Labarai

01 Muhimmancin Ayyukan Tasiri

Mutane da yawa, da zarar sun ji "juriyar tasiri," nan take suna tunanin "tauri." Amma menene ainihin tauri? A taƙaice dai, ko abu zai iya wargaza kuzari yadda ya kamata idan aka yi masa tasiri.

Idan makamashin zai iya wargazawa cikin sauƙi, kayan zai yi "tauri"; idan makamashin ya taru a wuri ɗaya, to "yana da rauni."

To ta yaya polymers ke wargaza makamashi? Galibi ta hanyoyi uku:

• Motsin sassan sarka: Idan wani ƙarfi na waje ya buge, sarƙoƙin kwayoyin halitta suna wargaza kuzari ta hanyar juyawa ta ciki, lanƙwasawa, da zamewa. Sarƙoƙin kwayoyin halitta na iya "tserewa," lanƙwasawa, da zamewa;

• Canzawar ƙananan yankuna: Kamar roba, ƙwayoyin roba suna haifar da hauka a cikin matrix, suna shan kuzarin tasiri. Tsarin yanayin ciki na iya canzawa sannan ya murmure; 

• Hanyoyin karkatar da tsagewa da kuma shakar kuzari: Tsarin ciki na kayan (kamar hanyoyin haɗin lokaci da abubuwan cikawa) yana sa hanyar yaɗuwar tsagewa ta zama mai wahala, tana jinkirta karyewa. A cikin sauƙi, tsagewar ba ta gudana a layi madaidaiciya amma tsarin ciki yana wargaza ta, yana karkatar da ita, kuma ba ta da alaƙa da tsarin.

Ka gani, ƙarfin tasiri ba a zahiri "ƙarfin da za a iya jure wa karyewa ba," a'a, "ikon wargaza kuzari ta hanyar mayar da shi baya."

Wannan kuma yana bayanin wani abu da ya zama ruwan dare gama gari: wasu kayan suna da ƙarfin tauri mai yawa kuma suna karyewa cikin sauƙi idan aka yi musu tasiri; misali, injinan robobi kamar PS, PMMA, da PLA.

Sauran kayan, duk da cewa suna da matsakaicin ƙarfi, suna iya jure wa tasiri. Dalilin shi ne cewa na farko ba shi da inda zai "rage kuzari," yayin da na biyun kuma "rage kuzari." Misalan sun haɗa da zanen gado da sandunan PA,PP, da kayan ABS.

Daga hangen nesa na ƙananan halittu, lokacin da wani ƙarfi na waje ya buge nan take, tsarin yana fuskantar babban ƙarfin matsin lamba, wanda ya yi gajere har ma ƙwayoyin ba za su iya "mayar da martani" cikin lokaci ba.

A wannan lokacin, karafa suna watsa makamashi ta hanyar zamewa, yumbu yana fitar da makamashi ta hanyar fashewa, yayin da polymers ke shan tasirin ta hanyar motsi na sassan sarka, fashewar haɗin hydrogen mai ƙarfi, da kuma daidaita canjin yanayin lu'ulu'u da amorphous.

Idan sarƙoƙin ƙwayoyin halitta suna da isasshen motsi don daidaita yanayinsu da sake tsara kansu a kan lokaci, suna rarraba makamashi yadda ya kamata, to aikin tasirin yana da kyau. Akasin haka, idan tsarin ya yi tsauri sosai - motsi na sassan sarka yana da iyaka, lu'ulu'u yana da yawa, kuma zafin canjin gilashin ya yi yawa - lokacin da ƙarfin waje ya iso, duk kuzarin yana ta'azzara a kan wuri ɗaya, kuma fashewar tana yaɗuwa kai tsaye.

Saboda haka, ainihin aikin tasiri ba shine "taurin" ko "ƙarfi ba," amma ikon kayan na sake rarrabawa da kuma wargaza makamashi cikin ɗan gajeren lokaci.

 

02 Notched vs. Unnotched: Ba Gwaji Ɗaya Ba, Amma Hanyoyi Biyu Na Rashin Nasara

"Ƙarfin tasiri" da muke magana akai a kai a zahiri yana da nau'i biyu: 

• Tasirin da ba a san shi ba: Yana bincika "ƙarfin watsar da makamashi gaba ɗaya" na kayan; 

• Tasirin da aka gano: Yana bincika "juriyar tip ɗin tsagewa."

