Search

In collaboration with Isao Noda, I have been using Raman spectroscopy to study the properties of the bioplastic polyhydroxybutyrate hexanoate (PHBHx), which depend on the percentage of hexanoate (which produces propyl side branches to the polymer chain). The percentages of hexanoate determine the maximum crystallinity that the polymer can experience, and that determines its physical and chemical properties, which include its optical clarity, dyability, flexibility, and thermal properties (melting and glass transition temperature). It is useful to have an easy way to determine the composition; in this column, we describe how Raman spectroscopy was used to show that this is feasible at an accuracy greater than expected. [ABSTRACT FROM AUTHOR]

The article discusses the importance of drying hygroscopic resins to prevent possible loss of essential performance properties of polymers. It offers tips on how to determine the dryness of a resin before processing. It also provides information on resins that do not need drying and some polymers that are not susceptible to hydrolysis but may need drying.

The article discusses the importance of mobile phase pH and elevated temperatures in modern drug discovery. It states that the two important tools are well-suited for Hamilton's PRP-C18 column because the polymer-based stationary phase is chemically inert and has excellent thermal stability above 100 degrees. It adds that these tools allow rapid separation of closely-related basic solutes in their charge-neutral forms that would co-elute under non-alkaline conditions.

The article discusses how overfeeding can cause surges in the extrusion process of plastics. According to the author, the feed rate can exceed the melting capacity of the screw and create plugging in the melting section. The author notes that the melting rate is controlled by the shear stress in the film near the barrel wall, barrel temperature, the thermal and viscous properties of the polymer, and the design of the screw.

The article focuses on the effect of thermal properties of polymers on extrusion. Among the key polymer properties include specific heat, solid and melt density or their specific weights, and thermal conductivity. Data from a rheometer is needed in determining viscosity ranges of materials. Comparing polymers by their typical extrusion processing temperatures and estimating the relative power needed to process various polymers are explained.