The structure of urea-formaldehyde (UF) resin was studied in light of the influence of various synthesis parameters on the chemical structure of the resulting resin solutions. The structural variability was analyzed by 13C nuclear magnetic resonance spectroscopy (NMR). Using appropriate pulse ...
Cycloaliphatic epoxy resins contain an epoxy ring that is internal to the ring structure. They are designed for applications requiring: high-temperature resistance, good electrical insulation performance, UV resistance, and high glass transition temperatures in the range of 200°C Cycloaliphatic epoxy res...
focused on overview of the chemical composition,structure features,extraction and separation methods as well as biological activities and applications of raw lacquer,lacquer polysaccharides,laccases,glycoproteins,lacquer wax(oil),etc.The present problems and ideas on development of lacquer trees were put ...
展开 关键词: cromatografia, analisis, lignins, espectrometria, analyse, bois de resineux, analysis, lignine, softwood, ligninas, chromatography, spectrometry, chromatographie, madera de coniferas, spectrometrie DOI: 10.1515/hfsg.1987.41.5.299 被引量: 2 年份...
The main products of the HSGC-MS analysis of the liquid tar were vanillin, cresols, dihydroeugenol, methoxy- eugenol, trans-isoeugenol and guaiacol forming the non-condensed structure of lignin in the feedstocks. In addition, the presence of p-cresol in the tar is due to high abundance of...
1.1 Composition and structure 1.1.1 Composition 1.1.1.1 Chemical composition The chemical composition of a material can be defined as the distribution of the individual components that constitute the material. The material can be a pure substance, which contains only one chemical component; in this ...
hosted a greater number of different natural, organic and mineral inclusions. The third variety (III) was a white–grey and opaque type of resin with a foam-like structure. It was also most likely to have been secreted outside the tree trunk, and then flowed down to the forest bedding. ...
Its structure is proposed as 3β, 19α-dihydroxy-urs-... GW Qin,ZX Chen,RS Xu,... - 《Chinese Journal of Chemistry》 被引量: 32发表: 1987年 Chemical constituents from the roots of cultivated Ilex pubescens Phytochemical study of butanol extract from the roots of cultivated Ilex pubescens...
AIM: To investigate the chemical constituents of the roots of Streptocaulon griffithii. METHODS: Chemical constituents were isolated and purified by silica gel,Sephadex LH-20 and Rp-18 column chromatographic method. Their structure were elucidated on the basis of the physiochemical characteristics and...
Chemical degradation is defined here as processes that involve breaking (and potentially re-forming) of covalent bonds within the polymer structure. This can lead to: • main-chain scission leading to a less rigid network structure and hence softening of the material; • main-chain scission ...