Properties Of Thermoplastic Polyurethane Elastomers Research Articles

Influence of the composition on the crystallinity and adhesion properties of thermoplastic polyurethane elastomers

Crystallinity and adhesion properties of nine thermoplastic polyurethanes (TPUs) prepared by varying the hard-to-soft segments ratio, the molecular weight of the macroglycol (related to the size of the soft segments) and the chain extender size and nature (i.e. hard segments length and morphology) were studied. TPUs structure was characterised using 1 H Nuclear Magnetic Resonance ( 1 H NMR), and their properties were studied using Differential Scanning Calorimetry (DSC) and Wide Angle X-ray Diffraction (WAXD). TPUs were used as raw materials of solvent-based adhesives. The adhesion properties were measured from T-peel tests of solvent-wiped polyvinyl chloride (PVC)/polyurethane adhesive joints. It was found that the composition of the TPUs influenced their structure and properties. An increase in the hard segments content in the TPUs reduced the degree of phase separation and the organisation of their structure, resulting in less crystalline polymers with worse adhesion properties.

Properties of thermoplastic polyurethane elastomers containing liquid crystalline chain extender (I) synthesis and properties of hard segments

Polyurethanes prepared from 1,6-diisocyanate hexane (HDI) and 2,4-tolylene diisocyanate (2,4-TDI) with liquid crystalline chain extender 4,4′-bis( n-hydroxyalkyloxy)biphenyl ( n-PBP, n = 2, 3, 6) were reported. Characterizations of monomers and polymers were performed by infrared spectroscopy (IR), 1H-NMR, solid-state C 13-NMR, and elemental analysis. The phase transition behaviors of polyurethanes were investigated by Global TSC, DSC, and polarized microscopy (POM). Our results showed that monomers 4,4′-bis(n-hydroxyalkyloxy) biphenyl exhibit smectic type mesophase. It was observed that the longer the spacer length of polyurethanes, the higher the chain mobility, the larger DOD (degree of disorder) value and the lower the relaxation time. Also the phase transition temperature of polyurethanes decreases with increasing spacer length. DSC measurements and texture observations indicated that H2, H3, H6 and T6 exist in both mesophase and crystal phase. Quantitative analysis of temperature dependence hydrogen bonding revealed that hydrogen bonded content ( X b) of the C group for all samples decreased with increasing temperature. For the H series, both X b and ΔH decrease with increasing spacer length of the mesogenic diol.

Strain effects on thermal transitions and mechanical properties of thermoplastic polyurethane elastomers

An investigation on the effect of strain on the domain structure of thermoplastic polyurethane elastomers (TPEs) is reported. Thermal characterization utilizing differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) is presented along with mechanical properties of model TPEs before, and after, varying degrees of strain aging. Model TPEs were subjected to tensile strains between 100 and 400% elongation and aged for varying lengths of time at ambient and elevated temperatures. DSC and DMA were utilized to investigate the changes in morphology that occurred as a result of strain elongation. The effect of strain aging on the TPEs mechanical properties such as abrasion resistance is also discussed. DSC results indicated that the polymer undergoes morphology changes due to strain, resulting in some degree of phase mixing. DMA data indicated that polyester TPEs and polyether TPEs respond differently to induced strain, suggesting that domain re-ordering in these materials may occur by different mechanisms.

Comparison of properties of thermoplastic polyurethane elastomers with two different soft segments

Comparison of properties of thermoplastic polyurethane elastomers with two different soft segments

Comparison of properties of thermoplastic polyurethane elastomers with two different soft segments

Two series of thermoplastic polyurethane elastomers [poly(propylene glycol) (PPG) based PP samples and poly(oxytetramethylene)glycol (PTMG) based PT samples] were synthesized from isophorone diisocyanate (IPDI)/1,4-butanediol (BD)/PPG and IPDI/BD/PTMG. The IPDI/BD based hard segments contents of polyurethane prepared in this study were 40–73 wt %. These polyurethane elastomers had a constant soft segment molecular weight (average Mn, 2000) but a variable hard segment block length (n, 3.5–17.5; average Mn, 1318–5544). Studies were made on the effects of the hard segment content on the dynamic mechanical thermal properties and elastic behaviors of polyurethane elastomers. These properties of PPG based PP and PTMG based PT samples were compared. As the hard segment contents of PP and PT samples increased, dynamic tensile modulus and α-type glass transition temperature (Tg) increased; however, the β-type Tg decreased. The permanent set (%) increased with increasing hard segment content and successive maximum elongation. The permanent set of the PT sample was lower than that of the PP sample at the same hard segment content. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1349–1355, 1998

Short fiber reinforced thermoplastic polyurethane elastomer composites

AbstractMechanical properties of thermoplastic polyurethane elastomer (TPE) reinforced with short fibers were studied. Two types of fibers were used as the discontinuous phase: an aromatic polyamide (Twaron, diameter: 12 μm) and carbon fiber (FCI 140/90‐R33—diameter: 8–10 μm). Because of processing limitations, the maximum length of both fibers, after incorporation in the composites, was reduced to 3 mm. The TPE (continuous phase) was a polyol‐polyester type [Elastollan—glass transition of short fiber segments: −42°C (1)]. Both types of composites had fiber concentration of 10, 20, and 30 phr. Component interaction is discussed, as well as the application of a third power polynomial to establish a relationship between the amount of fiber added and stress at break data. Stress‐strength, tear resistance, shore A and B hardness, abrasion resistance, and compression set tests were performed. Composites reinforced with aromatic polyamides showed higher values in most of the tests, except in the abrasion resistance test, in which a smaller material loss was observed.

Synthesis and properties of thermoplastic polyurethane elastomers modified by poly(γ-methyl- l-glutamate) segment

Thermoplastic polyurethane elastomers (TPUs) from diol-terminated poly(tetramethylene glycol) (PTMG), 1,4-butanediol (BD) and 4,4′-diphenylmethane diisocyanate (MDI) were modified by copolymerizing with diamine-terminated poly(γ-methyl- l-glutamate) oligomer (γ-PMG). In TPUs modified by the γ-PMG segment, the hard segment showed a decreased crystallinity and a melting point depression, as some of the hard segments were replaced by the γ-PMG segment. This behaviour is probably due to the strong interaction and phase mixing between γ-PMG and hard segments. The melting behaviour of the PTMG segment suggested a weaker interaction between γ-PMG and PTMG segments compared with that between hard segments and PTMG segments. When a small amount of hard segments was replaced by γ-PMG segments, the modulus increased and the elongation at break decreased.

Thermal and mechanical properties of thermoplastic polyurethane elastomers from different polymerization methods

AbstractThermoplastic polyurethane elastomers (TPUs) based on 4,4′‐methylene‐diphenyl diisocyanate, poly(tetramethylene glycol), diamine‐terminated aliphatic nylon oligomer, and 1,4‐butanediol were synthesized by two different polymerization methods, i.e. one shot and prepolymer methods. The effects of the polymerization method on the thermal and mechanical properties of the TPUs have been studied. A broader distribution of hard segment lengths in TPUs prepared by the one shot method was observed from thermal and tensile property measurements, compared with those prepared by the prepolymer method. TPUs by the one shot method showed a higher Tm of the hard segments and better tensile properties when soft‐hard segment interaction was relatively small. However, inferior tensile properties were observed when the soft‐hard segment interaction was high; typically when nylon oligomer was used as a soft segment.