High Tg and tough poly(butylene 2,5-thiophenedicarboxylate-co-1,4-cyclohexanedimethylene 2,5-thiophenedicarboxylate)s: Synthesis and characterization

The purpose of this study was to enhance the glass-transition temperature of poly(butylene 2,5-thiophenedicarboxylate) (PBTF). A series of poly(butylene-co-1,4-cyclohexanedimethylene 2,5-thiophenedicarboxylate)s (PBCTFs) were synthesized from 2,5-thiophenedicarboxylic acid, 1,4-cyclohexanedimethanol (CHDM), and 1,4-butanediol. CHDM can increase the chain rigidity and lead the β relaxation temperature shift to lower temperature. Consequently, PBCTFs showed not only the high glass-transition temperature, but also high elongations at break. PBTF was a crystalline polyester. However, differential scanning calorimetry and wide-angle X-ray diffraction results suggested PBCTFs were amorphous polyesters. Thermogravimetric analysis results indicated the thermal stability of copolyesters was gradually enhanced with increasing the CHDM content. When the CHDM content was 95 mol %, PBCTF95 exhibited high glass-transition temperature (69.2 °C), tensile strength (44.4 MPa), and elongation at break (205%). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48634.     

Completely amorphous high thermal resistant copolyesters from bio-based 2,5-furandicarboxylic acid

Polyesters from renewable resources with glass transition temperature (T_g) higher than 100°C are crucial in broadening their application range. In this work, a series of high molecular weight copolyesters, poly(butylene bis[4-(2-hydroxyethoxy) phenyl] sulfone 2,5-furandicarboxylate) (PBSF), was synthesized from bis[4-(2-hydroxyethoxy) phenyl] sulfone (BHEPS), bio-based 1,4-butanediol (BDO), and 2,5-furandicarboxylic acid (FDCA) via transesterification. Nuclear magnetic resonance spectroscopy (¹H-NMR and ¹³C-NMR) was used to confirm their chemical structures, composition, and sequence distribution. Characterizations demonstrated that with the increasing content of BHEPS unit, T_g of synthesized polyesters was increased from 38.2°C for PBF to 122°C for PBSF-95, in which the content of BHEPS unit was 95%. However, the weight average molecular weight (M_w) of PBSF was dramatically decreased after the addition of BHEPS, from 95,300 g/mol for PBF to only 9600 g/mol for PBSF-95, which was too low for practical application. Taking molecular weight, T_g, and mechanical properties into account, PBSF-65 was considered to be a promising polyester with M_w of 28,500 g/mol, T_g of 104.7°C, tensile strength of 82 MPa, and elongation-at-break of 98%. Besides, it was a completely amorphous polyester with a transmittance of 89.9% by cutoff at 700 nm. Summarily, PBSF-65 showed great potential to be used as raw material for the manufacture of baby bottles, children's toys, kitchen appliances, and beverage packaging, especially in the case when high transparency and heat resistance are required.     

Preparation of biobased poly(propylene 2,5-furandicarboxylate) fibers: Mechanical,thermal and hydrolytic degradation properties

In this work, a fully biobased poly(propylene 2,5-furandicarboxylate) (PPF) was synthesized from 2,5-furan dicarboxylic acid (FDCA) and 1,3-propanediol (1,3-PDO) via traditional two-step melting polycondensation. Then, the resultant PPF was characterized with ¹H NMR, FTIR, GPC, intrinsic viscosity, TGA, and DSC measurements, respectively. Next, the prepared PPF was melt-spun into fibers. The morphology and thermal stability of the as-spun PPF fibers were firstly investigated by SEM and TGA. Furthermore, the mechanical properties of the PPF fibers were evaluated. The results showed that the tensile of the PPF fibers increased with increasing of the draw ratios following gradual decrease of the breaking elongation from 307.1% to 48.9%. In addition, the crystallization ability and the hydrolytic degradation behavior of the as-spun PPF fibers were investigated in detail as well. The results presented that comparing to traditional fossil-based poly(trimethylene terephthalate) (PTT) fibers, the PPF fibers exhibited lower crystallinity, however, it displayed a better hydrolytic degradation performance. Based on these results, it confirmed that the PPF fiber based on biomass polymer is a kind of promising environmentally friendly synthetic fiber for potential application in various fields.     

