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Thermal, mechanical, and barrier properties of polyethylene terephthalate‐platelet nanocomposites prepared by in situ polymerization
Author(s) -
Li Shigeng,
Auddy Kausick,
Barber Peter,
Hansen Tara J.,
Ma Jisheng,
zur Loye HansConrad,
Ploehn Harry J.
Publication year - 2012
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.23146
Subject(s) - hectorite , materials science , crystallinity , nanocomposite , crystallization , polyethylene terephthalate , in situ polymerization , chemical engineering , polymerization , glass transition , polyethylene , polymer , polymer chemistry , composite material , montmorillonite , engineering
This study used in situ polymerization to prepare polyethylene terephthalate (PET) nanocomposites incorporating Ethoquad‐modified montmorillonite (eMMT), unmodified hectorite (HCT), or phenyl hectorite (phHCT) particles to study the impact of platelet surface chemistry and loading on thermal, mechanical, and gas barrier properties. eMMT platelets reduced the PET crystallization rate without altering the ultimate degree of crystallinity. In contrast, HCT and phHCT platelets accelerated the polymer's crystallization rate and increased its crystallinity. DMA results for thermally‐quenched samples showed that as T increased past glass transition temperature ( T g ), HCT and phHCT nanocomposites (and control PET) manifested precipitous drops in G ′ followed by increasing G ′ due to cold crystallization; in contrast, eMMT nanocomposites had much higher G ′ values around T g . This provides direct evidence of eMMT reinforcement in thermally‐quenched eMMT nanocomposites. These results suggest that eMMT has a strong, favorable interaction with PET, possibly through Ethoquad‐PET entanglement. HCT and phHCT have a fundamentally different interaction with PET that increases crystallization rate and T g by 11 to 17°C. Water barrier improvement in eMMT nanocomposites agrees with previously published oxygen barrier results and can be rationalized in terms of a tortuous path gas barrier model. POLYM. ENG. SCI., 52:1888–1902, 2012. © 2012 Society of Plastics Engineers