Nkhani

01 Chiyambi cha Kugwira Ntchito Mogwirizana

Anthu ambiri, akangomva "kukana mphamvu," nthawi yomweyo amaganiza za "kulimba." Koma kodi kulimba kwenikweni n'chiyani? Mwachidule, ndi ngati chinthu chingachotse mphamvu bwino chikakhudzidwa.

Ngati mphamvuyo ingathe kufalikira bwino, zinthuzo zimakhala "zolimba"; ngati mphamvuyo yakhazikika pamalo amodzi, "imakhala yofooka."

Ndiye kodi ma polima amachotsa bwanji mphamvu? Makamaka kudzera m'njira zitatu:

• Kusuntha kwa magawo a unyolo: Mphamvu yakunja ikagunda, maunyolo a mamolekyulu amataya mphamvu kudzera mu kuzungulira kwamkati, kupindika, ndi kutsetsereka. Maunyolo a mamolekyulu amatha "kuthawa," kupindika, ndi kutsetsereka;

• Kusintha kwa malo ang'onoang'ono: Monga mphira, tinthu ta mphira timayambitsa kusokonezeka mu matrix, zomwe zimayamwa mphamvu ya impact. Kapangidwe ka gawo lamkati kamatha kusokonekera kenako nkuchira; 

• Kupatuka kwa ming'alu ndi njira zoyamwira mphamvu: Kapangidwe ka mkati mwa chinthucho (monga ma phase interfaces ndi fillers) kamapangitsa njira yofalitsira ming'alu kukhala yozungulira, zomwe zimachedwetsa kusweka. Mwachidule, ming'aluyo siyenda molunjika koma imasokonezedwa, imapatuka, ndipo imachotsedwa mphamvu ndi kapangidwe ka mkati.

Mukuona, mphamvu ya kugwedezeka si "mphamvu yopirira kusweka," koma "kuthekera kotaya mphamvu poiwongolera."

Izi zikufotokozanso chinthu chofala: zipangizo zina zimakhala ndi mphamvu yokoka kwambiri ndipo zimasweka mosavuta zikagundidwa; mwachitsanzo, kupanga mapulasitiki monga PS, PMMA, ndi PLA.

Zipangizo zina, ngakhale zili ndi mphamvu zochepa, zimatha kupirira kugwedezeka. Chifukwa chake n'chakuti zoyambazo zilibe malo oti "zifafanize mphamvu," pomwe zomalizazo "zifafanize mphamvu." Zitsanzo zikuphatikizapo mapepala ndi ndodo za PA,PP, ndi zipangizo za ABS.

Kuchokera pa kawonedwe ka microscopic, pamene mphamvu yakunja ikugunda nthawi yomweyo, dongosololi limakumana ndi kuthamanga kwakukulu kwambiri, kochepa kwambiri kotero kuti ngakhale mamolekyu sangathe "kuchitapo kanthu" pakapita nthawi.

Pa nthawiyi, zitsulo zimafalitsa mphamvu kudzera mu kutsetsereka, zoumbaumba zimatulutsa mphamvu kudzera mu kusweka, pomwe ma polima amayamwa mphamvu kudzera mu kayendedwe ka unyolo, kusweka kwa mgwirizano wa haidrojeni, ndi kusintha kwa madera a kristalo ndi amofous.

Ngati maunyolo a mamolekyu ali ndi kuyenda kokwanira kuti asinthe kaimidwe kawo ndikudzikonzanso pakapita nthawi, ndikugawa mphamvu moyenera, ndiye kuti magwiridwe antchito amakhudzidwa amakhala abwino. Mosiyana ndi zimenezi, ngati dongosololi ndi lolimba kwambiri—kuyenda kwa unyolo kumakhala kocheperako, kristalo ndi wokwera kwambiri, ndipo kutentha kwa kusintha kwa galasi kumakhala kokwera kwambiri—mphamvu yakunja ikafika, mphamvu zonse zimakhazikika pamalo amodzi, ndipo ming'aluyo imafalikira mwachindunji.

Chifukwa chake, tanthauzo la magwiridwe antchito a mphamvu si "kuuma" kapena "mphamvu," koma mphamvu ya chinthucho yogawanso ndikuchotsa mphamvu munthawi yochepa kwambiri.

 

02 Yodulidwa vs. Yosadulidwa: Osati Mayeso Amodzi, Koma Njira Ziwiri Zolephera

"Mphamvu ya mphamvu" yomwe timalankhula nthawi zambiri ili ndi mitundu iwiri: 

• Kukhudza kosawoneka bwino: Kuwunika "mphamvu yonse yotayira mphamvu" ya chinthucho; 

• Kugundana kopanda kanthu: Kumafufuza "kukana kwa nsonga ya ming'alu."

