Polypropylene wani nau'in polymer ne da ake amfani da shi sosai a aikace-aikace daban-daban saboda kyawun haɗinsa na kaddarorin. Ana iya ƙara inganta halayensa, kamar na zahiri, na inji da na gani ta hanyar amfani da sinadarai masu hana nucleating da kuma sinadarai masu bayyana abubuwa. Waɗannan ƙarin abubuwa suna taimakawa wajen samar da PP yayin sarrafawa, don haka suna haɓaka kaddarorin da aka riga aka samu.

Fahimci yadda ake amfani da sinadaran nucleating da kuma masu fayyace abubuwa, da kuma samun shawarwari kan zaɓi don ƙara yawan samarwa yadda ya kamata, gyara tsari da yanayin halitta, da kuma rage hayaki a cikin tsarin polypropylene ɗinku.

I. Matsayin Masu Bayyana Nuclearing a cikin PP

Kwayar halittar polymers masu siffar semi-crystalline tana da alhakin halaye da yawa, kamar kwanciyar hankali, tsabta, da tauri.

Ga wani ɓangare da tsari da aka ƙayyade, tsarin polymer, tsari, da yanayin sarrafawa wanda ke haifar da daidaito na tarawa da sanyaya zafi. Saboda haka, lu'ulu'u sau da yawa ba shi da bambanci, tarihin zafi ya bambanta ga fata da kuma tsakiyar sassan ko kayayyaki.

Masu samar da sinadarin Nucleating da clearifiers suna hanzarta da daidaita crystallization, wanda ke ba da damar daidaita halayen ƙarshen polymers na semi-crystalline zuwa ga buƙatun aiki.

A cikin tsarin polypropylene, ƙara sinadaran nucleating (wanda kuma ake kira nucleators) yana haifar da ingantaccen aiki da kaddarorin sarrafawa, kamar:

· Ingantaccen haske da rage hazo

· Inganta ƙarfi da tauri

· Ingantaccen Zafin Rage Zafi (HDT)

· Rage lokacin zagayowar

· Rage yawan warpage da kuma ƙara yawan raguwar haske

· Rage yawan jin daɗin launin fata dangane da canje-canjen halaye tare da launuka daban-daban

· Ingantaccen aiki a wasu aikace-aikace

Saboda haka, nucleation hanya ce mai ƙarfi don inganta halayen zahiri, na inji, da na gani na polypropylene. Haske, kwanciyar hankali na girma, warpage, raguwa, CLTE, HDT, halayen injiniya da tasirin shinge za a iya inganta su ta hanyar zaɓar nucleators ko clearifiers da kyau.

II. Polypropylene da kuma yadda yake lu'ulu'u

Polypropylene wani nau'in lu'ulu'u ne da ake amfani da shi sosai, wanda aka yi shi da polymerization na propene monomer. Bayan polymerization, PP na iya samar da tsarin sarkar guda uku (atactic, isotactic, syndiotactic) dangane da matsayin ƙungiyoyin methyl. Ana siffanta lu'ulu'u na polymer ta hanyar:

· Siffofi da girman lu'ulu'u

· Rabon lu'ulu'u, kuma daga ƙarshe

· Tsarin lu'ulu'u

Isotactic polypropylene (iPP) wani nau'in polymer ne mai siffar rabin-crystalline. Yana da kyakkyawan rabo na farashi da aiki, wanda hakan ya sa yake da kyau sosai a fannoni daban-daban kamar su mota, kayan aiki, bututu, marufi, da sauransu.

Ma'aunin isotacticity na iPP yana da alaƙa kai tsaye da matakin kristal wanda ke da babban tasiri akan aikin polymer. Isotacticity yana ƙara kinetics na crystallization, yanayin lankwasawa, tauri & bayyananne, kuma yana rage juriya da ikon yin tasiri.

Teburin da ke ƙasa yana kwatanta halayen polypropylene homopolymers guda biyu waɗanda ke da ma'aunin isotacticity daban-daban.

III. Girgizar Polypropylene
Dangane da yanayin, Isotactic Polypropylene na iya zama lu'ulu'u zuwa matakai huɗu daban-daban waɗanda aka nuna α, β, γ da mesomorphic smectic. Matakan α da β sune mafi mahimmanci.

α Phase

1. Wannan matakin ya fi kwanciyar hankali kuma sananne ne.

2. Waɗannan lu'ulu'u suna cikin tsarin lu'ulu'u na monoclinic.

Matakin β

1. Wannan matakin yana da sauƙin narkewa, kuma lu'ulu'unsa suna cikin tsarin lu'ulu'u na ƙarya.

2. Matakin β galibi yana cikin polypropylene mai toshewa kuma ana iya samar da shi ta hanyar ƙara takamaiman abubuwan da ke haifar da nucleating.

