Length, average hard segment

Figure 14. Reciprocal of average hard segment length vs. 1/T for the 2,6-TD1 -polyurethane 8 relaxation...

Number Average and Weight Average Hard Segment Sequence Lengths at Separation As a Function of Soft Segment Content. 

Figure 3 illustrates the change in PDMS surface concentration with increase in the length of hard segment. In this group of PDMS-PU samples, the average molecular weights for the PDMS... 

Table 1 Average hard segment length, end of hard phase meting range, amount of hard phase, melt enthalpy, and shore hardness for the samples A-H. The end of the melting range shifts towards higher temperatures for hard TPU materials.

Although short-segment sequences are expected to be the most compatible, the 1/2/1 random copolymer with an average hard-block-sequence length of only two units does exhibit a phase-separated morphology—as reflected for the as-reacted sample in hard-segment crystal-... 

Figure 8. Effect of soft segment content on point of phase separation during polyurethane polymerization as indicated by discontinuity in DSC reaction profile. Dotted line shows theoretical prediction assuming separation at constant number-average sequence length (1.3) of hard segments ("see text).

Figure 3. Line widths of the C NMR (50.3 MHz) solid Hytrel scalar decoupled 29 ppm (O) and 73 ppm resonance fOl as a function of average hard block length at 34°C. The temperature below which the line width increases due to dipolar broadening is slightly different for the two types of aliphatic carbons fsee Figure 4). It also increases slightly as the hard segment content of the polymer increases. The -OCHi- line width for the Hytrel 7246 sample was measured at a temperature below this point and therefore does not fall on this line.

Figure 10.1 Calculated PBT block-length distribution (a - number average b - weight average) in TPEEs with different wt % of PBT hard segments (denoted in the abbreviation) and PTMO (1000 g/mol) soft segment.

---