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Lenzinger Berichte, 85 (2006), 22-30
22
THE FUNCTIONAL PROPERTIES OF TENCEL® - A CURRENT UPDATE
Heinrich Firgoa, K. Christian Schustera*, Friedrich Suchomela, Johann Männera, Tom Burrowa,
Mohammad Abu-Rousb
a Textile Innovation, Lenzing AG, Austria
b Christian Doppler-Laboratory / Chemistry Cellulosic Fibers and Textiles, Institute of Textile
Chemistry and Textile Physics of Leopold-Franzens-University Innsbruck, Austria
* Corresponding Author: c.schuster@lenzing.com, tel.:+43 -7672 - 701 - 3081
For many years the textile world was very
simple when it came to the function of textiles:
hydrophilic natural fibers like cotton and wool
and the man made cellulosic fibers stood for
absorbency and breathability and the synthetic
fibers stood for strength and easy care.
With increasing use of the term “functional
textile“, the situation has become more complex.
The synthetic fiber industry has been developing
new products and marketing approaches
claiming enhanced “physiological function in
textiles” for sportswear and other fields.
Consumers have accepted these arguments and
there is a general belief that synthetic fibers are
the product of choice for active sportswear, even
where the hydrophilic fibers may be superior.
In order to redress the situation, Lenzing AG as
a leading producer of cellulosic fibers [1][2]
decided that a deeper insight into the “inherent
physiological properties and functions” of
hydrophilic fibers was needed. A research
program was started to look at the inherent
properties of fibers using new methods and
approaches. The objective was to produce the
evidence needed to make our customers aware
of the excellent “inherent functionality” of
Lenzing’s cellulosic fibers and that in many
cases there is no need to use highly sophisticated
functional synthetic fibers and finishes to
achieve a “functional textile”.
There are two ways of developing the
physiological functions of a textile product.
Properties can be modified or enhanced by work
on the fabric development level and/or fibers
can be used which offer physiological functions
on the fiber level. The best products will result
from a combination of the two approaches.
However this paper does not consider specific
textile product development possibilities; it
presents statements of the “inherent
physiological fiber properties” of Lenzing’s
hydrophilic fibers. For each physiological
function that is described, evidence is presented.
To help understand the origins of the “inherent
physiological functions” of textile fibers it can
be postulated that:
1. When hygroscopic or hydrophilic fibers come
into contact with water, they absorb it into the
fiber structure.
2. Cellulosic fiber type A will not handle/absorb
water in the same way as cellulose fiber type B.
There are significant differences between
different types of cellulosic fibers.
3. Cellulosic fiber plus water gives inherent
physiological functions. It is only the
combination of cellulose with water that gives
interesting physiological properties.
4. TENCEL® plus water gives enhanced
physiological properties
5. Hydrophobic synthetic fibers do not absorb
water into the fiber structure, they can only
adsorb water onto the fiber surface.
6. Therefore the combination of synthetic fibers
with water normally will not result in added
physiological properties (or only to a very low
extent).
To demonstrate the difference between
cellulosic fibers and synthetic fibers, samples of
fiber were placed in the specimen chamber of an
environmental scanning electron microscope.
The atmosphere surrounding the fibers was
saturated with water.
Figure 1 shows the result [3]. The fiber on the
left is polyester; the fiber on the right is a
TENCEL® fiber.
Lenzinger Berichte, 85 (2006), 22-30
23
Figure 1: Polyester (left) and TENCEL® fibers (right) in
water vapor atmosphere in environmental SEM.
Water droplets have condensed on the surface of
the polyester fiber. The TENCEL® fiber does
not show any water on the surface. This is the
major difference between synthetic fibers and
cellulosic fibers. Synthetic fibers such as
polyester are non-absorbing, non-hygroscopic
and therefore not breathable. They will only
adsorb water on the fiber surface. Cellulosic
fibers like TENCEL® are hygroscopic, water
absorbing and breathable. Water is absorbed into
the fiber structure.
The ability to absorb water into the fiber
structure is a common feature of all cellulosic
fibers and is the basis of some very important
physiological properties. All cellulosic fibers
show the following eight physiological
properties to a certain extent:
- High absorbency
- Warm and dry (as an insulation layer)
- High heat capacity
- Cool and dry to the touch
- Can actively reduce temperature
- Neutral electric properties
- Strongly retards bacterial growth
- Gentle to the skin
TENCEL® has a very high absorption capability,
a unique nano-fibril structure and a very smooth
surface. As a result, all these physiological
functions are much more pronounced for
TENCEL® than for other cellulosic fibers. The
inherent physiological properties depend on the
amount of water which is absorbed and how it is
distributed within the swollen fiber structure.
Absorbency of cellulosic fibers
Transmission electron microscopy can be used
to show the location of water in a fiber. For
imaging, water-containing pores are filled and
stained with a contrasting substance. The water-
containing pores show up black, but the
cellulose without stain shows up white.
Figure 2 shows the cross-sections of four water
swollen cellulosic fibers [4]. Cotton absorbs
much less water than TENCEL®, Modal or
Viscose. The crystalline skin of Modal contains
less water than the core. The water distribution
of TENCEL® is very uniform over the whole
fiber cross section. Modal and Viscose have a
rather coarse pore system with a wide range of
pore size distribution from nanometer to
micrometer size dimensions The voids in
TENCEL® (Lyocell) are very small and quite
uniform, in the nanometer range. Latest findings
on Lyocell (TENCEL®) fiber structure are
reported in [4]-[6].
