Toughening effects of poly(butylene terephthalate) with blocked isocyanate-functionalized poly(ethylene octene)

BACKGROUND: Blocked isocyanate-functionalized polyolefins have great potential for use in semicrystalline polymer blends to obtain toughened polymers. In this study, poly(butylene terephthalate) (PBT) was blended with allyl N-[2-methyl-4-(2-oxohexahydroazepine-1 -carboxamido)phenyl] carbamate-functionalized poly(ethylene octene) (POE-g-AMPC).RESULTS: New peaks at 2272 and 1720 cm(-1), corresponding to the stretching vibrations of NCO and the carbonyl of NH-CO-N, respectively, in AMPC, appeared in the infrared spectrum of POE-g-AMPC. Both rheological and X-ray photoelectron spectroscopy results indicated a new copolymer was formed in the reactive blends. Compared to uncompatibilized PBT/POE blends, smaller dispersed particle sizes with narrower distribution were found in the compatibilized PBT/POE-g-AMPC blends. There was a marked increase in impact strength by about 10-fold over that of PBT/POE blends with the same rubber content and almost 30-fold higher than that of pure PBT when the POE-g-AMPC content was 25 wt%.

Incidence of diverse integrons and beta-lactamase genes in environmental Enterobacteriaceae isolates from Jiaozhou Bay, China

Environmental microbiology investigation was performed to determine the molecular diversity of beta-lactamase genes among ampicillin-resistant bacteria from Jiaozhou Bay. beta-lactamase genes were detected in 93.8% of the bacterial isolates identified as Enterobacteriaceae. The most frequently detected gene was bla(TEM), followed by bla(SHV), bla(OAX-1), bla(MOX) and bla(CMY). Most of the isolates (68.8%) were positive for the intI1 integrase gene, and two isolates were also found for the intI2 gene. The dfr and aadA gene cassettes were predominant. Anthropogenic contamination from onshore sewage processing plants might contribute predominantly to the beta-lactamase gene reservoir in the studied coastal waters. Environmental antibiotic-resistant bacteria and resistance genes may serve as bioindicators of coastal environmental quality or biotracers of the potential contamination sources. This is the first report of the prevalence and characterization of beta-lactamase genes and integrons in coastal Enterobacteriaceae from China.