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.

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ABSTRACT:We used three kinds of alkyl diallyl ammonium salts (methyl, ethyl, and propyl) in combination with dimethyloldihydroxyethyleneurea (DMDHEU) as crosslinking agents. The nitrogen content, dry crease recovery angle (DCRA), moisture regain, and wicking height for the DM-DHEU/alkyl diallyl ammonium salts were in the order of OCH 3 Ͼ OC 2 H 5 Ͼ OC 3 H 7 , but the wet crease recovery angle (WCRA) and tensile strength retention (TSR) were in the opposite order at the same resin concentration. For the same DCRA and TSR, the WCRA values for only DMDHEU were lower than those for DMDHEU/alkyl diallyl ammonium salts, and the WCRA values for DMDHEU/alkyl diallyl ammonium salts were in the order of OC 3 H 7 Ͼ OC 2 H 5 Ͼ OCH 3 . Both the OOH group of the cellulose and DMD-HEU could react with the vinyl or epoxy groups of the alkyl diallyl ammonium salts during the pad-dry-cure process. The surface migration for DMDHEU/alkyl diallyl ammonium salts was in the order of OCH 3 Ͼ OC 2 H 5 Ͼ OC 3 H 7 . Fabrics treated with DMDHEU/alkyl diallyl ammonium salts showed good antibacterial properties.

A conventional plasma grafting (PG) process for surface treatment has limitations; thus, it should be modified to boost its efficiency. In this study, a new process called immersion−pad-pressing−drying−plasma (IPDP) was proposed. We applied IPDP to graft a quaternary methyl diallyl ammonium salt on the surface of a polypropylene (PP) nonwoven. Ar and O 2 were used as carrier gases for the plasma treatment. For this IPDP process, the optimum acid catalyst concentration was established to be 0.2 M. The grafted PP exhibited excellent antibacterial and hydrophilic properties. Because of the introduction of more peroxides or carboxylic acid groups into the PP nonwoven, the graft ratio for the PG and IPDP processes with O 2 as the carrier gas was demonstrated to be higher than that for the processes with Ar as the carrier gas. The finished PP fabric obtained using the IPDP process indicated antibacterial and hydrophilic properties superior to those of the fabric obtained from the traditional PG process. The IPDP process could overcome the disadvantages of the conventional plasma process, one of which is that the PG process requires a long period of time to bring a grafting reaction to completion. This new IPDP process is shown to be an efficient technique for industrial applications.

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