At a higher magnification using transmission
electron microscopy, it can be seen that the pore
structure of TENCEL® is a true nano-structure.
This is unique amongst the man made cellulosic
fibers. TENCEL® consists of countless, very
hydrophilic, crystalline nano-fibrils, which are
arranged in a very regular manner. The fibrils
themselves do not absorb water; water
absorption only takes place in the capillaries
between the fibrils.
A single TENCEL® fiber, therefore, will behave
like an ideally wetting bundle of nano-fibrils
with pores in nanometer range in between
[4][5][6], something which does not exist in the
synthetic fiber world. This is the reason for the
excellent water management and the very good
comfort in wear of textiles containing
TENCEL®.
Lenzinger Berichte, 85 (2006), 22-30
24
Cotton TENCEL®Modal Viscose
Cotton TENCEL®Modal Viscose
Water vap our sorption isotherms at 20 °C
0
5
10
15
20
25
0 102030405060708090100
relativ e humidity (%)
water vapour sorption (%)
PES
Cotton
Down
CLY
Wool
Water vapour sorption [%]
Water vapour sorption iso therms at 20 °C
Relative humidity [%]
Water vap our sorption isotherms at 20 °C
0
5
10
15
20
25
0 102030405060708090100
relativ e humidity (%)
water vapour sorption (%)
PES
Cotton
Down
CLY
Wool
Water vapour sorption [%]
Water vapour sorption iso therms at 20 °C
Relative humidity [%]
Figure 2: Position of absorbed water in cellulosic fibers. Transmission electron micrographs. Water appears dark (electron
dense), cellulose bright [4]
Figure 3. Water vapor absorption isotherms of various
textile fibers
Figure 3 is a graph of the “water vapor
absorption isotherms” of some fibers [7]. It
shows how much water vapor will be absorbed
into a fiber from air of a given relative humidity
at a given temperature (20°C in this case).
Polyester fiber absorbs only negligible amounts
of water; cotton absorbs much more.
TENCEL® absorbs up to 20% water at 90%
relative humidity, which is approximately the
same water vapor absorption capacity as wool
or down.
The absorption capacity and rate of liquid water
absorbency is another important feature of
textile fibers. Good water vapor absorbency
does not necessarily mean also a high rate of
liquid water absorption; the wicking properties
of a fabric greatly influence the absorption rate.
One way to measure the absorbency of a fabric
for liquid water is the “gravimetric absorbency
testing system”, the “GATS” test [12]. In this
test the sample is exposed to liquid water from
below without any hydrostatic pressure.
Therefore the sample will only take up water as
it “demands” it. The test allows measurement of
the total water absorption and the absorption
rate.
Figure 4. Schematic drawing of the GATS (gravimetric
absorbency testing) device [11]
Results with polyester and TENCEL® fabrics of
comparable weight which had been washed
once before testing have been reported
previously. The TENCEL® jersey clearly
outperformed the hydrophobic polyester fabric
in absorption rate and the amount absorbed [8].
Figure 5 is another example of a GATS test,
which was performed on commercial high
performance fabrics developed by IBQ in Spain
Lenzinger Berichte, 85 (2006), 22-30
25
Figure 5. GATS test results on fabrics for sports wear
applications
The material is used for mountaineering pants.
In two different two-layered constructions
(“ARAN” and “KHUMBA”), normally made
from 70% Polyamide/ 10% Elastane/ 20%
cotton, the cotton was replaced by TENCEL®.
Both TENCEL® containing fabrics perform very
well in terms of quantity and rate of absorption
whereas the cotton variant of “ARAN” absorbs
less water more slowly.
The cotton variant of “KHUMBA” did not
absorb any water in this test. As the samples
were not machine washed before the test, the
very bad performance of the cotton -
“KHUMBA”- could be due to hydrophobic
softeners.
Insulation Properties – Warm and Dry
TENCEL® FILL (a fiber specially designed for
use as the filling in duvets) is used to make
duvets with very good thermal insulation
combined with high water vapor transport, and
high absorption of water [7], leading to a high
overall comfort compared to polyester fillings
[7] and even compared to down fillings [8].
To confirm the laboratory tests for bedding
material, a study with test persons was also
arranged. Details are reported by Helbig, this
volume [13]. Briefly, a group of strongly
sweating persons rested in beds with differing
bedding materials. Three types of beds were
used:
1) a “standard bed” with a mattress having a
polyester fleece and a cotton cover. The bed
linen was cotton, the duvet and pillow were
polyester filled and had a cotton shell.
2) a “polyester bed” with all materials made
from polyester and
3) a “TENCEL® bed” with all materials
produced from TENCEL®.
The humidity and the temperature were
measured in the middle of the duvet filling,
under the duvet and close to the body. In Figure
6, the graph shows the humidity under the duvet
and close to the body. The TENCEL® bed gave
the lowest air humidity both under the duvet (the
upper value of the bar) and close to the body
(the lower value of the bar).
Standard PES TENCEL®
Mattress
Fabric
Filling
Cotton
PES
PES
PES
CLY blend
CLY blend
Bed linen Cotton PES µ CLY
Duvet/Pillow
FillingCover
PES
Cotton
PES
PES
CLY Fill
µ CLY
Figure 6. Humidity in bed, and composition of test beds
[13]
The insulation properties of TENCEL® fibers in
waddings of outdoor jackets were tested under
wear conditions. A volunteer cycled on an
ergometer in a cooled climate room at -20°C.
