1.5 Text Synthetic fibres

The first synthetic fibre is nylon（one of polyamide fibres）that was commercially produced in United State in 1939.The main kinds of the synthetic fibres include：polyamide，polyester and polyacrylonitrile fibres，which are used in textile industry widely.

1.Polyamide fibres

Among the polyamide fibres，nylon 66 and nylon 6 are used more frequently.Nylon 66 is produced by polycondensation from adipic acid and hexamethylene diamine.Nylon 6 is the polymerization product made from caprolactam.Both of them are manufactured through the fibre production process called melt extrusion in which the polymer is converted to a liquid form just by heat and then extruded through a spinnerette to form filament.^[1]The chemical structures of nylon 66 and nylon 6 are shown as follows：

The chemical structure of nylon 6

The chemical structure of nylon 66

Nylon filaments are smooth and shiny.When viewed in cross-section，nylon is usually perfectly round.It is highly resistant to alkalis and relatively less resistant to acid.Nylon is a very strong，quick-drying fibre with high wet strength and has excellent elasticity.Nylon has a lower specific gravity than other fibres.These properties make them very suitable for stockings，parachute fabrics，shirts，underwear，carpet and reinforcement of rubber in tyres and belts.^[2] Nylon blends well with other fibres and adds strength to such blends.Nylon has low absorbency，which makes it quick drying.In recent years many modified nylon fibres have been developed and produced to meet some particular requirements.For example，polybenzimidazole fibre is obtained by reacting diaminobenzidine with diphenylisophthalate and is used as an alternate to asbestos in high temperature filtration and thermal protection clothing.^[3] The modified nylons can take several forms：changing cross-section of shape and changing the physical and chemical properties to improve dyeability，handle，tenacity，heat stability etc.

2.Polyester fibres

Polyester fibre is now the largest man-made fibre in terms of volume of production.^[4] Polyester polymer that is often manufactured in chemical factories is obtained by the condensation of terephthalic acid or dimethyl terephthalate with ethylene glycol at high temperature.The condensation reaction is shown as follows：

After polymerization they are extruded in the form of ribbon，then cut into chips.The chips are dried and sold to spinning mills.In the spinning mills the chips of polyester polymer are converted into the form of filament usually through melting spinning process，in which the polymer is melted to form a solution by heating；and then the solution is forced through the fibre spinnerette to form filaments；the filaments solidify by contact with cool air and are drawn and stretched to impart strength and control elongation.^[5] Polyester fibres can be produced in the form of filament or staple fibre.Polyester staple is very commonly blended with cotton or other cellulosic fibres in shirts，blouses，dresses，trousers and sheeting.^[6] Blends of polyester with wool are used in suitings and trousers.Polyester continuous yarn is often used for seat belts，sewing threads and yacht sails，as well as apparel items such as blouses.

The physical properties of polyester are given in Table 1-5.

Table 1-5 physical properties of polyester

The polymer system is estimated to be about 65% to 85% crystalline.Polyester fibre has high tensile strength，low moisture regain，high initial modulus and good crease recovery.Strong caustic soda at high temperature can hydrolyze and degrade the fibre and concentrated sulphuric acid can disintegrate the fibre.

Polyester fibres have also been modified by changing cross-section of shape and by changing the physical and chemical properties.An interesting development is polyester superfine fibre，extremely fine filaments which give fabrics a soft silky handle.The chemical modifications of polyester are mainly intended to overcome some of the inherent drawbacks of the fibres such as low dyeability，low moisture regain，static accumulation，soiling tendency，pilling property and flammability.

3.Polyacrylonitrile fibres

Polyacrylonitrile fibres include acrylic and modified acrylic fibres.All of them are made from the copolymers of acrylonitrile with comonomers such as acrylic acid，vinylidine chloride，etc.The common molecular structure of the copolymers is represented as below：

Where，m and n are number of acrylonitrile and comonomer units respectively in the long chain copolymer；p is the polymerization degree；X and Y are the substitute groups of the comonomer.

