The radiation chemistry of dihydromyrcene

1967 ◽  
Vol 45 (2) ◽  
pp. 101-108 ◽  
Author(s):  
John L. Brash ◽  
Morton A. Golub
Keyword(s):  
Hydrogen Evolution ◽  
Pure State ◽  
Room Temperature ◽  
Benzene Solution ◽  
Radiation Chemistry ◽  
Cross Linking ◽  
Double Bonds ◽  
Trans Isomerization ◽  
The Cross ◽  
G Value

Dihydromyrcene was irradiated with 1-MeV electrons at room temperature both in the pure state and in benzene solution. The main reactions observed, and their G-values for the pure diisoprene, were loss of unsaturation (~7.8–9.9), cross-linking (or dimerization) (2.4–2.6), evolution of hydrogen (0.81), and trans → cis isomerization (< 0.5). As with squalene, the loss of double bonds in dihydromyrcene occurred only in the cross-linked residue, obtained on distillation of the irradiated isoprenoid. Although the residue (mainly dimer, with some trimer) was considered to be partially cyclized, no cyclization of uncross-linked (monomeric) dihydromyrcene was observed. Dihydromyrcene in 10% benzene solution (by weight) showed trans → cis and cis → trans isomerization with G-values of 0.63 and 1.2, respectively, hydrogen evolution with a G-value of 0.08, and a higher rate of loss of original unsaturation than in the pure state.

THE RADIATION CHEMISTRY OF SQUALENE

1964 ◽  
Vol 42 (7) ◽  
pp. 1577-1594 ◽  
Author(s):  
Jeanne Danon ◽  
Morton A. Golub
Keyword(s):  
Room Temperature ◽  
Benzene Solution ◽  
Radiation Chemistry ◽  
Double Bonds ◽  
Large Drop ◽  
Efficient Energy Transfer ◽  
Efficient Energy ◽  
Radiation Induced ◽  
Γ Rays ◽  
G Value

Squalene was irradiated with Co60 γ-rays at room temperature and with 1-MeV electrons at −30 °C. The main radiation-induced effects, and their G-values for the room temperature irradiations, were loss of unsaturation (4.6), crosslinking (1.35), trans → cis isomerization (0.83), and evolution of hydrogen (0.58). The G-values for the first three processes in the low temperature runs were 3.8, 0.82, and 0.83, respectively. The large drop in unsaturation is attributed in part to the formation of crosslinks involving double bonds, but principally to cyclization. The loss of double bonds occurs only in the immediate vicinity of the crosslinks and not at random throughout the irradiated squalene. This result has important implications for the radiolysis of diene polymers. Squalene in 10% benzene solution isomerizes with a much higher yield (apparent G-value of 2.6 trans double bonds converted initially per 100 eV absorbed by both solute and solvent) than that of the pure olefin, indicating very efficient energy transfer from excited benzene molecules to the squalene double bonds. The isomerization in the solution case was accompanied by a loss of double bonds in squalene (G-value of 0.98) due to phenylation as well as to the other indicated saturation reactions.

Radiation Chemistry of DNA Model Compounds, IX. Carbohydrate Products in the γ-Radiolysis of Thymidine in Aqueous Solution. The Radical-Induced Scission of the N-Glycosidic Bond

1976 ◽  
Vol 31 (2) ◽  
pp. 227-233 ◽  
Author(s):  
Miral Dizdaroglu ◽  
Klaus Neuwald ◽  
Clemens Von Sonntag
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Radiation Chemistry ◽  
Oh Radical ◽  
Glycosidic Linkage ◽  
Model Compounds ◽  
Sugar Moiety ◽  
G Value ◽  
Radical Attack