The jacket she used contained an insulation
fleece of TENCEL® / Polyester on the left side
and polyester on the right side. The outside
surface temperature on the back was measured
by an infrared camera. The sides showed a
temperature difference of around 1 degree C.
Figure 7 shows the situation after 15 minutes
cycling.
Lenzinger Berichte, 85 (2006), 22-30
26
Figure 7. Infrared image of the surface temperature of an outdoor jacket in wear trial at -
20°C ambient temperature. Left, TENCEL® /polyester wadding, 0.08 °C average in the
marked box, right, polyester wadding, 1.23 °C average in box
Table 1 shows the textile data of the wadding
fleeces and the textile physiological
measurements taken by the sweating guarded
hot plate instrument [10]. It can be seen by the
infrared image and by the Rct -value that with
basically the same textile properties, the fleece
containing TENCEL® fibers shows better
insulation. A temperature difference of more
than 1 degree on the outside of the jacket will
lead to a marked difference in heat loss.
Table 1. Textile physical and physiological data of the waddings used. Rct, , thermal resistance; imt , water vapor
permeability index
Fiber data
Wadding [dtex] [mm]
Area weight
[g/m2]
Fleece thickness
[cm] Rct i
mt
100 % PES 3.3 55 120 1.5 0.287 0.73
70% Tencel®
30% PES
1.7
3.3
51
55 120 1.7 0.430 0.68
Heat Capacity and Thermoregulation
Water has a high heat capacity. Therefore,
fibers which contain water will also have a high
heat capacity. This can be used to help the
human body’s temperature regulation. On the
water vapor absorption isotherm we have seen
that TENCEL® FILL always contains water [7].
Figure 8 shows small samples of fiber fill with a
defined water content sealed into plastic bags.
The samples were placed in an oven at 50°C
until they had equilibrated. They were then
taken out of the oven at the same time and the
cooling rate was monitored with an infrared
camera.
Lenzinger Berichte, 85 (2006), 22-30
27
Figure 8: Cooling of duvets. Duvets were heated
to 50°C, then left at ambient to cool. The difference
is shown by an infrared camera.
The first trial (top) used very realistic conditions
with TENCEL® having a moisture content of
11% and polyester 2%. The brighter colors of
the TENCEL® sample show that it is retaining
heat much more effectively than the polyester
sample.
In the second trial both fiber fills had a water
content of 11%, but still TENCEL® shows a
higher heat capacity and slower cooling rate.
The water absorbed within the fiber structure of
TENCEL® has a higher heat capacity than the
liquid water which is only adsorbed on the
surface of the polyester fibers.
TENCEL® FILL in duvets, therefore, acts like a
hot water bottle and has a high heat capacity. It
can help to smooth out the temperature
fluctuations in bed and supports more restful
sleep.
Cool and Dry to the Touch
The “Thermal Absorptivity” of a fabric is a
measure of the amount of heat conducted away
from the surface of the fabric per unit time. A
fabric which does not conduct heat away from
its surface will feel warm; one that does conduct
heat away will feel cold.
Figure 9: Thermal absorptivity of bed linen
The “Thermal Absorptivity” can be measured
using the “Alambeta Test” (Prof. Lubos Hes in
Liberec, CZ; [14]).
Figure 9 shows test results on bed linen made
from 100% TENCEL® and from 100% cotton.
It shows that TENCEL® feels cooler to the touch
and that the “cool feeling” increases with
increasing air humidity because the moisture
content of the fibers increases. With TENCEL®
this behavior is much more pronounced than
with cotton as the increase in water content with
increasing air humidity is much steeper for
TENCEL® than for cotton.
Figure. 10: Thermal absorptivity of shirt fabrics ,
TENCEL® / cotton blends
Even in minority blends TENCEL® will enhance
the “cool feeling” of textiles. Blends of 25% to
40% TENCEL® with cotton in a shirting fabric
will give a cooler feeling compared to 100%
cotton - especially at higher air humidity (Figure
10). This represents a self-regulating system: In
warm and humid ambient conditions, the cool
feeling is increased.
Lenzinger Berichte, 85 (2006), 22-30
28
Active Cooling
At very high physical activity levels or in very
hot and humid climates the temperature control
of the human body mainly relies on the
production and evaporation of sweat. As the
sweat evaporates it carries energy away from the
body in the form of the latent heat of
vaporization. To do this the sweat must either
evaporate from the skin and pass through the
covering fabric as vapor or it must be transferred
from the skin to the fabric and subsequently
evaporate. If the sweat cannot be transported
through the fabric, the cooling effect will be too
low and the physical performance will drop
accordingly.
The ideal “active cooling” textile, therefore, has
to have good water transport properties,
however it should allow water evaporation next
to the skin in order to achieve maximum cooling
of the human body. (Many of today’s high
performance 2 layer sports shirts evaporate the
moisture from the surface of the fabric, instead
of from next to the skin!)
To investigate the differences of the active
cooling properties of TENCEL® and polyester
fibers, ergometer tests were performed on
subjects wearing T-shirts consisting of 2 halves.
The left half was polyester, the right half
TENCEL® - both single jersey with the same
construction. The test subjects performed a
strenuous exercise with the power output
increasing in stages to 250 Watts, which
guaranteed full sweat production. There were
two relaxation stages in between.
The surface temperature of the two halves of the
T-shirts was monitored with an infrared camera.