Kugunda kosadulidwa kumayesa kuthekera konse kwa chinthucho kuyamwa ndi kufalitsa mphamvu ya kugunda. Kumayesa ngati chinthucho chingayamwe mphamvu kudzera mu kutsetsereka kwa unyolo wa mamolekyu, kupangika kwa kristalo, ndi kusintha kwa gawo la rabara kuyambira nthawi yomwe chagwiritsidwa ntchito mpaka kusweka. Chifukwa chake, kuchuluka kwakukulu kwa kugunda kosadulidwa nthawi zambiri kumasonyeza dongosolo losinthasintha komanso logwirizana ndi kufalikira kwa mphamvu kwabwino.

Kuyesa kwa Notched Impact kumayesa kukana kwa zinthu kufalikira kwa ming'alu pansi pa mikhalidwe yopsinjika. Mutha kuganiza kuti ndi "kulekerera kwa dongosolo kufalikira kwa ming'alu." Ngati kuyanjana kwa mamolekyulu kuli kolimba ndipo magawo a unyolo amatha kukonzedwanso mwachangu, kufalikira kwa ming'alu "kuchedwa" kapena "kungokhala chete."

Chifukwa chake, zipangizo zomwe zimakhala ndi mphamvu yolimba nthawi zambiri zimakhala ndi mphamvu zolumikizirana pakati pa zinthu kapena njira zotulutsira mphamvu, monga ma hydrogen bond pakati pa ma ester bond mu polycarbonate, kapena kupunduka kwa ma interfacial ndi kusweka mu makina omatira a rabara. 

Ichi ndichifukwa chake zinthu zina (monga PP, PA, ABS, ndi PC) zimachita bwino poyesa mphamvu zomwe sizimayikidwa bwino koma zimawonetsa kuchepa kwakukulu kwa mphamvu zomwe sizimayikidwa bwino, zomwe zikusonyeza kuti njira zawo zochepetsera mphamvu zomwe sizikugwira ntchito bwino pansi pa zovuta.

 

03 N’chifukwa chiyani zinthu zina sizimakhudzidwa ndi kugwedezeka?

Kuti timvetse izi, tiyenera kuyang'ana mulingo wa mamolekyu. Kukana kwa zinthu za polima kumathandizidwa ndi zinthu zitatu zazikulu:

1. Zigawo za unyolo zili ndi madigiri a ufulu:

Mwachitsanzo, mu PE (UHMWPE, HDPE), TPU, ndi ma PC ena osinthasintha, zigawo za unyolo zimatha kufalitsa mphamvu kudzera mu kusintha kwa mawonekedwe pamene zakhudzidwa. Izi makamaka zimachokera ku kuyamwa kwa mphamvu ndi mayendedwe amkati mwa mamolekyu monga kutambasula, kupindika, ndi kupotoza ma bond a mankhwala.

2. Kapangidwe ka gawo kali ndi njira yotetezera: Machitidwe monga HIPS, ABS, ndi PA/EPDM ali ndi magawo ofewa kapena ma interfaces. Akagunda, ma interfaces amayamba kutenga mphamvu, kuchotsa ma bond, kenako n’kubwereranso.Monga magolovesi a nkhonya—magolovesiwa sawonjezera mphamvu, koma amawonjezera nthawi yopsinjika maganizo ndi kuchepetsa kupsinjika maganizo. 

3. "Kumamatirana" pakati pa mamolekyulu: Machitidwe ena ali ndi ma hydrogen bond, π–π interactions, komanso ma dipole interactions. Ma connection ofooka awa "amadzipereka" kuti atenge mphamvu ikagundana, kenako n'kuchira pang'onopang'ono.

Chifukwa chake, mupeza kuti ma polima ena okhala ndi magulu a polar (monga PA ndi PC) amapanga kutentha kwakukulu pambuyo pa kugundana—zomwe zimachitika chifukwa cha "kutentha kokangana" komwe kumapangidwa ndi ma elekitironi ndi mamolekyu. 

Mwachidule, khalidwe lofala la zinthu zosagwedezeka ndi lakuti zimagawa mphamvu mwachangu mokwanira ndipo sizimagwa nthawi imodzi.

 

KUPITA KUMENEUHMWPE ndiPepala la HDPENdi zinthu zopangidwa ndi pulasitiki zaukadaulo zomwe zimakhala ndi kukana kwakukulu kwa kugwedezeka. Monga chinthu chofunikira kwambiri m'makampani oyendera makina amigodi ndi ukadaulo, zasintha chitsulo cha kaboni ndipo zakhala chisankho chabwino kwambiri cha zingwe zamagalimoto ndi zingwe zamakala. 

Kukana kwawo kugunda mwamphamvu kwambiri kumawateteza ku kugundana ndi zinthu zolimba monga malasha, kuteteza zida zonyamulira. Izi zimachepetsa nthawi yosinthira zida, motero zimapangitsa kuti ntchito igwire bwino ntchito komanso kuonetsetsa kuti ogwira ntchito ali otetezeka.