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Polytetrahydrofuran
  A sportswear manufacturer in Fujian had been producing compression leggings for three seasons without a quality issue. Then a new shipment of polyurethane elastomer arrived from their fiber supplier and the complaint rate jumped. The garments were passing basic stretch tests at the warehouse but failing within a few weeks of use — elongation at break had dropped, and the fabric was recovering slowly after repeated stretching cycles. The fiber supplier ran their production records and found nothing unusual. The elastomer pellets met the same specification they had always used. The root cause took six weeks to trace: the PTMEG used to synthesize the soft segment had shifted in molecular weight by about 150 g/mol, from the usual 1800 to approximately 1950, without triggering a specification violation because the acceptable range was wide.
 
  ♦Polytetrahydrofuran, commonly abbreviated PTMEG or poly-THF, is a linear polyether diol produced by ring-opening polymerization of tetrahydrofuran. The polymer has the repeating unit [-CH2CH2CH2CH2-O-]n with hydroxyl end groups, and its average molecular weight determines the segment length in polyurethane and polyurea networks. CAS 25190-06-1 designates the commercial polymer rather than a single discrete compound, since molecular weight can range from several hundred to several thousand daltons depending on the polymerization conditions used.
 
  In spandex and other segmented polyurethane fibers, Polytetrahydrofuran serves as the soft segment that gives the material its rubber-like extensibility. The hard segments, formed from diisocyanate and chain extender, create physical crosslinks through hydrogen bonding and crystallization. The soft segment length — controlled by PTMEG molecular weight — governs how far the fiber can stretch before the hard segment network resists further deformation. A longer soft segment gives higher elongation at break but lower modulus; a shorter one gives more snap-back and higher modulus at the cost of elongation. The Fujian factory’s problem was that the shift to higher molecular weight PTMEG had subtly changed the phase separation morphology of their elastomer, producing fibers with lower recovery stress. The change was within specification but above the practical tolerance of a high-performance compression garment.
  This is why Polytetrahydrofuran buyers in fiber applications typically go beyond the molecular weight average reported on a CoA and request information about the molecular weight distribution as well. A narrow distribution around 2000 g/mol behaves differently from a broad distribution centered at the same average. Gel permeation chromatography can distinguish between these profiles, and the dispersity index gives a sense of how tightly the polymerization was controlled.
 
  The other major application sector for Polytetrahydrofuran is in thermoplastic polyether ester elastomers, sold commercially as COPE or TPEE grades. In these materials, PTMEG soft segments are incorporated into copolyesters such as poly(butylene terephthalate-co-tetramethylene ether). The resulting thermoplastics combine the processability of a thermoplastic with the flex fatigue resistance of a rubber, which makes them useful in automotive bellows and boots, hose assemblies, and cable jacketing. The molecular weight of the PTMEG in these applications tends to be lower, around 1000 g/mol, because the COPE formulation benefits from a higher hard segment content to maintain dimensional stability at elevated temperatures.
  Handling Polytetrahydrofuran requires attention to its viscous liquid state at room temperature, since most commercial grades are viscous oils or soft waxes depending on molecular weight. At temperatures below roughly 20°C, higher molecular weight grades can solidify and require heated storage to maintain pumpability. Exposure to moisture must be controlled because the hydroxyl end groups are reactive, and water contamination affects the NCO:OH stoichiometry in subsequent urethane reactions. Storage under dry nitrogen in sealed containers at 15–25°C is standard practice for production environments.
 
  From a regulatory standpoint, PTMEG is covered under REACH as a polymeric substance and is generally considered low hazard for routine handling. However, its relatively low vapor pressure and hygroscopic character mean that thermal decomposition products — which include THF and related compounds — can accumulate in confined spaces if the material is processed at elevated temperatures without adequate ventilation.
Polytetrahydrofuran
  Shandong Lookchemical Co, Ltd. supplies Polytetrahydrofuran in standard molecular weight grades (1000, 1800, and 2000 g/mol are the most commonly requested) with GPC-verified molecular weight data included in the CoA alongside hydroxyl number determination. Export quantities ship with full REACH and TSCA compliance documentation. Technical support on grade selection for specific elastomer formulations is available from the sdlookchem team.
 

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