Showing posts with label Hemp. Show all posts
Showing posts with label Hemp. Show all posts
28 October 2012
Flow Chart of Hemp Spinning
Hemp Preparation and Spinning:
The preparation process of long staple fibers allows to transform the sliver produced by the hackling machine into a 2 - 4 g/m roving through a series of drawing passages and a high number of doublings, which ensure the high blending rate necessary for heterogeneous fibers like hemp. The flow chart is similar to that used for flax processing and the machines employed are practically the same. At the delivery from last drawing passage, the sliver can be subjected to one of two alternative processes:
We point out that the card sliver has not the cleanness degree which is necessary to produce a regular yarn, therefore it requires a hackling operation on machines very similar to wool combers.
Tows can be dry or wet spun. For dry spinning, two kinds of spinning frames are used:
In
the case of hemp the processing of long staple yarns differs from the
processing of tow. Hemp reaches the mill in form of 400 to 1000 g
sheafs, which feed the hackling machine. The short fibers are collected
in boxes and delivered to the packing department as hackling tows.
The preparation process of long staple fibers allows to transform the sliver produced by the hackling machine into a 2 - 4 g/m roving through a series of drawing passages and a high number of doublings, which ensure the high blending rate necessary for heterogeneous fibers like hemp. The flow chart is similar to that used for flax processing and the machines employed are practically the same. At the delivery from last drawing passage, the sliver can be subjected to one of two alternative processes:
- Wet spinning, the typical process used for bast fibres, with bobbin drying and winding. As for flax, the roving can be degummed and bleached before spinning.
- Dry spinning directly from sliver through the same spinning frames used for flax tow spinning.
We point out that the card sliver has not the cleanness degree which is necessary to produce a regular yarn, therefore it requires a hackling operation on machines very similar to wool combers.
Tows can be dry or wet spun. For dry spinning, two kinds of spinning frames are used:
- With drafting cylinder systems which operate according to the typical criteria of the semi-worsted system, with settings suited to the high length of these fibres
- With gill-bars, i.e. with needle bars placed in the drafting fields assigned to the guide of the fibres, which are similar to those used for long fiber dry spinning.
Flow Chart of Hemp Spinning
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As already for flax, the prospects for a widening of hemp use are conditioned by the finishing operations. In fact the fibre can undergo some important changes, if the order and the crystalline lay-out of the fibrous cells are adequately varied ; moreover, if full advantage is taken of the inner channels (lumens) for fluid diffusion by preparing them for a more efficient migration of fluids capable of modifying the fiber’s physical properties, completely new handle and appearance effects, even adjustable by the finisher, can be obtained.
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9 May 2012
Difference of Flax and Hemp
Flax (in fibre form) is practically
undifferentiated from hemp, which threatens possible confusion with the
latter, which is considerably different in price. Flax and hemp are
cellulose fibres produced from stocks of row material. Their properties
are similar and they are scarcely differentiated at the fibre form.
Analytical differentiation is complicated by strong interventions into
these fibres during the textile treatment, which is similar in both flax and hemp: the fibres are separated, blanched, and undesirable additions are removed.
These operations are connected with the change of average chemical composition of fibre material, e.g. the concentration of lignin decreases, the portion of low molecular celluloses decreases and the macromolecules of cellulose are abbreviated. There is also a wide variance in fibre characteristics at wide intervals, e.g. the specific strength of fibres and the length of fibre fluctuations.
Difference between Flax and Hemp
Differentiating flax and hemp is a long-time analytical problem, which is becoming more and more relevant with the wider loading of bast fibres. Flax and hemp are very similar fibres in all aspects, and their differentiation is often controversial. In this work, the literature is researched for the classic methods of differentiating these two types of fibres. Additionally, a further to twist discrimination methods (the twist test method and the method using polarised light) were analysed. The method most suitable for practical use was tested on a wide spectrum of fibres and compared with the usual methods.Review of analytical methods resulting of literature research .
Microscopic differentiation
The morphological characteristics mentioned in Table 1 can be used for microscopic differentiation of flax and hemp. The observation is mostly oriented towards the observation of the shapes of the fibre’s cross-sections and fibre ends at the longitudinal view. This method is time-consuming (requiring preparations to be prepared), the appreciation of the characteristics observed is rather subjective, and it also requires considerable experience. An advantage is the fact that the shape of the elementary fibres does not change during the processing.
