Figure 1 - uploaded by Himanshu Jain
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The sugar/water phase diagram for the sugar/water system with boiling point line included. Prepared from data referenced in the text.
Source publication
We have developed a program to connect students, as well as the general public, with glass science in the modern world through a series of hands-on activities and learning experiences using sucrose based glass (a.k.a. hard candy). The scientific content of these experiments progresses systematically, providing an environment to develop an understan...
Contexts in source publication
Context 1
... the material scientist the behavior of the sucrose water system is best visualized through the binary phase diagram shown in figure 1. Data for the solubility as well as the freezing point depression for sucrose in water are available, from which the students could readily construct their own diagram [8]. ...
Context 2
... hardness of the candy (at room temperature) depends on the final boiling temperature (and thus the water content). This is reflected in the concentration dependence of the glass transition temperature curve, also shown on figure 1. A good hard candy should have a T g of 40-50°C if it is to retain its hardness at room temperature. ...
Context 3
... calibration of temperature for the sample on the plates can be achieved by using an appropriate low melting standard such as stearic acid. Figure 10. Photograph of crystal growth (right) in a sugar glass sample after one hour at 100°C. ...
Context 4
... both experiments, the students observed a distinct maximum in the crystal growth rate near 120°C. Example data are shown in figure 11. Additional details for both of the student experiments are included on our website together with their presentations. ...
Context 5
... the distinctions between homogeneous and heterogeneous nucleation are discussed as well as basic models for understanding the temperature dependence. Figure 11. Examples of data measured in two different student experiments. ...
Context 6
... exact calibration is not important for the differential temperature (∆T) measurement, we have constructed the differential pair from a single piece of constantan wire soldered at each end to two pieces of thin copper wire (#24 gauge used, available from telephone hookup wire). A sketch and photograph of our apparatus are shown in figure 13 and additional details on the construction are available on our website. ...
Context 7
... they enable a differential measurement essential to the method; second, they introduce the student to yet another method of temperature measurement used in the laboratory; and third, they allow the extension of this experiment to higher temperatures than the thermistor based digital probes can tolerate. Figure 12. Sketch of the arrangement of a student-built DTA apparatus, together with the photo of a simple implementation with digital thermometer for bath temperature, and a single thermocouple meter for measuring the differential temperature. ...
Context 8
... data for our sugar glass (standard 2:1 recipe) using our DTA are shown in figure 13. Here a very distinct T g is observed with a step that commences just above 29°C that flattens by 55°C. ...
Citations
... To this end, we have been developing a series of experiments for the quantitative exploration of glass science fundamentals, using readily accessible materials and home-built apparatus [4,5]. For many of these experiments we examine glasses made from sugars and the artificial sweetener Isomalt (a sugar alcohol), which the student can prepare on a kitchen stove. ...
... Steric acid provides an excellent crystallization standard, with a melting point near 70 ºC. Sucrose based sugar glasses [4] and the artificial sweetener, Isomalt, provide two low Tg glasses that can be made in the kitchen. The Tg of these sugar-based glasses will vary with water content, which in turn is determined by the final boiling temperature. ...
... To this end, we have been developing a series of experiments for the quantitative exploration of glass science fundamentals, using readily accessible materials and home-built apparatus [4,5]. For many of these experiments we examine glasses made from sugars and the artificial sweetener Isomalt (a sugar alcohol), which the student can prepare on a kitchen stove. ...
... Steric acid provides an excellent crystallization standard, with a melting point near 70 ºC. Sucrose based sugar glasses [4] and the artificial sweetener, Isomalt, provide two low Tg glasses that can be made in the kitchen. The Tg of these sugar-based glasses will vary with water content, which in turn is determined by the final boiling temperature. ...
Glass is among the most common materials in our everyday lives. And yet the science behind this interesting, complex and ubiquitous material is seldom considered in the undergraduate science curriculum. The glass transition (Tg) is both a fundamental and defining concept in understanding the glassy state. To facilitate the experimental exploration of this important topic we have developed a simple home-built apparatus for measuring the Tg and the associated relaxation phenomena. The simple differential thermal analysis (DTA) apparatus requires only basic mechanical and electronic construction skills yet provides excellent resolution of the Tg for the low temperature sugar glasses examined. We also demonstrate the strong effect of thermal history on Tg, including both the effect of cooling rate and aging. This apparatus provides an interesting and intuitive path to the student's exploration and understanding of the glassy state and provides a resource for deeper, independent and open-ended study of the relaxation phenomena, especially appropriate for an advanced undergraduate laboratory.