Tasirin da ba a san shi ba yana auna ƙarfin kayan gabaɗaya na sha da kuma wargaza kuzarin tasiri. Yana auna ko kayan zai iya shan makamashi ta hanyar zamewar sarkar kwayoyin halitta, samar da kristal, da kuma nakasar matakin roba tun daga lokacin da aka tilasta shi har zuwa karyewa. Saboda haka, babban maki na tasirin da ba a san shi ba sau da yawa yana nuna tsarin sassauƙa, mai jituwa tare da ingantaccen watsa makamashi.

Gwajin tasirin da aka yi wa alama yana auna juriyar abu ga yaɗuwar tsagewa a ƙarƙashin yanayin yawan damuwa. Za ku iya ɗaukarsa a matsayin "juriyar tsarin don yaɗuwar tsagewa." Idan hulɗar tsakanin ƙwayoyin halitta tana da ƙarfi kuma sassan sarka za su iya sake tsarawa da sauri, yaɗuwar tsagewa za ta "rage gudu" ko "ba ta da amfani."

Saboda haka, kayan da ke da juriya ga tasirin da ba su da ƙarfi galibi suna da ƙarfin hulɗar fuska ko hanyoyin watsa makamashi, kamar haɗin hydrogen tsakanin haɗin ester a cikin polycarbonate, ko haɗin fuska da haɓaka a cikin tsarin tauri na roba. 

Wannan kuma shine dalilin da ya sa wasu kayayyaki (kamar PP, PA, ABS, da PC) suke yin aiki mai kyau a gwajin tasiri mara kyau amma suna nuna raguwar juriyar tasiri mai ƙarfi, wanda ke nuna cewa hanyoyin watsa makamashin su na ƙananan ƙwayoyin cuta ba sa aiki yadda ya kamata a ƙarƙashin yanayin tattarawar damuwa.

 

03 Me yasa wasu kayan aiki ke jure wa tasirin abubuwa?

Domin fahimtar wannan, muna buƙatar duba matakin kwayoyin halitta. Juriyar tasirin kayan polymer yana da alaƙa da muhimman abubuwa guda uku:

1. Sassan sarka suna da matakan 'yanci:

Misali, a cikin PE (UHMWPE, HDPE), TPU, da wasu sassan sarka masu sassauƙa, sassan sarka na iya wargaza makamashi ta hanyar canje-canjen yanayi a ƙarƙashin tasirinsu. Wannan a zahiri ya samo asali ne daga shaƙar makamashi ta hanyar motsin ƙwayoyin halitta kamar shimfiɗawa, lanƙwasawa, da karkatar da haɗin sinadarai.

2. Tsarin tsari yana da tsarin buffering: Tsarin kamar HIPS, ABS, da PA/EPDM suna ɗauke da matakai masu laushi ko hanyoyin haɗin gwiwa. Bayan tasiri, hanyoyin haɗin gwiwa suna fara shan makamashi, suna cire haɗin gwiwa, sannan su sake haɗawa.Kamar safar hannu ta dambe—safofin hannu ba sa ƙara ƙarfi, amma suna tsawaita lokacin damuwa kuma suna rage matsin lamba. 

3. "Mannewa tsakanin ƙwayoyin halitta": Wasu tsarin suna ɗauke da haɗin hydrogen, hulɗar π–π, har ma da hulɗar dipole. Waɗannan hulɗar masu rauni suna "sadaukar da kansu" don shan kuzari bayan tasiri, sannan a hankali su murmure.

Saboda haka, za ku ga cewa wasu polymers masu ƙungiyoyin polar (kamar PA da PC) suna samar da zafi mai yawa bayan tasiri - wannan ya faru ne saboda "zafin gasa" da electrons da molecules ke samarwa. 

A taƙaice dai, halayyar da aka fi sani da kayan da ke jure wa tasiri ita ce suna sake rarraba makamashi cikin sauri kuma ba sa rugujewa gaba ɗaya.

 

WATA KWANAUHMWPE naTakardar HDPEs sune kayayyakin injiniya na filastik waɗanda ke da kyakkyawan juriya ga tasiri. A matsayin babban kayan aiki a masana'antar kera ma'adinai da sufuri na injiniya, sun maye gurbin ƙarfen carbon kuma sun zama zaɓin da aka fi so ga layin manyan motoci da rufin bunker na kwal. 

Ƙarfin juriyarsu ga tasirin yana kare su daga tasirin kayan aiki masu tauri kamar kwal, kare kayan aikin sufuri. Wannan yana rage zagayowar maye gurbin kayan aiki, ta haka yana inganta ingancin samarwa da kuma tabbatar da tsaron ma'aikata.