Macroscale analysis techniques

3 Material Property Tests One way to confirm a polymer nanocompos-ite morphology is to collect the various properties of interest in the final material (mechanical, thermal, conductivity, gas barrier, etc.) in relation to a traditional filled or composite material, or the base polymer, and see how much these properties have been improved. It can be a successful argument that when normally X% of an additive is added to a polymer, it yields property improvement Y, 

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This article highlights the most commonly used methods to perform cell sorting in microfluidic devices. Some of the microfluidic techniques presented here are a miniaturized version of conventional laboratory analysis techniques and devices, and take advantage of the reduced sample volumes and increased speed of analysis. Many other types of devices have successfully exploited the novel effects that arise in a microfabricated environment that are not evident on the macroscale. 

Study of thermal transitions in polymers and other materials (Gorbunov et al. 1999, 2000c). The information on thermal properties garnered from such studies need not be an end in itself and is indeed used more often as a tool for understanding material structure and processes. The microanalogs of traditional thermal analysis techniques yield results that are similar to those obtained using macroscale techniques, but with the additional benefit that these results are spatially resolved. 

Carbon-14 content is measured by specially designed gas proportional counters (7. Aerosol samples are first converted to CO2 by combustion in a macroscale version of the thermal evolution technique. A clam shell oven was used to heat the sample for sequential evolution of organic and elemental carbon under equivalent conditions. Due to the possibility of thermal gradients, conditions in the macroscale apparatus were adjusted to produce the same recoveries of total carbon (yg C per cm of filter area) as for the microscale apparatus. Carbon-14 data are reported as % contemporary carbon based on the 1978 1 C02 content in the atmosphere. Aldehyde data referred to in this paper were obtained by impinger sampling in dinitrophenylhydrazine/acetonitrile solution and analysis of the derivatives by HPLC with UV detection (12). Olefin measurements were made by a specially designed ozone-chemiluminescence apparatus (13) difficulties in calibration accuracy and background drift with temperature limit its use to inferences of relative reactive hydrocarbon levels. 

Micro-thermal Analysis (p-TA) A family of techniques has recently been introduced that enables a range of thermal methods to be applied to regions of a material only a few micrometers wide. They are based on the use of an atomic force microscope (AFM) with a heatable tip. Many materials are heterogeneous, and the microstructure can influence the material properties on the macroscale. After acquiring the conventional AFM topographic image, selected features can be subjected to DTA and TMA with the probe tip. The tip can also be used to pyrolyze the selected area, and the vapors are then analyzed by GC-MS [23]. 

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