worksheet and assessment card masters - National STEM Centre

More documents

Recommendations

Info

IS IT REALLY WATERPROOF? YOU WILL NEED: _ Sewing machine oil Zepel or Scotchgard fabric protector Detergent 3 squares, 5 cm X 5 cm, of each of the following fabrics: cotton lawn, cotton canvas, thin nylon weave, industrial nylon, and wool gaberdine Watch or clock with seconds hand Wire cooling tray Pipette or eye dropper 1 Following the instructions on the container, spray two squares of each type of fabric with Zepel or Scotchgard. CAUTION Use by an open window. Avoid h... breathing vapour. Avoid contact with eyes. ili 2 Rub one drop of sewing machine oil into one treated sample of each type of fabric. 3 Set the fabric samples out on a wire cooling tray as shown below. 4 Using the dropper, place one drop of water in the centre of each of the three squares of wool. 5 Note how long it takes for the water to soak into each. Draw up a table and record your results on it. treated and soiled treated 6 Repeat for each fabric in turn. 7 Very carefully, without disturbing any remaining droplets, touch the underside of each fabric just under the droplet. What do you observe? Where have you seen this effect before? How can it be avoided? 8 Wash each clean treated square in warm water and detergent. Rinse them carefully and set them out as before on the wire tray to dry. 9 .Now wash the oily fabric squares. Rinse and set them out to dry. 10 Repeat the water droplet test on these squares. Record your results. Wash the cooling tray. Has washing affected the water resistance of the treated fabric? Can you explain why? Does the oily fabric behave differently?" You could try the droplet test using coffee or Coca Cola instead of water. What are the active ingredients in Zepel and Scotchgard?
fabric cling and anti-stat Garments that cling feel uncomfortable, particularly when they ride up the body. They look unsightly and may spoil the drape of other clothing worn over them. They also attract dust from the air and become quickly soiled. The clinging of charged garments to the body arises with certain types of fibres (especially nylon), particularly when worn next to each other in warm, dry conditions. This clinging effect is due mainly to the electro-static forces between the charge on the clothing and the opposite charge built up on the body. The charge on the body may be caused by layers of clothing next to each other (such as a dress and a petticoat) rubbing together when the wearer is walking about, causing the petticoat to be drawn to the legs and cling to them as shown on the right. Outer clothing may become charged when you get up from a plastic covered chair or seat or when top clothing is removed. As before, the electric field from the charge can induce an opposite charge on the adjacent skin, causing the garment to be attracted to the body and taking with it the undergarments. Static electricity is produced by rubbing. If the materials are poor conductors the charge builds up. Different materials generate different amounts of electricity. They can be arranged in a series (the triboelectric series). The further apart two materials are in the series the more electricity they will generate when rub bed together. Positive Negative wool nylon viscose cotton human skin triacetate polyester acrylic PVC 'C Anti-static substances added to nylon at the melt stage of production provide a permanent conducting layer on the fibre surface. Some brand names of this type of fibre are: Counterstat, Ultron, Antistatic Celon, and Perlon Antistatic. Untreated fabrics can be improved by adding a small amount of detergent to the rinsing water. Domestic fabric softeners (such as Comfort, Lenor, Soft Rinse, and Softlan) also reduce the build-up of static and are particularly useful when a tumble drier is used. + = positive charge - = negative charge + = positively charged - = negatively charged + + NUFFIELD HOME ECONOMICS FIBRES AND FABRICS: WORKSHEET FM17a "'" '-..... skin + + + + + underslip positively charged nylon underslip has induced a negative charge on leg causing underslip to cling to the leg wool and nylon dress becomes positively charged when the wearer gets up from a PVC-covered chair - this induces an opposite charge on the skin causing the garment to cling taking the underslip with it © 1984 Nuffield-Chelsea Curriculum Trust
Page 1 and 2: FIBRES i\.ND ,ABRICS WORKSHEET AND
Page 3 and 4: Suppose you have collected some dat
Page 5 and 6: Why do we have curtains and carpets
Page 7 and 8: Note. It is essential to examine fi
Page 9 and 10: Effect of wetting on thermal insula
Page 11 and 12: Spinning, knitting:, and • weavin
Page 13 and 14: Spinning, knitting, and • weaving
Page 15 and 16: WHAT MAKES UP WHITE LIGHT? If you s
Page 17 and 18: Colour fastness of household dyes W
Page 19 and 20: Colour fastness of curtain fabric W
Page 21: All wool fibres have a protective c
Page 25 and 26: Surface tension and detergents A dr
Page 27 and 28: 1 Which is the odd one out in each
Page 29 and 30: 1 Rewrite the following two lists p
Page 31 and 32: 1 Underline the odd one out. The qu
Page 33 and 34: 1 Select the odd one out in each of
Page 35 and 36: In questions 1, 2, and 3, select th
Page 37 and 38: In questions 1, 2, and 3, select th
Page 39 and 40: 1 We all have constant contact with

worksheet and assessment card masters - National STEM Centre

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?