26 resultados para supplementary stabilizers
Resumo:
A facile method to obtain polydisperse chemically-converted graphene sheets that are covalently functionalized with ionic liquid was reported-the resulting graphene sheets, without any assistance from polymeric or surfactant stabilizers, can be stably dispersed in water, DMF, and DMSO.
Resumo:
High-solids, low-viscosity, stable poly(acrylamide-co-acrylic acid) aqueous latex dispersions were prepared by the dispersion polymerization of acrylamide (AM) and acrylic acid (AA) in an aqueous solution of ammonium sulfate (AS) medium using anionic polyelectrolytes as stabilizers. The anionic polyelectrolytes employed include poly(2-acrylamido-2-methylpropanesulfonic acid sodium) (PAMPSNa) homopolymer and random copolymers of 2-acrylamido-2-methylpropanesulfonic acid sodium (AMPSNa) with methacrylic acid sodium (MAANa), acrylic acid sodium (AANa) or acrylamide (AM). The influences of stabilizer's structure, composition, molecular weight and concentration, AA/AM molar feed ratio, total monomer, initiator and aqueous solution of AS concentration, and stirring speed on the monomer conversion, the particle size and distribution, the bulk viscosity and stability of the dispersions, and the intrinsic viscosity of the resulting copolymer were systematically investigated. Polydisperse spherical as well as ellipsoidal particles were formed in the system. The broad particle size distributions indicated that coalescence of the particles takes place to a greater extent.
Resumo:
A new molecular topological index, EATI is proposed based on the extended adjacency matrix, It has a hitherto unheard of power of discrimination and can be applied to discriminate various kinds of organic compounds, such as structures containing heteroatoms, etc.. Thus EATI might be possibly used as supplementary reference for CAS Registry Numbers for structure documentation.
Resumo:
Reverse phase high performance liquid chromatography (HPLC) was used to separate and quantify aromatic diester-diacids isomers which arise from the opening selectivity of anhydride rings towards methanol. C-13 NMR spectroscopy was a supplementary tool to characterize the isomer structure. It was found that a meta-position attack is slightly preferred in pyromellitic dianhydride (PMDA), while the preferred position of an attack in bridged dianhydrides is determined by the chemical nature (donors or accepters) of the bridged group. The stronger its electron-withdrawing abilities, the lower the probability of a meta-position attack.
Resumo:
A highly discriminating molecular topological index, EAID, is proposed based on the extended adjacency matrix. A systematic search for degeneracy was performed for 3 807 434 alkane trees, 202 558 complex cyclic or polycyclic graphs, and 430 472 structures containing heteroatoms. No counterexamples (two or more nonisomorphic structures with the same EAID number) were found. This is a hitherto unheard of power of discrimination. Thus EAID might be possibly used as supplementary reference for CAS Registry Numbers for structure documentation.
Resumo:
In order to study the oriented (epitaxial) crystallization of thermoplastic polymers on oriented polymer substrates, generally the transmission electron microscopy (TEM) is used. With this instrument, the crystallized material can easily be resolved and orientation relationships can be monitored by electron diffraction. Disadvantages are the time consuming sample preparations and difficulties in the in-situ observations of the crystallization events, because of the radiation sensitivity of the polymer crystals. It is demonstrated that these disadvantages of the TEM can be eleminated by the use of different methods of light optical contrasts under specific preparation conditions of the samples and that the optical microscopy being a supplementary method to the TEM for investigations of epitaxial crystallization.
Resumo:
The melt flow behaviour of LDPE/HDPE blends with various compositions have been determined by melt flow index (MFI) measurement. The effects of stabilizers, photo-sensitizers, multiple extrusions and short-term photooxidation have been studied. The results show that there is no marked thermal stability difference between homopolymers and blends without multiple extrusions, no matter whether stabilizers or photo-sensitizers are added. Multiple extrusions or photo-sensitizers reduce their thermal stability, shown by the decrease in MFI. The decrease in MFI of photooxidized samples does not imply serious structural change and shows that the active species formed during photooxidation induce a crosslinking reaction in the melt indexer. Multiple extrusions increase the number of active species formed in LDPE or blends and lead to an obvious decrease in MFI. It is suggested that LDPE and LDPE-rich blends after short-term photooxidation can be characterized by MFI measurement. In contrast, HDPE cannot be characterized by this method due to its linear structure.
Resumo:
The thermal oxidation behaviour of polypropylene containing tetramethylpiperidine compounds and corresponding pentamethylpiperidine compounds are compared using air oven aging, oxygen uptake and thermogravimetry. Carbonyl formation, the induction period of oxygen absorption and weight loss have been selected to characterize the degree of oxidation. The results show that the stabilizing effectiveness of pentamethylpiperidines is always higher than that of tetramethyl types. Radical-trapping mechanisms cannot explain this, because large amounts of nitroxyl radicals are formed by the tetramethylpiperidine compounds. The quenching of singlet oxygen appears to be involved in thermal oxidation of polypropylene containing pentamethylpiperidine compounds. Specific hydrogen bonding between pentamethylpiperidines and hydroperoxide may account for their better thermal stabilizing action than tetramethylpiperidines.
