Micromechanical Properties of Injection-Molded Starch–Wood Particle Composites

The micromechanical properties of injection molded starch–wood particle composites were investigated as a function of particle content and humidity conditions. The composite materials were characterized by scanning electron microscopy and X-ray diffraction methods. The microhardness of the composites was shown to increase notably with the concentration of the wood particles. In addition,creep behavior under the indenter and temperature dependence were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density and weight uptake of the injection-molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starch–wood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that the wood in the starch composites did not prevent water loss from the samples.Peer reviewe

Methanol Cannon Demonstrations Revisited

The methanol cannon is a popular demonstration where emphasis is placed on a vapor-phase explosive mixture simulating the explosions occurring in a car engine when a cylinder is filled with a fuel mixture from a carburetor. Here we describe two interesting variations to the demonstration. The first is a chain reaction using real metal chains. The second involves using easily available components to produce sequential explosions that can be musical in nature

Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus

An inexpensive apparatus is described for the determination of the vapor pressure of a liquid as a function of temperature for the purpose of calculating enthalpy changes of vaporization. The solid-state pressure transducer is linear above 100 torr, is useful in the range -40 to 85 °C, and is calibrated using pure water. The experimental enthalpies of vaporization for ten solvents are within ca. 0 to 13% of literature values. Two different versions of the static vapor pressure apparatus are described. Also described are a simple air thermostat and an inexpensive temperature controller (±0.1 K) based on an integrated temperature sensor. The measurement time is under three hours

Methanol Cannon Demonstrations Revisited

The methanol cannon is a popular demonstration where emphasis is placed on a vapor-phase explosive mixture simulating the explosions occurring in a car engine when a cylinder is filled with a fuel mixture from a carburetor. Here we describe two interesting variations to the demonstration. The first is a chain reaction using real metal chains. The second involves using easily available components to produce sequential explosions that can be musical in nature

Enthalpy of Vaporization and Vapor Pressures: An Inexpensive Apparatus

An inexpensive apparatus is described for the determination of the vapor pressure of a liquid as a function of temperature for the purpose of calculating enthalpy changes of vaporization. The solid-state pressure transducer is linear above 100 torr, is useful in the range -40 to 85 °C, and is calibrated using pure water. The experimental enthalpies of vaporization for ten solvents are within ca. 0 to 13% of literature values. Two different versions of the static vapor pressure apparatus are described. Also described are a simple air thermostat and an inexpensive temperature controller (±0.1 K) based on an integrated temperature sensor. The measurement time is under three hours

Carbohydrate Dehydration Demonstrations

The charring reaction of a carbohydrate with concentrated H2SO4 is a demonstration of the dehydrating power of H2SO4. In this paper several sugars and supermarket carbohydrates are systematically studied with respect to size of particles, addition of water, and amount of H2SO4 added. The results are tabulated as to the amount of time to blackening and to the attainment of a particular volume of the charred material. Detailed safety precautions are included

Carbohydrate Dehydration Demonstrations

The charring reaction of a carbohydrate with concentrated H2SO4 is a demonstration of the dehydrating power of H2SO4. In this paper several sugars and supermarket carbohydrates are systematically studied with respect to size of particles, addition of water, and amount of H2SO4 added. The results are tabulated as to the amount of time to blackening and to the attainment of a particular volume of the charred material. Detailed safety precautions are included