In Figure 11, the surface temperature on the
right side of the T-shirt – the TENCEL® fabric –
is higher.
This demonstrates the better heat dissipation
through the TENCEL® fabric during high sweat
production. The temperature difference of 0.5 to
1°C seems to be small, however in physiological
terms it is significant.
Figure 11: T-shirt in two halves after exercise. Left,
polyester. Right, TENCEL® The temperature measured
on average over the boxes are 31.5°C (left) and 32.3 °C
(right)
Neutral Electrical Properties
Friction induces electrostatic charging of
textiles. The extent of electrostatic charging
depends on the electrical resistance of the textile
surface. A physical measure for the tendency to
build up electric charge is the surface resistance
of textiles. A surface resistance of higher than
1010 Ohm will cause electrostatic charging when
friction is applied to a fabric. A high level of
electric charge on textiles can cause a very
unpleasant experience when the static charge is
suddenly discharged and can even cause sparks.
Measurements have been made of the electrical
surface resistance of TENCEL® and Polyester
fabric. Even at a very low air humidity of 25%,
the TENCEL® fabric has a surface resistance
which is 3 orders of magnitude lower than for
the polyester fabric. At higher air humidity
(65% RH), the surface resistance of the
TENCEL® fibers is 6 orders of magnitude lower
[8].
As direct measure for the charge build-up in
textiles in contact with the human body, a
volunteer stood on an isolated rubber matt and
pulled various textiles from his naked shoulders.
The electrostatic charging of the body was
measured. Polyester and polypropylene cause
very high charging in this test (>2500 V);
TENCEL® and cotton gave a neutral result;
polyamide was much better than the other
synthetic fibers but still worse than the cellulosic
fibers. An electrostatic charge of more than
1800 Volts can be felt [8].
Lenzinger Berichte, 85 (2006), 22-30
29
Not much is known about the impact of this
electrostatic charging on the well being of
human individuals, but there are hints of
negative effects on muscle coordination
[15][16].
Strongly Retards Bacterial Growth
If a dry TENCEL® fabric absorbs 60% water, all
the water will be absorbed into the fiber, which
will cause the fiber to swell. No film of liquid
water will cover the surface of the fibers.
However if a polyester fabric absorbs 60%
water, none of the water will be absorbed by the
fibers; all of the water will sit on the surface of
the fibers as a water film and/or droplets on and
between the fibers of the fabric.
Bacteria and fungi require liquid water for
optimum growth. Thus it would be expected
that micro-organisms would be more likely to
grow rapidly on moist polyester than on moist
TENCEL®.
This is the most probable reason for a lower
bacterial growth on textiles made from cellulosic
fibers as compared to textiles made from
synthetic fibers, as was shown by in vitro
(laboratory) tests [8] under conditions of a
challenge test with growth medium (Figure 12).
Figure 12: Bacterial growth as multiplication factor in the
Challenge Test. Circle areas are proportional to the
multiplication factors.
All cellulosic fibers perform well in this test.
The bacterial growth on synthetic fibers can be
higher by some orders of magnitude. However,
within the family of cellulosic fibers TENCEL®
shows 10 times lower bacterial growth than
cotton. This is probably due to the very good
water absorption of TENCEL® in combination
with its smooth surface.
In vivo trials (wear trials) with divided T-Shirts
confirmed the trend: Under an identical wear
situation, on one side of the divided T-Shirt of
sports wear fabrics made from synthetic fibers,
more bacteria could grow than on the other side
made of TENCEL® fabric [6].
For the methods applied to assess interactions of
microorganisms and textiles see [17].
Gentle to the Skin
Fibers with poor water absorption capacity result
in textiles which cling to the skin when they are
wet. Wet skin is much more sensible to irritation
than dry skin. The coarseness, the stiffness and
the surface character of the fibers will also have
an impact on the skin’s sensory perception.
Both cotton and wool have rather good water
absorbency, however they have a rather rough
fiber surface.
TENCEL® combines good water absorbency
with a smooth fiber surface which makes it a
fiber which is very gentle to the skin.
All these positive inherent properties of
TENCEL® - good breathability and moisture
absorption, dry and cool micro-climate on the
skin, smooth fiber surface, low wet cling effect
and no electrostatic charging – mean that textiles
made from TENCEL® might offer relief to
people who suffer from skin diseases.
A clinical test was organized at the University
Hospital in Heidelberg (Germany) which was
led by the dermatologist Prof. Diepgen [18]. 60
patients suffering from atopic dermatitis or
psoriasis tested commercially available
TENCEL® products including bedding, T-shirts,
polo-shirts and nightwear. People suffering
from these conditions have had to optimize their
clothing to identify materials that will cause
them the least discomfort.
In summary, approximately 80% of the patients
suffering from atopic dermatitis or psoriasis
preferred TENCEL® products over their
normally used textiles.
A second study was performed by Dr. I. König
using a specially designed sleeping overall with
scratch protection, tested by children aged 2 to
Lenzinger Berichte, 85 (2006), 22-30
30
13. Children and parents were very positive
about the properties, reported less itching and
scratching, leading to a better night’s sleep and a
more relaxed overall situation [19].
The outcome of these studies is a very
convincing argument for the sensorial properties
of TENCEL® textiles [20].The main comfort
properties noted by the patients were:
thermoregulatory properties, cool, smooth and
dry feeling, and the overall excellent skin
compatibility.
