Control of Mechanical Properties of Thermoplastic Polyurethane Elastomers by Restriction of Crystallization of Soft Segment

Abstract

Mechanical properties of thermoplastic polyurethane elastomers based on either polyether or polycarbonate (PC)-glycols, 4,4’-dipheylmethane diisocyanate (1,1’-methylenebis(4-isocyanatobenzene)), 1,4-butanediol, were controlled by restriction of crystallization of polymer glycols. For the polyether glycol based-polyurethane elastomers (PUEs), poly(oxytetramethylene) glycol (PTMG), and PTMG incorporating dimethyl groups (PTG-X) and methyl side groups (PTG-L) were employed as a polymer glycol. For the PC-glycol, the randomly copolymerized PC-glycols with hexamethylene (C6) and tetramethylene (C4) units between carbonate groups with various composition ratios (C4/C6 = 0/100, 50/50, 70/30 and 90/10) were employed. The degree of microphase separation and mechanical properties of both the PUEs were investigated using differential scanning calorimetry, dynamic viscoelastic property measurements and tensile testing. Mechanical properties could be controlled by changing the molar ratio of two different monomer components.

Role of the interactions between carbonate groups on the phase separation and properties of waterborne polyurethane dispersions prepared with copolymers of polycarbonate diol

“…On the contrary, the change in the mechanical properties exhibited similar values that these found by Kojio et al [30] concluding that the introduction of different methylene chains between carbonate groups by random copolymerization was an effective method to improve the mechanical properties of the polyurethanes. To the best our knowledge, there are not studies in the existing literature considering the influence of adding copolymers of polycarbonate diol of different composition on the properties of aqueous polyurethane dispersions and on their structure-properties relationship.…”

“…Furthermore, Young's modulus of the polyurethanes increased with an increase in the methylene number due to the degree of microphase separation and the ease of packing of the polycarbonate chains. In a more recent paper, Kojio et al [30] established that the mechanical properties of thermoplastic polyurethane elastomers based on either polyether or polycarbonate diols were controlled by restriction of the crystallization of the soft segments. The values of the glass transition temperature of the soft segments increased with increasing C4 composition ratio in the polycarbonate diol copolymer giving stronger degree of phase separation.…”

Microstructure–property relationships of organo-montmorillonite/polyurethane nanocomposites: Influence of hard segment content

“…An intensive reflection at around 20°was visible in all hard segment contents. The high intensity of this reflection can be attributed to its overlap with the crystals formed by the soft segment chains of poly(tetrahydrofuran) at 2θ = 19.8° (Kojio et al, 2010). There were also two prominent reflections apparent at around 21.5°and 24°, which have been frequently related to the lateral distances at the interfaces of the hard crystallized segments (Androsch et al, 1997;Nanda et al, 2006).…”

“…PU20 and NC20 displayed a clear elastomeric behavior whereas thermoplastic behavior was revealed for the systems with higher hard segment contents. This was due to the higher Young's modulus and lower flexibility of the samples, which is known (Kojio et al, 2010) to be the straightforward outcome when the hard segment concentration is increased; especially when the hard segments are entangled with strong HS-HS hydrogen bonding as demonstrated earlier from Mid-IR spectroscopy.…”

Influence of β-cyclodextrin on morphologies and chemical, thermal, and mechanical properties of non-chain extended polyurethane elastomers

“…In case of PUE 1 , PUE 2 , and PUE 3 , phase separation is not obvious, either. This may be the result of cross-linking, which could increase the compatibility between hard segments (HS) and soft segments (SS) and thus reduces the degree of phase separation [27][28][29]. However, this nanoscale phase separation is also observed in PUE 5 , wherein the low intensity regions are brighter and a little larger compared to PUE 0 .…”