In the γ-radiolysis of deoxygenated N2O-saturated aqueous solutions of thymidine (10-3 M, room temperature, dose rate 4· 1018 eV/g.h., dose 6.7 1017-3.3 • 1018 eV/g) the following products (G-values in parentheses) have been identified : 2,5-dideoxy-pentos-4-ulose (1) (0.01), 2,4-dideoxy-pentodialdose (2) (0.02), 2,4-dideoxy-pentos-3-ulose (3) (0.03), 2,3-dideoxy-pentos-4-ulose (4) (0.01), 2-deoxy-pentos-4-ulose (5) (0.1), 2-deoxyribonic acid (6) (0.02) and thymine (8) ( ≤ 0.2). In the presence of oxygen (N2O/O2 80/20 v/v saturated) products 1-4 are absent, G (5) = 0.2, G (6) = 0.07 and G (8) ≤ 0.4. Furthermore, 2-deoxy-tetrodialdose (7) which is absent in deoxygenated solution is formed with a G-value of 0.03. Mechanisms are proposed to account for the scission of the N-glycosidic linkage. Product 6 is thought to be due to a primary OH radical attack at C-1′ of the sugar moiety, 8 arises from an attack at C-3′, 1, 4 and 5 from an attack at C-4′, and 2 and 7 from an attack at C-5′.

Mechanical Properties of Epoxidized Palm Oil/Epoxy Resin Blend

2014 ◽  
Vol 695 ◽  
pp. 655-658 ◽  
Author(s):  
Zyad Salem Alsagayar ◽  
Abdul Razak Rahmat ◽  
Agus Arsad ◽  
Alireza Fakhari ◽  
Wan Nurhayati binti Wan Tajulruddin
Keyword(s):  
Mechanical Properties ◽  
Impact Strength ◽  
Epoxy Resin ◽  
Palm Oil ◽  
Room Temperature ◽  
Flexural Properties ◽  
Cross Linking ◽  
Impact Tests ◽  
Epoxidized Palm Oil ◽  
The Cross

In this paper, a blend of epoxy resin and epoxidized palm oil (EPO) was prepared to investigate its mechanical properties. Epoxy and EPO were mixed for 20 minutes at room temperature before mixed with hardener and followed by curing for 2 hours at 100 °C. Tensile, flexural and impact tests were conducted to characterize the blend. In general, the tensile and flexural properties of epoxy resin/EPO decreased when the amount of EPO increased. However, strain at break, toughness and impact strength was slightly increased when the amount of EPO was increased up to 20%.The mechanical properties were reduced due to the reduction of the cross linking density and effect of plasticizer.

A Delayed-Curing Cotton Fabric Based on an Internally Catalyzed Cotton Cellulose and Divinyl Sulfone

1969 ◽  
Vol 39 (2) ◽  
pp. 173-180 ◽  
Author(s):  
Stanley P. Rowland ◽  
Mary Ann F. Brannan
Keyword(s):  
Elevated Temperature ◽  
Room Temperature ◽  
Cotton Cellulose ◽  
Cross Linking ◽  
Cure Reaction ◽  
Divinyl Sulfone ◽  
Cross Links ◽  
The Cross ◽  
Catalyzed Reactions ◽  
Recovery Angle

2-(Diethylamino)ethyl cotton celluloses in the form of print cloth and at three levels of nitrogen have been quaternized and converted to the strong bases. Studies were made of internally catalyzed reactions of these cotton cellulose quaternary ammonium hydroxides with divinyl sulfone at room temperature in a “wet-cure” and with bis-(2-hydroxyethyl) sulfone in a “bake-cure.” Moderate levels of conditioned wrinkle-recovery angles and high levels of wet wrinkle-recovery angles result from the “wet-cure” reaction. The wrinkle-recovery angles of these modified cotton celluloses are compared to those of the corresponding cotton celluloses cross-linked by conventional external catalysis. The internally catalyzed fabrics from the “wet-cure” are particularly interesting among these compositions with regard to (a) the developed levels of wrinkle-recovery angle, (b) the capability of these compositions to develop high conditioned wrinkle-recovery angles as a result of recure in a “bake-cure” in the absence of external catalysis, and (c) the evidence of mobility of the cross links (i.e., reversibility of the cross-linking reaction followed by reformation of new or old cross linkages) at elevated temperature.