Conclusion
The combination of absorbent fibers and the
water that they absorb is the basis of the positive
physiological functions of cellulosic fibers.
High absorbency, the unique nano-structure and
the smooth surface of TENCEL® result in
enhanced physiological functions that make it
stand out amongst the family of cellulosic fibers.
Acknowledgement
This work was in part supported by the Christian
Doppler Research Society, Vienna, Austria.
References
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comfort properties of textile fabrics and
garments. Proceedings of the World Congress
of the Textile Institute, Cairo, 2002
[15] Zimniewska M., Huber J., Krucińska I.,
Torlińska T., Kozłowski R., The Influence Of
Natural And Synthetic Fibers On Activity Of
The Motor Units In Chosen Muscles Of
Forearm; Fibers and Textiles in Eastern
Europe No. 4/ 2002
[16] Zimniewska M., Krucińska I., Kozłowski R.,
Muscle activity as one of the well-being
factors. Lenzinger Berichte 85 (2006), in press
[17] Teufel L., Redl B., Improved methods for the
investigation of the interaction between text-
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85 (2006), in press
[18] Diepgen T.L., Schuster K.C., Dermatological
Examination on the Skin Compatibility of
Textiles Made from TENCEL®, Lenzinger
Berichte 85 (2006), in press
[19] König I, Project “Polar Bear”, a wear study.
Available on request from Lenzing AG
[20] Diepgen T.L., Schuster K.C., König I.,
Emlinger G., Textilien aus TENCEL® und
Hautverträglichkeit. Dermatologisches
Alpenseminar, Grainau / DE, 25.-27.May 2006
... In addition to that, the obtained TENCEL ® fibers in this process offer various advantages compared to cotton and viscose fibers, among others a higher tensile strength and water sorption capability (Chavan 2004). The good water transport properties and the high and uniform water absorption in the fabric are a result of very regular arrangement of hydrophilic nanofibrils inside the fiber (Firgo et al. 2006). Furthermore, the lyocell process has the lowest environmental impact in comparison to other cellulosic fibers and cotton (Shen et al. 2010). ...
Thesis
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One of the most pressing issues of today is the global waste challenge. Due to their longevity, plastics contribute to global pollution and accumulate not only in the oceans and onshore, but enter as well the food chains in form of micro- and nanosized particles. In this respect not only better recycling and waste disposal strategies have to be developed, but also a fundamental rethinking is required aiming at the reduction of oil-derived and non-degradable plastics in everyday products. Cellulose as the most abundant polymer source shows great promise as an alternative to plastics. Nanocelluloses obtained from native cellulose fibers (cellulose I) have extensively been explored due to their sustainability, biodegradability, biocompatibility, high specific surface area, excellent mechanical and heat-insulating properties. Still, certain obstacles remain to be overcome by researchers and industry: the high production and energy costs of native fibrillated cellulose and the difficulties in drying due to its tendency to agglomerate irreversibly in this procedure and to lose many of their beneficial properties. Keeping these issues in mind, this thesis focuses on a novel nanomaterial from the cellulose II allomorph, namely TENCEL® gel, its first-time in-depth physicochemical characterization and novel ways for chemical modification. In comparison to native cellulose nanofibrils, this gel is produced with much higher energy-efficiency from a precursor obtained directly out of the lyocell process, which manufactures cellulosic textiles and non-wovens by a direct dissolution approach. The gel is composed of individual microparticles forming particle-like aggregates with a uniform nanostructure consisting of nanofibrils of 40-60 nm diameter. In this thesis, water-redispersible TENCEL® gel was obtained according to a new drying protocol, based on simple oven drying in the presence of negatively charged polysaccharides. Furthermore, the gel was used as precursor to produce highly porous aerogels with specific surface areas of up to 423 m2/g. The powders featured low thermal conductivity, low bulk density and high acoustic absorption at low frequencies and these properties render them promising as insulating material. The introduction of negative charges onto the amorphous regions of the cellulose II gel via carboxymethylation caused a reorganization into spherical nanoparticles. Dependent on the amount of introduced charges, the particle size was tuned from a mean diameter of 73nm to 129 nm. The small nanoparticle (73 nm) fraction was found to be easily redispersible after drying and forms densely aggregated and transparent films with possible application as oxygen barriers in packaging. A novel, straightforward and generally applicable functionalization strategy was established to introduce chemical anchor groups onto never-dried cellulosic surfaces. Based on an aqueous silanization protocol, never-dried nanocelluloses were decorated with azido groups and the resulting functional materials were successfully post-modified by a click chemistry approach. In summary, the economic and straightforward production of this gel, its high surface area and porosity, the possibility to influence its particle size and to derivatize it in non-dried form; make it a promising contribution to the family of nanocelluloses with lots of scientifically interesting and economically feasible future applications.
... The potential factors explaining why the composites containing HT TMP fibres had a higher β-crystals content compared to one with Tencel™ fibres are probably related to the fibre surface. Tencel™ fibres have a smooth surface [59] and HT TMP fibres are rough with a coating of lignin. A rough surface increases the interfacial shear strength [60] which is a factor favouring β-interfacial structures [61]. ...
