Chapter 18 Chemistry and materials Diamond Paper, plastic, metals, glass, ceramics
Chapter 18 Chemistry and Materials Diamond Paper, plastic, metals, glass, ceramics
18.1 Paper is made of cellulose fibers Paper was first made HARDWOOD FIBERS in China as early as AD 100, of mulberry bark, and then introduced to Western SOFTWOOD FIBERS world by arabs in eighth century. The first paper mills were built in Spain in 11th centum ry
18.1 Paper is made of cellulose fibers • Paper was first made in China as early as AD 100, of mulberry bark, and then introduced to Western world by Arabs in eighth century. The first paper mills were built in Spain in 11th century
The use of wood to produce paper was started in USA Additives such as rosin(松香) and alum(明矾)Were added to strengthen paper and make it accept ink well Chlorine as used to bleaching paper and titanium dioxide (钛白粉) was used to make the paper white. Acidic paper, acid-free paper and alkaline paper Plants alternative to trees: willow(tp), kenaf(K). They usually have high fiber content and grow fast 70 million tons of paper are used in USA: one person 230 kilograms or six trees
• The use of wood to produce paper was started in USA. • Additives such as rosin (松香) and alum (明矾) were added to strengthen paper and make it accept ink well. Chlorine as used to bleaching paper and titanium dioxide （钛白粉）was used to make the paper white. • Acidic paper, acid-free paper and alkaline paper • Plants alternative to trees: willow (柳), kenaf (麻). They usually have high fiber content and grow fast. • 70 million tons of paper are used in USA: one person 230 kilograms or six trees
18.2 The development of plastics involved experimentation and discovery · The search for Isoprene a lightweight, nonbreakable lymerization moldable polyisoprene material began with the Fig185 isoprene molecules invention of react with one another to vulcanized form polyisoprene, the fundamental chemical unit rubber(硫化橡 of natural rubber which 胶) comes from rubber trees
18.2 The development of plastics involved experimentation and discovery • The search for a lightweight, nonbreakable, moldable material began with the invention of vulcanized rubber (硫化橡 胶). + + isoprene polyisoprene polymerization Fig18.5 isoprene molecules react with one another to form polyisoprene, the fundamental chemical unit of natural rubber, which comes from rubber trees
Charles goodyear discovered the rubber vulcanization in 1837 Polymer strands Fig18.6 (a) when stretched the individual poly-isoprene strands in (a)Original form Stretched with little tendency natural rubberlip past to snap back to original form one another and the rubberstays stretched Polymer strands (b)when vulcanized rubber is stretched the sulfur crosslinks hold the strands together allowing the rubber to return to its original shape (b)Original form with disulfide Stretched with great tendency to cross-inks snap back because of cross-links
Charles Goodyear discovered the rubber vulcanization in 1837. (a) Original form Stretched with little tendency to snap back to original form Stretched with great tendency to snap back because of cross-links (b) Original form with disulfide cross-links Fig18.6 (a) when stretched, the individual poly-isoprene strands in natural rubber slip past one another and the rubber stays stretched. (b) when vulcanized rubber is stretched, the sulfur cross-links hold the strands together, allowing the rubber to return to its original shape Polymer strands Polymer strands