Synthesis,characterization, and properties of degradable poly(l‐lactic acid)/poly(butylene terephthalate) copolyesters containing 1,4‐cyclohexanedimethanol

High‐molecular‐weight copolyesters based on poly(butylene terephthalate) as rigid aromatic segments and poly(l‐lactic acid) (PLLA) as degradable aliphatic segments were synthesized via the polycondensation of terephthalic acid, 1,4‐butanediol (BDO), 1,4‐cyclohexanedimethanol (CHDM), and PLLA oligomer. By tailoring the molar ratio of diols (BDO and CHDM), we investigated in detail the effects of the CHDM rigid hexacyclic ring on the synthesis, mechanical properties, thermal stabilities, and degradation behaviors of the copolyesters. With increasing CHDM content, the initial decomposition temperature increased from 282.5 to 322.2°C, and the tensile strength improved by nearly four times, from 5.4 to 19 MPa. When the molar ratio of BDO/CHDM was 95/5, the weight‐average molecular weight of the copolyester was 89,400 g/mol with a polydispersity of 1.96. In addition, hydrolytic degradation results in phosphate buffer solution indicate that the degradation rate of the copolyesters displayed a strong dependency on the temperature and CHDM composition. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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

The effects of incorporating 5‐tert‐butylisophthalic acid (^tBI) and 1‐3/1‐4 cyclohexanedimethanol (CHDM) in the polymer chain of poly(ethylene terephthalate) (PET) on the crystallization behavior and thermal, optical and tensile properties of this polyester (PETGB) were evaluated. These random copolyesters that contained between 0 and 20 mol % of CHDM and between 0 and 10 mol % of ^tBI units were prepared by esterification followed by melt copolycondensation. The compositions and molecular weights of the copolyesters were determined by ¹H‐NMR spectroscopy and viscometry, respectively. The composition of the polyester was consistent with the composition of the feed. The intrinsic viscosities of the copolymers ranged between 0.62 and 0.74 dL/g. The thermal behaviors were investigated over the entire range of copolymer compositions, using DSC under the heating and cooling rate of 20°C/min and TGA. The copolyesters with ^tBI and CHDM of < 20 mol % were crystallizable, whereas the copolyesters with ^tBI and CHDM of ≥ 20 mol % were amorphous. They appeared to be stable up to 395°C. The optical transmissions of the amorphous polyesters were more than 88% in the visible region. The mechanical behavior was investigated by performing a tensile test. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 279–285, 2007     

Conductive fibers based on poly(ethylene terephthalate)–polyaniline composites manufactured by electrochemical polymerization

A novel method of manufacturing composite conductive fibers was developed through electrochemical polymerization with an apparatus consisting of insulating fibers, cotton fabrics as electrolytic solution holders, an electrolytic solution, and planer electrodes. By this method, poly(ethylene terephthalate) (PET) fibers coated with polyaniline (PAN) were prepared readily and yielded PET–PAN composite conductive fibers (PPCFs). The content of PAN in PPCFs increased with an increase in both the aniline concentration in the electrolytic solution and the polymerization voltage, although it did not depend on the load applied to the electrodes. Observations of the PPCF surface by scanning electron microscopy confirmed that the formation processes of PPCFs could be divided into three steps: (1) fine (nanometer‐size) granular PAN was generated from the anode and adsorbed onto the PET fiber surface, (2) the size of the granular PAN increased up to about 90 nm in a short time, and (3) the granular PAN was linked together to form networks. The conductivity of PPCFs increased with an increasing content of PAN networks. The surface resistance of the PPCF fabric was about 3 × 10⁵ Ω/□ at a PAN content of approximately 2 wt %. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1073–1078, 2003     

