Small‐angle neutron scattering, SANS, stands forth as one of the most important of the new tools for evaluating polymer chain conformation and morphology. This paper reviews the SANS literature through 1982, with a f...
Small‐angle neutron scattering, SANS, stands forth as one of the most important of the new tools for evaluating polymer chain conformation and morphology. This paper reviews the SANS literature through 1982, with a few early 1983 references added. The theory of SANS is outlined and compared to light scattering. SANS values of polymer molecular weights and radii of gyration obtained in the bulk state were found to be in agreement with values obtained from dilute solutions by light scattering. In each case, deuterated fractions of polymer were inserted into the hydrogeneous matrix, or vice versa, to provide contrast. Several new research areas are then discussed, including unidirectional stretching of elastomers, stress‐relaxation, polymer‐polymer miscibility, crystallization from the melt compared with crystallization from dilute solutions, nonclassical aggregation during bulk polymerization of thermoset systems, morphology of polymer blends, block copolymers and ionomers, the core‐shell structure of latexes and polymer blocks, and grafts as surfactants in emulsions and latexes. Much new and sometimes unexpected information is being provided by the SANS research now in progress.
作者：
ZABORSKY, OROskar R. Zaborsky
Ph.D. is a program director in the Division of Chemical and Process Engineering of the National Science Foundation 1800 G Street Washington DC 20550. The views conclusions and recommendations expressed herein are those of the author and do not necessarily reflect the views and policies of the National Science Foundation.REFERENCES Conference on "Genetic Control of Environmental Pollutants" July 31-August 3 1983 University of Washington School of Public Health & Community Medicine and Department of Environmental Health Seattle WA. The proceedings are to be published by Plenum Press.Recent reports covering the handling of hazardous industrial wastes including biological processes are (a) "Management of Hazardous Industrial Wastes: Research and Development Needs" National Research Council National Academy Press Washington D.C. 1983 (b) "Technologies and Management Strategies for Hazardous Waste Control
" Congress of the United States Office of Technology Assessment Washington D.C. 1983.An expanded report on the technology market analysis regulatory and legislative factors dealing with biotechnology applications to hazardous wastes has been produced by Dr. Thomas O.Peyton AmTech Consultants Vienna VA for the OTA study.Baross J.A. and Deming J.W.1983. Growth of 'black smoker' bacteria at temperatures of at least 250C. Nature303: 423-426.|Article|ISI|ChemPort|
作者：
KORWEK, ELEdward L. Korwek
Ph.D. J.D. is associated with the law offices of Keller and Heckman 1150 17th St. N.W. Washington D.C. 20036.REFERENCES Committee on Recombinant DNA "Potential Biohazards of Recombinant DNA Molecules" Nature250: 175 (1974) Proc. Nat. Acad. Sci.71: 2593 (1974)Science185: 303 (1974).|Article|Fed. Regist.48: 24556 (1983).Milewski
E. Editor's Note. Recombinant DNA Tech. Bull.4: i (1981).Inside EPA 4 1 (1983). EPA has already held a meeting and published a draft report on the subject of its regulation of this area under the TSCA. EPA "Administrator's Toxic Substances Advisory Committee Meeting"
Fed. Regist.48: 8342 (1983) Regulation of Genetically Engineered Substances Under TSCA
Chemical Control Division Office of Toxic Substances Office of Pesticides and Toxic Substances Environmental Protection Agency Washington D.C. (March 1982). Congress also recently held a hearing on the subject of existing federal authority over the release of R-DNA-containing organisms into environment. M. Sun Science221: 136 (1983).Sects. 2-30 15 U.S. Code sects. 2601-2629 (1976 and Supp. V 1981). Hereinafter all references in the text to TSCA refer to the section numbers as enacted and not to the corresponding U.S. Code sections.The Administrative Procedure Act specifically states that the reviewing court shall "hold unlawful and set aside agency action findings and conclusions found to be hellip in excess of statutory jurisdiction
authority or limitations or short of statutory right. hellip " 5 U.S. Code
sect. 706(2)(C) (1976).PHS Act 42 U.S. Code sects. 217a and 241 (1976) Charter
Recombinant DNA Advisory Committee Department of Health and Human Services (1982).Korwek E. Food Drug and Cosm. L. J.35: 633 (1980) p. 636.Although DHHS has some authority under Section 361 of the PHS Act to regulate R-DNA materials that cause human disease and are communicable most types of experimentation would not fall into this category. Because of this limitation the Sub committee of the Federal
In this study molecular alignment in copolymers of polyethylene terephthalate (PET) and p-hydroxybenzoic acid (PHB) was examined by means of differential radial distribution function (DRDF) analysis of wide angle X-ra...
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In this study molecular alignment in copolymers of polyethylene terephthalate (PET) and p-hydroxybenzoic acid (PHB) was examined by means of differential radial distribution function (DRDF) analysis of wide angle X-ray scattering data. The study was carried out using two representative copolymers with the PHB content of 30 and 60 mol%. The DRDF curves for the amorphous and the partially crystalline samples of these copolymers showed periodic intermolecular peaks up to various radial distances. The appearance of these peaks at periodicity suggested the existence of more-or-less parallel chain segments in the copolymers. The extent of the lateral molecular organization was for the amorphous copolymers containing 30 and 60 mol% PHB, respectively. A substantial structural difference was therefore shown for the copolymers in this composition range. The DRDF curve for the amorphous copolymer with 30 mol% PHB was found to be very similar to that for the previously reported glassy PET with 0 mol% PHB, indicating that the two materials had almost the same intermolecular structure. The structural information revealed by these DRDF results was in agreement with the various property changes caused by varying PHB contents of the copolymers.