The polymer of acrylonitrile has some undesired properties，so the comonomers are added to increase the polymer thermoplasticity，solubility，dyeability，moisture regain，etc.Acrylic fibres are composed of at least 85% by weight of acrylonitrile and 15% or less comonomer；but the modified acrylic fibres such as modacrylic fibre are comprised of less than 85% but at least 35% by weight of acrylonitrile.The production of the polyacrylonitrile filaments also includes three stages：polymerization，dope preparation and spinning.

The acrylic fibres possess a very pleasing，warm and soft handle.Fabrics made from it exhibit a silk-like luster，hand and drape.^[7]An outstanding property of acrylic fibres is the comparatively low density which provides bulk and good coverage.The fibre has only 1.5% moisture regain and hence susceptible to static electricity.It has no definite melting point；it yellows on heating at 300℃ and decomposes at 350℃.It has glass-transition between 85℃ and 100℃，which is important for dyeing.Its resistance to sunlight is good.It has poor resistance to strong acids，alkalis and to a few polar organic solvents.Acrylic fibres are found many applications in knitwear，carpets and pile fabrics.The modacrylic fibre has similar properties to those of acrylics.However，it has greatly reduced flammability.^[8] This fibre is a good textile material used for children's nightwear as well as upholstery fabrics for aircrafts，trains and public rooms.It is also used for wig.

New words

1.nylon['nailən]n.锦纶

2.polyacrylonitrile[,pɔli'ækrələu'naitril]n.聚丙烯腈

3.polycondensation[,pɔlikɔnden'sei∫ən]n.缩聚（作用）

4.caprolactam[,kæprəu'læktəm]己内酰胺

5.diaminobenzidine[,dai,æminəu'benzi,di:n]n.二氨基联苯胺

6.diphenylisophthlate[dai'fenl,aisə'fθleit]n.间苯二甲酸二苯酯

7.chips[t∫ips]n.切片，小片，碎片

8.yacht[jɔt]n.游艇，快艇

9.soiling[sɔiliŋ]n.弄脏，沾污，传色

10.pilling['piliŋ]n.起球

11.flammability[,flæmə'biləti]n.可燃性，易燃

12.copolymer[kəu'pɔlimə]n.共聚物

13.acrylonitrile[,ækrələu'naitril]n.丙烯腈

14.comonomer[kəu'mɔnəmə]n.共聚单体

15.drape[dreip]n.织物悬垂性

Phrases and expressions

1.hexamethylene diamine 己二胺

2.polybenzimidazole fibre 聚苯并咪唑纤维

3.terephthalic acid 对苯二甲酸

4.dimethyl terephthalate 对苯二甲酸二甲酯

5.ethylene glycol 乙二醇

6.initial modulus 初始模量

7.superfine fibre 细旦纤维，超细纤维

8.acrylic acid 丙烯酸

9.vinylidine chloride 偏二氯乙烯

10.modacrylic fibre 改性聚丙烯酸纤维

Notes

[1] Both of them are manufactured through the fibre production process called melt extrusion in which the polymer is converted to a liquid form just by heat and then extruded through a spinnerette to form filament.

这两种纤维都是通过“熔体挤出”这种生产工艺制造而成。在这个工艺中，聚合物经加热形成流体后通过纺丝头挤出成长丝。

[2] Nylon has a lower specific gravity than other fibres.These properties make them very suitable for stockings，parachute fabrics，shirts，underwear，carpet and reinforcement of rubber in tyres and belts.

尼龙的密度比其他纤维要小，这个特征使得尼龙非常适合用于长袜、降落伞织物、衬衫、内衣、地毯以及作为轮胎和输送带的增强材料。

[3] For example，polybenzimidazole fibre is obtained by reacting diaminobenzidine with diphenylisophthalate and is used as an alternate to asbestos in high temperature filtration and thermal protection clothing.

例如，聚苯并咪唑纤维是通过二氨基联苯胺与二苯基间苯二甲酸酯反应而获得，它作为石棉的替代品用于高温过滤材料和热保护服。

[4] Polyester fibre is now the largest man-made fibre in terms of volume of production.

