Anisotropic Linear and Volumetric Thermal‐Expansion Behaviors of Self‐Standing Polyimide Films Analyzed by Thermomechanical Analysis (TMA) and Optical Interferometry. Issue 3 (11th October 2017)

• Record Type: Journal Article
• Authors: Ando, Shinji; Sekiguchi, Kenji; Mizoroki, Masashi; Okada, Tomohiro; Ishige, Ryohei
• Other Names: Unterlass Miriam M. guestEditor.; Ando Shinji guestEditor.; Tsui Ophelia K. C. guestEditor.
• Is Part Of: Macromolecular chemistry and physics. Volume 219:Issue 3(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-10-11
• Subjects: β‐relaxation temperature -- coefficient of thermal expansion -- molecular packing -- orientation coefficient -- polyimide; Polymers -- Periodicals; Polymerization -- Periodicals; Synthetic products -- Periodicals; Macromolecules -- Periodicals; 547.7
• DOI: 10.1002/macp.201700354
• Languages: English
• ISSNs: 1022-1352

Abstract

Abstract: The relationships between the molecular structure, polymer chain orientation, β‐transition temperature, and the coefficients of in‐plane and out‐of‐plane linear thermal expansions (CTE, α), as well as the coefficients of volumetric thermal expansion (CVE, β), are extensively examined for ten types of self‐standing aromatic polyimide (PI) films via thermomechanical analysis, near‐infrared optical interferometry, and dynamic mechanical analysis. The out‐of‐plane CTEs (α⊥ ) of PI films having rigid‐rod structures are 20–40 times larger than their in‐plane CTEs (α// ), whereas the α⊥ values of PI films having bent linkages in the main chains are comparable to their α// values. In addition, the values of normalized anisotropy in CTE for PIs (η), defined as (α⊥ −α// )/β, are proportional to the orientation coefficients ( P 200 ) estimated from the in‐plane/out‐of‐plane birefringence (Δ n ) and molecular polarizability tensor. Furthermore, larger CVE values are observed for PIs exhibiting lower β‐relaxation temperatures ( Tβ ), at which localized molecular motion occurs. In contrast, smaller CVE values are observed for PIs exhibiting higher Tβ s because their local molecular motions are suppressed due to the structural rigidity and dense molecular packing. Abstract : In‐plane and out‐of‐plane thermal‐expansion behaviors, as well as volumetric thermal expansion behavior, are quantitatively examined for ten types of self‐standing polyimide films via thermomechanical analysis (TMA), near‐Infrared interferometry, and dynamic mechanical analysis (DMA). The relationships between the molecular structure, chain orientation, β‐transition temperatures, and the coefficients of in‐plane and out‐of‐plane linear thermal expansions, as well as those of volumetric thermal expansion, are discussed.