Water proof and strength retention properties of thermoplastic starch based biocomposites modified with glutaraldehyde.

Water proof and strength retention properties of thermoplastic starch (TPS) resins were successfully improved by reacting glutaraldehyde (GA) with starch molecules during their gelatinization processes. Tensile strength (σf) values of initial and aged TPS100BC0.02GAx and (TPS100BC0.02GAx)75PLA25 specimens improved significantly to a maximal value as GA contents approached an optimal value, while their moisture content and elongation at break values reduced to a minimal value, respectively, as GA contents approached the optimal value. The σf retention values of (TPS100BC0.02GA0.5)75PLA25 specimen aged for 56 days are more than 50 times higher than those of corresponding aged TPS and TPS100BC0.02 specimens, respectively. New melting endotherms and diffraction peaks of VH-type starch crystals were found on DSC thermograms and WAXD patterns of aged TPS or TPS100BC0.02 specimens, respectively, while negligible retrogradation effect was found for most aged TPS100BC0.02GAx and/or (TPS100BC0.02GAx)75PLA25 specimens.

Preparation and Characterization of Bioplastic-Based Green Renewable Composites from Tapioca with Acetyl Tributyl Citrate as a Plasticizer.

Granular tapioca was thermally blended with poly(lactic acid) (PLA). All blends were prepared using a plasti-corder and characterized for tensile properties, thermal properties and morphology. Scanning electron micrographs showed that phase separation occurred, leading to poor tensile properties. Therefore, methylenediphenyl diisocyanate (MDI) was used as an interfacial compatibilizer to improve the mechanical properties of PLA/tapioca blends. The addition of MDI could improve the tensile strength of the blend with 60 wt% tapioca, from 19.8 to 42.6 MPa. In addition, because PLA lacked toughness, acetyl tributyl citrate (ATBC) was added as a plasticizer to improve the ductility of PLA. A significant decrease in the melting point and glass-transition temperature was observed on the basis of differential scanning calorimetry, which indicated that the PLA structure was not dense after ATBC was added. As such, the brittleness was improved, and the elongation at break was extended to several hundred percent. Therefore, mixing ATBC with PLA/tapioca/MDI blends did exhibit the effect of plasticization and biodegradation. The results also revealed that excessive plasticizer would cause the migration of ATBC and decrease the tensile properties.

Ultradrawing novel ultra-high molecular weight polyethylene fibers filled with bacterial cellulose nanofibers.

Novel ultrahigh molecular weight polyethylene (UHMWPE)/bacterial cellulose (BC) (F100BCy) and UHMWPE/modified bacterial cellulose (MBC) (F100MBCx-y) as-prepared fibers were prepared and ultra-drawn. The achievable draw ratio (Dra) values of each F100MBCx-y as-prepared fiber series specimens approached a maximum value as their MBC contents reached the optimal value at 0.0625phr. In which, the maximum Dra value obtained for F100MBCx-0.0625 as-prepared fiber specimen prepared at the optimal MBC content reached another maximum value at 347 as the weight ratio of maleic anhydride grafted polyethylene to BC approach an optimal value at 10. In contrast, no significant improvement in Dra values was found for F100BCy as-prepared fiber specimens. To understand these interesting ultradrawing properties described above, Fourier transform infra-red, specific surface areas, and transmission electron microcopic analyses of original and modified BC nanofibers together with the thermal, orientation and tensile properties of F100BCy and F100MBCx-y fiber specimens were performed.

Biocompatibility and characterization of renewable agricultural residues and polyester composites.

Composites of sesame husk and glycidyl methacrylate-grafted polytrimethylene terephthalate (PTT-g-GMA/SH) exhibit noticeably superior mechanical properties compared to PTT/SH composites due to greater compatibility between the two components. The dispersion of SH in the PTT-g-GMA matrix is highly homogeneous as a result of condensation reaction formations. Human lung fibroblasts (FBs) were seeded on these two series of composites to characterize the biocompatibility properties. In a time-dependent course, the FB proliferation results demonstrated higher performance from the PTT/SH series of composites than from the PTT-g-GMA/SH composites. In addition, collagen production by FBs present in the PTT/SH series was 20% higher than in regular culture-plates after 7 days of incubation. The water resistance of PTT-g-GMA/SH was higher than that of PTT/SH, although the weight loss of both composites buried in soil compost indicated that they were both biodegradable, especially at higher levels of SH substitution. The PTT/SH and PTT-g-GMA/SH composites were more biodegradable than pure PTT, implying a strong connection between SH content and biodegradability.