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51.
Enhancement of pro‐degradant performance in polyethylene/starch blends as a function of distribution
Long Yu Xingxun Liu Eustathios Petinakis Stuart Bateman Parveen Sangwan Anne Ammala Katherine Dean Susan Wong‐Holmes Qiang Yuan Chee Kiong Siew Farid Samsudin Zulkifli Ahamid 《应用聚合物科学杂志》2013,128(1):591-596
The effect of pro‐degradant distribution in polyethylene (PE)/starch blends on ultraviolet (UV) photo‐oxidative degradation was investigated. Two kinds of pro‐degradants, Fe and Co‐based, were used in this study. The distribution of pro‐degradants in the different phases was varied by a dual step process using a side‐feed on a reactive extruder. The variation in mechanical properties and evaluation of carbonyl groups by FTIR were conducted to investigate the effect of degradation following exposure to UV photo‐oxidative degradation. It was found that the variation in mechanical properties was higher when the pro‐degradants were distributed in the PE phase. The concentration of carbonyl groups increased as a function of UV exposure, and the concentration of carbonyl groups was higher when the pro‐degradants were distributed in the PE phase. Micro‐cracking was observed on the interface between starch and PE after adding the pro‐degradants. When the pro‐degradants were distributed in high‐density polyethylene (HDPE) phase, the micro‐cracks mainly appeared in HDPE matrix, and the density of micro‐crack was higher. In general, the function of the pro‐degradants in PE/starch blends was enhanced when their distribution was varied within HDPE phase. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
52.
Parveen Saini Veena Choudhary B.P. Singh R.B. Mathur S.K. Dhawan 《Materials Chemistry and Physics》2009,113(2-3):919-926
Highly conducting polyaniline (PANI)–multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by in situ polymerization. The FTIR and XRD show systematic shifting of the characteristic bands and peaks of PANI, with the increase in MWCNT phase, suggesting significant interaction between the phases. The SEM and TEM pictures show thick and uniform coating of PANI over surface of individual MWCNT. Based on observed morphological features in SEM, the probable formation mechanism of these composites has been proposed. The electrical conductivity of PANI–MWCNT composite (19.7 S cm?1) was even better than MWCNT (19.1 S cm?1) or PANI (2.0 S cm?1). This can be ascribed to the synergistic effect of two complementing phases (i.e. PANI and MWCNT). The absorption dominated total shielding effectiveness (SE) of ?27.5 to ?39.2 dB of these composites indicates the usefulness of these materials for microwave shielding in the Ku-band (12.4–18.0 GHz). These PANI coated MWCNTs with large aspect ratio are also proposed as hybrid conductive fillers in various thermoplastic matrices, for making structurally strong microwave shields. 相似文献
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Nawaz Bushra Ullah Muhammad Obaid 《Journal of Materials Science: Materials in Electronics》2021,32(11):14509-14518
Journal of Materials Science: Materials in Electronics - Electrode materials with the benefits of high working voltage, low cost, and environmental benign are needed for the realization of... 相似文献
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Muhammad Farooq Warsi Bushra Bashir Sonia Zulfiqar Muhammad Aadil Muhammad Usman Khalid Philips O. Agboola Imran Shakir Muhammad Asif Yousuf Muhammad Shahid 《Ceramics International》2021,47(4):5044-5053
The narrow optical band gap, higher electrical conductivity, and wider-absorption range are three key features that a good photocatalyst must possess. Herein, we have fabricated Cu-doped MnO2 (Mn1-xCuxO2) nanostructure by facile wet chemical approach and formed its nanocomposite with r-GO (Mn1-xCuxO2/r-GO) via ultra-sonication approach. The successful replacement of host metal ions (Mn4+) with the dopant metal ions (Cu2+) was supported with the PXRD, FT-IR, and EDX characterizations. The effect of Cu-doping on the band gap and r-GO matrix on the conductivity of the fabricated nanocomposite was also evaluated via Tauc plots and I–V tests, respectively. The photocatalytic efficiency of the fabricated photocatalysts was tested and compared against the methylene blue (MB) under visible light irradiation. The photocatalytic experiments revealed that Mn1-xCuxO2/r-GO photocatalyst exhibited superior photocatalytic aptitude than that of pristine MnO2 and Mn1-xCuxO2 photocatalysts. More precisely, the Mn1-xCuxO2 photocatalysts degraded 86.89% MB dye at the rate of 0.021 min?1 after a 90-min exposure to the visible light. Observed superior catalytic activity of the nanocomposite can be attributed to the synergistic effects between the Cu doped MnO2 and r-GO nanosheets that resulted in its narrow band-gap (2.19 eV) and excellent conductivity (2.217 × 10?2 Scm?1). 相似文献
58.
