华东师大二附中校本课chemistryaroundus.ppt

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,Chemistry Around Us,Plastics,Plastics are used for thousands of different objects,Plastics are used for thousands of different objects,The most common types of plastics,The most common types of plastics,Polythene(PE),聚乙烯,The most common types of plastics,Polypropene(PP),聚丙烯,The most common types of plastics,Polyvinyl chloride(PVC),聚氯乙烯,The most common types of plastics,Polystyrene(PS),聚苯乙烯,The most common types of plastics,polyterafluoroethene(PTFE)or teflon,聚四氟乙烯,The most common types of plastics,Nylon,尼龙,The most common types of plastics,Urea-methanal,脲甲醛,The most common types of plastics,Perspex,有机玻璃,The most common types of plastics,Malamine,三聚氰酰胺,1.The classification of plastics,Two simple tests for classification:,The first test-heating a sample of the plastics in,boiling water or in the oil.,The second test-heating a sample of the plastics,strongly.,Two simple tests for classification,Test 1,Test 2,The wall socket chars and cracks when heated strongly,Plastics can be classified into two main types according to their thermal behavior,Thermoplastics,(,热塑性塑料,),Examples:,polythene,(PE),聚乙烯,polypropene,(PP),聚丙烯,polyvinyl chloride,(PVC),聚氯乙烯,polystyrene,(PS),聚苯乙烯,perspex,有机玻璃,nylon,尼龙,Thermosetting plastics,（,热固性塑料）,Examples:,urea-methanal,脲甲醛,melamine,三聚氰酰胺,-They are flexible.They soften and melt on,heating and re-harden on cooling.,-They are hard and rigid.They do not,soften or melt but decompose on,strong heating.,bakelite,电木,2.The formation of plastics,n,monomer,polymer,ethene,polyethene,vinyl chloride,polyvinyl chloride,n,2.The formation of plastics,Polymer（,聚合物）,-,very long molecules（,分子）,Monomer（,单体）,-,smaller molecules,Polymerization（,聚合反应）,-,the joining-up process,Polymerization can be classified into two main types,Addition polymerization,(,加聚反应,),Condensation polymerization,（缩聚反应）,2.The formation of plastics,Most of plastics are made by addition polymerization,（,加聚反应）,of Alkenes and Substituted Alkenes,(,烯烃,),(,取代烯烃,),Polythene(PE),聚乙烯,Polyvinyl chloride(PVC),聚氯乙烯,Polypropene(PP),聚丙烯,Polystyrene(PS),聚苯乙烯,Polyterafluoroethene(PTFE),聚四氟乙烯,Perspex,有机玻璃,2.The formation of plastics,Some of thermoplastics and all of thermosetting plastics,are made by condensation polymerization,（缩聚反应）,Nylon,尼龙,Urea-methanal,脲甲醛,Making nylon in the laboratory,2.The formation of plastics,2.The formation of plastics,Laboratory preparation of urea-methanal,3.,Some,useful properties of Plastics,easily shaped,reactive,waterproof,good insulators,easily colored,light,hardly shaped,unreactive,good conductors,hardly colored,heavy,flexible,strong,tough,Some useful properties of Plastics,Plastics are easily shaped,Some useful properties of Plastics,Plastics are unreactive,Some useful properties of Plastics,Plastics are flexible,Plastics are good insulators,Some useful properties of Plastics,Plastics are easily colored,Some useful properties of Plastics,Some useful properties of Plastics,Plastics are light,Some useful properties of Plastics,Plastics are waterproof,Some useful properties of Plastics,Plastics are quite strong,Some useful properties of Plastics,Plastics are tough,This is not the useful property of plastics!,Comparing plastic water pipe with metal water pipe,just as strong,more resistant to corrosion,easier to make,bend or cut,cheaper,Plastic,water pipe,Metal,water pipe,4.,Problems with Plastics,4.,Problems with Plastics,Ways of waste disposal,By incineration,Incinerating plastics as a methods of disposal is not,only wasteful but dangerous!,Air pollution,Ways of waste disposal,By landfills,Waste of land and space,Most of plastics are non-biodegradable,（,不可生物降解,）,The disposal of waste into landfill takes up a lot of,space and land,Plastic wastes are disposed into the sea,Death of many sea animals,The plastic wastes not only pollute the sea,but kill,many sea animals such as sea birds and fishes.,A sea bird gets tangled in plastic,objects,Large amount of plastic wastes,disposed to the sea.,Large amount of plastic wastes are thrown away,Waste of petroleum,All plastics are made from petroleum.,It would be worth saving if it is possible,What is the problem with plastics?,Disposal of plastic waste,What should we do?,Reusing plastics,Empty margarine box can,be used to hold stationery,Soft drink bottle can be,used to fill water,Plastic bag can be,used repeatedly,Recycled plastic,Collection points like this one can help to recycle plastics,Recycling plastics,Labels like this help to identify,the plastic for recycling,Different rubbish bins for,collection different types of,plastics,Producing more environmentally friendly products,Biodegradable plastic,Photodegradable plastic,Replacing plastics with some other materials,Reducing the use of plastics,The edible cling wrap has been produced,据报道，可食用保鲜膜在美问世。,Improving incinerating plastic waste to produce electricity,据报道，浦东新建的垃圾焚烧发电厂为缓解每年夏季,的用电高峰出了力。,Ways of recycling,They can be used as raw materials to make cheap building,materials.,2.,They can be softened by heat and passed through rollers to,make plastic sheets.,3.Specific plastics can be recycled for reuse either as the,plastic article itself or as a source of that plastic.,4.The plastic can be used as a raw material to produce more,monomers.,Ways of recycling,Black rubbish bags,Problems with recycling,The recycling of plastics from ordinary domestic waste is,very difficult.,Plastic waste is a mixture of many different chemical compounds.,There is an increasing tendency to use a mixture of plastics in the,same article.,65%polythene,and,polypropene,15%polystyrene,10%PVC,5%PET,5%other plastics,and mixtures,of plastics,Problems with recycling,This video tape is made of at least three different plastics.,How recycling is carried out,By hand,workers,consumer,The success of the operation relies on:,1.Manufacturers,2.The public and consumers,3.Government,expensive,Manufacturers just use one single type of plastic to,make plastic products.,The articles need to be clearly labeled to show the,name of this plastic.,Recycling code,PET(Polyethylene terephthalate),聚对苯二甲酸乙二酯,Recycling code,HDPE(high density polythene),高密度聚乙烯,Recycling code,PVC(Polyvinyl chloride),聚氯乙烯,Recycling code,LDPE(low density polythene),低密度聚乙烯,Recycling code,PP(Polypropene),聚丙烯,Recycling code,PS(polystyrene),聚苯乙烯,The public need to be educated on the common sense,of recycling.,Consumers should be encouraged to purchase plastic,products properly coded with the recycling codes.,The public should sort out plastic waste and place,them into,plastic-only,waste bins.,The government set up sufficient collection points to,help recycling.,The government funds the recycling program.,Another way of recycling,By pyrolysis(catalytic cracking),Pyrolysis can only play a small part in the overall problem of,what to do with plastic waste.,not very economical,Discussion,Which plastic should be,the plastic of the future,?,Why?,4.What can the general public do to help recycling,useful plastics?,2.Do you agree with the statement,to keep the two,kinds of plastics separate would be almost impossible,?,Justify your answer.,3.In your opinion,what to do with plastic waste?,