HIGH ENERGY Γ-Irradiation OF VINYL MONOMERS. II. INFRARED SPECTRA OF RADIATION-POLYMERIZED ACRYLONITRILE

Arthur, Jett C.; Demint, Robert J.

doi:10.1021/j100838a502

Cited by 8 publications

(8 citation statements)

References 1 publication

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“…According to this proposed model, even tactic polyacrylonitrile would be sufficiently distorted to satisfy the requirements of previous studies that had been interpreted as evidence of an atactic structure.11p12 Note also that alternative methods of synthesis of polyacrylonitrile all showed essentially the same type of structure (Ref. 13 and Sample Preparation section). Such methods as polymerization a t low temperatures, which yields crystalline poly(viny1 chloride) l 4 or poly(methy1 methacrylate),l5 and the use of organometallic initiators, which also yields crystalline poly-(methyl methacrylate) l5 and crystalline poly(tert-butyl acrylate) as well as many crystalline polyhydrocarbons, gave a polyacrylonitrile almost identical with that prepared by conventional free-radical initiation.…”

Section: Polyacrylonitrile Modelmentioning

confidence: 79%

Laterally ordered polymers: Polyacrylonitrile and poly(vinyl trifluoroacetate)

1961

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The structure and properties of two laterally ordered (directionally crystallized) polymers are discussed, namely, polyacrylonitrile and poly(vinyl trifluoroacetate). Evidence from x‐ray diagrams, infrared measurements, thermal expansion data, and fiber properties are interpreted in terms of molecular structure. It is concluded that the existence of only chain‐to‐chain order (lateral order) in polyacrylonitrile and poly(vinyl trifluoroacetate) is principally due to steric and dipolar intramolecular repulsions. These lead to a chain stiffening effect, regardless of tacticity, which is so great in the former case that the backbone chain is forced to assume a twisted, kinked configuration. The stiff molecular chains may be thought of as rigid rods which pack in a lattice array. The side groups, nitrile or trifluoroacetate, assume varying angles with the respect to the rod axis in order to minimize the steric and dipolar repulsion forces. This variation gives rise to diffuse off‐equatorial scattering in the x‐ray diagram of the oriented polymers and low values of the dichroic ratios of selected bands in the infrared. The chain stiffening effect is greater in polyacrylonitrile and this polymer exhibits a higher “melting point”, higher fiber tenacity at equivalent orientation, less solubility, more general diffuse scattering in the x‐ray diagram, and lower dichroic ratios in the polarized infrared spectrum than does poly(vinyl trifluoroacetate). In fact, polyacrylonitrile, in contrast to poly(vinyl trifluoroacetate), acts as if it were all ordered and contained no amorphous regions in the usual sense, as judged from thermal expansion data and the lack of a definite amorphous halo in the x‐ray diagram. Poly(vinyl trifluoroacetate) is concluded to be no more syndiotactic than conventional poly(vinyl acetate), since laterally ordered poly (vinyl trifluoroacetate) can be derived from commercial poly (vinyl alcohol) by esterification. Therefore, the observed lateral order in poly (vinyl trifluoroacetate) is not due to a predominantly syndiotactic structure. These laterally ordered polymers have a properties intermediate between those of normally crystalline polymers and those of amorphous polymers.

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Section: Polyacrylonitrile Modelmentioning

confidence: 79%

Laterally ordered polymers: Polyacrylonitrile and poly(vinyl trifluoroacetate)

1961

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“…22, 23, 47 ± 50 The yields of hydrogen, carbon dioxide, and carbon monoxide measured in a vacuum in the g-irradiation of cellulose were 1.3, 1.6, and 0.8, respectively. 22,23 Carbon dioxide predominates in the products of radiation-chemical transformations of cellulose. A systematic study of gas formation in the irradiation of cellulose in vacuum has been carried out.…”

Section: Products Of Radiation-chemical Transformations Of Cellulosementioning

confidence: 99%

Radiation-chemical degradation of cellulose and other polysaccharides

Ершов

1998

Russ. Chem. Rev.