Synthesis and evaluation of dioctyl 2,5-thiophenedicarboxylate as a potentially bio-based plasticizer for poly(vinyl chloride)

In this work, dioctyl 2,5-thiophenedicarboxylate (DOT), a potentially bio-based plasticizer, was synthesized and evaluated as an alternative to traditional petroleum-based plasticizers. The chemical structure of DOT was confirmed by FTIR and ¹H NMR. Besides, its plasticization effect on poly(vinyl chloride) (PVC) was investigated in detail, and dioctyl 2,5-furandicarboxylate (DOF) as well as dioctyl isophthalate (DOIP) with similar chemical structures were used as references. The DMA results showed that the glass transition temperature (T_g) of PVC/DOT, PVC/DOF, and PVC/DOIP was 45.1°C, 33.6°C, and 51.3°C, respectively, indicating that the plasticizing efficiency of DOT was better than that of DOIP but lower than that of DOF. However, the tensile test results exhibited that the elongation at the break of PVC/DOT was higher than that of PVC/DOF, which was attributed to the easy phase separation between DOF and PVC. In addition, DOT displayed the best volatility resistance and exudation resistance among the three plasticizers, attributed to its highest molecular weight. Moreover, the migration loss of DOT in non-polar solvents was much smaller than that of DOIP because of its stronger molecular polarity. In conclusion, DOT has good potential to replace traditional petroleum-based plasticizers and be used as a primary plasticizer for PVC.     

New copolyesters derived from terephthalic and 2,5-furandicarboxylic acids: A step forward in the development of biobased polyesters

A straightforward partial substitution of non-renewable poly(ethylene terephthalate) by renewable homologous poly(ethylene furandicarboxylate) was successfully done by random copolymerisation of bis(2-hydroxyethyl) terephthalate and bis(hydroxyethyl)-2,5-furandicarboxylate. Different stoichiometric amounts of these monomers were used and the ensuing copolyesters were characterised in detail by several physical chemistry, thermal and mechanical techniques. All copolyesters have the expected chemical structure incorporating both aromatic and furanic units in different amounts accordingly to the stoichiometric feed-ratio. In particular the copolyester having 20% of furan units (PET-ran-PEF 4/1) have similar properties to those of PET homopolyester, despite some minor differences, being a semi-crystalline copolyester with similar glass transition and melting temperatures to those of PET. Also, the mechanical performance of this PET-ran-PEF 4/1 copolyester was in accordance with the PET operating temperature range, tan δ and modulus.     

High molecular weight poly(butylene terephthalate-co-butylene 2,5-furan dicarboxylate) copolyesters: From synthesis to thermomechanical and barrier properties

Poly(butylene terephthalate-co-butylene 2,5-furandicarboxylate) copolyesters (PBTFs) were synthesized from 1,4-butanediol, dimethyl terephthalate (DMT), and 2,5-furandicarboxylic acid (FDCA) by a two-step polymerization method. Their chemical structures were confirmed by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and carbon nuclear magnetic resonance before thermal properties were explored with differential scanning calorimeter and thermogravimetric analyzer. Results showed that PBTFs changed from semi-crystalline to completely amorphous when the content of FDCA unit was increased to 45 mol% at first, and then became crystallographic again with the further increment of FDCA unit to 75 mol%. For their mechanical properties, the tensile modulus and strength showed the similar trend, decreasing firstly and then increasing later. Their barrier to carbon dioxide and oxygen became better with the increasing of furan content due to the rigidity and higher polarity of furan ring. The performance of PBTFs copolyesters was investigated clearly, and the relative content of FDCA and DMT can be adjusted to satisfy different performance requirements.     

