The kinetics of poly(butylene succinate) synthesis and the influence of molar mass on its thermal properties

Abstract

The synthesis of poly(butylene succinate) (PBS) of Mw ranging from 4000 to 180,000 g mol−1 is realized with molar ratios [COOH]0/[OH]0 of 1 and 0.98, and varying amounts of titanium (IV) tetrabutoxide (TBT) catalyst. Polycondensation kinetics are followed by chemical titration of carboxylic groups, and the kinetic rate constants of self‐catalyzed and external‐catalyzed reactions are calculated. The synthesis of PBS with high molar mass follows the classical Flory theory. The effect of molar mass on PBS thermal properties is also studied. A faster crystallization rate and a higher temperature of crystallization are observed, for very high molar masses. This behavior could be due to a memory effect of the polymer. Complex melting behavior of PBS is induced by a continuous reorganization of the crystalline phase, as observed by MTDSC. DSC measurements also reveal that the crystallinity—and so the amorphous phase—is limited to about 35% when the molar mass Mn is higher than 40,000 g mol−1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40639.

Supertough and Biodegradable Poly(Lactic Acid) Blends with “Hard–Soft” Core–Shell Unsaturated Poly(ether-ester) through Self-Vulcanization

“…In order to develop a simple and effective synthesis method for the tunable polyester with a wide range of applications, we adopted an esterification condensation process for PBSFG similar to that used in PBS synthesis. Ti­(OBu) 4 was chosen as the catalyst, as it has been widely reported as the most effective metal catalyst for the synthesis of polyester. − To prevent free radical polymerization induced by fumaric acid, the addition of 4-methoxyphenol as a polymerization inhibitor is necessary. The reaction pathway is illustrated in Scheme .…”

Poly(butylene succinate) (PBS): Materials, processing, and industrial applications

“…More recently, Mathieu Garin et al reported on the kinetics of PBS synthesis of and stated that the high molar mass synthesis of PBS merely follows classical Flory theory. Moreover, a very high molecular weight PBS polymer exhibited a higher crystallization temperature and faster rate of crystallization [123] . Different synthesis methods have been adopted to obtain PBS with a reasonably high molecular weight.…”

Feasibility of Solid-State Postpolymerization on Fossil- and Bio-Based Poly(butylene succinate) Including Polymer Upcycling Routes

“…Nowadays, the negative environmental impact caused by the use and disposal of conventional nondegradable plastics has intensified the efforts of academia and industry toward the development of bio-based and biodegradable polymers. − As a representative of these new materials, poly­(butylene succinate) (PBS) is considered to be promising for the replacement of polyolefins, like polyethylene (PE) and polypropylene (PP) . Compared to the most commercialized biopolymer [poly­(lactic acid), PLA; T g = 60 °C], the PBS lower glass transition point ( T g = −32 °C) renders it flexible, as well as more easily melt-processable at lower cost. − In addition, PBS possesses a relatively high melting point ( T m = 112–114 °C) , compared to other soft polyesters derived from aliphatic diols and diacids, mechanical properties similar to those of PP and low-density PE, and a tunable structure via alteration of the monomer composition. ,, Finally, the high potential for industrial production of partially or fully bio-based PBS has stimulated interest for its research and development; already ameliorated fermentation processes have given rise to the production of a bio-based diacid monomer (succinic acid, SA) at industrial scale, ,− while the diol monomer, 1,4-butanediol (BDO), can also be prepared from bio-based SA. , …”

“…A significant number of publications have dealt with the synthesis of PBS: it is conventionally prepared via a two-stage melt polycondensation process (Figure ) ,,− with a first step of esterification between BDO and SA usually in a molar ratio of 1.1:1 at temperatures from 190 to 225 °C. After removal of the stoichiometric water and in the presence of an efficient catalyst, the formed oligomers are further polycondensed at higher temperatures of 230–250 °C under vacuum, resulting in high-molecular-weight PBS, for example, with a number-average molecular weight ( M̅ n ) of 120000 g mol –1 . ,− Typical catalysts include tin­(II) chloride (SnCl 2 ), tetrabutyl titanate (TBT), ,, distannoxane, − lanthanide triflates, p -toluenesulfonic acid, with the most common being TBT.…”

“…However, melt polymerization products usually suffer from drawbacks associated with the high reaction temperatures and residence times in the melt, as well as yellowing caused by titanium-based catalysts. ,− Especially in the case of PBS, high esterification temperatures for prolonged times and application of vacuum favor BDO loss (boiling point, T b = 230 °C), its dehydration to tetrahydrofuran, ,, and other side reactions, all resulting in a disturbed end-group balance and impaired properties such as hydrolysis stability. , These phenomena may even be more intense in bio-based PBS production; the organic acid-nature impurities, e.g., acetic acid, which are recovered from the fermentation broth together with SA, , are likely to contribute to side reactions, lowering the obtainable maximum molecular weight (MW) and changing the polymer characteristics, such as thermal and mechanical ones …”