The correlation between structure and β-nucleation efficiency of Ba, Sr, Ca and Mg pimelates in isotactic polypropylene

Abstract

The pimelates of the earth-alkaline elements and pimelic acid have been synthesized and studied. All prepared pimelates are crystallohydrates and Ba and Sr pimelates are isotypic. The obtained compounds have been characterized using infrared spectroscopy and X-ray diffraction, and it was found that, near and above the melting temperature of polypropylene, the pimelates of Ba and Sr are crystalline, whereas the ones of Ca and Mg are amorphous. The nucleation activity of these pimelates has been studied in the process of crystallization of polypropylene in non-isothermal conditions and followed by differential scanning calorimetry (at cooling rate V c = 1-20 K min -1 ). It was found that their nucleation activity, even at concentration of 0.1 %, differs considerably with regards to the cooling rate, and they induce different polymorphic composition of the polymer. The nucleation activity was mostly exhibited by Ca pimelate, and when it was used the content of the β crystalline phase (U β ) in polypropylene ranged from 0.90 to 0.94, depending on the cooling rate, compared to 0.18-0.35 when Mg pimelate was used. In the polymer crystallized by using Ba and Sr pimelate as nucleators, U β ranged from 0.47 to 0.77. Based on the theoretical concepts for nucleation activity of solid substrates, an attempt was made to correlate the structurаl features of the synthesized pimelates with their β-nucleation activity in the process of nonisothermal crystallization of iPP. ). Беше најдено дека нивната нуклеациона активност и при концентрации од 0,1 % значително се разликува во зависност од брзината на ладење и се добива различен однос на полиморфните модификации на полимерот. Најизразена беше нуклеационата активност на пимелатот на Ca, а во случајот кога тој беше употребен, содржината на β-кристалната фаза (U β ) во полипропиленот беше од 0,90 до 0,94, во  Dedicated to Academician Gligor Jovanovski on the occasion of his 70 th birthday.A. Janevski, G. Bogoeva-Gaceva, V. Stefov, M. Najdoski Maced. J. Chem. Chem. Eng. 34 (1), 189-199 (2015) 190 зависност од брзината на ладење, споредено со 0,18-0,35 кога беше употребен пимелат на Mg. Во полимерот кристализиран со употреба на пимелати на Ba и Sr како нуклеатори, U β е од 0,47 до 0,77. Имајќи ги предвид теоретските концепти за нуклеационата активност на супстратите, беше направен обид да се корелираат структурите на синтетизираните пимелати со нивната β-нуклеациона активност во процес на неизотермална кристализација на iPP.

New Understanding on Regulating the Crystallization and Morphology of the β-Polymorph of Isotactic Polypropylene Based on Carboxylate–Alumoxane Nucleating Agents

“…Lanthanum complex of β-cyclodextrin-maleicanhydride (β-CD-MAH-La), heteronuclear dimetal complexes of lanthanum and calcium containing some specific ligands also shown to nucleate iPP in the β-phase. However, a correlation of the molecular structure with efficiency is not available although preliminary efforts have not yielded concrete results on their elusive role in controlling the morphology. − …”

Novel polypropyleneβ‐nucleating agent with polyhedral oligomeric silsesquioxane core: synthesis and application

“…In previous literature, various β ‐NAs have been reported, such as: γ ‐quinacridone E3B, Indigosol Grey IBL and Cibantine Blue 2B pigments, calcium salts of suberic or pimelic acid, calcium tetrahydrophthalate, dicyclohexylterephthalamide, p ‐cyclohexylamidecarboxybenzene, the most commonly used N , N ′‐dicyclohexylnaphthalene‐2,6‐dicarboxamide and others …”