Synthesis and characterization of isomeric polyesters based on sebacic acid and hexanediols

Abstract

Isomeric homopolymers and random copolyesters based on sebacic acid and isomeric hexanediols were synthesized by condensation techniques and characterized by NMR, GPC, intrinsic viscosity, and DSC. Among the homopolymers, only the polyester derived from the linear 1,6‐hexanediol was found to be crystalline. Typical melting points were 65–70°C, depending on molecular weight, and a Tg of −62°C was measured on a high molecular weight sample. Other isomeric homopolymers derived from the branched diols 2‐methyl‐2‐ethyl‐1,3‐propanediol and 2,5‐hexanediol were amorphous tacky fluids with glass temperatures of −69 and −66°C, respectively. In the case of the random copolymers, NMR analysis was particularly useful in determining the copolymer composition or the diol isomer ratio. DSC data indicated that all the random copolymers containing the linear 1,6‐diol were crystallizable and their melting points depended on copolymer composition. The heat of fusion per repeat unit of poly(hexamethylene sebacate) was found to be 32 cal/g from measurements of the molecular weight dependence of the melting point.

Analysis of the Multistep Solidification Process in Polymer Blends

“…Both polyesters have primary OH groups at their chain ends, whereas PPG has secondary OH end groups. Equilibrium melting points ( ) of PHMA and PHMS are 58 and 70 °C, respectively. , Since the melting points of these polyesters differ, the degree of supercooling (Δ T = − T c , where T c indicates the crystallization temperature) was used for crystallization analysis. The glass transition temperature ( T g ) of P(MMA- co - n -BMA) is 85 °C.…”

“…The heating rate was 10 °C/min. The degree of crystallinity of binary or ternary blends was calculated by comparing the melting enthalpy (Δ H m ) of an isothermally crystallized sample with the equilibrium melting enthalpy of polyester (Δ ), as shown in Table . , Blend morphology was observed using an Olympus Vanox optical microscope equipped with a digital camera.…”

Synthesis of potentially biobased poly(hexamethylene sebacate) via reactive extrusion

“…The choice of the catalysts is of importance. The work of O'Malley and Stauffer is an example of the use of para-toluenesulfonic acid (PTSA), a typical catalyst for esterification, for the synthesis of PE 6-10 [26]. The authors have synthesized oligomers with an excess of 10 mol% of diol and 5,000 ppm of PTSA relative to the overall mass of the monomers.…”

“…Sebacic acid may be derived from castor oil and 1,6-hexanediol can be obtained by degradation and reduction of hemicellulose [23,24]. PE 6-10 is semi-crystalline with a melting point of 67 • C [25][26][27]. This polyester is biodegradable and easily hydrolyzed in soil.…”

Crystalline isomeric polyester block copolymers. Scanning calorimetry and density measurements

“…(1) % cryst. = AH,/AIH,* I X ilb0 (1) where AHf is the measured heat of fusion for the sample and AHf; is the heat of fusion (32 cal/g) for ~W O crystalline poly(HMS).' The % crystallinity of only the crystallizable component (HMS) was obtained by dividing the right side of eq.…”