孔分析服务s

材料的孔结构可能与化学的重要性一样重要，因为孔径，孔体积和渗透率对从药物的生物利用度到过滤器的吸附能力的许多应用中的性能产生了重大影响。这些孔测量可以使用气体吸附，汞入侵，毛细血管流或液体液位位移技术进行。

Available Tests

  • Gas Adsorption Technique
  • 汞入侵技术
  • Capillary Flow Technique
  • Liquid-Liquid Displacement Technique

Gas Adsorption Technique

为了通过气体吸附测量孔径，等温线（通常使用N2，AR或CO2）从低压（约0.00001 Torr，最小值，最小值）到饱和压力（约760 Torr）记录。压力范围取决于要测量的孔的尺寸范围。微孔材料的等温线在大约0.00001 TORR至0.1 TORR的压力范围内测量。介孔材料的等温线通常在1 Torr的压力范围内测量到约760托尔。总体而言，气体吸附适用于从3.5埃的毛孔到直径约4000埃的毛孔。

Once details of the isotherm curve are accurately expressed as a series of pressure vs. quantity adsorbed data pairs, a number of different methods (theories or models) can be applied to determine the pore size distribution. Available micropore methods include: Density Functional Theory (DFT), MP-Method, Dubinin Plots (Dubinin-Radushkevich D-R, Dubinin-Astakov D-A), and Horvath-Kawazoe (H-K) calculations. Available Mesopore methods include: Barrett, Joyner and Halenda method (BJH), and Density Functional Theory (DFT). T-Plot analysis is also available for total micropore area as well.

汞入侵技术

Mercury intrusion porosimetry involves placing the sample in a special sample cup (penetrometer), then surrounding the sample with mercury. Mercury is a non-wetting liquid to most materials and resists entering voids except when pressure is applied. The pressure at which mercury enters a pore is inversely proportional to the size of the opening to the void. Pressures ranging from 0.2 to 60,000 psi allow for measurement of pores from 30 Angstroms up to 900 micrometers in diameter. As mercury is forced to enter pores within the sample material, it is depleted from a capillary stem reservoir connected to the sample cup. The incremental volume depleted after each pressure change is determined by measuring the change in capacitance of the stem. This intrusion volume is recorded with the corresponding pressure or pore size.

NOTE: The maximum pore size that any mercury porosimeter can characterize depends on a number of factors. The primary limiting factors are 1) the contact angle between mercury and the sample material, and 2) the head pressure gradient associated with a volume of mercury and the volume of sample material subjected to these pressures.

Capillary Flow Technique

Capillary flow Porometry (CFP) is used to measure pore sizes of 500 to 0.015 microns in diameter.

With this method, pore properties are calculated by measuring the fluid flow when an inert, pressurized gas is applied to displace an inert and nontoxic wetting fluid impregnated in the porous network of the sample.

Parameters such as first bubble point (corresponding to the largest pores present) can be calculated with accuracy and repeatability according to ASTM F316.

Liquid-Liquid Displacement Technique

Liquid-liquid displacement porometry (LLDP) measures pores 1,000 to 2 nanometers in diameter.

使用这种方法，我们可以在低压下用不混溶的液体在压力增加的压力下用不混溶的液体来测量纳米孔（1,000至2 nm）。这消除了测量诸如空心纤维等材料时高压造成的崩溃或机械损伤的错误。