nbss final presentation

8/12/2019 NBSS Final Presentation

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2010 by Chong Chi Ping, Mich Koh En, Pal, Sures

Miss Lisa Boon and Mr Kong Chung Ang

(NBSS Science Teachers)

Miss Ivane Tay (RP Advisor)


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Hypothesis

In this project, some hypotheses were considered as

follows:

Different vegetables, fruits or spices can dyedifferent fabric.

The chemical composition of fibers and thechemical nature of the dye determine thestickiness of the dye on the fabric.

The use of mordant not only it can intensify thecolour but also increase the interaction of the fiberto the dye.

The post treatment of the dyed fabric with acid orbase can make the dye stay permanent.


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Materials

Blueberry Dragonfruit (Flesh & Skin) Red Cabbage

Tumeric Pomengranate Lime Orange Chrysanthemum Strawberry Beetroot Onion skin-purple Onion skin-brown Blender Beaker (Boiling & Measuring) Tripod Stand

Bunsen Burner

Wire Gauze

Distilled Water

KnifeChopping Board

Weighing Scale

Forceps

Fabric used:

100% nylon

35% woolBaskets

Paper towels

Stop watch

Glass rod

Strainer

The following are the materials used in this project:


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Procedures(A) Selection of the dye material (fruits, vegetables or spices).

(B) Extracting the dye from the dye material.

(C) Enhancing the dyeing by pre-treatment of the fabric.

(D) Dyeing the fabric(Nylon and Wool) swatches(10 cm by 10 cm)

(E) Post-treatment of fabric with hydrochloric acid and base (sodium hydroxide).

(F) Soak the fabrics in water for a day.


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Experiment 1


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Experiment 2


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Experiment 3


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Experiment 4


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Experiment 5


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Experiment 6


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Reason for Pre-treatment For the dyes to interact with the fibers more

effectively, a mordant is used.

Most natural dyes need a mordant to fix the colorto the fiber.

The mordant is the chemical link that fixes the dyeto a substrate by combining with the dye pigment

to form an insoluble compound.

The choice of mordant is very important asdifferent mordants can change the final colorsignificantly. Hence, alum mordant is used in these

experiments as it gives bright colours.


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Nylon Nylon is a good fiber due to the amide groups, which are

strongly attracted to each other.

The chains form strong bonds which hold onto eachother are called hydrogen bonds, which make nylonstrong.

The dyeing efficiency of nylon fibers is enhanced due to

the end groups -COOH and -NH2, which exhibit polar andhydrophilic characteristics.


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The bonds present in wool are disulfide bonds,isopeptide bonds, hydrophobic interactions andhydrocarbon side groups interactions.

The ionic interactions between acidic and basic sidechains are the most important interactions because theyare amphoteric.

They are able to absorb and desorb both acids andalkalis, thus controlling the dyeing behavior of the fabric.

Wool


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Post-treatment with Acid vs. Base

Post treating the dyed fabric with acid are thought to fix the dye tofibers by hydrogen bonding, Van der Waals forces and ionicbonding.

Synthetic Nylon fibers contain many cationic sites therefore there isan attraction of anionic dye molecule to a cationic site on the fiber.

The strength (fastness) of this bond is related to the desire/chemistry of the dye to remain dissolved in water over fixation tothe fiber. Hence, we can see the effectiveness of post-treating the

dyed fabric to be effective in keeping the colours.

Post treating the dyed fabric with base are mainly applied to acrylicfibers, but find some use for wool and silk. Hence, we can see theresult of post treating the dyed fabric to be ineffective in keepingthe colours.


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ConclusionFrom the evidence collected from the experiments, we concluded that:(i) pre-treatment with alum have a slight effect on the intensity of the

colour after pre-treatment of both fabrics

(ii) tumeric produces the best dyed fabric

(iii) the dyed fabric that has the colour closest to the colour of the dyematerial is nylon. This could be due to the stronger bondingbetween nylon and the dye material than between wool and the

dye material.

(iv) post-treating the dyed fabric with acid is more effective than post-treating with base because the acid helps to fix the dye to fibersby hydrogen bonding, Van der Waals forces and ionic bonding.

nbss final presentation

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