Soft segment effect effects

Z. Ma, Y. Hong, D. Nelson, J. Pichamuthu, C. Leeson, W. Wagna-, Biodegradable polyurethane ureas with variable polyesto" or polycarbonate soft segments effects of crystallinity, molecular weight, and composition on mechanical properties. Biomacromolecules 12 (9) (2011) 3265-3274. 

PU with hard and soft segments, effect of irradiation-induced contrast enhancement [24, 25] ... 

Puskas J.E., Antony P., ElFray M., and Altstadt V. The effect of hard and soft segment composition and molecular architecture on the morphology and mechanical properties of polystyrene-polyisobutylene thermoplastic elastomeric block copolymers, Eur. Polym. J., 39, 2041, 2003. 

Antony, P., Puskas, J.E., Ott, H., Altstadt, V., Kovar, M., and Norton, P.R. Effect of Hard and Soft Segment Composition on the Morphology and Mechanical Properties of Polystyrene-Polyisobutylene Thermoplastic Elastomeric Block Copolymers. Proceedings of the Polymer Processing Society Meeting, May 21-24, Montreal, Canada, 2001. 

In an NMR analysis of the effects of /-irradiation induced degradation on a specific polyurethane (PU) elastomer system, Maxwell and co-workers [87] used a combination of both H and 13C NMR techniques, and correlated these with mechanical properties derived from dynamic mechanical analysis (DMA). 1H NMR was used to determine spin-echo decay curves for three samples, which consisted of a control and two samples exposed to different levels of /-irradiation in air. These results were deconvoluted into three T2 components that represented T2 values which could be attributed to an interfacial domain between hard and soft segments of the PU, the PU soft segment, and the sol... 

This paper describes two types of novel urethane-acrylic IPNs for coating applications. The mode of preparation used was the simultaneous or SIN technique. In order to examine the effect of the soft segment on the properties and morphology of IPN coatings, the pendant hydroxy group in the hydroxyethylacrylate-butylmethacrylate copolymer was reacted with caprolactone to increase the chain length of the pendant hydroxy group. 

Effect of Soft-Segment Content on the Properties of Lignin-Based Polyurethanes... 

It is important to be aware of the chemical effects of isocyanates. The polynre-thanes you will develop will be combinations of polyols and isocyanates. The ratio of the two compounds will in pait dictate both the physical and chemical properties of the product. As a general rule, the isocyanates are hard segments that impart rigidity to the polymer. The polyol is the so-called soft segment. The various molecular weights (more correctly equivalent weights available in the form of polymeric MDIs) provide certain advantages. Table 2.2 lists a few commercially available polyisocyanates and their physical properties. 

Wiggins MJ, MacEwan M, Anderson JM, Hiltner A. Effect of soft-segment chemistry on polyurethane hiostability during in vitro fatigue loading. Journal ofBiomedical Materials Research A 2004, 68, 668-683. 

One effective approach in increasing the fire resistance of polyurethane (PU) is to incorporate PDMS into its structure.28 Microphase-segregated PU block copolymers containing hydroxyl-terminated silicone as the soft segment have been synthesized. The enhanced siliconated surface of the block copolymer has been confirmed by ESCA and x-ray analyses. 

Figure 3. Small-angle x-ray scattering intensity curves demonstrating the effect of soft-segment molecular weight for three polycaprolactone polyurethanes (MDI/BD) of approximately equal hard-segment content. (A) 57% by wt, FCL 2000-178 (S) (B) 53% by wt FCL 830-123 (S) and (C) 61% by wt, FCL 830-134 (S).

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