1-Methyl-3-methylenecyclobutene (MMCB) and 1,2-dimethylenecyclobutane (DMCB) copolymerized readily with isobutene with aluminum chloride as initiator in methyl chloride solution at temperatures from −95 to −78°C....
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1-Methyl-3-methylenecyclobutene (MMCB) and 1,2-dimethylenecyclobutane (DMCB) copolymerized readily with isobutene with aluminum chloride as initiator in methyl chloride solution at temperatures from −95 to −78°C. No polymers were obtained with methylenecyclobutene (MCB) under similar conditions. The copolymerization of MMCB with isobutene took place through a 1,5-addition reaction while that of DMCB through both 1,2- and 1,4-addition reactions. Large amounts of gel were present in the copolymers obtained from DMCB if the reaction was carried to high conversion. The commonly observed effects of dienes (i.e., rate retardation and molecular weight depression) on cationic copolymerization reactions were observed but to a much higher degree with these small ring dienes. The thermal crosslinking behavior of the resulting copolymers was investigated. In conjunction with the copolymerization studies, homopolymers of MMCB, DMCB, and 3,3-dimethyl-1-isopropylidene-2-methylenecyclobutane (IMCB) were prepared and their chemical structures examined.
The hydrolysis of smooth pea starch (PS), in both crude and purified forms was studied using two commercially available enzyme preparations (α-amylase and glucoamylase). Corn starch (CS), wheat starch (WS) and wheat ...
The hydrolysis of smooth pea starch (PS), in both crude and purified forms was studied using two commercially available enzyme preparations (α-amylase and glucoamylase). Corn starch (CS), wheat starch (WS) and wheat flour (WF) were used for comparative purposes. CS and WS showed quite similar hydrolytic characteristics. Despite its higher amylose content, PS could be solubilized by α-amylase as completely and as rapidly as the other starches, but the hydrolysate had a significantly lower dextrose equivalent. Subsequent hydrolysis by glucoamylase occurred most rapidly with PS. Crude PS hydrolysates were dark in colour, darker than those of WF and much darker than those of any of the purified starches. They contained less N than those of WF. Impurities present in crude PS had no detectable effects on the susceptibility of the starch to α-amylase activity but appeared to have a slight depressing effect on glucoamylase. L'hydrolyse de l'amidon de pois lisse, à l'état brut et à l'état purifié, fut étudiée à l'aide de préparations d'enzymes du commerce (α-amylase et glucoamylase). L'amidon de maïs, l'amidon de blé et la farine de blé ont servi de comparaisons. Les amidons de maïs et de blé furent semblables sur le plan des caractéristiques hydrolytiques. En dépit de sa teneur plus élevée en amylose, l'amidon de pois a pu être solubilisé par l'α-amylase aussi complètement et aussi rapidement que les autres amidons, mais l'équivalent dextrose de l'hydrolysat fut significativement inférieur. L'hydrolyse subséquente à la glucoamylase fut la plus rapide pour l'amidon de pois. Les hydrolysats d'amidon de pois bruts furent de couleur foncée, plus foncée que ceux de la farine de blé et beaucoup plus foncée que ceux de tout amidon purifié. Ils étaient moins riches en N que ceux de la farine de blé. Les impuretés présentes dans l'amidon de pois brut furent sans effet sur la susceptibilité de l'amidon à l'activité de l'α-amylase, mais diminuèrent un peu l'activité de la glucoamylase
A series of α,α‐disubstituted β‐propiolactams (substituted nylon 3 polymers) was prepared from non‐optically active lactams. Their thermal characteristics, densities, and x‐ray fiber diffraction patterns were r...
A series of α,α‐disubstituted β‐propiolactams (substituted nylon 3 polymers) was prepared from non‐optically active lactams. Their thermal characteristics, densities, and x‐ray fiber diffraction patterns were recorded. One of the α‐substituents was always a methyl group while the other was either CH 3 , C 2 H 5 , n ‐C 3 H 7 , or n ‐C 4 H 9 . The melting point for the dimethyl substituted polymer was 268°C; the others were respectively 76, 74, and 72°C. X‐ray fiber diffraction data on all four samples yielded the same fiber repeat of ≈8,4 Å. A minimum energy based conformational analysis for the α,α‐dimethyl derivative indicates that two conformations correspond to this repeat, each of which is a 2 1 helix.
Optically active α-phenyl-ααethyl-β-propiolactone of high optical purity was prepared and polymerized by homogeneous anionic initiation to the isotactic polyester. The racemic and isotactic polymers had apparently...
Optically active α-phenyl-ααethyl-β-propiolactone of high optical purity was prepared and polymerized by homogeneous anionic initiation to the isotactic polyester. The racemic and isotactic polymers had apparently different crystalline properties suggesting that the former may be syndiotactic or may crystallize with unit cells containing both R and S blocks. Similar attempts to prepare α-methyl-α-isopropyl-β-propiolactone of high optical purity were unsuccessful although a partially crystalline polymer was obtained from the racemic monomer.
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