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Preparation of long‐chain branching polypropylene and investigation on its foamability
Author(s) -
Zhang Wen,
Yang Lili,
Chen Peng,
Zhang Huaji,
Lin Wei,
Wang Yuexiang
Publication year - 2013
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.23416
Subject(s) - branching (polymer chemistry) , polypropylene , materials science , rheology , scanning electron microscope , fourier transform infrared spectroscopy , polymer chemistry , compression molding , composite material , chemical engineering , mold , engineering
In this work, zinc N , N ‐dimethyldithiocarbamate (ZDMC) was used to mediate the melt modification of polypropylene (PP) with 1,6‐hexanediol diacrylate (HDDA) in an internal mixer in the presence of dicumyl peroxide (DCP). Fourier transformed infrared spectroscopy analysis revealed that HDDA was directly grafted onto PP backbone. The dependence of torque on processing time indicated that the presence of ZDMC restrained the degradation of PP, and the end‐torque value increased with the addition of ZDMC. Dynamic rheological measurement indicated that the modified PP possessed higher G ′ and lower tan δ at low frequency, displaying an increase in η* and disappearance of Newtonian plateau in η*–ω plot, as well as larger radius of semicircle in Cole–Cole plot. All the rheological characterizations, together with the decreased gel content with the increase of ZDMC, confirmed the formation of long‐chain branching. Subsequently, the foamability of the modified samples was investigated by one‐step compression–molding process. The cellular structure and morphology of the obtained foams were observed by scanning electron microscopy, and the results showed that the addition of ZDMC decreased the cell size, increased the cell density, and brought about well‐defined closed cell structure. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers