Monday, 20 April 2009
How to select Blend Constituents
Selection of Blend Constituents depends upon the following factors:
1. Type of Fibre
- Depending upon the end use of the fabric, blend constituents are chosen.
- For example, it is well known hat a polyester-cotton yarn looks fuller as compared to the lean look of polyester-viscose yarn.
- Therefore for light constructions like shirtings, polyester-cotton blend is used.
- However polyester-viscose blend is preferred for medium and heavy construcitons such as suitings.
2. Compatibility of blend fibres
Compatibility must be there in terms of the following properties:
a. Length and Denier of Fibres:
- As a general rule, these two fibre properties should be nearly the same for all the constituents.
- For example in a viscose rayon cotton blend, the rayon staple of 1.5 denier and 29-32 mm length is generally used since the cotton component used has a denier of around 1.5 and a length of 28mm.
- A large difference in the breaking elongation of the fibres in a blend adversly affects the yarn tenacity.
- The blend fibres should prefereably have the same density. Any large differences on this account will lead to selctive separation while conveying the blended stock through ducts under the influence of air suction in the blow rooms.
d. Dispersion Properties
- This property describes the ability of an individual fibre to separate from its group and disperse thoroughly within the fibre matrix of the blend to produce an intimate and homogeneous blend.
e. Drafting Properties
- Some fibres like viscose are outstanding it terms of draftability. These fibres, when blended with other fibres act as good carriers to obviate the trouble relating to drafting.
f. Dyeing Properties
- In case the blend yarn or fabric is to be dyed subsequently, due consideration should be given to the dyeing properties of individual fibre components.
CHARACTERISTICS DESIRED IN A BLEND YARN
A. The constituent fibres should be arranged at random in the yarn cross section.
B. The ratio between the blended fibres should be uniform at any cross section of the yarn.
C. There should not be any long-term or short-term irregularity in blend ratio of blended fibres.