Linear and branched poly(butylene adipate) polyesters with number-average molecular weights ranging from 700 to 10 000 g/mol, and degrees of branching ranging from very low to hyperbranched were solution cast with PVC to study the effects of chemical structure, molecular weight, end-group functionality, and chain architecture on plasticizing efficiency and durability. Miscibility was evaluated by the existence of a single glass transition temperature and a shift of the carbonyl group absorption band. Desirable mechanical properties were achieved in flexible PVC films containing 40 weight-% of polyester plasticizer. Methyl-ester-terminated polyesters with a low degree of branching and an intermediate molecular weight enhanced the plasticizing efficiency, as shown by greater elongation, good miscibility, and reduced surface segregation. A solid-phase extraction method was developed to extract the low molecular weight products that migrated from pure poly(butylene adipate) and PVC/ poly(butylene adipate) films during aging in water. The effects of branching, molecular weight, end-group functionality, and polydispersity on plasticizer permanence were evaluated by quantification of low molecular weight hydrolysis products, weight loss, surface segregation, and the preservation of material properties during aging. A more migration-resistant polymeric plasticizer was obtained by combining a low degree of branching, hydrolysis-protecting end-groups, and higher molecular weight of the polyester. Films plasticized with a slightly branched polyester showed the best durability and preservation of material and mechanical properties during aging. A high degree of branching resulted in partial miscibility with PVC, poor mechanical properties, and low migration resistance. The thermal stability of polyester-plasticized films was higher than that of films containing a low molecular weight plasticizer, and the stabilizing effect increased with increasing plasticizer concentration. / QC 20100805

<p>A solid phase extraction (SPE) method was developed for simultaneous extraction of dicarboxylic acids and diols formed during hydrolysis of poly(butylene succinate), PBS, and poly(butylene adipate), PBA. The developed SPE method and subsequent GC-MS analysis were used to extract, identify and quantify low molecular weight products migrating from linear and branched poly(butylene adipate) (PBA) and poly(butylene succinate) (PBS) during aging in aqueous media. The combination of SPE and GC-MS proved to be a sensitive tool, able to detect small differences in the degradation rate during early stages of hydrolysis before any significant differences were observed by weight loss and molecular weight measurements. The detected low molecular weight products included monomers i.e. adipic acid and 1,4-butanediol for the PBA polymers and succinic acid and 1,4-butanediol for PBS. Several dimers and trimers i.e. hydroxybutyl adipate, hydroxybutyl succinate, di(hydroxybutyl) adipate, di(hydroxybutyl) succinate and hydroxybutyl disuccinate were also detected. Best extraction efficiency for 1,4-butanediol and succinic acid was achieved with a hydroxylated polystyrene-divinylbenzene resin as solid phase. Linear range for the extracted analytes was 1-500 ng/ml for adipic acid and 2-500 ng/ml for 1,4-butanediol and succinic acid. Detection and quantification limits for all analytes were between 1-2 ng/ml (S/N=3) and 2-7 ng/ml (S/N=10) respectively. Relative standard deviations were between 3 % and 7 %. Comparison of measured weight loss and the amount of monomeric products showed that weight loss during early stages of hydrolysis was mainly caused by the release of water-soluble oligomers that on prolonged ageing were further hydrolyzed to monomeric species. Significant differences in degradation rate could be assigned to degree of branching, molecular weight, aging temperature and degradation medium.</p><p>Linear and branched PBA was mixed with PVC in solution cast films to study the effects of molecular weight and branching on plasticizer efficiency. Used as polymeric plasticizer, PBA formed a semi-miscible two-phase system with PVC where the amorphous part exhibited one single glass transition temperature and the degree of polyester crystallinity was dependent on molecular weight, degree of branching and blend composition. Plasticizing efficiency was favored by higher degree of branching and a 40 weight-percent polyester composition.</p>

The blending of lignin as a component in a thermoplastic blend poses a challenge in the form of dispersion and compatibility. Polyesters such as poly(lactic acid) and poly(butylene adipate-co-terephthalate) offer the best opportunity of compatibility in melt blending with lignin due to their ability to form hydrogen bonds. The fractionation of lignin into more homogeneous fractions offers better dispersion and more consistent properties, retaining the toughness of the original polymer in addition to bridging stress transfer between PLA and PBAT. Functionalization of lignin was done by lactic acid grafting. The resulting blend of PLA/PBAT/modified fractionated lignin showed improved interaction between lignin and PLA, but reduced compatibility between lignin and PBAT. This thesis provides a deeper understanding on the effect of lignin heterogeneity, its fractions, and the functionalization of lignin on lignin and bioplastic blends to further the use of a largely produced industrial by-product in high value applications. / Natural Sciences and Engineering Research Council (NSERC) – Lignoworks Biomaterials and Chemicals Strategic Research Network, Canadian Foundation for Innovation (CFI), Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA)

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A solid phase extraction (SPE) method was developed for simultaneous extraction of dicarboxylic acids and diols formed during hydrolysis of poly(butylene succinate), PBS, and poly(butylene adipate), PBA. The developed SPE method and subsequent GC-MS analysis were used to extract, identify and quantify low molecular weight products migrating from linear and branched poly(butylene adipate) (PBA) and poly(butylene succinate) (PBS) during aging in aqueous media. The combination of SPE and GC-MS proved to be a sensitive tool, able to detect small differences in the degradation rate during early stages of hydrolysis before any significant differences were observed by weight loss and molecular weight measurements. The detected low molecular weight products included monomers i.e. adipic acid and 1,4-butanediol for the PBA polymers and succinic acid and 1,4-butanediol for PBS. Several dimers and trimers i.e. hydroxybutyl adipate, hydroxybutyl succinate, di(hydroxybutyl) adipate, di(hydroxybutyl) succinate and hydroxybutyl disuccinate were also detected. Best extraction efficiency for 1,4-butanediol and succinic acid was achieved with a hydroxylated polystyrene-divinylbenzene resin as solid phase. Linear range for the extracted analytes was 1-500 ng/ml for adipic acid and 2-500 ng/ml for 1,4-butanediol and succinic acid. Detection and quantification limits for all analytes were between 1-2 ng/ml (S/N=3) and 2-7 ng/ml (S/N=10) respectively. Relative standard deviations were between 3 % and 7 %. Comparison of measured weight loss and the amount of monomeric products showed that weight loss during early stages of hydrolysis was mainly caused by the release of water-soluble oligomers that on prolonged ageing were further hydrolyzed to monomeric species. Significant differences in degradation rate could be assigned to degree of branching, molecular weight, aging temperature and degradation medium. Linear and branched PBA was mixed with PVC in solution cast films to study the effects of molecular weight and branching on plasticizer efficiency. Used as polymeric plasticizer, PBA formed a semi-miscible two-phase system with PVC where the amorphous part exhibited one single glass transition temperature and the degree of polyester crystallinity was dependent on molecular weight, degree of branching and blend composition. Plasticizing efficiency was favored by higher degree of branching and a 40 weight-percent polyester composition. / QC 20101209