Polymer Processing Sumo Chikamu 2

Rudzi rwevanhu rwakashandisa zvinhu zvakasikwa zvepolymeric senge huni, dehwe nemvere kubva pakutanga kwenhoroondo, asi zvakagadzirwa.polymerszvakazogoneka chete mushure mekugadzirwa kwehunyanzvi hwerabha muma1800s.Iyo yekutanga synthetic polymer zvinhu, celluloid, yakagadzirwa naJohn Wesley Hyatt muna 1869, kubva ku cellulose nitrate uye camphor.Kubudirira kukuru mukugadzirwa kwemapolima kwaive kugadzirwa kweBakelite naLeo Hendrik Baekeland muna 1907. Basa raHermann Staudinger kuma1920s rainyatsoratidza macromolecular maitiro emacheni marefu anodzokorora mayunitsi.1 Shoko rokuti 'polymer' rinobva muchiGiriki, uye rinoreva 'zvizhinji. zvikamu'.Kukura nekukurumidza kweindasitiri yepolymer kwakatanga nguva pfupi Hondo Yenyika Yechipiri isati yatanga, nekuvandudzwa kwema acrylic polymers, polystyrene, nylon, polyurethanes uye kwakazounzwa polyethylene, polyethylene terephthalate, polypropylene uye mamwe mapolymers kuma1940 nema1950s.Nepo matani angangoita miriyoni imwe chete akagadzirwa muna 1945, kugadzirwa kwemapurasitiki muhuwandu kwakapfuura kuya kwesimbi muna 1981, uye gaka iri riri kuramba richikura kubva ipapo.

Thermoplastics inowanzogadziriswa munzvimbo yakanyungudutswa.Mapolymer akanyungudutswa ane akanyanya kunaka e viscosity uye anoratidza shear kutetepa maitiro.Sezvo mwero wekuveura unowedzera, iyo viscosity inodzikira, nekuda kwekumisikidza uye kupatsanurwa kwemaketani akareba mamorekuru.Iyo viscosity zvakare inoderera nekuwedzera tembiricha.Pamusoro pehunhu hwe viscous, mapolima akanyunguduka anoratidza elasticity.Elasticity inokonzera huwandu husina kujairika rheological phen- omena.1 ,5 - 7 Izvi zvinosanganisira kuzorora kwekunetseka uye normalstress kusiyana.Kuzorora kunonoka kushushikana kunokonzeresa chando mukushushikana mune jekiseni rakaumbwa uye extruded zvigadzirwa.The zvakajairika kushushikana misiyano vane mhosva vamwe ow instabilities panguva processing uyewo extrudate kuzvimba, kureva kuti signiŽ cant kuwedzera muchinjikwa-Sectional nzvimbo kana yakanyungudutswa zvinhu extruded kunze kufa.

Iyo inonyanya kukosha polymer kugadzirisa mashandiro ndeye extrusion uye jekiseni kuumba.Extrusion inonetsa zvinhu uye jekiseni kuumba kune basa rakawanda.Maitiro ese aya anosanganisira kutevedzana kwematanho anotevera: (a) kupisa nekunyungudusa polima, (b) kupomba polima kuchikamu chekuumba, (c) kugadzira kunyunguduka kuita chimiro chinodiwa uye zviyero uye (d) kutonhora uye solidiŽ cation. .Dzimwe nzira dzekugadzirisa dzinosanganisira calendering, kuumba kuvhuvhuta, thermoforming, compression molding uye kutenderera kuumbwa.Kune anopfuura 30 000 mamakisi emapolymer akagadziriswa nenzira idzi.Kukodzera kwezvinhu zveimwe nzira inowanzosarudzwa pahwaro hweiyo melt ow index (MFI, inonziwo melt ow rate kana MFR).Iyi inverse chiyero che viscosity yakavakirwa pamuyedzo wakashata unosanganisira extrusion yepolymer kuburikidza nekufa kwezviyero zvakajairwa pasi pekuita kwehuremu hwakatarwa.8 Iyo MFI inhamba yemagiramu epolymer akaunganidzwa kubva muyedzo mudziyo mu10 min.Low MFI values ​​zvinoreva high viscosity uye yakakwirira molecular uremu, uye yakakwirira MFI tsika dzinoratidza zvinopesana.Izvi zvinotevera zvakajairwa MFI renji kune mamwe maitiro: extrusion 0 .01 - 10, jekiseni molding 1 - 100, blow molding 0 .01 - 1, rotational molding 1.5 - 20.

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