Article
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The mechanical performance of composites made from isotactic polypropylene reinforced with natural fibres depends on the interface between fibre and matrix, as well as matrix crystallinity. Sizing the fibre surface with nucleating agents to promote transcrystallinity is a potential route to improve the mechanical properties. The sizing of thermo-mechanical pulp and regenerated cellulose (Tencel™) fibres with α- and β-nucleating agents, to improve tensile strength and impact strength respectively, was assessed in this study. Polarised microscopy, electron microscopy and differential scanning calorimetry (DSC) showed that transcrystallinity was achieved and that the bulk crystallinity of the matrix was affected during processing (compounding and injection moulding). However, despite substantial changes in crystal structure in the final composite, the sizing method used did not lead to significant changes regarding the overall composite mechanical performance.
... До перспективних інноваційних матеріалів, які можуть використовуватися для білизняних виробів, можна також віднести тканини з волокна Тенсел (Tencel®), яке виготовляють з деревини евкаліпта. Ці матеріали характеризуються високою гігроскопічністю, міцністю, м'якістю, приємністю на дотик, бактеріостатичністю [18]. Метою дослідження є вивчення впливу особливостей сировинного складу і структури традиційних та інноваційних тканин білизняного призначення на їх гігієнічні властивості. ...
Article
Investigation of the influence of the peculiarities of raw material composition and structure of traditional and innovative linen textile materials on their hygienic properties. Theoretical and experimental investigations are based on the main positions of textile materials science. In experimental studies, modern standardized methods for determining the hygienic properties of textile materials were used, as well as techniques specially developed taking into account the peculiarities of the operating conditions of underwear. The peculiarities of the operating conditions and the basic functions of hospital underwear were determined. The comparative analysis of hygienic properties of traditional and modern fabrics for underwear was carried out. Using the standardized and the developed methods, adapted to the peculiarities of the conditions of use of the products, the indicators characterizing the processes of water absorption of the materials were experimentally determined. On the basis of the obtained values of quality indicators, a comprehensive assessment of the ability of materials to transfer moisture and air, with the calculation of the arithmetic complex quality index was done. This allowed to determine the material that is optimal in properties, which provides thermophysiological comfort when operating hospital underwear. Using the developed methods, which take into account the specifics of the operating conditions, a comparative analysis of the hygienic properties of traditional and innovative materials for underwear was carried out. A new range of textile materials for underwear has been proposed, taking into account the peculiarities of the operational situation of consumption.
... Firgo et al., found that the thermal absorptivity of 100% Tencel fibre was higher than that of 100% cotton fibre and an increase in the thermal absorptivity of Tencel fibre was observed as the air humidity was increased [13]. The hydroentangled fabric developed in this study is composed of 70% Tencel and 30% bicomponent sheath/core PE/PET fibre and it is the addition of the bicomponent fibre in the developed hydroentangled fabric that lowered the thermal absorptivity of the fabric, as shown in Figure 6. ...
... Therefore moisture management by the fabric is very important in order to optimise the wearer's comfort. The fibre types (natural or synthetic), blending ratio of fibres, the fabric structure and fabric characteristics (densities of yarns, thickness) etc. are the parameters that affect the moisture management and the thermal properties of the fabrics [14]. ...
Article
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The cost of making apparel fabrics for garment manufacturing is very high because of their conventional manufacturing processes and new methods/processes are being constantly developed for making fabrics by unconventional methods. With the advancements in technology and the availability of the innovative fibre, durable nonwoven fabrics by using the hydroentanglement process that can compete with the woven fabrics in terms of their aesthetic and tensile properties are being developed. In the work reported here, the hydroentangled nonwoven fabrics were developed through a hybrid nonwoven manufacturing processes by using fibrillated Tencel® and bi-component (sheath/core) polyethylene/polyester (PE/PET) fibres, in which the initial nonwoven fabrics were prepared by the needle-punching method followed by hydroentanglement process carried out at optimal pressures of 50 to 250 bars. The prepared fabrics were characterised according to the British Standards (BS 3356:1990, BS 9237:1995, BS 13934-1:1999) and the attained results were compared with those for a standard plain-weave cotton, polyester woven fabric and commercially available nonwoven fabric (Evolon®). The developed hydroentangled fabrics showed better drape properties owing to their flexural rigidity of 252 mg.cm in the MD, while the corresponding commercial hydroentangled fabric displayed a value of 1340 mg.cm in the MD. Tensile strength of the developed hydroentangled fabrics showed an approximately 200% increase than the commercial hydroentangled fabrics. Similarly, the developed hydroentangled fabrics showed higher properties in term of air permeability, such as the developed hydroentangled fabric exhibited 448 mm/sec and Evolon fabric exhibited 69 mm/sec at 100 Pa pressure. Thus for apparel fabrics, the work combining the existing methods of nonwoven production, provides additional benefits in terms of cost, time and also helps in reducing the carbon footprint for the apparel fabric manufacture.
... Earlier in the literature, it was noted that the fibers obtained by the NMMO process are characterized by a lower speed distribution of bacteria in comparison with synthetic and cotton fibers [27]. The antimicrobial properties of composite films based on cellulose and betulin were evaluated using E. coli as an example (Figure 8). ...
Article
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Composite fibers and films based on cellulose and betulin were spun for the first time from solutions in N-methylmorpholine-N-oxide using the dry–wet jet method. The rheological properties of the composite solutions did not reveal any fundamental difference from those of the cellulose solutions. Introduction of betulin into the cellulose matrix (up to 10%) led to a decrease in the mechanical properties of the obtained fibers. The structure of the composite fibers was analyzed using SEM and X-ray diffraction methods. It was shown that the introduction of an additive into the cellulose matrix led to a decrease in the structural ordering of the cellulose. Comparative studies of the antibacterial activity of the composite films on Escherichia coli (E. coli) were carried out. The antifungal activity of the composite films was estimated using the strain of the O-97 Trichoderma viride Pers ex Fr (Gause Institute of New Antibiotics, Moscow, Russia).
