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English
Published
: 2022-09-21
Processing and property improvement in isotactic polypropylene by heterogeneous nucleation
Abstract
Crystallization temperature (Tm) was measured for poly-(ethyl-ene-b-propylene) copolymer in relation to 0-0.5 wt.% of a single-component nucleating agent (NA) (natrium benzoate, talc, or sorbitol derivatives) (Fig. 1) and the content of the pseudohexagonal beta-phase in PP-i (tacticity 95.6%, 97.1%; MWD 3.9, 6.3, resp.) was studied in relation to 0-0.2 wt. % of pimelic acid-calcium stearate used as a two-component NA (Fig. 3). Starting with ~ 0.2 wt % NA, the Tm leveled out. Thus, upwards of 0.15-0.25 wt.%, NA failed to raise Tm. However, even low amounts of NA gave rise to homogeneous morphology, regardless of the processing conditions (cf. Figs. 4-6). p-phase orientation was studied in relation to position along flow path at mold temperatures of 45°C and 90°C (Fig. 7). Heterogeneous-nucleated PP-i revealed somehow "frozen" flow-elongated and flow-sheared macromolecular chains, i.e., a higher level of macromolecular orientation. Nucleators, beta-phase formation, heterogeneous nucleation and like problems are reviewed (44 refs.).
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Sterzyński, T. (2022). Processing and property improvement in isotactic polypropylene by heterogeneous nucleation. Polimery, 45(11-12), 786–791. https://doi.org/10.14314/polimery.2000.786
