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31.
Yusuf Kayali Şükrü Talaş 《Protection of Metals and Physical Chemistry of Surfaces》2019,55(6):1148-1153
Protection of Metals and Physical Chemistry of Surfaces - AISI 316 L austenitic stainless steel is widely used in various sectors of the industry (chemical, petro-chemical industry, paper industry,... 相似文献
32.
The emergence, historical and recent developments of phenolic resins are reviewed. The history of the invention of the first man made plastics and a short bibliography of the inventor Leo H. Baekeland is provided. Moreover, the basic chemistry of phenol-formaldehyde resins, as synthesis of resol and novolak, their structures, variations, and curing are discussed. Modification of these resins and molecular designs for specific applications in retro perspective are highlighted. This review also provides a comprehensive account on the development of benzoxazine resins as an alternative to classical phenolics. In addition to the benzoxazine synthesis and their curing mechanism, special monomers and polybenzoxazine precursors as curable thermoplastics are reviewed. Besides classical chemicals, the potential of renewables for phenolic resin production is also highlighted. Finally, the relative advantages and disadvantages of these systems are discussed and their future potentials are presented. 相似文献
33.
Thermally exfoliated graphene oxide reinforced fluorinated pentablock poly(l‐lactide‐co‐ε‐caprolactone) electrospun scaffolds: Insight into antimicrobial activity and biodegradation
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Burcu Saner Okan Azucena Marset Jamal Seyyed Monfared Zanjani Pınar Akkus Sut Ozlem Sen Mustafa Çulha Yusuf Menceloglu 《应用聚合物科学杂志》2016,133(22)
Three‐dimensional fluorinated pentablock poly(l ‐lactide‐co‐ε‐caprolactone)‐based scaffolds were successfully produced by the incorporation of thermally exfoliated graphene oxide (TEGO) as an antimicrobial agent with an electrospinning technique. In a ring‐opening polymerization, the fluorinated groups in the middle of polymer backbone were attached with a perfluorinated reactive stabilizer having oxygen‐carrying ability. The fiber diameter and its morphologies were optimized through changes in TEGO amount, voltage, polymer concentration, and solvent type to obtain an ideal scaffold structure. Instead of the widely used graphene oxide synthesized by Hummer's method, TEGO sheets having a low amount of oxygen produced by thermal expansion were integrated into the fiber structure to investigate the effect of the oxygen functional groups of TEGO sheets on the degradation and antimicrobial activity of the scaffolds. There was no antimicrobial activity in TEGO‐reinforced scaffolds in the in vitro tests in contrast to the literature. This study confirmed that a low number of oxygen functional groups on the surface of TEGO restricted the antimicrobial activity of the fabricated composite scaffolds. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43490. 相似文献
34.
A model study of the sonochemical removal of nitric oxide (NO) in a bubble column reactor is presented. The detailed model is developed to investigate the actual cavitation phenomena taking place during the absorption of NO. The expansion and subsequent collapse of cavitation bubble according to the theory of cavity collapse—initially developed by Lord Rayleigh and then improved on by coupling the energy balance equation of the bubble and the chemical reactions taking place inside the cavity to calculate the composition of different species formed during the collapse—are modeled. The model takes into consideration (1) cavitation bubble dynamics, (2) generation and transfer of oxidizing species from bubble collapse through reaction kinetics, (3) transfer of NO from gas to liquid, and (4) chemical reactions of oxidizing species with dissolved NO. The results of the simulations surprisingly indicate that the chemistry induced by ultrasonic cavitation cannot explain the absorption of NO beyond about 30% of the inlet concentration if the mass transfer is assumed to be the same as that in the bubble column without ultrasound. When experimental values of mass‐transfer coefficients, calculated in the studies by other researchers (which are in the range of about five times the physical mass‐transfer coefficient in a bubble column), are used, absorption up to 80% are calculated in the simulations consistent with experimental results obtained from the sonochemical bubble column reactor. The present model provides a framework on which more robust and rigorous models can be developed for the complex gas‐liquid sonochemical systems and reactors. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2397–2411, 2012 相似文献
35.
The relative change in insulation property of the ordinary concrete due to adding polymeric based waste material is experimentally investigated here. The polyethylene (PET) bottle and automobile tire pieces, which can easily be obtained from the environment with almost no cost, are shredded and added into ordinary concrete to examine heat insulation behaviors of specimens. Five different concrete samples (one ordinary concrete, one concrete with scrap rubber pieces and three concretes with waste PET bottle pieces of various geometries) are considered. The adiabatic hot-box technique is used for comparing effective thermal transmittances of these concrete samples. The results reveal that proper addition of selected waste materials into concrete can significantly reduce heat loss or improve thermal insulation performance. The degree of improvement in thermal insulation is found to vary with the added waste material and geometry of shredded-pieces. 相似文献
36.
Simultaneous production of C‐phycocyanin and extracellular polymeric substances by photoautotrophic cultures of Arthrospira platensis
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38.
Macromonomers based on poly(ε-caprolactone) (PCL) with α,ω-thiophene functional end groups were prepared in bulk by enzymatic
polymerization using immobilized Candida Antarctica lipase B (Novozym 435) as the catalyst. In the synthesis strategy, 3-thiophenemethanol was used to initiate the enzyme-assisted
ring-opening polymerization of ε-caprolactone (ε-CL) to yield PCL with α-thiophene end group (initiation reaction, ThPCL)
and then 3-thiopheneacetic acid was added to prepolymerized ε-CL to introduce ω-thiophene functionality in termination step
(ThPCLTh). Macromonomers were characterized by 1H and 13C NMR, FTIR, and GPC. Moreover, the obtained macromonomers were employed in electropolymerization experiments and copolymers
with thiophene or pyrrole were synthesized through their end thiophene groups. These polymers were characterized by cyclic
voltammetry (CV), FTIR, and scanning electron microscopy (SEM). Conductivity measurements were carried out by the four-probe
technique. 相似文献
39.
The molecular motions of spin probes at the interphase region of poly(methyl methacrylate) particles sterically stabilized by polyisobutylene (PIB) were studied by ESR spectroscopy. The correlation times (τ) were measured by using the methods of Freed and Kivelson. Activation energies for different modes of motion were calculated at wide temperature range between ?140 and 140°C. Viscosities were estimated in methanol saturated PIB channels in the polymer particles. © 1994 John Wiley & Sons, Inc. 相似文献
40.
Summary Cationic polymerisations of n-butylvinylether, tetrahydrofuran and a typical bis-epoxide are readily induced in the presence of AgPF6 by thermal and photochemically active sources of free radicals. 相似文献