Topic: Natural fibres

Target group

High school / technical school student

Core curriculum:

New core curriculum:

High school and technical high school. Chemistry – basic level:

XXI. Chemistry around us. Pupil:

1) classifies fibers into: cellulose, protein, artificial and synthetic; indicates their uses; describes the pros and cons; justifies the need for these fibers;
2) designs and conducts an experiment to identify cellulose, protein, artificial and synthetic fibers.

High school and technical high school. Chemistry – extended level:

XXI. Chemistry around us. Pupil:

1) classifies fibers into: cellulose, protein, artificial and synthetic; indicates their uses; describes the pros and cons; justifies the need for these fibers;
2) designs and conducts an experiment to identify cellulose, protein, artificial and synthetic fibers.

Old core curriculum:

High school and technical high school. Chemistry – basic level:

XXI. Chemistry around us. Student:

1) classifies fibres into: cellulose, protein, artificial and synthetic; indicates their applications; describes the advantages and disadvantages; justifies the necessity of their application;
2) designs and conducts experiments to identify cellulose, protein, artificial and synthetic fibres.

General aim of education

The student discusses and identifies natural fibers

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to classify fibers for natural (protein and cellulose), artificial and synthetic, as well as give examples;

• to identify the type of fibers;

• to describe the applications of natural, artificial and synthetic fibers, taking into account their advantages and disadvantages.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• exposing

  • film.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers.

Lesson plan overview

Introduction

1. The teacher hands out Methodology Guide or green, yellow and red sheets of paper to the students to be used during the work based on a traffic light technique. He presents the aims of the lesson in the student's language on a multimedia presentation and discusses the criteria of success (aims of the lesson and success criteria can be send to students via e‑mail or posted on Facebook, so that students will be able to manage their portfolio).

2. The teacher together with the students determines the topic – based on the previously presented lesson aims – and then writes it on the interactive whiteboard/blackboard. Students write the topic in the notebook.

3. Health and safety – before starting the experiments, students familiarise themselves with the safety data sheets of the substances that will be used during the lesson. The teacher points out the need to be careful when working with them.

Realization

1. The lecturer divides the fibers into natural, artificial and synthetic ones. Defines natural fibers.

2. The teacher divides the students into three groups (there can be a total of six groups), distributes sheets of paper and markers. At the beginning students will work with the use of a mental map showing the division of natural fibers. They can use the content contained in the abstract, textbook and the Internet. After making a mental map, each group deals with the development of issues related to one type of natural fiber, including its advantages and disadvantages and the use of:
   group I - vegetable fibers
   group II - animal fibers
   group III - mineral fibers.
   After the work, the group leaders present the effects of the team's activities using the talking wall technique. The teacher sums up the students' work.

3. The teacher informs students that he will display the illustrations of „Vegetable Fibers” and „Animal Fibers” on the multimedia board. Using the materials contained in the abstract, the teacher together with students discusses the use of vegetable and animal fibers in everyday life.

4. At the end of the lesson, the teacher asks students to do interactive exercises - individual work.

Summary

1. The teacher asks the students to finish the following sentences:

   • Today I learned ...

   • I understood that …

   • It surprised me …

   • I found out ...

   The teacher can use the interactive whiteboard in the abstract or instruct students to work with it

2. The student indicated by the teacher sums up the lesson, telling what he has learned and what skills he/she has been practicing.

Homework

1. Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Natural fibres

Among the natural fibres, there are fibres of vegetable, animal and mineral origin.

Vegetable fibres are obtained from various parts of the plant – seeds (cotton), stems (flax, hemp, jute, ramie), leaves (sisal) or fruit (coconut fibres).

Animal fibres are obtained from, e.g. hair of mammals (wool, bristle), as well as from animal secretions (silk).

Mineral fibres are fibrous inorganic substances (asbestos) or artificial (asbestos substitutes, glass fibres, rockwool or slag wool, ceramic fibres).

Most commonly used – especially for the production of clothing – natural fibres are cotton, wool, linen and silk. Therefore, it is worth to learn more about these fibres.

All fibres are made of macromolecules. Natural fibres are made of biopolymers, i.e. cellulose, proteins, and artificial fibres made of natural macromolecules, modified as a result of chemical processes.

Natural fibres occur in nature in a ready‑for‑processing state. These can be supplied by plants, animals and occur in the form of minerals. All vegetable fibres are made of cellulose. In addition to it, vegetable fibres contain small quantities of lignin (a polymer where monomer is alcohol), as well as plant‑based adhesives (pectin).