Swelling test
Various morphological structures of flax and hemp are exhibited by the diverse extents of the swelling property of the fibres. in the cuoxam solution. The flax swells uniformly and relatively rapidly, the tube in the non-blanched fibre contracts in a serpentine fashion, and it resists the solvent. The hemp swells slowly; during this process the tube in the raw fibre often obtains a typical periodic-shape. The swelling of the flax and the hemp has been photographically documented by Koch [8] and Felix [9]. For observing fibres it is necessary to use the microscopic technique.
Dyeing tests
Hemp contains more lignin and non-cellulose portions than flax. On this basis, a group of tests has been prepared in which the dyestuff of the agent is e.g. sorbed only by the lignin part of the fibre, for example, or when the agent reacts with the non-cellulose parts of the fibre depending on the colour compound applied. Dyeing tests are especially applicable to raw fibres before eliminating non-cellulose substances from fibres (preliminary finish or otherwise); after their elimination, the fibres will not colour. The methods are easily executed, and their results are apparent by visual evaluation even without microscopic equipment.
Twist tests
These operations are connected with the change of average chemical composition of fibre material, e.g. the concentration of lignin decreases, the portion of low molecular celluloses decreases and the macromolecules of cellulose are abbreviated. There is also a wide variance in fibre characteristics at wide intervals, e.g. the specific strength of fibres and the length of fibre fluctuations.
Difference between Flax and Hemp
Differentiating flax and hemp is a long-time analytical problem, which is becoming more and more relevant with the wider loading of bast fibres. Flax and hemp are very similar fibres in all aspects, and their differentiation is often controversial. In this work, the literature is researched for the classic methods of differentiating these two types of fibres. Additionally, a further to twist discrimination methods (the twist test method and the method using polarised light) were analysed. The method most suitable for practical use was tested on a wide spectrum of fibres and compared with the usual methods.Review of analytical methods resulting of literature research .
Microscopic differentiation
The morphological characteristics mentioned in Table 1 can be used for microscopic differentiation of flax and hemp. The observation is mostly oriented towards the observation of the shapes of the fibre’s cross-sections and fibre ends at the longitudinal view. This method is time-consuming (requiring preparations to be prepared), the appreciation of the characteristics observed is rather subjective, and it also requires considerable experience. An advantage is the fact that the shape of the elementary fibres does not change during the processing.
Swelling test
Various morphological structures of flax and hemp are exhibited by the diverse extents of the swelling property of the fibres. in the cuoxam solution. The flax swells uniformly and relatively rapidly, the tube in the non-blanched fibre contracts in a serpentine fashion, and it resists the solvent. The hemp swells slowly; during this process the tube in the raw fibre often obtains a typical periodic-shape. The swelling of the flax and the hemp has been photographically documented by Koch [8] and Felix [9]. For observing fibres it is necessary to use the microscopic technique.
Dyeing tests
Hemp contains more lignin and non-cellulose portions than flax. On this basis, a group of tests has been prepared in which the dyestuff of the agent is e.g. sorbed only by the lignin part of the fibre, for example, or when the agent reacts with the non-cellulose parts of the fibre depending on the colour compound applied. Dyeing tests are especially applicable to raw fibres before eliminating non-cellulose substances from fibres (preliminary finish or otherwise); after their elimination, the fibres will not colour. The methods are easily executed, and their results are apparent by visual evaluation even without microscopic equipment.
Twist tests
Indirect method of determination of fibril slope in the flax and the hemp
Flax and hemp have different orientations of fibril bundles in the fibre. Indirectly, this fact is verified by the opposing behaviour of flax and hemp in polarised light (as directed from above), and by the possibility of distinguishing the fibres by X-ray diffraction.
From the analytical aspect, the orientation of the fibrils at the hydration and dehydration of lamellas is important. During these processes, changes to the geometry characteristics of the fibril bundles occur. These changes are macroscopically expressed by the fibre’s effort to turn, and so eliminate the internal stress at the sorption (or desorption) of water. Sonntag [16]used this method for the analytical distinction of flax and hemp.
