No abstract

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.

Maleic anhydride grafted poly(lactic acid) (PLA g MAH) was prepared by blending with wood flour (WF). The effect of MAH and WF inclusion on the mechanical and thermal properties of the compos ites was examined. PLA g MAH/WF had optimum tensile properties compared with PLA/WF. Scanning electron microscopic images indicated poor interfacial adhesion of the PLA/WF. It was enhanced after MAH was grafted onto PLA; the PLA g MAH/WF showed excellent compatible morphology. Results also revealed that the biodegradation of PLA and PLA g MAH was improved with increasing of WF content.

In this study, novel biodegradable long-segment fluorine-containing polyurethane (PU) was synthesized using 4,4′-diphenylmethane diisocyanate (MDI) and 1H,1H,10H,10H-perfluor-1,10-decanediol (PFD) as hard segment, and polycaprolactone diol (PCL) as a biodegradable soft segment. Nuclear magnetic resonance (NMR) was used to perform 1H NMR, 19F NMR, 19F–19F COSY, 1H–19F COSY, and HMBC analyses on the PFD/PU structures. The results, together with those from Fourier transform infrared spectroscopy (FTIR), verified that the PFD/PUs had been successfully synthesized. Additionally, the soft segment and PFD were changed, after which FTIR and XPS peak-differentiation-imitating analyses were employed to examine the relationship of the hydrogen bonding reaction between the PFD chain extender and PU. Subsequently, atomic force microscopy was used to investigate the changes in the microphase structure between the PFD chain extender and PU, after which the effects of the thermal properties between them were investigated through thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. Finally, the effects of the PFD chain extender on the mechanical properties of the PU were investigated through a tensile strength test.

In this study, helium/oxygen/nitrogen (He/O2/N2)‐plasma was used to etch/modify the surface of ultra‐high‐molecular‐weight polyethylene (UHMWPE) fiber. After coated with polyurethane (PU), the plasma treated UHMWPE fabrics were laminated. It was found that the values of peeling strength between the laminated UHMWPE fabrics treated with He/O2/N2‐plasma were significantly higher (3–4 times) than that between pristine fabrics. The hydrophilic property and the value of the surface roughness of the UHMWPE fibers increased significantly after treated with He/O2/N2‐plasma. The mechanism of the oxidation/degradation of the polymers on the surface of the UHMWPE fiber during He/O2/N2‐plasma treatment was suggested. In addition, it was found that the higher content of functional groups (carbonyl, aldehyde, and carboxylic acid) on fiber surface and the higher value of surface roughness of the UHMWPE fiber treated with He/O2/N2‐plasma could significantly improve the adhesion‐strength of the laminated UHMWPE fabric. Especially, the micro‐aperture on the surface of UHMWPE fiber caused by the strenuous etching of He/O2/N2‐plasma treatment was also an important factor on improving the adhesion‐strength between the laminated UHMWPE fabrics. Copyright © 2010 John Wiley & Sons, Ltd.