Iindaba

01 Intsingiselo Yokusebenza Kwempembelelo

Abantu abaninzi, xa besiva "ukuchasana nempembelelo," bacinga ngoko nangoko "ngokuqina." Kodwa yintoni kanye kanye ukuqina? Ngamafutshane, kukuba ingaba into ethile inokukhupha amandla ngokufanelekileyo xa ichaphazeleka.

Ukuba amandla angasasazeka kakuhle, loo nto "inzima"; ukuba amandla agxininiswe kwindawo enye, "ayaqina."

Ngoko ke iipolymers ziwachitha njani amandla? Ngokuyintloko ngeendlela ezintathu:

• Intshukumo yecandelo leentambo: Xa amandla angaphandle ehlasela, iintambo zemolekyuli zikhupha amandla ngokujikeleza kwangaphakathi, ukugoba, nokutyibilika. Iintambo zemolekyuli zinoku "phepha," zigobe, kwaye zityibilike;

• Ukuguquguquka kwendawo encinci: Njengerabha, amasuntswana erabha abangela ukurhawuzelelwa kwi-matrix, efunxa amandla empembelelo. Ulwakhiwo lwesigaba sangaphakathi lunokuguquka luze lubuyele esiqhelweni; 

• Iindlela zokuphambuka kweentanda kunye nokufunxa amandla: Ulwakhiwo lwangaphakathi lwezinto (ezifana ne-phase interfaces kunye nezizalisi) lwenza indlela yokusasazeka kweentanda ibe nzima, ibambezele ukuqhekeka. Ngamafutshane, intanda ayihambi ngendlela ethe tye kodwa iyaphazamiseka, iphambukile, kwaye ayisebenzi kakuhle yisakhiwo sangaphakathi.

Uyabona, amandla okuchasana asikokuba "amandla okumelana nokuqhekeka," kodwa "kukukwazi ukulahla amandla ngokuwathumela kwenye indawo."

Oku kukwachaza into eqhelekileyo: ezinye izinto zinamandla aphezulu okutsalwa kwaye ziyaqhekeka lula xa zitshayiswa; umzekelo, iiplastiki zobunjineli ezifana ne-PS, i-PMMA, kunye ne-PLA.

Ezinye izinto, nangona zinamandla aphakathi, zinokumelana nempembelelo. Isizathu kukuba ezo zokuqala azinandawo "yokuchitha amandla," ngelixa ezo zamva nje "zichitha amandla." Imizekelo ibandakanya amaphepha kunye neentonga ze-PA,PPkunye nezixhobo ze-ABS.

Ngokwembono ye-microscopic, xa amandla angaphandle ehlasela ngephanyazo, inkqubo ifumana isantya esiphezulu kakhulu soxinzelelo, esifutshane kangangokuba neemolekyuli azinakusabela ngexesha.

Kule ndawo, iintsimbi zisasaza amandla ngokutyibilika, iiseramikhi zikhupha amandla ngokuqhekeka, ngelixa iipolymers zifunxa impembelelo ngokuhamba kwecandelo leetyathanga, ukuqhekeka kwebhondi yehydrogen enamandla, kunye nokuguquguquka okudibeneyo kweendawo zekristale kunye ne-amorphous.

Ukuba iitsheyini zemolekyuli zinokuhamba okwaneleyo ukulungisa ukuma kwazo nokuzihlela kwakhona ngexesha, zisasaze amandla ngokufanelekileyo, ngoko ukusebenza kwempembelelo kulungile. Ngokwahlukileyo koko, ukuba inkqubo iqinile kakhulu—intshukumo yecandelo letsheyini ithintelwe, ikristali iphezulu kakhulu, kwaye ubushushu bokutshintsha kweglasi buphezulu kakhulu—xa kufika amandla angaphandle, onke amandla agxininiswa kwindawo enye, kwaye umngxuma usasazeka ngokuthe ngqo.

Ngoko ke, eyona nto iphambili ekusebenzeni kwempembelelo asikokuba "bulukhuni" okanye "amandla," kodwa kukwazi kwezinto ukusasaza kwakhona nokukhupha amandla ngexesha elifutshane kakhulu.

 

02 I-Notched vs. I-Notched: Akukho Luvavanyo Lunye, Kodwa Iindlela Ezimbini Zokusilela

"Amandla empembelelo" esidla ngokuthetha ngawo aneentlobo ezimbini: 

• Impembelelo engachazwanga: Ihlola "umthamo wokusasazwa kwamandla ngokubanzi" wesixhobo; 

• Impembelelo echongiweyo: Ihlola "ukuxhathisa kwencam yokuqhekeka."

Impembelelo engachazwanga ilinganisa amandla esixhobo okufunxa nokukhupha amandla empembelelo. Ilinganisa ukuba ingaba isixhobo sinokufunxa amandla ngokutyibilika kwe-molecular chain, ukujika kwe-crystalline, kunye nokuguquguquka kwesigaba serabha ukususela ngexesha apho sinyanzelwa khona de kube sekwaphukeni. Ke ngoko, amanqaku aphezulu empembelelo engachazwanga adla ngokubonisa inkqubo eguquguqukayo, ehambelanayo nenokusasazeka kakuhle kwamandla.