The so-called ‘Twist test’ method for differentiating flax and hemp is founded on this basis, , the merit of which is the observation of the spontaneous twisting of the fibre as it dries. If a wet flax is held by one end and dried, then its free end, which is oriented towards the observer, will turn clockwise (right handed, according to Figure 3). Under the same conditions, hemp will turn round in the opposite direction. The direction of twisting is characteristic for both flax and hemp, whereas cotton fibres twist in various directions during this test. Ramie twists as flax. [15] This process described in literature [15] was modified according to the possibilities of our laboratory and is presented below.
http://textilelearner.blogspot.com/
Flax and hemp have different orientations of fibril bundles in the fibre. Indirectly, this fact is verified by the opposing behaviour of flax and hemp in polarised light (as directed from above), and by the possibility of distinguishing the fibres by X-ray diffraction.
From the analytical aspect, the orientation of the fibrils at the hydration and dehydration of lamellas is important. During these processes, changes to the geometry characteristics of the fibril bundles occur. These changes are macroscopically expressed by the fibre’s effort to turn, and so eliminate the internal stress at the sorption (or desorption) of water. Sonntag [16]used this method for the analytical distinction of flax and hemp.
The so-called ‘Twist test’ method for differentiating flax and hemp is founded on this basis, , the merit of which is the observation of the spontaneous twisting of the fibre as it dries. If a wet flax is held by one end and dried, then its free end, which is oriented towards the observer, will turn clockwise (right handed, according to Figure 3). Under the same conditions, hemp will turn round in the opposite direction. The direction of twisting is characteristic for both flax and hemp, whereas cotton fibres twist in various directions during this test. Ramie twists as flax. [15] This process described in literature [15] was modified according to the possibilities of our laboratory and is presented below.
http://textilelearner.blogspot.com/
2 May 2012
Chemical Composition of Natural Fiber
Chemical Composition of Natural Fiber:
Every fiber consists of some chemical elements. Such as cotton contains cellulose, protein, pectin etc. Wool contains keratin, dirt, suint etc. Chemical composition of natural fibers are given below:
Chemical Composition of Cotton Fiber:
Chemical Composition of Jute Fiber:
Chemical Composition of Linen/Flax Fiber:
Chemical Composition of Hemp Fiber:
Chemical Composition of Sisal Fiber:
Chemical Composition of Coir Fiber:
Chemical Composition of Wool Fiber:
Chemical Composition of Keratin:
Every fiber consists of some chemical elements. Such as cotton contains cellulose, protein, pectin etc. Wool contains keratin, dirt, suint etc. Chemical composition of natural fibers are given below:
Chemical Composition of Cotton Fiber:
- Cellulose 94%
- Protein 1.3%
- Ash 1.2%
- Pectin 1.2%
- Oil, Fat and Wax 0.6%
- Sugar 0.3%
- Pigment trace
- Others 1.4%
Chemical Composition of Jute Fiber:
- Cellulose 65.2%
- Hemicellulose 22.2%
- Lignin 10.8%
- Water soluble 1.5%
- Fats and wax 0.3%
Chemical Composition of Linen/Flax Fiber:
- Cellulose 92%
- Hemicellulose 2%
- Lignin 4%
- Others 2%
Chemical Composition of Hemp Fiber:
- Cellulose 77.77%
- Hemicellulose 10%
- Lignin 6.8%
- Pectin 2.9%
- Fat & wax 0.90%
- Water soluble 1.73%
Chemical Composition of Sisal Fiber:
- Cellulose 71.5%
- Hemicellulose 18%
- Lignin 6%
- Pectin 2.3%
- Fat & wax 0.5%
- Water soluble 1.7%
Chemical Composition of Coir Fiber:
- Husk 14%
- Fiber 22%
- Pith 16%
- Kernel 30%
- Water 18%
Chemical Composition of Wool Fiber:
- Keratin 33%
- Dirt 26%
- Suint 28%
- Fat 12%
- Mineral matter 1%
Chemical Composition of Keratin:
- Carbon 50%
- Hydrogen 12%
- Oxygen 10%
- Nitrogen 25%
- Sulfher 3%
Chemical Composition of Silk Fiber:
- Fibroin 76%
- Sericin 22%
- Fat & wax 1.5%
- Mineral salt 0.5
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