TITLE:
Mechanical, Thermal and Morphology Properties of Thermoplastic Polyurethane Copolymers Incorporating α,ω-Dihydroxy-[poly(propyleneoxide)-poly (dimethylsiloxane)-poly(propyleneoxide)] of Varying Poly(propyleneoxide) Molecular Weight
AUTHORS:
Zeliang Dai, Kai Yang, Qingzhi Dong
KEYWORDS:
Thermoplastic Polyurethane Copolymers, Mechanical Properties, Thermal Performance, Hydrophobicity Property, Morphology, α, ω-Dihydroxy-[poly(propyleneoxide)-poly(dimethylsiloxane)-poly(propyleneoxide)]
JOURNAL NAME:
Open Journal of Synthesis Theory and Applications,
Vol.4 No.3,
July
20,
2015
ABSTRACT: Novel segmented thermoplastic polyurethane (TPU) copolymers were synthesized using two-step
solventless bulk polymerization. 4,4’-methylenediphenyl diisocyanate (MDI) and 1,4-Butanediol
(BDO) were used to form hard segment of TPU and α,ω-dihydroxy-[poly(propyleneoxide)-poly
(dimethylsiloxane)-poly(propyleneoxide)] (α,ω-dihydroxy-(PPO-PDMS-PPO)) was used to form soft
segment of TPU, where the molar ratio of the –N=C=O/OH was 1.02 and the hard segment weight
percentage was 30%. A series of TPUs were characterized by fourier transform infrared spectroscopy
(FT-IR). The investigation of triblock oligomer’s PPO molecular weight impact on the derived
TPU’s mechanical properties, thermal performance, surface water repellency and morphology
performance was carried by Instron material tester, thermogravimetric analysis (TGA), differential
scanning calorimetry (DSC), water contact angles (WCA), scanning electron microscope and
energy dispersive X-ray spectroscopy (SEM-EDX) and wide angle X-ray diffraction (WAXD), respectively.
FT-IR confirmed α,ω-dihydroxy-(PPO-PDMS-PPO) well cooperating into urethane structure
and analyzed hydrogen bonding between N-H group with hard segment C=O group and N-H
group with soft segment C-O-C group. DSC and WAXD results showed α,ω-dihydroxy-(PPO-PDMS-PPO) segments crystallization. SEM-EDX results showed that the presence of a spherulitic morphology,
which arose from the crystallization of the PPO segments. The thermal properties measured
by TGA and DSC were slightly affected by molecular weight of PPO and microphase separation.
The weight loss of TPUs started between 294°C and 300°C, and Tg was in the range of -70°C to
-107°C. TPU copolymers’ surface hydrophobicity property was excellent with WCA range of 95°to
112°. TPU-3 with 1000 molecular weight PPO has the optimized mechanical properties with tensile
strength 16.4 MPa and the modulus at 100% elongation 6.2 MPa and elongation 398%.