Uvavanyo lwempembelelo olunezikhewu lulinganisa ukumelana kwezinto nokwanda kweentanda phantsi kweemeko zoxinzelelo. Ungacinga ngayo "njengokunyamezela kwenkqubo ukwanda kweentanda." Ukuba ukusebenzisana phakathi kweemolekyuli kunamandla kwaye amacandelo eetsheyini anokuphinda ahlengahlengise ngokukhawuleza, ukwanda kweentanda kuya "kuncitshiswa" okanye "kungashukumi."

Ngoko ke, izixhobo ezinokumelana nempembelelo ephezulu zihlala zineendlela ezinamandla zokunxibelelana phakathi kwe-interfacial okanye iindlela zokusasaza amandla, ezifana neebhondi ze-hydrogen phakathi kweebhondi ze-ester kwi-polycarbonate, okanye ukuqhekeka kunye nokuqhekeka phakathi kwe-interfacial kwiinkqubo zokuqinisa irabha. 

Kungoko ke ezinye izinto (ezifana nePP, PA, ABS, kunye nePC) zisebenza kakuhle kuvavanyo lwempembelelo olungakhange lubekwe kodwa zibonisa ukwehla okukhulu kukumelana nempembelelo okuphawulweyo, nto leyo ebonisa ukuba iindlela zazo zokusasaza amandla ngemicroscope azikwazi ukusebenza kakuhle phantsi kweemeko zoxinzelelo.

 

03 Kutheni ezinye izinto zingachaphazeleki?

Ukuze siqonde oku, kufuneka sijonge kwinqanaba leemolekyuli. Ukumelana nempembelelo yezinto zepolymer kuxhaswa zizinto ezintathu ezisisiseko:

1. Amacandelo eetsheyini aneedigri zenkululeko:

Umzekelo, kwi-PE (I-UHMWPE, HDPE), i-TPU, kunye neePC ezithile eziguquguqukayo, iziqwenga zetyathanga zinokusasaza amandla ngotshintsho lwesakhiwo phantsi kwempembelelo. Oku ngokusisiseko kuvela ekufunxweni kwamandla ziintshukumo zangaphakathi kweemolekyuli ezifana nokolula, ukugoba, kunye nokujija kweebhondi zeekhemikhali.

2. Ulwakhiwo lwesigaba lunendlela yokubopha: Iinkqubo ezifana neHIPS, ABS, kunye nePA/EPDM ziqulathe ii-soft phases okanye ii-interfaces. Xa zitshatyalaliswa, ii-interfaces ziqala ngokufunxa amandla, zikhuphe i-bond, zize ziphinde zihlangane.Njengeeglavu zebhokisi—iiglavu azinyusi amandla, kodwa zandisa ixesha loxinzelelo kwaye zinciphisa uxinzelelo oluphezulu. 

3. "Ukunamathelana" phakathi kweemolekyuli: Ezinye iinkqubo ziqulathe iibhondi zehydrogen, ukusebenzisana kwe-π–π, kwanokusebenzisana kwe-dipole. Ezi ntsebenziswano zibuthathaka "zizincama" ukuze zifunxe amandla xa zitshayiswa, zize emva koko zibuyele esiqhelweni kancinci kancinci.

Ngoko ke, uza kufumanisa ukuba ezinye iipolymers ezinamaqela e-polar (afana ne-PA kunye ne-PC) zivelisa ubushushu obukhulu emva kokuchaphazeleka—oko kungenxa “yobushushu obuqhawukayo” obuveliswa zii-electron kunye neemolekyuli. 

Ngamafutshane, uphawu oluqhelekileyo lwezinto ezinganyangekiyo kukuba zisasaza amandla ngokukhawuleza ngokwaneleyo kwaye aziwi zonke ngaxeshanye.

 

NGAPHEZU's UHMWPE kunyeIphepha le-HDPEIimveliso zeplastiki zobunjineli ezinokumelana okuhle kakhulu nempembelelo. Njengezinto eziphambili kumashishini oomatshini bemigodi kunye noobunjineli bokuthutha, zithathe indawo yentsimbi yekhabhoni kwaye zaba lolona khetho lukhethwayo kwiilinings zelori kunye neelinings ze-bunker zamalahle. 

Ukumelana kwazo kakhulu nempembelelo kuyabakhusela kwiimpembelelo ezivela kwizinto eziqinileyo ezifana namalahle, ukukhusela izixhobo zothutho. Oku kunciphisa imijikelo yokutshintshwa kwezixhobo, ngaloo ndlela kuphucula ukusebenza kakuhle kwemveliso nokuqinisekisa ukhuseleko lwabasebenzi.