3. Padden da Keith ne suka gano wannan siffar lu'ulu'u a shekarar 1953; ana iya haɓaka shi ta hanyar lu'ulu'u tsakanin 130°C da 132°C, yanayin yankewa mai yawa, ko ƙara takamaiman abubuwan da ke haifar da nuclearity.

4. Kasancewar matakin β a cikin polypropylene homopolymers yawanci yana inganta sassaucin samfurin da aka gama, kuma tasirin yana da mahimmanci lokacin da abun ciki na matakin β ya kai kashi 65%.

γ Phase

1. Wannan matakin kuma yana iya canzawa, tare da lu'ulu'u na triclinic.

2. Wannan nau'in lu'ulu'u ba kasafai yake faruwa ba; galibi yana bayyana a cikin polypropylene mai ƙarancin nauyin ƙwayoyin halitta kuma yana samuwa ne ta hanyar lu'ulu'u a ƙarƙashin matsin lamba mai yawa da ƙarancin saurin sanyaya.

Ⅳ. Tsarin Nucleation a cikin Polypropylene

An san cewa wurin farawa na lu'ulu'u na polymers shine ƙananan ƙwayoyin cuta (ƙananan ƙwayoyin cuta) waɗanda aka haɗa a cikin ragowar mai narkewa kamar narkewa, ƙazanta, ƙura, da sauransu. Sannan yana yiwuwa a gyara da kuma sarrafa yanayin lu'ulu'u ta hanyar ƙara ƙwayoyin cuta "na wucin gadi" da aka shigar a cikin narkewar polymer. Ana kiran wannan aikin Nucleation.

Ana amfani da nucleators ko nucleating agents waɗanda ke samar da wurare don fara lu'ulu'u.

Clarifiers wani ɓangare ne na nucleators waɗanda ke samar da ƙananan lu'ulu'u waɗanda ke warwatse ƙasa da haske, kuma sakamakon haka, suna ƙara haske ga kauri ɗaya na bango na wani ɓangare.

Aikin waɗannan sinadaran nucleating shine inganta halayen jiki da na injiniya na sassan da aka gama.

Ⅴ. Masu Nukiliya da Masu Bayyanawa: Wani Babban Fannin Ƙarin Abubuwa

Ma'aikatan Nucleating Barbashi

Sinadaran nucleating/nucleants yawanci mahadi ne masu narkewa masu yawa waɗanda ake warwatsewa a cikin narkewar polymer ta hanyar haɗa su. Waɗannan barbashi suna aiki a matsayin 'nuclei mai mahimmanci' wanda girman lu'ulu'u na polymer zai iya farawa.

Babban yawan ƙwayoyin cuta yana haifar da ƙarin saurin lu'ulu'u (lokacin zagayowar gajere), da kuma matakan lu'ulu'u mafi girma, wanda ke inganta ƙarfi, tauri, da HDT na PP.

Ƙaramin girman tarin lu'ulu'u (spherulites) yana haifar da raguwar watsawar haske da ingantaccen haske.

Sinadaran nucleating da ake amfani da su a yau da kullum sun haɗa da gishiri da ma'adanai, kamar talc, sodium benzoate, phosphate esters da sauran gishirin halitta.

Ana ɗaukar Talc da sodium benzoate a matsayin ƙananan aiki, masu ƙarancin farashi, kuma suna ba da ɗan ƙaramin ci gaba a ƙarfi, tauri, HDT, da lokacin zagayowar.

Manyan sinadarai masu aiki da tsada, kamar su phosphate esters da bicycloheptane gishiri suna ba da ƙarin sifofi na zahiri da kuma ɗan ci gaba a cikin haske.

Masu Nucleating Masu Narkewa

Sinadaran nucleating masu narkewa, waɗanda kuma ake kira 'masu saurin narkewa', galibi suna da ƙananan wuraren narkewa kuma suna narkewa a cikin PP mai narkewa.

Yayin da narkewar polymer ke sanyaya a cikin mold, waɗannan nucleants ɗin suna fara fitowa suna samar da hanyar sadarwa mai rarraba sosai tare da babban yanki mai faɗi.

Yayin da zafin jiki ke ci gaba da raguwar fibrils ɗin da ke ɗauke da wannan hanyar sadarwa tana aiki azaman nuclei don fara lu'ulu'u na polymer.

Yawan sinadarin nuclei yana haifar da ƙananan tarin lu'ulu'u na PP, waɗanda ke ba da mafi ƙarancin matakin watsa haske da kuma mafi kyawun haske.

