Enhancing the Compatibility of Poly (1,4-butylene adipate) and Phenoxy Resin in Blends

Abstract

This work concerns the enhancement in the compatibility of blends of poly (1,4-butylene adipate) (PBA) with poly (hydroxy ether of bisphenol-A) (phenoxy) via alcoholytic exchange. Results on the thermal behavior and morphology show that the blended PBA/phenoxy system exhibits a homogeneous phase and a composition-dependent glass transition temperature (Tg). The interaction parameter (χ12) of PBA/phenoxy blends was calculated using the melting point depression method and was found to be −0.336. However, the compatibilization of PBA/phenoxy blends can be enhanced by chemical exchange reactions between PBA and phenoxy upon annealing. Annealed PBA/phenoxy blends were found to have a homogeneous phase with a higher Tg than that of the blended samples, and a smooth surface topography that could be improved by annealing at high temperature. The results of this investigation demonstrate that promotional phase compatibilization in the PBA/phenoxy blend can only be obtained upon thermal annealing, thus causing transreactions to occur between the dangling –OH of the phenoxy and the ester functional groups in PBA. Extensive transreactions cause alcoholytic exchange between the PBA and phenoxy to form a network, thus reducing the mobility of the polymer chain. Finally, the crystallinity of PBA decreased as the degree of transreaction in the blends increased.

Chemical Interaction-Induced Evolution of Phase Compatibilization in Blends of Poly(hydroxy ether of bisphenol-A)/Poly(1,4-butylene terephthalate)

“…One of our earlier studies illustrated that a transreaction arises in blends of phenoxy and copolyesters. Phenoxy, with a -OH in the structure, causes interaction with the C=O of copolyesters in polymer blends [ 3 , 4 , 5 ]. These chemical interactions result in the replacement of covalent bonds in the polymers, changing the linkages adjacent to the carbonyl group of polyesters.…”

“…In reactive blending, chemical reactions between reactive groups progress during melt blending or heat treatment. Thus, a phase-separated compatibilized blend can be achieved with controllable morphology and interfaces [ 2 , 3 , 4 , 5 , 6 , 7 ].…”

“…Phenoxy contains ether linkages in the backbone and pendant hydroxyl groups that exhibit outstanding mechanical properties, such as toughness and dimensional stability [ 3 , 5 , 8 , 9 ]. In its organic chemistry, the oxygen in the hydroxyl group has two lone pairs with negative charges on the para and ortho positions, which become the activated positions when electron-donating substituents are present [ 10 ].…”

“…Additionally, phenoxy can also form immiscible or partially miscible blends with some aliphatic polyesters (e.g., poly(ethylene succinate) [ 20 ], poly(butylene acid) (PBA) [ 5 ], and poly(3-hydroxybutyrate) (PHB) [ 21 ]) and aromatic polyesters (e.g., poly(ethylene terephthalate) (PET) [ 22 ], poly(trimethylene terephthalate) (PTT) [ 23 ], and poly(ethylene 2,6-naphthalenedicarboxylate) [ 24 ]). However, the chemical interactions that occur following high-temperature annealing enhance miscibility.…”

“…As a result of this, a stable and fine morphology is attained with enhanced interfacial adhesion between the phases. Additionally, compatibilization can introduce reactive molecules that are capable of forming the desired copolymers, both in situ and directly during the blending or annealing of the reactive polymer blends [ 2 , 3 , 4 , 5 ].…”