聚酯纤维是目前产量最大的化学纤维。

句中“in terms of”表示“就而言”。

[5] In the spinning mills the chips of polyester polymer are converted into the form of filament usually through melting spinning process，in which the polymer is melted to form a solution by heating；and then the solution is forced through the fibre spinnerette to form filaments；the filaments solidify by contact with cool air and are drawn and stretched to impart strength and control elongation.

在纺织厂，聚酯切片一般通过熔融纺丝工艺加工成丝；在这一工艺过程中，首先切片通过加热变成流体，然后流体经纤维纺丝头挤压形成丝，丝与冷空气接触而固化，通过牵伸赋予纤维强力并控制伸长。

[6] Polyester staple is very commonly blended with cotton or other cellulosic fibres in shirts，blouses，dressess，trousers and sheeting.

聚酯短纤维和棉花或其他纤维素纤维混纺非常普遍，用于衬衫、宽松衣、妇孺服装、裤子和床单中。

句中“in”作“用于”解释。

[7] The acrylic fibres possess a very pleasing，warm and soft handle.Fabrics made from it exhibit a silk-like luster，hand and drape.

腈纶纤维具有令人满意的、温暖和柔软的手感。用它生产的织物显现出丝一般的光泽、手感和悬垂性。

[8] The modacrylic fibre has similar properties to those of acrylics.However，it has greatly reduced flammability.

改性聚丙烯腈纤维有类似于腈纶纤维的性质，而它的可燃性较后者大大降低。

副词“greatly”修饰“reduced”。连在一起译为“极大地降低了”。

Exercises

Ⅰ.Answer the following questions.

1.When was the first synthetic fibre commercially produced？

2.What is the difference between nylon 6 and nylon 66？

3.What methods can be used in nylon modifications？

4.What is the production process of polyester fibre？

5.What are the applications of polyester fibre？

6.What are the characteristics of acrylic fibre？

Ⅱ.Translate the following sentences into Chinese.

1.The main kinds of the synthetic fibres include：polyamide，polyester and polyacrylonitrile fibres，which are used in textile industry widely.

2.The modified nylons can take several forms：changing cross-section of shape and changing the physical and chemical properties to improve dyeability，handle，tenacity，heat stability etc.

3.Polyester polymer that is often manufactured in chemical factories is obtained by the condensation of terephthalic acid or dimethyl terephthalate with ethylene glycol at high temperature.

4.Polyester fibre has high tensile strength，low moisture regain，high initial modulus and good crease recovery.

5.Where，m and n are number of acrylonitrile and comonomer units respectively in the long chain copolymer；p is the polymerization degree；X and Y are the substitute groups of the comonomer.

6.Acrylic fibres are composed of at least 85% by weight of acrylonitrile and 15% or less comonomer；but the modified acrylic fibres such as modacrylic fibre are comprised of less than 85% but at least 35% by weight of acrylonitrile.

Reading material Fibre lustre

Fibre's luster is resulted from the interaction of light with the fibre.

Consider a beam of white light incident on the surface of an object.As soon as the light meets the surface the beam undergoes refraction and reflection.The reflection can be divided into two types：diffuse and specular reflection.That light is reflected in all directions is known as diffuse reflection，whereas，specular reflection means that light is reflected only in one direction.

The specular reflection is caused by the smooth surface such as mirror.Un-smooth surface does not reflect light in one direction and results in diffuse reflection.

Fibres appear lustrous when there are specular reflections from the outer surface and/or the internal surface.

Thus，fibres with circular cross section generally appear more lustrous than those with irregular cross sections.Fibres with smooth longitudinal surfaces appear more lustrous.Fibres with optical cross section，such as silk or trilobal nylon，also appear more lustrous，for example mercerized cotton appears more lustrous than raw cotton as a result of the more circular cross section.

If all other parameters are the same，then finer fibres produce a more lustrous effect because they have a greater surface area for reflection，for the same mass of the fibre.This can be significant in dyeing because the surface reflection is‘white’light and tends to dilute the colour from the dye.