Duk masu bayyana bayanai na nucleans ne, amma ba duk masu bayyana bayanai na nucleans ne masu kyau ba.

Wasu ƙwayoyin halittar da aka saba amfani da su, kamar sodium benzoate da talc, ba sa rage girman spherulite da isasshen adadin da zai ba da ƙarancin hazo da kuma wani ɓangare mai haske. Mafi kyawun haske galibi ana samunsa ne idan aka yi amfani da ƙwayoyin halittar da ke narkewa.

Sinadaran halitta masu narkewa waɗanda ke aiki azaman masu bayyana abubuwa sun haɗa da sorbitols, nonotols, da trisamides.

Duk da cewa ana amfani da waɗannan nucleans ne musamman don cimma babban haske da ƙarancin hazo, suna kuma inganta halayen jiki da rage lokacin zagayowar.

Siffar Barbashi da Rabon Al'amari

Ƙwayoyin Nuclean masu siffofi irin na allura (kamar ADK STAB NA-11) na iya haifar da ƙima daban-daban na raguwa a cikin na'ura da kuma alkiblar da ke juyawa. Wannan raguwar anisotropy na iya haifar da raguwa a ɓangaren ƙarshe. Ƙwayoyin Nuclean masu yanayin planer na iya ba da ƙarin raguwa iri ɗaya a alkibla biyu wanda zai haifar da ƙarancin raguwa.

Girman Barbashi & Rarraba Girman Barbashi

Ƙaramin girman ƙwayoyin cuta yana haifar da ingantaccen nucleation, amma ƙananan ƙwayoyin cuta kuma na iya zama da wahalar wargazawa. Wasu ƙwayoyin cuta na nuclean, kamar sodium benzoate, suna sake taruwa.

An Yi Amfani da Na'urar Rage Acid

Wasu sinadarai masu tara sinadarin acid, kamar gishirin fatty acid (misali calcium stearate) na iya zama masu adawa da wasu sinadarai masu tauri, kamar su phosphate esters da sodium benzoate. Ya kamata a yi amfani da Dihydrotalcite tare da waɗannan sinadarai masu tauri.

Kada a taɓa amfani da sinadarin calcium stearate tare da sodium benzoate domin sinadarin calcium stearate zai kawar da sinadarin sodium benzoate gaba ɗaya.

Matakin Watsawa & Kasancewar Ƙungiyoyin da Ba a Rarraba ba

Sodium benzoate sau da yawa yana samar da agglomerates kuma yana da wahalar warwatsewa yadda ya kamata.

Zafin Narkewa

Sorbitols suna buƙatar yanayin zafi mai yawa don ba da mafi kyawun haske, tunda dole ne su narke gaba ɗaya a cikin narkewar polymer.

Haɗin kai da kuma saɓani tsakanin Nucleans da sauran ƙari

Masu tattara sinadarin acid na iya zama masu haɗin kai ko kuma masu adawa da juna. Gishirin mai mai yana da mummunan tasiri ga tsarin sinadarin phosphate ester nucleated PP.

Zaɓi DamaNucleansda kuma masu bayyana PP

Kafin zaɓar wakilin nucleating ko fayyace abubuwa masu dacewa don aikace-aikacen PP ɗinku, ƙayyade wane gyara kadara kuke sha'awar:

a. Idan ƙarancin hazo da haske mai yawa suna da mahimmanci, to zaɓi ɗaya daga cikin masu bayyana haske mai narkewa.

b. Domin ƙarancin buƙatun tsabta,esters na phosphateana iya amfani da shi.

c. Idan babban modulus yana da matuƙar muhimmanci, to sai a zaɓi ɗaya daga cikin phosphate esters.

d. Idan ƙarancin farashi shine mafi mahimmanci, to sai a zaɓi sodium benzoate.

e. Idan ƙarancin warpage da ƙarancin tasirin launi sune mafi mahimmanci, to sai a zaɓi gishirin bicycloheptane.

Haka kuma yana da matuƙar muhimmanci a yanke shawara kan yadda za a haɗa sinadarin nucleant a cikin sinadarin PP. A koyaushe a gudanar da gwaje-gwaje masu dacewa don tabbatar da cewa an cimma ingantaccen warwatsewa da kuma nucleation.

A kunna DSC akan resin PP mai nucleated. Ingantaccen lokacin zagayowar gabaɗaya yana da alaƙa da ƙaruwar zafin crystallization (Tc). Gwaji halayen samfurin da aka ƙera.

Idan kuna son yin tambaya game da samfuran da suka shafi wakilan nucleating, da fatan za ku iyatuntuɓe mua kowane lokaci.