Poly­[2-(tert-butylaminoethyl) methacrylate] (PTA), an important class of antimicrobial polymers, has demonstrated its great biocidal efficiency, favorable nontoxicity, and versatile applicability. To further enhance its antimicrobial efficiency, an optimization of the chemical structure of PTA polymers is performed via atom transfer radical polymerization (ATRP) in terms of the antimicrobial ability against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). After the optimization, the resulting PTA is blended into a polylactide (PLA) matrix to form PTA/PLA composite thin films. It is first found, that the antimicrobial efficiency of PTA/PLA composites was significantly enhanced by controlling the PLA crystallinity and the PLA spherulite size. A possible mechanistic route regarding this new finding has been rationally discussed. Lastly, the cytotoxicity and mechanical properties of a PTA/PLA composite thin film exhibiting the best biocidal effect are evaluated for assessing its potential as a new material for creating antimicrobial biomedical devices.

No abstract

This study uses a single screw extruder to make short coir (SC), an agricultural waste, high-strength short glass fiber (SGF), and polypropylene (PP) into pellets, which are then made into wood plastic composites (WPC) on an injection machine. During the process, maleic anhydride grafted polypropylene (PP-g-MA) is used as a coupling agent to improve the interfacial adhesion between coir and PP as well as between SGF and PP. A tensile strength test, flexural strength test, and Izod impact strength test are performed on the samples to examine the mechanical properties. The experiment results show that when the content of SGF increases from 3 wt% to 12 wt%, the tensile strength increases from 26.08 MPa to 36.68 MPa, and flexural strength increases from 36.01 MPa to 49.91 MPa, but the Izod impact strength decreases from 286.16 J/m to 218.14 J/m. In addition, the addition of 2 wt% of PP-g-MA improves the interfacial adhesion between matrices (PP) and reinforcement (SC or SGF), thereby fortifying the mechanical properties of the composites.

Maleic anhydride grafted polypropylene (PP-g-MA) is used as a coupling agent, and the influence of its used amount on the mechanical properties of the polypropylene/short glass fiber (PP/SGF) composites is examined. 1, 2, and 3 wt% of PP-g-MA is separately added to PP/SGF composites that are made at an 80/20 ratio (wt%), made into pellets on a single screw extruder, and then made into test samples on an injection machine. When PP-g-MA increases from 1 wt% to 3 wt%, the tensile strength of the PP/SGF composites increases from 56.22 MPa to 64.85 MPa; likewise, flexural strength increases from 67.29 MPa to 81.24 MPa, and Izod impact strength increases from 197.70 J/m 269.61 J/m. SEM images show that the surface of SGF are encapsulated with a layer of PP matrix, which indicates that PP-g-MA can effectively improve the interfacial adhesion between PP and SGF and thus increase the mechanical properties of the resulting composites.

This study presents polyvinyl alcohol (PVA)/multi-walled carbon nanotubes (MWCNTs) composites, and examines the influence of the content of MWCNTs on the tensile and thermal properties of the PVA matrices. The test results show that an increase of 1.5 wt% of MWCNTs results in greater tensile properties of the PVA matrices, while decreasing their toughness. The interaction between MWCNTs and PVA pertains to the thermal properties of PVA matrices, which is exemplified by a significant increase in their glass transition temperature (Tg).