Poly(ethylene terephthalate) copolymers containing 5‐tert‐butyl isophthalic units

Abstract

Poly(ethylene terephthalate‐co‐5‐tert‐butyl isophthalate) copolymers, abbreviated as PETtBI, with compositions ranging between 95/5 and 25/75, as well as the two parent homopolymers, PET and PEtBI, were prepared from comonomer mixtures by a two‐step melt‐polycondensation. Polymer intrinsic viscosities varied from 0.4 to 0.7 dL g−1 with weight‐average molecular weights ranging between 31,000 and 80,000. The copolymers were found to have a random microstructure with a composition according to that used in the corresponding feed. The melting temperature and crystallinity of PETtBI decreased with the content in 5‐tert‐butyl isophthalic units, whereas the glass‐transition temperature increased from 82 °C for PET up to 99 °C for PEtBI. Copolymerization slightly improved the thermal stability of PET. Preliminary X‐ray diffraction studies revealed that PETtBI adopt the same crystal structure as PET with the alkylated isophthalic units probably excluded from the crystal lattice. The homopolymer PEtBI appeared to be a highly crystalline polymer taking up a crystal structure clearly different from that of PET and PETtBI copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 1994–2004, 2001

Amorphous copolyesters based on 1,3/1,4‐cyclohexanedimethanol: Synthesis, characterization and properties

“…The details of the synthesis can be found elsewhere. [9][10][11] In each preparation, the reaction mixture comprised excess EG, various amounts of diol and diacid (molar ratio of diol/diacid 5 1.4), 350 ppm Ti(O(CH 2 ) 3 CH 3 ) 4 and 90 ppm Co(OAc) 2 by weight. The reaction mixture was heated to the final temperature (220-2508C) in an atmosphere of nitrogen, and was stirred at a constant speed (500 rpm).…”

Poly(ethylene terephthalate) copolymers that contain 5‐tert‐butylisophthalic acid and 1‐3/1‐4‐cyclohexanedimethanol: Synthesis, characterization, and properties

“…15,18 In each preparation, the reaction mixture comprised excess EG, various amounts of diol and diacid (molar ratio of diol/diacid ¼ 1.4), 350 ppm Sb(OAc) 3 , and 90 ppm Co(OAc) 2 by weight. The reaction mixture was heated to the final temperature of 2808C in an atmosphere of nitrogen and stirred at a constant speed (500 rpm).…”

“…The utilization of isophthalic acid with bulky side groups that enhance chain stiffness is considered to be a valuable alternative. [16][17][18][19] Thus, enhancement of T g of a wide variety of polycondensates, including polyamides and polyesters, by 5-tert-butylisophthalic units ( t BI) has been reported. 8,9 Furthermore, a series of PETrelated copolyesters prepared from ethylene glycol, terephthalic acid, and 5-tert-butylisophthalic acid has been claimed to exhibit a reduced tendency to crystallize and to have a higher T g than PET.…”

Structural characterization and thermal properties of poly(ethylene terephthalate) copolymers containing 2‐butyl‐2‐ethyl‐1,3‐propanediol

“…16 Experimentally observed and calculated data are compared in Table V. In PET copolymers composed of comonomeric units with markedly different geometry or size, like poly(ethylene terephthalate-co-5-tert-butylisophthalate) 9 or poly(ethylene terephthalate-co-5-nitroisophthalate) 17 copolymers, selective rejection of the minor comonomer from the crystalline phase is generally assumed to occur. Although it could also be the case for PEBEPT copolymers, incorporation of BEPD units in the crystal lattice of PET cannot be absolutely discarded because structural differences between EG and BEPD are not so apparent as those existing between terephthalic and isophthalic units.…”