Cotton is a fibre obtained from cotton bushes. White fibres surround the plant's seeds, creating numerous white tufts resembling the appearance of cotton wool on the bushes. The mature fibre was once harvested by hand, and today it is harvested mainly by machine.
The properties of cotton fabrics – softness, airy and concurrent durability – create many possibilities for their use. These are easy to care for – can be machine washed, can undergo spinning and be wet pressed at high temperature.

Cotton is used for the production of clothing, bedding fabrics, tablecloths, dressings, fishing nets, and coffee filters.

Another plant that provides natural fibres is flax. Flax fibres are obtained from the stems of this plant. It is a long and complicated process, it involves many stages. Flax was the most popular raw material for clothing production until cotton was mechanically processed. Fabrics made of flax are absorbent and „can breathe”. These provide special comfort on hot days. These are also durable and resistant to dirt. Their disadvantage is the susceptibility to creases, which are difficult to iron out (a high ironing temperature is required, marked as level 3. – the highest). Linen clothing and other products made of flax fibre are now treated as exclusive and elegant.

Sisal are hard and very durable fibres obtained from a special grade of agave. These are used to make twines (ropes, cords), mats and sacks.

Initially, the man used only natural raw materials for making clothes.

In the Stone Age, next to the primitive clothing from the skin, fabrics made of vegetable fibres were also used. The Egyptians wore linen garments, Indians – cotton ones. Nowadays, fibres with various properties and applications are synthesized. However, some features of natural fibres are still very difficult or even impossible to achieve in technological processes.

At first, devices used to spin the thread were very simple, and over time more and more complicated. Over time, manual looms began to be replaced with machines and that's how the modern textile industry raised.

Wool is animal hair. It is obtained mainly from sheep's pelage and from other graminivorous animals – goats, llamas and camels. The most popular is sheep's wool, produced in many types. The highest quality wool is obtained from Merino sheep. It has such advantages appreciated by the users as extremely thin fibres, softness and fluffiness. Excellent thermoregulation properties characterise wool products – woollen clothing provides warmth and quickly absorbs and drains moisture. In addition, the wool is not susceptible to dirt and does not absorb odours. Warmer clothing, carpets, blankets, pillows, quilts are made of wool. Today, wool is mainly used in blends with other fibres and has lost its popularity in favour of synthetic fibres.

Natural silk is a fibre produced by the larva of domestic silk moth. The most popular is Bombyx mori. The caterpillars spin two threads of silk, forming a cocoon in which they pupate. These two fibres are glued together; only the separation and unravelling of the cocoon and the appropriate treatment in hot water allow obtaining strands with a length of even 1 - 3 km. Silk fibres are the most durable among natural fibres. The silk fabric has a characteristic, recognizable from the first touch structure. It is light and airy, it fits perfectly. It is considered the noblest of fabrics. Due to the useful properties and the cost of production, silk is a very expensive fibre. Silk fabrics require gentle treatment – hand washing is recommended at temperatures up to 30°C and ironing at temperatures below 150°C (indicated as level 1).

Until recently, asbestos was a commonly used and valued natural mineral fibre, which occurs in several varieties with different chemical composition. Fibrous asbestos is made of thin, soft, shiny fibres of white or grey colour, which are characterised by high‑temperature resistance and poor conductivity of heat and electricity. The asbestos yarn (produced with the addition of cotton) was used in the production of fireproof and acid‑resistant fabrics as well as in the manufacture of cardboard and asbestos tar paper, used for thermal and electrical insulation.

• Natural fibres can be cellulose fibres (vegetable fibres) or protein fibres (animal fibres). Mineral fibres (asbestos) are also known.

• Human‑made fibres are chemically synthesised – made of raw materials of natural origin, e.g. viscose from cellulose – and artificial fibres – made of substances obtained by chemical synthesis.

• Today, many types of fibres are produced, which are used to manufacture products that sometimes meet very specialized requirements and serve the safety and comfort of use.

• Observation of fibres combustion allows approximate determination of the type of fibre. In addition, protein fibres undergo reactions characteristic for proteins, e.g. xanthoproteic reaction.

natural fibres, animal fibres, fibres of vegetable origin, fibres of animal origin, mineral fibres, silk, wool, cotton, sisal, flax