A review of experimental studies of the role of free-radicals in polyethylene oxidation
Publication date: Available online 11 July 2018Source: Polymer Degradation and StabilityAuthor(s): Pierangiola Bracco, Luigi Costa, Maria Paola Luda, Norman BillinghamAbstractThis paper reviews current understanding of the role of free radicals in the oxidation of polyethylene induced by high-energy irradiation (gamma or e-beam). To evaluate the reactivity, stability and mobility of different macroradicals, their reactions after gamma irradiation of different polyethylenes (LDPE, LLDPE, VLLDPE, HDPE, UHMWPE) are considered. Macroradicals are formed in all phases of PE (crystalline, amorphous and interphase). Their overall determination is possible only if both irradiation and detection are carried out at 100 K, or below. At this temperature, the most abundant macroradical formed is the secondary alkyl macroradical (R’’°). On gradually raising the temperature, the macroradicals decay with formation of vinylene double bonds and molecular hydrogen. At room temperature, the macroradical concentration is about 4% of the original quantity at 100 K for LDPE and around 15% for HDPE. In HDPE and UHMWPE; the macroradicals are mainly present in the crystalline phase and in short times (hours) they migrate to the amorphous phase. In LDPE and LLDPE macroradicals are mainly allylic, present in minimal amounts at the crystalline-amorphous interphase. In the nearly fully amorphous VLDPE no residual macroradicals can be detected at room temperature.The mobility of R’...
CONCLUSION: The remains in the LTB tomb were not a traditional nuclear family (father, mother and son/daughter) and it was probably a tomb where two women, one of them pregnant, were buried. PMID: 30027753 [PubMed - as supplied by publisher]
Authors: Liew M, Rowe LR, Szankasi P, Paxton CN, Kelley T, Toydemir RM, Salama ME PMID: 30027711 [PubMed - in process]
Authors: Kim YJ, Ko JM, Song J, Lee KA PMID: 30027710 [PubMed - in process]
Authors: Oh J, Yoo IY, Song DJ, Lee JW, Kim YJ, Ki CS, Lee NY, Huh HJ PMID: 30027709 [PubMed - in process]
Authors: Sebastian S, Malhotra R, Sreenivas V, Kapil A, Chaudhry R, Dhawan B PMID: 30027708 [PubMed - in process]
Authors: Kim JH, Lee E, Lee Y PMID: 30027707 [PubMed - in process]
Authors: Heo ST, Kwon KT, Yoo JR, Choi JY, Lee KH, Ko KS PMID: 30027706 [PubMed - in process]
Authors: Shin KH, Lee HJ, Kim HH, Hong YJ, Park KU, Kim MJ, Kwon JR, Choi YS, Kim JN Abstract Frequencies of red blood cell (RBC) blood group antigens differ by ethnicity. Since the number of immigrants is increasing in Korea, RBC antigens should be assessed in children/youths with parents of different ethnicities to ensure safe transfusions. We investigated the frequency of RBC antigens, except for ABO and RhD, in 382 children and youths with parents having Korean and non-Korean ethnicities. Subjects were divided into those with ethnically Korean parents (Korean group; N=252) and those with at least one parent of ...
CONCLUSIONS: rs3761549, rs5902434, and rs2232365 are associated with an increased risk of acute GVHD and decreased risk of post-HSCT infection. PMID: 30027704 [PubMed - in process]
CONCLUSIONS: Our algorithm omitting weak D testing in D- patients with C-E- phenotype may be a cost-effective testing strategy in Korea. PMID: 30027703 [PubMed - in process]