 |
4,37 |
M3+Nv2 |
3,741 |
Table 4: Thickness (mm) results of the meltblown-needle punched combination samples.
Bending rigidity
When bending rigidity results of meltblown-needling samples were examined, the lowest bending resistance was observed in samples with fine viscose surfaces and it was shown that bending surface values of samples increased as the thickness.
The bending rigidity results can be correlated with the hardness/softness and formability of the surfaces. It can be said that the samples with the lowest values in the measurement results have the highest softness and the easiness to form, while the samples with the highest values have the highest hardness. Bending rigidity measurements of meltblown-needling combinations can be seen in Figure 2.
Basis weight
As it can be clearly observed in meltblown-needling samples, fine viscose combinations had lowest weights and thick viscose combinations had highest weights and also decrease from M1 to M3 have been observed samples with all combinations. Basis weight measurements of meltblown-needling combinations can be seen in Figure 3.
Moisture transport properties (MMT)
The Moisture Management Tester (MMT) is an instrument used to test the liquid moisture management capabilities of textiles dynamically. A series of indexes are defined and calculated to characterize liquid moisture management performance of the test sample by using moisture management tester, such as wetting time, absorption rate and spreading speed [8].
In meltblown-needle punched combinations, spreading speed, bottom maximum wetted radius and bottom absorption rates were influenced by the thickness, weight and air permeability of pinned viscose surface which was used in lower viscose surfaces.
The top spreading speed value decreased since viscose was not used in the lower surfaces. However, when viscose was used in surfaces, as thickness and weight values increased, the top spreading speed value also increased. Furthermore, this value decreased when the air permeability of the sample increased.
The bottom maximum wetted radius [mm] value decreased in samples with viscose layer since viscose was not radius value increased as the air permeability of the sample decreased. In samples such as number 2 M1+Nv2, number 4 M2+Nv2, and number 6 M3+Nvk, the bottom maximum wetted radius value was high whereas it was almost zero in number 1 M1+Nv1 and number 3 M2+Nv1 samples. The bottom maximum wetted radius and bottom absorbtion rate values shown in Tables 5 & 6.
Combination of Meltblown and Needling |
Bottom Maximum Wetted Radius Values (mm) |
M1+Nv1 |
0 |
M2+Nv1 |
0 |
M1+Nv2 |
8 |
M2+Nv2 |
3 |
M3+Nv2 |
7 |
Table 5: Bottom maximum wetted radius (mm) values of meltblown-viscose combinations.
Combination of Meltblown and Needling |
Bottom Absorbtion Rate Values (%) |
M1+Nv1 |
0 |
M2+Nv1 |
0 |
M1+Nv2 |
44,47 |
M2+Nv2 |
47,66 |
M3+Nv2 |
16,21 |
Table 6: Bottom absorbtion rate (%) values of meltblown-viscose combinations.
In this study, doublelayer nonwoven structures which will be used under the orthopedic bandages and plaster casts in order to provide comfort to patients during the long-term fracture treatment were developed.
Doublelayer structures have various advantages such as good air permeability, moisture and thermal conductivity, absorption, very good physiological and thermal comfort, good compressibility resistance, providing a soft touch in contact with skin, adjustable cushioning, and energy absorbtion during impact and capacity to return to the original state, lightness, and low production cost [9].
Air permeability, thickness, bending rigidity, basis weight and moisture transmission (MMT) tests were performed for these doublelayer nonwoven structures. When the samples are examined, it is clear that the surface forming the difference in thickness results is the surface formed by the needling method. The samples with low weight viscous needling surfaces were given low results compared to the samples with high weight viscous needling surfaces. According to the results of the basis weight measurement were examined, it was found that when the low weight viscose was used, the lowest values were given in the combinations; higher results were obtained in combinations using high weight viscose.
According to the air permeability measurement results of the combinations are examined; the air permeability measurements of the combinations made with the meltblown M1 surface was given the lowest values. In the combinations were made with the M2 and M3 surfaces, the values increased respectively. When the bending rigidity results were examined, it was observed that the values of bending strength were low in the combinations using low viscose (Nvi), while the values increased as the thickness of the samples increased. MMT has been investigated as an indication of the excretion of the moisture caused by perspiration, and better results were obtained in the case of fine meltblown and viscose combination.
According to the results of these tests, have shown that doublelayered nonwoven materials are good candidates to be replaced with cotton pads for applications under the orthopedic bandages, to give better comfort to the wearer.
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