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Crystallization kinetics and tensile modulus of blends of metallocene short‐chain branched polyethylene with conventional polyolefins
Author(s) -
Peng Ya,
Zhang Qin,
Du Rongni,
Fu Qiang
Publication year - 2005
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.20702
Subject(s) - materials science , polyethylene , high density polyethylene , low density polyethylene , crystallization , composite material , differential scanning calorimetry , polyolefin , tacticity , crystallite , polymer blend , ultimate tensile strength , polymer chemistry , dynamic mechanical analysis , phase (matter) , polymerization , chemical engineering , copolymer , polymer , organic chemistry , chemistry , thermodynamics , physics , layer (electronics) , engineering , metallurgy
In this study, blends of metallocene short‐chain branched polyethylene (SCBPE) with low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), polystyrene (PS), ethylene–propylene–diene monomer (EPDM), and isotactic polypropylene (iPP) were prepared in weight proportions of 80 and 20, respectively. The crystallization behaviors of these blends were studied with polarized light microscopy (PLM) and differential scanning calorimetry. PLM showed that SCBPE/LDPE, SCBPE/HDPE, and SCBPE/EPDM formed band spherulites whose band widths and sizes were both smaller than that of pure SCBPE. No spherulites were observed, but tiny crystallites were observed in the completely immiscible SCBPE/PS, and the crystallites in SCBPE/iPP became smaller; only irregular spherulites were seen. The crystallization kinetics and mechanical properties of SCBPE were greatly affected by the second polyolefin but in different way, depending on the phase behavior and the moduli of the second components. SCBPE may be phase‐miscible in the melt with LDPE, HDPE, and EPDM but phase‐separated during crystallization. A big change in the crystal morphology and crystallization kinetics existed in the SCBPE/iPP blend. The mechanical properties of the blends were also researched with dynamic mechanical analysis (DMA). DMA results showed that the tensile modulus of the blends had nothing to do with the phase behavior but only depended on the modulus of the second component. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1816–1823;2005