Synthesis and thermal characterization of random poly(butylene terephthalate‐co‐2‐methyl‐ethylene terephthalate) copolyesters

Poly(butylene terephthalate‐co‐2‐methyl‐ethylene terephthalate) (PBT/MET) was synthesized by incorporating 1,2‐propandiol(1,2‐PDO) into PBT chains. The molar composition and chemical structure of PBT/MET copolyesters were confirmed by means of FT‐IR and ¹H‐NMR. To investigate the effect of 1,2‐PDO on the thermal properties of PBT/MET copolyesters, the copolymerizations were carried out by varying various contents of MET units, and the prepared materials were evaluated by differential scanning calorimetry and thermogravimetric analysis. Results suggested that with the increase of the content of 1,2‐PDO, the amount of crystallinity and the melting temperature decline, while the glass transition temperature increases and the copolyesters become more transparent and brittle with respect to PBT homopolymer. In addition, the T_g‐composition and T_m‐composition data are well subjected to the Wood equation and Flory's equation, respectively. All these copolyesters are found to consist of the general trend displayed by copolymers reported elsewhere. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and crystallinity of poly(butylene 2,5-furandicarboxylate)

Poly(butylene 2,5-furandicarboxylate) (PBF) was obtained by esterification of 2,5-furandicarboxylic acid (FDCA) and 1,4-butylene glycol (BG). By using ¹H NMR at 750 MHz to recognize the trace end groups at different polymerization stages, the study provides a clear picture that the polymerization proceeds cleanly to give the desirable linear structure. On the basis of the end group analysis, the degree of polymerization of PBF was determined to be as high as 125, which is in agreement with the molecular weight from the viscosity study. Solid state ¹³C NMR revealed that one of the furan carbons is sensitive to local morphology. DSC and X-ray diffraction further revealed that the polymer had high tendency to form crystalline materials (T_m = 130 °C & 169 °C; T_g = 32 °C). On the basis of DSC and NMR evidences, the two crystalline states are assumed to be β-phase (less stable) and α-phase (more stable), respectively, by analogy with the crystalline structure of PBT. High tendency of forming crystalline structure allows the continuous fibers to be drawn from the PBF's melt. The results thus raise the hope that the biomass-derived PBF could be a promising furan counterpart of the petroleum-based poly(butylene terephthalate) (PBT).     

Bio-based semi-aromatic polyesters for coating applications

Linear and branched bio-based semi-aromatic (co)polyesters were evaluated as resins for solvent-based and powder coatings. Dimethyl-2,5-furandicarboxylate (DMF), 2,3-butanediol and various multifunctional comonomers were used to synthesize amorphous hydroxyl-end-capped (co)polyesters. The resins were cross-linked using the ?-caprolactam blocked trimer of isophorone diisocyanate. Both the solvent-based and powder coatings proved to be hard but brittle, which was a result of the very stiff molecular structure of the formed network. This was corroborated by the T_g values obtained for the coatings, which exceeded 100 °C for both the solvent-based and powder coatings. The poly(ester urethane) coatings prepared from the branched copolyesters show a reasonable solvent resistance. However, swelling occurred during the solvent treatment, indicating an insufficient network formation. The solvent-based and powder coatings exhibit similar mechanical and physical performance, showing that in this study there was no significant influence of the preparation method. In view of the obtained results it can be concluded that DMF-based branched polyesters are interesting candidates for solvent-based and powder coating applications.     

Electrical conductivity of polyblends of poly(1,4-phenylene vinylene) and poly(2,5-dimethoxy-1,4-phenylene vinylene)

Summary A series of polyblends of poly(1,4-phenylene vinylene), PPV, and poly(2,5-dimethoxy-1,4-phenylene vinylene), PDMPV, were prepared in film form from precursor polyblends of the respective sulfonium salt polymers, which were separately prepared from the respectivebis(sulfonium salt) monomers. The blend films were doped with I₂ at room temperature to obtain a wide range of electrical conductivities (10^–2 to 10²Scm^–1) depending on the blend composition. The higher the content of PDMPV in the blends the higher was the conductivity.     

