Application

SETRALIT® - natural fibres can be used in nearly all areas which were dominated by asbestos and later on by synthetic or glass fibres. They can be treated additionally or they can be applied without further treatment dependent on application.

The length of the technical SETRALIT® fibre and trends of application are shown:


long fibre     > 100 mm      
textile application

yarn, texture, fleece
short fibre  0,5 - 10 mm
reinforcement fibre

material fortification  < 1    
process fibre

improvement of processing
The selection of the appropriate type of fibre depends on its final application. The following attributes of natural fibres in general as well as of ultrasonically treated natural fibres can therefore be decision-making:

  • Purity
  • Consistency
  • Stiffness
  • Low concentration of impurities
  • High brightness,
  • High specific surface
  • Good processing attributes
  • Matting effect
  • Stable to corrosion  
  • Insensible against alkaline
  • Wettability  
  • High water absorption  
  • No electrostatic charge  
  • Thermoshock resistance
  • Non-poisonous (especially in case of fire)
  • Easy to reuse  
  • Handy disposal
  • Low price

Typical areas of use for SETRALIT® - fibres are:

Sector of construction:

  • Plaster, dry mortar
  • Fibre-cement  
  • Various sorts of concrete
  • Sand-lime brick
  • Gypsum, floor pavement  
  • Insulation
  • Emulsion paint

Plastics:

  • Injection moulding
  • Moulds
  • Other composites (fibre-reinforced plastics)

Textiles:

  • Garments and household textiles
  • Industrial textiles  
  • Filter
  • Medical and hygienic items  
  • Geo-textiles

Chemical Industry:

  • Friction lining  
  • Sealing
  • Filter media
  • Fillers  
  • Thixotropic agents  
  • Bitumen
  • Rubber  
  • Polishing agent  
  • Mastic, spackle, glue

Paper:

  • Technical papers
  • Paper board container  
  • Special papers

Other applications (particularly for shives and other by-products):

  • Bedding for animals
  • Bulk solids  
  • Animal feed (pectin and others)  
  • Biogas
  • Energy generation

Temperature stability of Setralit® natural fibers

their use in friction linings and gaskets

1) Temperature stability: Setralit® natural fibers are cellulosic and - if not embedded in a matrix – exhibit a stability range of up to 270 °C (but not with an unshielded flame, this would burn the fibers). At higher temperature values the fiber decomposes gradually, depending on intensity and duration of heat. Aramid is stable up to approx. 500 °C.

2) Unlike aramid, however – and this is the very advantage – the Setralit® fiber does not melt beyond 500 °C but can bear short-time temperature peaks of up to 800 °C (i.e. high thermo-shock stability), whereas the aramid fiber will definitely be ruined at those temperatures and moreover releases toxic degradation products. Temperature values like that may well occur on hard braking. The natural Setralit® fiber, however, does not degrade; at most it may carbonize at the proximate brake surface without loosing its structure.

3) If bonded within a matrix as realized in brake linings or gaskets, the stability behaviour of natural fibres may be completely different compared to that of a free fibre. It then depends on the chemistry of the matrix and maybe high-temperature reactions between cellulose (or its decomposition products) and the surroundings. This has to be tested for each single formulation, especially concerning highly sophisticated matrices, as in the case of friction linings.

4) It may be possible to increase the temperature stability of Setralit® natural fibres by special treatment (e.g. flame retardants). We are currently involved in an international project, which is (amongst others) subject to this topic. However, one has to be realistic about that the stability limit can scale up some 10 degrees centigrade at best. According to the present state of the art one will certainly not reach the 500 °C of aramid.

5) In friction linings a 100% substitution of aramid pulp by the Setralit® fibre is already realized without showing any quality loss.  It always has to be our aim – also in the case of gaskets – to completely substitute aramid by Setralit®. But already a partial exchange (aramid- und natural fibre pulp can be mixed in all proportions) – can be accounted as a success.

