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Natural fibres used .pdf



Nom original: Natural fibres used.pdf
Titre: Microsoft PowerPoint - 02_NATURAL_FIBRES_FOR_BIOCOMPOSITES-Ekotex [Compatibility Mode]
Auteur: TBurman

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Natural fibres used
for bio-composites.

EKOTEX
KOWALOWICE, ul. Parkowa 4,
46-100 Namysłów, POLAND
e-mail: biuro@ekotex.com.pl
http://www.ekotex.com.pl

Types of natural fibres

1

Comparison between natural and
glass fibers

Properties of natural fibers in relation
to those of E-glass

2

Flax cultivation





Tillage of soil
Fertilization
Sowing – end of march / aprill
Chemical protection against
weeds, diseases and insects

Pulling / deseeding
• Pulling - 92 – 100 days after sowing
• Deseeding – during pulling process or
about 7-10 days after pulling

3

Flax retting
• The most important and most difficult stage production
of flax fibre.
• This process has the greatest influence on the quality of
the fibre
Methods o retting
• 1. Dew retting ( field retting ) – the main
• 2. Water retting – old method – used only in Egypt
• 3. Osmotic degumming (osmotic retting). Method of
fiber extraction by osmotic degumming was
investigated at the Institute of Natural Fibres in
Poznań - Poland.

Dew retting
Dew retting of flax straw is a process in which
microorganisms mainly fungi grow through the stem
tissues and exert enzymes degrading pectin
substances. When pectinolytic enzymes decompose
the plant glue – pectin the bond between technical
fiber and surrounding tissues are loosened which
allows for relatively easy extraction of fiber by
mechanical processes (breaking, scutching).
a)

Undisturbed bast

b)

Cracked epidermis

c)

Ungluing of bast

d)

Underretted

e)

Well retted

f)

Over-retted, ungluing into
elementary fibres

4

• Optimum action of pectynolytic microorganisms is
possible only in suitable conditions. Among most
important ones are suitable air humidity and ambient
temperature. During dew retting, the stems on the top of
the swath take more moisture from rain or dew than those
located on the bottom. They also dry faster between rains.
This causes notable difference in retting between stems in
top and bottom part of the swath. To improve the quality
of obtained raw material the swath of straw is turned over
– 2 or 3 times.

• The process of dew retting must be controlled. When
the straw is not sufficiently retted ( underretted ), the
fiber resulting from mechanical processing will be
coarse, with high content of shives and with residues of
surrounding tissues still adhering to the fiber. Fiber
ribbons will be characterized by a low divisibility.
• Over-retting leads to reduction of fiber strength and
reduction of long fiber efficiency. In case of strong overretting also substances building fiber can be
decomposed.
• In Polish weather conditions time of dew retting varies
from 21 to 40 days. The shortest retting occurs when the
average air temperature is about 15 0 C and average
rainfalls sum is about 60 mm.

5

Flax harvesting

Scutching

6

Linen products

• It’s real flax



7

Some words about hemp
-

less soil requirements beside flax,
the greater resistance on the drought,
the crop of the fibre about 2 t per hectare,
use : paper, ropes, technical nowoven,
thermoplastic biocomposites

8

Hemp processing

Another aplications of natural fibres

9

Biocomposites

10

Processing of flax fibre for
biocomposites

Fibres for injection moulding:
- Cleaning of flax tow
- Carding – produce flax slivers – 18 -30 ktex
- Cutting of slivers – 1mm; 2mm; 4mm …etc

11

12

Chopped Natural Fibers
FLAX

SISAL

BLEACHED FLAX

KENAF

HEMP

Flax fibres for thermosetting and
thermoplastic composites






Process
Primary cleanning of flax tow ( shaking )
Tearing ( card opening )
Cutting – rotary cutter
Cottonising – 2 or 3 times – obtaining
cottnised flax fibre called KOTONINA

13

Another processses for improovment
of flax fibres

• Boiling
• Bleaching
• Plasma treatment

14

Conclusions


Natural fibres have many advantages to use them for reinforcing of
composites.
• Flax and hemp can be planted and processed in Europe.
• All additional improvements of natural fibres improve properties
biocomposites in which were used.
• The best and the cheapest method to obtain very good parameters
of flax- fibre is correct agricultural science ( fertilization, chemical
protection of plants, agricultural time-limits ), professional
supervising of dew retting of flax straw and its harvesting.
However at last, the quality of fibre is relative to weather, on
which people not yet have the influence. Therefore, scientists and
flax producers must work on new methods of extraction of flaxfibre from the straw.
• New methods of extraction must realize following conditions:
- parameters of obtained fibres must be satisfactory both for textile as
technical uses.
- the operating cost of the fibres with new methods must be
comparable with present methods
- new methods must be environmentally friendly and not increase
energy consumption

Thanks for cooperation

15

THANK YOU FOR YOUR
ATTENTION!!!

16


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