Temperature Dependent Line-Shape of the Silicon Dangling Bond EPR-Resonance in Polycrystalline Silicon

1996 ◽  
Vol 452 ◽  
Author(s):  
N. H. Nickel ◽  
E. A. Schiff
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Polycrystalline Silicon ◽  
Room Temperature ◽  
Dangling Bond ◽  
Temperature Dependent ◽  
Paramagnetic Resonance ◽  
Temperature Electron ◽  
Motional Narrowing ◽  
G Value ◽  
Electron Paramagnetic

AbstractThe temperature dependence of the silicon dangling-bond resonance in polycrystalline (poly-Si) and amorphous silicon (a-Si:H) was measured. At room temperature, electron paramagnetic resonance (EPR) measurements reveal an isotropie g-value of 2.0055 and a line width of 6.5 and 6.1 G for Si dangling-bonds in a-Si:H and poly-Si, respectively. In both materials spin density and g-value are independent of temperature. While in a-Si:H the width of the resonance did not change with temperature, poly-Si exhibits a remarkable T dependence of ΔHpp. In unpassivated poly-Si a pronounced decrease of ΔHpp is observed for temperatures above 300 K. At 384 K ΔHpp reaches a minimum of 5.1 G, then increases to 6.1 G at 460 K, and eventually decreases to 4.6 G at 530 K. In hydrogenated poly-Si ΔHpp decreases monotonically above 425 K. The decrease of ΔHpp is attributed to electron hopping causing motional narrowing. An average hopping distance of 15 and 17.5 Å was estimated for unhydrogenated and H passivated poly-Si, respectively.

scholarly journals Investigation of the functional network modifier loading on the stoichiometric ratio of epoxy resins and their dielectric properties

2021 ◽  
Author(s):  
Istebreq A. Saeedi ◽  
Sunny Chaudhary ◽  
Thomas Andritsch ◽  
Alun S. Vaughan
Keyword(s):  
Glass Transition ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Epoxy Resins ◽  
Functional Network ◽  
Cross Linking ◽  
Network Modifier ◽  
Epoxy Resin System ◽  
The Cross ◽  
The Impact

AbstractReactive molecular additives have often been employed to tailor the mechanical properties of epoxy resins. In addition, several studies have reported improved electrical properties in such systems, where the network architecture and included function groups have been modified through the use of so-called functional network modifier (FNM) molecules. The study reported here set out to investigate the effect of a glycidyl polyhedral oligomeric silsesquioxane (GPOSS) FNM on the cross-linking reactions, glass transition, breakdown strength and dielectric properties of an amine-cured epoxy resin system. Since many previous studies have considered POSS to act as an inorganic filler, a key aim was to consider the impact of GPOSS addition on the stoichiometry of curing. Fourier transform infrared spectroscopy revealed significant changes in the cross-linking reactions that occur if appropriate stoichiometric compensation is not made for the additional epoxide groups present on the GPOSS. These changes, in concert with the direct effect of the GPOSS itself, influence the glass transition temperature, dielectric breakdown behaviour and dielectric response of the system. Specifically, the work shows that the inclusion of GPOSS can result in beneficial changes in electrical properties, but that these gains are easily lost if consequential changes in the matrix polymer are not appropriately counteracted. Nevertheless, if the system is appropriately optimized, materials with pronounced improvements in technologically important characteristics can be designed.

scholarly journals The Effect of Surfactant-Modified Montmorillonite on the Cross-Linking Efficiency of Polysiloxanes

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2623
Author(s):  
Monika Wójcik-Bania ◽  
Jakub Matusik
Keyword(s):  
Total Pore Volume ◽  
Cross Linking ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
The Cross ◽  
Chain Lengths ◽  
First Time ◽  
Substituent Influence ◽  
Benzyl Substituent

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH3)2R’NR]+, where R = C12, C14, C16, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

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