Sequence analysis of poly(ethylene/1,4-cyclohexanedimethylene terephthalate) copolymer using H and C NMR

The triad-level sequence analysis of poly(ethylene/1,4-cyclohexanedimethylene terephthalate) copolymer was reported in a solvent system of o-chlorophenol/deuterated chloroform mixture (50/50 v/v) at 80 °C using 600 MHz ¹H NMR. The well-resolved alcoholic CH₂ proton peak of the glycol units was observed, which made the detailed sequence analysis possible. The peaks of the cis- and trans-forms of the 1,4-cyclohexanedimethylene glycol units were split into the triad sequence in the chain and could be assigned by a comparison of the spectra with those of homopolymers and by an additional two-dimensional heteronuclear multiple bond correlation observation. The triad sequence distributions centered on 1,4-cyclohexanedimethylene glycol units were determined, which was independent of the cis- and trans-forms of the units and controlled according to Bernoullian statistics.     

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

Two series of amorphous copolyesters, PETGN and PETGS, were synthesized by the copolymerization of 2,6‐naphthalene dicarboxylic acid (NDA) (0–40%), succinic acid (SA) (0–40%), 1,3/1,4‐cyclohexanedimethanol (1,3/1,4‐CHDM) (10–50%), ethylene glycol (EG), and terephthalic acid (TPA). The compositions and molecular weights of the copolyesters were determined by ¹H NMR spectroscopy and viscometry, respectively. The thermal behaviors were studied over the entire range of copolymer compositions, using DSC and TGA. The optical characteristics, heat‐shrinkable effects and tensile properties of these polymers were also determined. Experimental results indicated that the thermal, optical, tensile, and shrinkage properties of PETGN and PETGS were functions of NDA or SA content. DSC and X‐ray analysis demonstrated that both PETGN and PETGS series were amorphous. Incorporating NDA and SA influenced the T_g values of those polymers, from about 37°C for PETG₃₀S₄₀ to 89°C for PETG₃₀N₄₀. Furthermore, the shrinkage of these amorphous copolyesters was more than 40% when the heating temperature was higher than the corresponding T_g. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Composition,thermal properties,and biodegradability of a new biodegradable aliphatic/aromatic copolyester

A series of new aliphatic/aromatic copolyesters [poly(hexylene terephthalate‐co‐hexylene adipate) (PHTA)] were synthesized on the bases of 1,6‐hexanediol, adipic acid, and dimethyl terephthalate and characterized by gel permeation chromatography, ¹H‐NMR, wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and compost testing. ¹H‐NMR results show that the compositions of the copolyesters were in accordance with the feed molar ratios. The WAXD patterns indicated that the crystal structures of the PHTA copolyesters were determined by the dominant crystal units, and the copolyesters became less crystallizable, even amorphous, with increasing comonomer content. The DSC curves showed that the glass‐transition temperatures (T_g′s) of the PHTA copolyesters decreased linearly, and both the melting temperature (T_m) and heat of fusion decreased first and then increased with increasing hexylene adipate unit content. Under compost conditions, PHTA copolyesters with less than 60 mol % aromatic units were biodegradable. Particularly, compared with the copolyester poly(butylene terephthalate‐co‐butylene adipate), the PHTA copolyester with the same aliphatic/aromatic composition possessed a lower T_g and T_m and better biodegradability. Additionally, the biodegradability of the copolyesters could be predicted by the number‐average sequence length of aromatic units, T_g, and the temperature difference between T_m and the temperature at which biodegradation took place. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of poly(ethylene‐co‐trimethylene terephthalate)s

Taking advantage of a melt polycondensation process, a series of copolyesters composed of pure terephthalate acid (PTA), ethylene glycol (EG), and 1,3‐propanediol (1,3‐PDO) were synthesized. The component, molecular weight, molecular weight distribution, and thermal properties of the copolymers were characterized. The results show that the contents of trimethylene terephthalate (TT) units in the resulting copolyesters are higher than PDO compositions in original diol. Oligomer content in the copolyesters varies with the compositions and attains a minimum value when the TT ingredient is 49.52 mol %. The glass transition temperature (T_g) of the copolyesters varies from 78.5°C for PET (polyethylene terephthalate) to 43.5°C for PTT (polytrimethylene terephthalate) and decreases monotonically with the components. The copolyesters are amorphous copolymers when TT content is in the range of 32.4–40.8 mol %, as calculated from the melting enthalpy (ΔH_m) measured via differential scanning calorimetry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1511–1521 2006     