JM Leong H Wang L Magoun JA Field PE Morrissey D Robbins JB Tatro J Coburn N Parveen 《Canadian Metallurgical Quarterly》1998,66(3):994-999
PURPOSE: To compare failure-free survival (FFS) and overall survival (OS) for patients with metastatic breast cancer treated with the gonadotropin-releasing hormone (GN-RH) agonist, goserelin versus surgical ovariectomy. PATIENTS AND METHODS: Between August 1, 1987 and July 15, 1995 138 (136 eligible) premenopausal patients with estrogen receptor (ER)- and/or progesterone receptor (PgR)-positive metastatic breast cancer were entered by the Southwest Oncology Group (SWOG), North Central Cancer Treatment Group (NCCTG), and Eastern Cooperative Oncology Group (ECOG). Prior chemotherapy or hormone therapy for metastatic disease was not allowed. Patients were randomly assigned to goserelin (3.6 mg subcutaneously every 4 weeks; (n = 69) versus surgical ovariectomy (n = 67). The study was initially designed as an equivalence trial with 80% power to rule out a 50% improvement in survival due to ovariectomy. However, accrual was slow and the study was terminated early, which resulted in a final power of 60% for the alternative hypothesis of equal survival distributions. RESULTS: FFS and OS were similar for goserelin and ovariectomy. The goserelin/ovariectomy death hazards ratio was .80 and the associated 95% confidence interval (CI) was .53 to 1.20. The test of 50% improvement in survival due to ovariectomy was rejected at P = .006. Goserelin lowered serum estradiol to postmenopausal levels. Hot flashes (75% v 46%) and tumor flare (16% v 3%) were more common with goserelin. CONCLUSION: Goserelin and ovariectomy resulted in similar FFS and OS. We can rule out a moderate advantage for ovariectomy. Goserelin was safe and well tolerated. 相似文献
59.
Bushra Al-Duri Gordon McKay 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,55(3):245-250
The present work studies the intraparticle diffusivity in batch adsorption systems as a function of the initial sorbate concentration. The systems under investigation are basic dyes, namely Basic Blue 69, Basic Red 22 and Basic Yellow 21 and their binary and ternary combinations, all adsorbing onto activated carbon Filtrasorb 400. They study is based on the film-pore diffusion model and the output is a combination of the external mass transfer coefficient, kf and the effective diffusivity, Deff that yields congruent experimental and theoretical kinetic data. It has been found the Deff varies with Co in an exponential decay function. Furthermore. Deff values undergo a general reduction in the multisolute systems compared to the single component systems. Also, the relative diffusion rates in the multisolute systems are found to change such that Deff of the slower diffuser is enhanced and that Deff of the faster diffuser is inhibited. 相似文献
60.
An alternate inner wall variable, for flow over a transitional rough pipe surface, is defined as the ratio of normal coordinate measured above the mean roughness level to the wall roughness scale. The Reynolds equations for mean turbulent flow in a transitional rough pipe, in two layers (inner and outer) are considered. The predictions of the mean velocity and friction factor in fully developed turbulent flow in a rough pipe flow, presented here, covers all types of roughness. The data for a particular case of the machine honed Princeton superpipe roughness, analogous to inflectional type roughness of Nikuradse, is presented, as two expressions using our roughness scale. The velocity profile and friction factor, on a transitional rough wall, are shown to be governed by the new log laws, which are explicitly independent of the transitional wall roughness. Further, the inflectional roughness has also been connected with geometric roughness parameters; like, arithmetic mean roughness, mean peak to valley heights roughness, root mean square (rms), roughness based on texture measure; and the friction factor implicit and approximate explicit formulas have also been proposed. In entire transition region between fully smooth and fully rough wall, monotonic roughness of Colebrook (Moody Chart) over estimaton the friction factor when compared with present inlectional roughness. 相似文献