Tib neeg tau siv tej yam ntuj tso polymeric xws li ntoo, tawv thiab ntaub plaub txij thaum pib ntawm keeb kwm, tab sis hluavtawspolymersua tau tsuas yog tom qab kev txhim kho ntawm cov cuab yeej siv roj hmab hauv xyoo 1800s.Lub Ž rst hluavtaws polymer khoom, celluloid, tau tsim los ntawm John Wesley Hyatt hauv xyoo 1869, los ntawm cellulose nitrate thiab camphor.Ib qho kev ua txhaum loj hauv cov khoom siv hluavtaws yog qhov kev tsim ntawm Bakelite los ntawm Leo Hendrik Baekeland hauv xyoo 1907. Hermann Staudinger txoj haujlwm hauv xyoo 1920 tau qhia meej meej txog macromolecular xwm ntawm cov saw ntev ntawm kev rov ua dua units.1 lo lus 'polymer' los ntawm Greek, thiab nws txhais tau tias 'many. qhov chaw'.Kev loj hlob sai ntawm kev lag luam polymer pib sai ua ntej Tsov Rog Ntiaj Teb Zaum Ob, nrog rau kev txhim kho ntawm acrylic polymers, polystyrene, nylon, polyurethanes thiab tom qab kev taw qhia ntawm polyethylene, polyethylene terephthalate, polypropylene thiab lwm yam polymers nyob rau hauv 1940s thiab 1950s.Thaum tsuas yog kwv yees li ntawm 1 lab tons tau tsim nyob rau xyoo 1945, kev tsim cov yas hauv ntim tau dhau ntawm cov hlau hauv xyoo 1981, thiab qhov sib txawv tau loj hlob tsis tu ncua txij li thaum.
Thermoplastics feem ntau yog ua tiav hauv lub xeev molten.Molten polymers muaj qhov tseem ceeb viscosity siab heev thiab ua pov thawj shear thinning tus cwj pwm.Raws li tus nqi ntawm shearing nce, lub viscosity txo, vim yog alignments thiab disentanglements ntawm ntev molecular chains.Lub viscosity kuj txo nrog nce kub.Ntxiv nrog rau cov cwj pwm viscous, molten polymers nthuav tawm elasticity.Elasticity yog lub luag haujlwm rau ntau qhov txawv txav rheological phenomena.1 ,5 - 7 Cov no suav nrog kev so kev ntxhov siab thiab qhov sib txawv ntawm kev ntxhov siab.Kev ntxhov siab qeeb qeeb yog lub luag haujlwm rau khov hauv kev ntxhov siab hauv kev txhaj tshuaj molded thiab extruded khoom.Qhov sib txawv ntawm kev ntxhov siab ib txwm yog lub luag haujlwm rau qee qhov kev tsis sib haum xeeb thaum lub sijhawm ua haujlwm thiab tseem extrudate o, piv txwv li cov cim tsis tuaj yeem nce hauv cheeb tsam hla ntu thaum cov khoom molten yog extruded tawm ntawm qhov tuag.
Qhov tseem ceeb tshaj plaws ntawm kev ua haujlwm polymer yog extrusion thiab txhaj tshuaj molding.Extrusion yog cov khoom siv hnyav thiab kev txhaj tshuaj molding yog ua haujlwm hnyav.Ob qhov txheej txheem no suav nrog cov kauj ruam hauv qab no: (a) cua sov thiab melting lub polymer, (b) siv lub polymer rau hauv chav tsev shaping, (c) tsim cov yaj mus rau hauv cov duab thiab qhov ntev thiab (d) txias thiab solidiŽ cation. .Lwm cov txheej txheem suav nrog calendering, tshuab moulding, thermoforming, compression molding thiab rotational molding.Muaj ntau dua 30 000 qib ntawm cov polymers ua tiav los ntawm cov txheej txheem no.Qhov tsim nyog ntawm cov khoom siv rau cov txheej txheem tshwj xeeb feem ntau yog txiav txim siab los ntawm lub hauv paus ntawm melt ow Performance index (MFI, tseem hu ua melt ow rate lossis MFR).Qhov no yog ib qho kev ntsuas rov qab ntawm cov viscosity raws li qhov kev ntsuam xyuas tsis zoo uas cuam tshuam nrog kev extrusion ntawm ib lub polymer los ntawm kev tuag ntawm tus qauv qhov ntev raws li qhov kev txiav txim ntawm ib qho hnyav npaum li cas.8 Lub MFI yog tus naj npawb ntawm cov ntaub ntawv polymer sau los ntawm cov cuab yeej kuaj hauv 10 min.Tsawg MFI qhov tseem ceeb txhais tau tias siab viscosity thiab siab molecular hnyav, thiab siab MFI qhov tseem ceeb qhia qhov txawv.Cov nram qab no yog MFI ib txwm muaj rau qee cov txheej txheem: extrusion 0.01 - 10, txhaj tshuaj molding 1 - 100, tshuab moulding 0.01 - 1, rotational molding 1.5 - 20.
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Post lub sij hawm: Jan-14-2018