Structure–property relationship of poly(cyclohexane 1,4-dimethylene terephthalate) modified with high trans-1,4-cyclohexanedimethanol and 2,6-naphthalene dicarboxylicacid

A series of novel poly(1,4-cyclohexanedimthylene terephthalate-co-1,4-cyclohxylenedimethylene 2,6-naphthalenedicarboxylate) (PCTN) copolyesters were successfully melt polymerized using different content of trans- or cis-isomers. Before evaluations, the performance properties, their actual chemical composition, chemical structure, and molecular weight were determined using proton nuclear magnetic resonance (¹H-NMR), Fourier transform infrared spectroscopy (FTIR), and intrinsic viscosity (IV) measurements. Thermal studies of obtained copolyesters were carried out using differential scanning calorimetry (DSC). Thermal degradation behaviors were analyzed by thermogravimetric analysis (TGA). Randomly oriented film specimens were developed using a hot-press and their thermal, barrier, dimensional stability, and optical properties were analyzed and compared with conventional poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN). The results revealed that glass transition temperature (T_g), melting temperature (T_m), and crystallinity (X_c) of the synthesized copolyesters are increased in a linear trend by increasing the trans-1,4-cyclohexanedimethanol (trans-CHDM) isomers. It was also found that synthesized films had better thermal, barrier, optical, and dimensional stability properties than conventional PET and PEN films. Results clearly indicated that high trans-CHDM isomers significantly improve the performance properties of the fabricated films. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48950.     

Synthesis of novel biodegradable poly(butylene succinate) copolyesters composing of isosorbide and poly(ethylene glycol)

A series of biodegradable isosorbide‐based copolyesters poly(butylene succinate‐co‐isosorbide succinate‐co‐polyethyleneoxide succinate) (PB_xI_yE_zS) were synthesized via bulk polycondensation in the presence of dimethyl succinate (DMS), 1,4‐butanediol (BDO), poly(ethylene glycol) (PEG) and isosorbide (ISO). The crystallization behaviors, crystal structure and spherulite morphology of the copolyesters were analyzed by differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD) and polarizing optical microscopy (POM), respectively. The results indicate that the crystallization behavior of the copolyesters was influenced by the content of isosorbide succinate (IS) and polyethyleneoxide succinate (PEOS) units, which further tuned the mechanical and biodegradable properties of the copolyesters. The PB_xI_yE_zS copolyesters, compared to pure poly(butylene succinate), showed lower crystallization temperature, melting temperature, degree of crystallinity and degradation rate while a significant increase in glass transition temperature with increasing isosorbide content. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of the biodegradable copolymers from succinic acid and adipic acid with 1,4-butanediol

Biodegradable homopolyesters such as poly(butylene succinate) (PBSU) and poly(butylene adipate) (PBAD) and copolyesters such as poly(butylene succinate-co-butylene adipate) (PBSA) were synthesized, respectively, from succinic acid (SA) and adipic acid (AA) with 1,4-butanediol through a two-step process of esterification and deglycolization. The polyester compositions and physical properties of both homopolyesters and copolyesters were investigated by ¹H– and ¹³C–NMR, DSC, GPC, WAXD, and optical polarizing microscopy. The melting point (T_m) of these copolyesters decreased gradually as the contents of butylene adipate increased and the glass-transition temperature (T_g) of these copolyesters decreased linearly as the contents of the adipoyl unit increased. PBSA copolyesters showed two types of XRD patterns of PBSU and PBAD homopolyesters. Furthermore, the biodegradation and hydrolytic degradation of the high molecular weight PBSU homopolyester, PBAD homopolyester, and PBSA copolyesters were investigated in the composting soil and NH₄Cl aqueous solutions at a pH level of 10.6. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2808–2826, 2001