Resumo:
Sedimentary provenance direction,sedimentary facies,reservoir geological characteristic,pore structure; physical property characteristic,reservoir classification and evaluation ,forthermore,favorable area area are forecasted of Yanchang formation in ZhiDan region, by mainly study on the data of field section observation ,core observation, well logging explaination and routine microscope slice identification,scanning Electron Microscope and reservoir analysis of lithology and physical property , Under the guidance of such advanced theories and methods as sedimentology,reservoir sedimentology,lithological oil pool and so on,in the thesis. The following fruits are mainly achieved in this paper: Yanchang formation stratum is divided and correlated in this entire region, and the characteristic of oil layer unit is detailed discussed , respectively. According to main marker bed and supplementary ones.and research result shows that the source of provenance direction during Yanchang Formation mianly is north-east. Delta and lake are mainly developed in study area ,sub-facies and micro-facies are divided,distribution of sedimentary micro-facies in plane and palaeogeographic evolution are described,and gentle slope type- shallow water delta depositional model is established. Fine-grain arkose sandstone is the main reservoir,and which have experienced such different degree diagenesis as compaction, cementation, replacement and dissolution, and in which compaction and cementation are mainly factors to reduce sandstone physical property and dissolution effectively improved physical property during burial diagenesis procedure. All reservoirs of Yanchang Formation have entered A period of late diagenetic stage according to scheme of diagenesis period division . Intergranular porosity,dissolution porosity,fissure porosity are main pore types. And porosity structure are analyse by mercury penetration capillary pressure parameter,fine-shortness type and fine- length throat type are mainly developed. as a whole,the reservoir, with the characteristic of porosity and permeability altering apparently,strong inhomogeneity , is a medium- porosity and medium permeability one. In plane,higher- porosity and higher-permeability are corresponded well with distributary channel area, physical property and inhomogeneity are affected by both deposition and diagenesis,and distributary channel and underwater distributary channel are favorable facies . According to such characteristic as lithology,physical property,pore structure ,diagenesis and sandstone distribution, the sandy reservoir can be classified 4 types, and the main sandy in every oil layer unit are evaluated according to the standard. The analysis result of petroleum concentration rule shows that Yanchang Formation are with not only favourable oil source rock,reservoir,covering combination ,but also good entrapment condition in study area. Lithology and structure-lithology oil pool are mainly developed ,based on condition of favorable reservoir developments,accounting for deliverability and sandstone superface elevation,zone of profitabilitis are forecasted.
Resumo:
The relationship between the management and the culture was explored from the view of social norm's theory. In concrete terms, the differences of the hierarchical structure of the social norm among the Chinese, the Japanese and the American were studied systematically by using interview, case study, questionnaire survey and the structure equation model, etc. The results were: (1) The basic two types of the social norms of the Chinese, the American and the Japanese were the same: the external control norm and the internal control norm. The basic dimensions of the two types of norms composed of moral principle, value orientation, the law and the rules, and the social custom were consistent among the three countries. Furthermore, the dimensions of social norms were hierarchical because of the functioning of the different culture, which consisted of the hierarchical structure system. (2) Although there were the same dimensions among the three countries, the contents of these dimensions had both the common norms surpassing the specific culture and the particular norms depending on the specific culture. (3) The basic structures of the social norms in China and in Japan were the same: the internal control norms played a main role and the external control norm was auxiliary. On one hand, within the internal norm of the Chinese, the moral principle was the main force while the value orientation was the supplementary; within the external norm, the law and the rules was the main force while the social culture custom was supplementary. On the other hand, the relationship between the external and the internal dimensions of the Japanese turned out to be contrary to those of the Chinese. (4) The structure of the American social norms were different from the Chinese: for the American, the external control norm played a main role while the internal control norm was assistant. Furthermore, the law and the rule was the major aspect while the social costumes was the second in the external control dimension. In addition, the value orientation led the performance style of the American, while the moral principle played the second role in the internal control structure. (5) The social norms related to the management performance were found including work responsibility, organization commitment, meeting making-decision, communication style, work duty and interpersonal conflict by inventory and case study. The mangers from China, Japan and America had significant different views on paying attention to the management norms. In a word, the culture differences of the social norm were the fundamental reason of the management conflict.
Resumo:
An interface of chip-based capillary electrophoresis (CE)-inductively coupled plasma-atomic emission spectrometry (ICP-AES) that is based on cross-flow nebulization has been developed. A polydimethylsiloxane (PDMS) CE-chip with conventional cross channel layout was used. A stainless steel tube was placed orthogonal to the exit of the CE separation channel for cross flow nebulization. A supplementary flow of buffer solution at the channel exit was used to improve nebulization efficiency. Two capillaries were inserted into the CE chip near the inlet of the separation channel for sample and buffer solution injection. Syringe pumps were used to manipulate the flow rate and flow direction of the sample, buffer, and supplementary buffer solution. Peak broadening due to the shape (bulb and tube-shaped) and size of the spray chambers was studied. The smaller tube-shaped spray chamber was used because of smaller peak broadening effect due to aerosol transport. The nebulization and transport efficiency of the CE-ICP interface was approximately 10%. Ba2+ and Mg2+ ions were eluted from the CE-chip within 30 s. Resolution of the Ba2+ and Mg2+ peaks was 0.7 using the chip-based CE-ICP-AES system.