... The convolutions of the cotton fiber block the pores and decrease the air flow through the fabric [29]. Also, the spaces between the fibrils in the Tencel STD result in improved moisture absorption and smoothness, allowing air to pass easily through the fabric [30]. ...
Article
Silicone softeners make fabric soft, brilliant, greasy and more elastic, resulting is acceptable handle. In this research work, the effect of using different silicone softeners on pilling resistance and on some physical and mechanical properties of knitted fabrics was evaluated. Industrially applied silicone softeners of three different types (macro, semi-micro, micro) were used on fabrics knitted from different fiber materials (Egyptian cotton, Tencel LF, Tencel STD, bamboo, Modal and Micro-modal). The influence of using different silicone softeners on fabric pilling resistance, seam hole, air permeability, color strength, fastness to rubbing in wet and dry states and fastness to washing was investigated. Results have shown that the pilling performance of micro-modal fabrics finished with micro silicone is better than those finished with macro silicone. The higher number of fibers per cross-section for the micro modal yarns creates weak bonds between micro-modal fibers and macro silicone particles. The macro silicone fabric has the greatest air permeability, while the micro silicone reduces the porosity of the yarn and increases air resistance. The macro silicone softener method has more fastness to color than the other finishing methods investigated. © 2018, Association Nonwoven Fabrics Industry. All rights reserved.
... In the present investigation, the functional finishes imparted show antimicrobial activity. Wide range of natural and synthetic manmade fibres with better comfort properties and anti-microbial properties have been introduced commercially [17]. Wound healing is the general repair response of the body directly after the disruption of skin integrity. ...
Article
The world textile market is growing year by year at a tremendous rate, but the cotton supply has not increased at a similar rate. This creates a gap between demand and supply in the supply chain. The gap can only be filled by regenerated cellulosic fibres due to their natural origin and similar properties. This fact is being reflected in recent market trends of consumption of Regenerated Cellulosic Fibre i.e. Viscose. The continued success of regenerated viscose fibres over more than 100 years has been based on a broad spectrum of fibre properties. Viscose fibre is 100% biodegradable and produced from natural renewable pulp. The need for better quality goods have led to the modification of such regenerated viscose fibers. This article focuses on the development of cellulosic based viscose fibers to a new era of modified viscose yarns such as Tencel, Excel, Modal and their unique investigated physical and mechanical properties as compared to their precursor.
Article
Knitted fabrics made of natural, synthetic and regenerated fibres are presented to the final consumers at different fabric constructions. Reason to select different fibre types, fibre blends, and knitting constructions utilisation is to optimize consumer demands of comfort, functionality, fashion and price. Continuous fibre improving studies are one driving factor behind the fabric and clothing design possibilities. Collagen peptide added fibres are one recent fibre type in the regenerated cellulosic fibre family. Collagen peptide addition to the regenerated cellulosic fibre has been reported to improve fibre properties of moisture management, thermoregulation, anti-static, ultraviolet protection, biodegradable properties which make the fibre preferable material for active wear clothes. This study involves with the influence of new fibre type addition on moisture management, antimicrobial, and air permeability properties of the plated knitted fabric structures. Within this work; one plain knitted fabric is knitted using 100% collagen peptide added regenerated cellulosic yarn and polyamide yarn grounded six different plated knitted fabrics were studied. Moisture management transport (MMT) properties, antimicrobial properties (against Escherichia coli, Staphylococcus aureus and Candida albicans) and air permeability properties of those knitted samples were evaluated comparatively. Gathered results are statistically evaluated using one-way Anova test; it was determined that there was a significant difference on MMT and air permeability properties of knitted samples at significance level of 0.05. Additionally, presence of collagen peptide added fibre exhibits considerable level of antimicrobial effect against included microorganisms. The results of the experimental work represent an initial phase towards a better understanding of the influence of different fibre blended yarn utilization on plated knitted fabrics which would be appropriate for active wear cloth manufacturing.
Visualisation of the Nano-Structure of Tencel ® (Lyocell) and Other Cellulosics as an Approach to Explaining Functional and Wellness Properties in Textiles
  • M Abu-Rous
  • E Ingolic
  • K C Schuster
Abu-Rous M., Ingolic E., K.C. Schuster, Visualisation of the Nano-Structure of Tencel ® (Lyocell) and Other Cellulosics as an Approach to Explaining Functional and Wellness Properties in Textiles. Lenzinger Berichte 85 (2006), in press
Characterization of Fibrillar and Pore Structure in Natural and Man-Made Cellulosic Fibers by Modern Imaging Techniques, Proceeding of Polymer Fibers
  • K C Schuster
Schuster, K.C. et al.: Characterization of Fibrillar and Pore Structure in Natural and Man-Made Cellulosic Fibers by Modern Imaging Techniques, Proceeding of Polymer Fibers 2006, Manchester UK, 2006
Article
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The objective of this project was to produce moisture management performance fabrics in 100% cotton. Moisture management performance, as defined under the project, is rapid wicking (fast rate of absorbency) with a reduced absorbent capacity and rapid drying for end uses where moderate-to-heavy perspiration is likely. The goal was to show that 100% cotton performance fabrics could be developed using thin fabrics and various chemical treatments. The fabric structures and treatments were selected with commercial feasibility in mind. The knowledge generated can be used to expand the use of cotton or cotton blends in athletic apparel and related applications: Thorough scouring and bleaching of cotton to remove residual waxes and oils proved to be an effective means of increasing the wicking rate of cotton fabrics. The influence of construction variables such as yarn size and twist on wicking rates appeared to be small. A key step to making faster drying cotton materials would be to make thinner structures.
