Poly tetramethylene glycol

Tetrahydrofuran is polymerized to poly(tetramethylene glycol) with fuming sulfuric acid and potassium biduoride (29). 

The biodegradation of poly(alkylene glycols) is hindered by their lack of water solubiUty, and only the low oligomers of poly(propylene glycol) are biodegradable with any certainty (179—181), as are those of poly(tetramethylene glycol) (182). A similar xo-oxidation mechanism to that reported for poly(ethylene glycol) has been proposed. 

Polyether Polyols. Polyether polyols are addition products derived from cyclic ethers (Table 4). The alkylene oxide polymerisation is usually initiated by alkah hydroxides, especially potassium hydroxide. In the base-catalysed polymerisation of propylene oxide, some rearrangement occurs to give aHyl alcohol. Further reaction of aHyl alcohol with propylene oxide produces a monofunctional alcohol. Therefore, polyether polyols derived from propylene oxide are not truly diftmctional. By using sine hexacyano cobaltate as catalyst, a more diftmctional polyol is obtained (20). Olin has introduced the diftmctional polyether polyols under the trade name POLY-L. Trichlorobutylene oxide-derived polyether polyols are useful as reactive fire retardants. Poly(tetramethylene glycol) (PTMG) is produced in the acid-catalysed homopolymerisation of tetrahydrofuran. Copolymers derived from tetrahydrofuran and ethylene oxide are also produced. 

The hard-soft block copolymer approach employed to produce segmental PUs (Section 7.6) has also been used with polyesters, with the hard block formed from 1,4-butadienediol and terephthalic acid while the soft block is provided by oligomeric (approximate molecular weight of 2000 Da) poly(tetramethylene glycol) and is sold under the trade name Hytrel. 

Figure 10.4 Stress-strain curves for control and modular polymers. The curve in the bottom (—) is for the polyurethane (PU) made fiom poly(tetramethylene glycol) and...

Esters and ethers based on poly(tetramethylene glycol) and propylene oxide or a combination of propylene and ethylene oxides commonly are used in reactive processing. The chemistry of leading to polyurethane formation, has been analyzed in many publications 15 7 however, the practical problems of processing real initial oligomers and molding compounds based on them into articles for different applications have received less attention. 

The two elastomeric polyurethanes listed in Table 1.3, are synthesized in the following way PU-I is the reaction product of a prepolymer based on poly(tetramethylene glycol) ether and 2,4-toluylene diisocyanate (this product is analogous to Adiprenyl-167", Du Pont, USA) PU-II is the... 

A recent example of XPS analysis of polyurethane surfaces has been provided by Yoon et al. [30]. In these studies polyurethanes were prepared with 4.4 -methylenebisfphenyl isocyanate) (MDI)and hexafluoro- l.5-pentancdiol (FP) extenders as the hard segment, and poly(tetramethylene glycol) (PTMO) as the soft segment. The authors introduced hydrophobic soft segments, either poly-(dimethylsiloxan) (PDMS) or polyisobutylene (PIB) into this polyurethane structure. The concept underlying this polymer design was the desire to modify sur-... 

One further phenomena observed In all 73 systems Is the decrease In opacity on curing at elevated temperatures. Above about 60 C the poly(tetramethylene glycol) and excess Isocyanate become miscible. This miscibility may be assisted by the fact that the MDI-BDO hard segments are above their glass transition temperature. To an extent which has not been quantified as yet, llquld-llquld phase separation of MDI and MDI terminated polyol In the prepolymer at low temperatures preslsts Into the final adhesive. The dynamic mechanical behavior of transparent or opaque adhesive, l.e., cured at 60-100 C compared to room temperature are virtually Identical. Similar Immlsclblllty has been observed In other prepolymers (20). This does not appear to adversely affect the adhesive properties of these Halthanes. 

Thermoplastic polyurethane containing 4,4 -diphenylmethane diisocyanate, poly(tetramethylene glycol) and 1,4-butanediol has good mechanical strength, wear resistance and tear resistance and low-temperature elasticity. Aiming to improve the performance of sPS by exploiting these properties, Xu et al. [43]... 

The latter could be poly(tetramethylene glycol) (PTMG) or poly(ethylene glycol) (PEG). On the laboratory scale, as mentioned above, PEECs, which have also PCc as their soft segments, have been synthesized (Roslaniec et al, 1995). 

Other copolymers of polyamides include poly(glycols) sequences. Examples from this group are nylon 12-b/ock-poly(tetramethylene glycol) with the idealized formula -[NH-(CH2)ii-C(0)]x [-0-(CH2)4-O-]y and poly[(ethylene glycol)-co-1,6-hexanediamine-co-(methylpentamethylene diamine)-co-1,4-benzenedicarboxylic acid]. Pyrolysis of these copolymers generates a mixture of compounds, some typical for amides such as nitriles and some typical for polyethers. 

Vibrathane B605 A prepolymer based on diphenyl-methane diisocyanate (MDI) and poly-tetramethylene glycol 3.02 1333 Uniroyal... 

Three of the block polymers were DuPont Hytrels 4055, 5555, and 6355 (17, 18, 19). These materials have a crystallizable PTMT hard block and a poly(tetramethylene glycol) (PTMG) soft block with a molecular weight of about 1000. Hytrels 4055, 5555, and 6355 contained about 42.6, 35, and 27% PTMG, respectively. The fourth polymer was Uniroyal TPR-19 which has a... 

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