152

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The state-selective dissociation dynamics for anionic and excited neutral fragments of gaseous SiCl 4 following Cl 2p and Si 2p core-level excitations were characterized by combining measurements of the photoninduced anionic dissociation, x-ray absorption and UV/visible dispersed fluorescence. The transitions of core electrons to high Rydberg states/doubly excited states in the vicinity of both Si 2p and Cl 2p ionization thresholds of gaseous SiCl 4 lead to a remarkably enhanced production of anionic, Si − and Cl − , fragments and excited neutral atomic, Si * , fragments. This enhancement via core-level excitation near the ionization threshold of gaseous SiCl 4 is explained in terms of the contributions from the Auger decay of doubly excited states, shake-modified resonant Auger decay, or/and post-collision interaction. These complementary results provide insight into the state-selective anionic and excited neutral fragmentation of gaseous molecules via core-level excitation.

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“…7 ' 8 -* During irradiation dehydrogenation reactions occur, and hydrogen, carbon monoxide, and r^rbon dioxide are evolved. 7 Decrease in absorption and retention of water by irradiated celluloses, as compared with nonirradiated celluloses, was interpreted as evidence for the radiation-initiated formation of intermolecular crosslinking in cellulose. 10 ' 13 Similarly, decrease in moisture regain of cellulose that had been heated to 70°C was attributed to thermal auto-crosslinking through the formation of hemi-acetal and ether bonds.…”

Section: Irradiation Stability Of Cellulosic Materialsmentioning

confidence: 99%

Effect of Ionizing Radiation on Physical and Chemical Properties of Fiberboard and Paperboard

Killoran¹,

Agarwal²,

Burke³

1972

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Effect of ionizing radiation on physical and chemical properties of lLberboard and paperboard.• I'tlCKl'Tiyi NOTtl (Typ» ol report and Irclutlr* daia«)Technical Report I». ABSTRACTIn a large-scale production of prepackaged radappertized (irradiation sterilized) foods there ore advantages in performing the irradiation of filled metal cans or flexible packages while stacked in fiberboard or paperboard shipping container's. This study was performed to determine the effect of electron and gamma radiation on the physical and chemical properties and functional performance of the fiberboard and paperboard materials that are used in the packing of can. and flexible packages of radappertized foods. Electron and gamma radiation caused significant physical and chemical changes in the fiberboard and paperboard materials. Physical property values (puncture, burst, tear, tensile) decreased with increasing radiation dose (1, 3, and S megarads) and increasing irradiation temperature (-80°C, -30* and 21°C). Whereas the component testing of fiberboard and paperboard and laboratory drop tests of fiberboard containers indicated that irradiation at a food-sterilization dosage level caused marked reductions in performance of the materials and containers made therefrom, these changes were not great enough to seriously impair the functional performance of the fiberboard and paperboard containers for packing of cans or packages of food during irradiation processing and subsequent shipment and storage. In a large-scale production of prepackaged radappertized (irradiation sterilized) foods there are advantaqes in performing the irradiation of metal cans or flexible packages while in the shipping container, either fiberboard or paperboard containers. The work covered in this report represents an investigation to determine the effect of electron and gamma radiation on the chemical and physical properties of fiberboard and paperboard materials and to evaluate the performance of shipping containers during the irradiation processing and subsequent shipme nt and storage. The investigations described were performed by Messrs.

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HIGH ENERGY Γ-Irradiation OF VINYL MONOMERS. II. INFRARED SPECTRA OF RADIATION-POLYMERIZED ACRYLONITRILE

Cited by 8 publications

References 1 publication

Laterally ordered polymers: Polyacrylonitrile and poly(vinyl trifluoroacetate)

Laterally ordered polymers: Polyacrylonitrile and poly(vinyl trifluoroacetate)

Radiation-chemical degradation of cellulose and other polysaccharides

Effect of Ionizing Radiation on Physical and Chemical Properties of Fiberboard and Paperboard

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