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Clothing textiles are in permanent contact with microorganisms, which can cause serious problems, including fabric rotting, staining, unpleasant odours and health concerns ranging from simple discomfort to physical irritation, allergic sensitization, toxic responses, infection and disease. Therefore, the control of undesirable effects of microbes on textiles is becoming an important issue in textile industry. One possible approach to limit growth of microorganisms is the use of biocides in textile finishing. However, this may lead to health and environmental concerns in everyday use of textiles. Another approach might be the use of materials with inherent activity to reduce microbial growth. In this context the evaluation of biofilm development on the various materials and the interaction between microorganisms and textiles will be an essential part in textile research. In moderate climate most problems arise from bacteria transferred from human skin. The bacterial skin flora is highly complex with a large number of microorganisms, some of which can hardly be cultivated. Therefore, similar to other complex microbial communities there are serious difficulties to analyze these systems. This article summarizes the current microbiological methods used in textile research and gives some outlook for future developments in this field of research.
Chapter
Regenerated cellulosic fibers, such as viscose, modal and lyocell, combine the advantages of natural and synthetic fibers and offer unique properties in textile and nonwoven applications. Their production is feasible under environmentally friendly and essentially pollution-free manufacturing conditions. The viscose production line at Lenzing AG, Austria, which is based on dissolution of cellulose, is a simple and intrinsically clean route to regenerated fibers. The fiber products are presented, including recent developments of specialty fibers.
Article
Clothing is an inseparable attribute of whole human life. Human skin is in direct touch with textiles both during the day and during the night. The interaction of skin and apparels depends on many factors. As well raw materials, fabric structure and temperature, humidity, air movement and physical activity and individual characteristic of wearer are responsible for all the features of skin - clothing microcli- mate. Sensory receptors, the nerve endings in the skin collect signals from the skin surface, regulate the physiological processes in the human body. This paper will present the analysis of dependence of textile wearer muscle tension on polyester fibers content in blends with flax, which was the basic raw material in clothes, as well as changes of thermal conductivity of the textiles. We have examined the clothes made out of 100% linen, 100% PES and their blends with different percentage of both kinds of raw material. Every sort of raw material has been examined and the parameter of EMG of forearm muscle tension was registered each time with the volunteers wearing the clothes being examined. The special attention has been put during examination on monitoring of parameters of skin -clothing microclimate, during 5 hours of wearing the clothes by volunteers. The parameters being registered were: temperature of skin of the back and shoulder, and humidity of skin covered by the examined clothes, and also the potential difference of an electrostatic field of electrostatics charges collected on the surface of the clothes. The experiments were performed during the state of rest. The results of tests showed that the increase of the skin temperature covered by clothes is created by other changes of reg- istered EMG than increase of the potential difference of an electrostatic field of charges collected on the clothing surface. We have proved that there are serious changes in the parameters of skin-clothes microclimate which depends on the share of PES fibres in the blends with linen, even if the volunteers taking part in this experiment, has not been doing any physical exercises.
Article
Summary Background: Textiles play an important role in well-being, as the human body is in close contact with textiles most of the time. Especially, subjects with diseased or sensitive skin are able to feel small dif- ferences in well-being by using different textiles. It is well known that their skin is easily aggravated by contact with clothes of synthetic or woollen fibres. Objectives: To evaluate the skin compatibility of commercially available TENCEL® (generic fibre name: Lyocell) textiles in patients suffering from atopic dermatitis or psoriasis in an everyday situation. Methods: 30 patients with atopic dermatitis and 30 patients with psoriasis should wear and use TENCEL® textiles over the testing period of one week, during day and night. All textiles were com- mercially available products made from TENCEL®, produced through standard textile process routes, with no special additional treatment or finishing: 100% TENCEL® bedding (duvets, covers, bed linen, sheets), clothing from 70% TENCEL® / 30% Cotton (t-shirts, polo-shirts, pyjamas). As a control, pa- tients used their own clothing and their own bedding textiles. All patients were evaluated by a derma- tologist at baseline and 7 days after the initial examination. The overall severity of atopic eczema was evaluated using the SCORAD index, and the severity of psoriasis the PASI score, respectively. Results: During the test period the severity of atopic dermatitis and psoriasis improved significantly (p
Article
Applying transmission electron microscopy (TEM) on ultra-thin cross-sections of fibres, the main characteristics of the internal morphology of cotton and the main man-made cellulosic fibres (modal, viscose and lyocell) could be visualised. To obtain an appropriate contrast for TEM, isoprene was polymerised into the swollen fibres after a stepwise solvent exchange from water to acetone. The included polymer is stainable with osmium tetraoxide. Significant differences in distribution of pore sizes and pore arrangements in the cellulosic fibres were seen. Cotton showed very small pores in the bulk of the fibre, but drying cracks and flat pores between the sheets of the secondary wall appear as larger pores. Lyocell contains only nanopores in the bulk of the fibre with a slight gradient in pore density, and a very porous skin layer. In viscose and modal, a very wide pore size distribution from nanometer to micrometer size can be seen.