Effect Of Physical State Research Articles

Physical-state effect in the stopping cross section ofH2O ice and vapor for 0.3-2.0-MeVαparticles

The stopping cross sections of ${\mathrm{H}}_{2}$O ice and vapor for $\ensuremath{\alpha}$ particles of energy 0.3-2.0 MeV have been measured, respectively, by a thick-target elastic-scattering method and with a differentially pumped gas-cell system. The stopping cross section of ${\mathrm{H}}_{2}$O vapor (probable error \ensuremath{\simeq} 1.1%) was found to be (4-12)% higher than that of ${\mathrm{H}}_{2}$O ice (probable error \ensuremath{\simeq} 4%). This difference is less than that found previously for protons [(10-14)%] in the same velocity interval. It is proposed that the physical-state effect in the stopping cross section of ${\mathrm{H}}_{2}$O is caused by changes in the modes of electronic excitation in the molecule caused by the state of aggregation.

Bragg-Rule Applicability to Stopping Cross Sections of Gases forαParticles of Energy 0.3-2.0 MeV

The additivity of atomic stopping cross sections, Bragg's rule, is tested for $\ensuremath{\alpha}$ particles in the gaseous compounds ${\mathrm{H}}_{2}$, ${\mathrm{N}}_{2}$, ${\mathrm{O}}_{2}$, N${\mathrm{H}}_{3}$, ${\mathrm{N}}_{2}$O, CO, C${\mathrm{O}}_{2}$, C${\mathrm{H}}_{4}$, ${\mathrm{C}}_{2}$${\mathrm{H}}_{2}$, ${\mathrm{C}}_{2}$${\mathrm{H}}_{4}$, ${\mathrm{C}}_{2}$${\mathrm{H}}_{6}$, ${\mathrm{C}}_{3}$${\mathrm{H}}_{6}$ (propylene), and ${(\mathrm{C}{\mathrm{H}}_{2})}_{3}$ (cyclopropane). Compounds with single and double bonds are found to obey Bragg's rule. Compounds containing triple-bond structure are found to deviate from Bragg's rule by as much as 12.8%, but an empirical triple-bond correction is made to fit all the data of the present experiment. Evidence is seen for a possible physical-state effect.

Effect of physicalstate on tearing of filled systems based on linear amorphous polymers

A study has been made of the temperature dependence of the service behavior, deformation, and tear rate of filled systems based on SKS-85. It is established that the introduction of fillers which enhance the strength of systems in the high-elastic state effect a loss of strength in the vitreous state. The observed reversal of the strengthening effect from positive to negative is explained by weakening of the adhesive strength of the bond between polymer and filler particles caused by the increase and concentration of shrinkage stresses during cooling of the specimens. This effect is called temperature inversion of the reinforcing action of fillers.