Type, soft segment

Table I. Lignin source and soft segment type for polyurethanes discussed in this study...

Lignin Source Soft Segment Type Formulation Type Reference ... 

Soft segment type also influences the driving force for phase separation. However, improved phase separation does not necessarily lead to improved properties, since both polyether (Srichatrapimuk and Cooper, 1978) and... 

Soft segment type also influences the driving force for phase separation. However, improved phase separation does not necessarily lead to improved properties, since both poly ether [55] and polybutadiene soft segments generally show more complete phase separation than polyesters, yet the polyester-based materials have better mechanical properties. TTie most likely explanation for this result is poor interfacial adhesion in well-phase-separated systems [159]. 

Ester bonds in polyester soft segments, such as poly(caprolactone) (PCL), jx)ly(lactide) (PLA), poly(glycolide) (PGA), their copolymers, and polyhydroxyalkanoates (PHAs) Carbonate bonds in polycarbonate soft segments Hydrolysis it can be catalysed by enzymes Degradation rate depends on the soft segment type e.g. the presence of poly(ethylene glycol) (PEG) units increases the hydrolysis rate... 

One partieular form of thermoplastic polyurethane elastomers is the elastic fibre known as spandex fibre. Like the usual thermoplastic rubbers these materials consist of hard and soft segments but to qualify for the term spandex by the US Federal Trade Commission the polymer used should contain at least 85% of segmented polyurethane. The first commercial material of this type was introduced by Du Pont in 1958 (Lycra). Several other similar materials have since been introduced including Dorlastan (Bayer), Spanzelle (Courtaulds) and Vyrene (US Rubber). 

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. 

Note The types of domain in a segmented copolymer usually comprise hard- and soft-segment phase domains. 

Recent systematic studies on the relation between network structure and substituents in kraft lignin, steam exploded, have shown that the lignin containing networks can be modified in new ways, cf. e.g. (80). Also the toughening of glassy, structural thermosets can be achieved by incorporating a variety of polyether and rubber-type soft segment components in the polymer network structure. 

The Tg of polyurethanes crosslinked with aromatic isocyanates shows no difference between the PEG-extended and the CEHPL networks. The Tg values for both types of networks follow the same relationship. Networks without soft segment content generally have a higher Ttf than those with... 

In this variation of high performance liquid chromatography (HPLC), the columns are packed with material that will hold back molecules dependent on the molecular size. Using the correct solvent system and column types, the molecular weight and distribution of the polyols can be determined. Standard samples are needed to calibrate the system. The molecular weight distribution of prepolymers can also be determined. This will enable an estimation to be made of the number of soft segment chains there are. 

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