Mark‐Houwink‐Beziehung für Polytetramethylenterephthalat im Vergleich zu Polyethylen‐ und Polyhexamethylenterephthalat

Abstract

ZUSAMMENFASSUNG:Fur Polytetramethylenterephthalat wird an Fraktionen -ausgehend von der Molekulargewichtsbestimmung mit der Absolutmethode der Streulichtmessung -die Mark-Houwink-Beziehung fur das Losemittel Phenol/l,2-Dichlorbenzol Aus den an den Fraktionen durchgefuhrten Viskositats-und Molekulargewichtsmessungen werden die ,,ungestorten" Knaueldimensionen von Polytetramethylenterephthalat nach Stockmayer-Fixman berechnet, die friiher gefundene Werte bestatigen. Der fiir Polytetramethylenterephthalat ermittelte Behinderungsparameter zeigt, da8 innerhalb der Polyalkylenterephthalatreihe Estergruppen die Polymerkette flexipilisieren, was auch fur Polyester aus aliphatischen Dicarbons2uren und aliphatischen Diolen bekannt ist. SUMMARY:Using fractions, the Mark-Houwink relationship is established for poly(tetramethylene terephthalate) in the solvent phenol/l ,Zdichlorobenzene (1 : 1) at 25 "C, based on absolute determination of molecular weight by light scattering. As shown, the relationship is also valid for commercial poly(tetramethy1ene terephthalate)-products.To compare with poly(tetramethy1ene terephthalate) the [q]-M relationships for poly(ethy1ene terephthalate) and poly (hexamethylene terephthalate) are determined.The values of the exponents a in the Mark-Houwink relationship increase in the order aPET < apTMr c apHMT, indicating the increasing thermodynamical quality of the solvent phenol/dichlorobenzene with increasing number of methylene groups of the diol. From the viscosity data obtained for the fractions, the unperturbed dimensions of poly(tetramethy1ene terephthalate) are evaluated using the Stockmayer-Fixman method. The values agree with former investigations. The flexibility factor obtained for poly(tetramethy1ene terephthalate) indicates, that the flexibility of poly (alkylene terephthalates) increases with increasing content of ester groups, as known for polyesters from aliphatic dicarboxylic acids and aliphatic diols.

High Temperature Bulk Reaction between Poly(ethylene terephtalate) and Lactones: 1H NMR and SEC/MALDI‐TOF MS Study

“…Poly(ethylene terephthalate) (Aldrich Co), was powdered by cryogenic crushing and vacuum-dried overnight at 100 8C before use (M w ¼ 45 800 from inherent viscosity measurements in 1/1 phenol-o-dichlorobenzene at 25 8C, using the molar mass-viscosity relationship given in ref. [17] ).…”

Polyesters

“…• C while PHBV copolymers exhibit lower melting point (135)(136)(137)(138)(139)(140)(141)(142)(143)(144)(145)(146)(147)(148)(149)(150) • C) and higher impact resistance and flexibility. Selected properties of PLA and PHB are compared to those of biodegradable polymers in Table 2.10.…”

“…27 The number-average molar mass of thermoplastic polyesters varies from about 20,000 for film and fiber applications to 40,000 for injection-molding or blowmolding resins. Relationships between intrinsic or molten viscosity and molar mass have been published for PET, 131 -136 PBT, 135,137 and PEN.…”

“…Amorphous PDLLA has significantly lower tensile strength and modulus than PLLA (Table 2.10). When crystallized, it presents a much lower melting point than PLLA (130)(131)(132)(133)(134)(135) • C). Consequently, the properties of PLA are strongly affected by the optical purity of starting monomer, by polymerization and processing conditions, and by thermal history.…”

Synthesis of Aliphatic‐Aromatic Copolyesters by a High Temperature Bulk Reaction Between Poly(ethylene terephthalate) and Cyclodi(ethylene succinate)

“…Dibutoxydibutyltin (Aldrich Co.) was used without further purification. Poly(ethylene terephthalate) (PET) (Aldrich Co.) was powdered by cryogenic crushing and vacuum‐dried overnight at 100 °C before use ($\overline M _{\rm w}$ = 45 800 from inherent viscosity measurements in 1/1 phenol‐o‐dichlorobenzene at 25 °C, using the molar mass‐viscosity relationship given in ref 17…”