Biaxial fragmentation of thin silicon oxide coatings on poly(ethylene terephthalate)

Crack patterns of 53 nm and 103 nm thick silicon oxide coatings on poly(ethylene terephthalate) films are analyzed under equibiaxial stress loading, by means of a bulging cell mounted under an optical microscope with stepwise pressurization of film specimens. The biaxial stress and strain are modeled from classical elastic membrane equations, and an excellent agreement is obtained with a finite element method. In the large pressure range, the derivation of the biaxial strain from force equilibrium considerations are found to reproduce accurately the measured data up to 25% strain. The examination of the fragmentation process of the coating under increasing pressure levels reveals that the crack onset strain of the oxide coating is similar to that measured under uniaxial tension. The fragmentation of the coating under biaxial tension is also characterized by complex dynamic phenomena which image the peculiarities of the stress field, resulting in considerable broadening of the fragment size distribution. The evolution of the average fragment area as a function of biaxial stress in the early stages of the fragmentation process is analyzed using Weibull statistics to describe the coating strengt

Reduction of Postharvest Decay of Peaches and Nectarines with Heat Treatments

Excerpts from the report: In the United States and in several other countries experiments have been conducted for many years to reduce decay of peaches from the time they are picked until they are consumed. Most decay control operations include removing field heat from the peaches as quickly as possible followed by holding or shipping the fruit at low temperatures. Hydrocooling the fruit immediately after harvest is an extremely effective way of removing field heat. However, neither hydrocooling nor short transit periods at low temperatures reduce decay of peaches during the subsequent ripening period at more moderate temperatures. It is during this period that chemicals may be useful to reduce decay. Peaches were obtained from wholesale houses in Washington, D.C., or nearby orchards. Information is given on (a) effect of water temperature and length of exposure on decay development; (b) effect of holding at 50° or 32° F. and of hydrocooling on heated peaches; (c) peach temperatures during heating and hydrocooling; (d) decay of peaches at 70° F. as affected by hot water or hot air treatments; (e) effect of hot water on decay-producing organisms; (f) the effect of hot water on decay of peaches and nectarines packaged in open and overwrapped consumer-size units

Mechanics of thin films on polymer substrates produced by roll-to-roll manufacturing

International audienc