Co-crystallization of Blends of High-density Polyethylene with Linear Low-density Polyethylene: An Investigation with Successive Self-nucleation and Annealing (SSA) Technique

• Published in: Journal of macromolecular science. Physics Vol. 52; no. 10; pp. 1372 - 1387
• Main Authors: Sun, Xin, Shen, Guanghao, Shen, Hongwang, Xie, Banghu, Yang, Wei, Yang, Mingbo
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 2013; Taylor & Francis
• Subjects: Annealing; Applied sciences; Blends; Chain branching; Co-crystallization; Crystallization; Deviation; Exact sciences and technology; Melting; molecular weight distribution; Organic polymers; Physicochemistry of polymers; polyethylene blends; Polyethylenes; Polymer blends; Properties and characterization; Stepped; successive self-nucleation and annealing; Polymer blends; polyethylene blends; High density ethylene polymer; Cocrystallization; molecular weight distribution; Nanostructure; Experimental study; Lattice parameters; Structure composition relationship; Melt crystallization; Low density ethylene polymer; Olefin polymer; Co-crystallization; successive self-nucleation and annealing; Crystalline structure
• ISSN: 0022-2348; 1525-609X
• DOI: 10.1080/00222348.2013.768504

Two kinds of polyethylenes, high-density polyethylene (HDPE) with few chain branches and short-chain branched linear low-density polyethylene (LLDPE) with a relatively larger average molecular weight, were melt blended together in various mass ratios based on consideration of their practical applications. After identifying the good compatibility of the blends, their crystallization behaviors were studied by the successive self-nucleation and annealing (SSA) technique. The SSA analysis showed that not merely the number of melting fractions in the SSA curves changed with the blend composition, but also the content of the first two melting fractions at high temperature of SSA curves showed a positive deviation and a negative deviation with the blend composition, respectively. These phenomena, as well as the interesting appearance of a stepped increase of the lamellar thickness of each fraction with the highest temperature in each sample, indicated that co-crystallization occurred between HDPE and LLDPE. The results from wide-angle X-ray diffraction (WAXD) supported the conjecture obtained by the SSA analysis.