title: Unveiling the dependence of glass transitions on mixing thermodynamics in miscible systems.
abstract: The dependence of the glass transition in mixtures on mixing thermodynamics is examined by focusing on enthalpy of mixing, ΔHmix with the change in sign (positive vs. negative) and magnitude (small vs. large). The effects of positive and negative ΔHmix are demonstrated based on two isomeric systems of o- vs. m-methoxymethylbenzene (MMB) and o- vs. m-dibromobenzene (DBB) with comparably small absolute ΔHmix. Two opposite composition dependences of the glass transition temperature, Tg, are observed with the MMB mixtures showing a distinct negative deviation from the ideal mixing rule and the DBB mixtures having a marginally positive deviation. The system of 1, 2- propanediamine (12PDA) vs. propylene glycol (PG) with large and negative ΔHmix is compared with the systems of small ΔHmix, and a considerably positive Tg shift is seen. Models involving the properties of pure components such as Tg, glass transition heat capacity increment, ΔCp, and density, ρ, do not interpret the observed Tg shifts in the systems. In contrast, a linear correlation is revealed between ΔHmix and maximum Tg shifts.
authors: State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China.
authors: Wenkang
authors: W
authors: Tu
authors: State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China.
authors: Yunxi
authors: Y
authors: Wang
authors: School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, 100081 China.
authors: Xin
authors: X
authors: Li
authors: State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China.
authors: Peng
authors: P
authors: Zhang
authors: State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China.
authors: Yongjun
authors: Y
authors: Tian
authors: School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, 100081 China.
authors: Shaohua
authors: S
authors: Jin
authors: State Key Lab of Metastable Materials Science and Technology, and College of Materials Science and Engineering, Yanshan University, Qinhuangdao, Hebei, 066004 China.
authors: Li-Min
authors: LM
authors: Wang