6) A natural fibre pulp based on plant fibres which is to be applied in a higher temperature range (e.g. in high performance gaskets or injection moulding) has to be properly cleaned. This can be guaranteed by using the ultrasonic technology. All kinds of impurities (like herbal glues, scents, and dyes, maybe also fungi, spores, or bacteria) still adhere to insufficiently cleaned plant fibres. They singe or roast at raising temperature well below the stability limit of cellulose and may cause colour changes or bad smells, or they may even uncontrollably interact with the ambient chemistry. A clean Setralit® fibre, however, does not change at all (neither itself nor the matrix) up to its stability bound. In the temperature range above that limit only water and CO2 is released. Without oxygen or oxidation by the matrix only carbon remains which in general still exhibits a fibrous structure.

Advantages of vegetable fibres

Vegetable fibres are natural nonwood plant fibres gained from basically annual plants like flax, hemp, kenaf, jute, and others. Compared to synthetic (man-made) fibres (mineral like glass or chemical like aramid) and compared to natural mineral fibres (like asbestos which is no more allowed in Europe) they bear many advantages.

Some of them are:

  • Low density compared to mineral fibres
  • Resistant against steam and bases at high temperatures, therefore autoclavable
  • High ability to absorb moisture
  • No or small electrostatic charge (depending on degree of dryness)


Ecological attributes:

  • Harmless to health
  • Biologically and thermally degradable, therefore easy to dispose or useful for energy generation
  • Production has a neutral CO2-balance


Economical attributes:

  • Renewable raw material (especially annual plant fibres)
  • Available world-wide
  • Additional source of income for farmers
  • Low investment needs (developing countries)
  • Low disposal costs
  • Favourable price

The Ultrasonic Break-down Method for cleaning and refining of vegetable fibres

Advantages of the method and of industrial manufacturing:

1.     Continuous and economic production

2.     Environmentally sound method

3.     Established as add-on system, therefore:


  • Upscaling and extension of production facilities are no problem
  • Rebuilding, upgrading, or modernising of the production plant is quick and inexpensive
  • Changeover to other raw materials is swift and easy

4.   Directed manufacturing of different fibre types and qualities through choice of raw materials and variation of process parameters

5.   Unwanted fibre substances like glues, scents and pigments (which may inhibit setting of concrete) as well as contaminants like mineral dust, bacteria and spores, organic will be removed

6.   Sub-products like shives or filter sludge can serve as additional energy source for operating the plant

7.   Easy Assurance and controlling of quality compared to conventional methods

8.   Different fibre raw materials can be processed, including all levels of retting and orientation (parallel or disordered)

The ultrasonic method

SisalfaserRaw material: The basic raw material of SETRALIT® - Fibre is a non-wood natural fibre which is generally called “vegetable fibre”. In many cases this is a bast fibre like hemp, flax, nettle, kenaf, jute, or ramie, but leaf fibres like sisal or musa textiles (manilla hemp, abacá) or fruit fibre like coconut(coir) or cotton are also suited for ultrasonic treatment. In middle Europe we will mainly use hemp and flax. The material may be the whole plant, dried an coarsely broken, but also and more favourable, partly or completely decorticated meaning freed of the wooden plant constituents (shives).

Ultrasonic treatment: The fibrous raw material is being exposed to an ultrasonic field in a watery medium for a time period between 10 and 120, usually 30 seconds. During this continuous procedure and subsequent washing the fibrous is being cleaned and extensively freed of attendants like dust, soluble organic components, micro organisms, colour and scent stuffs. The level of cleaning can be determined by adjusting the process-parameters. 

Post-processing: As a rule immediately after treatment the fibre is being dried, opened and cleaned again. Shives and other coarse materials still attached as well as short fibres are being removed. The waste mixture mainly made of short fibres and shives can be regarded as a by-product.

Refinement: Following refining and finishing procedures are applicable on the cleaned ultrasound fibre material: cutting, grinding, fibrillating, and coating, which are being used alternatively or in a row. Cutting and grinding will shorten the fibres, fibrillation will amplify the specific surface. Coating can be useful to improve the binding attitudes of a fibre within a matrix (for example plastics). Additional possible refinement steps are bleaching, dyeing and mixing.


Setralit NfuFlachsfaser

 

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