6
The Total Sorption Solution www.TheSorptionSolution.com The Surface Energy Solution
The Total Sorption Solution
www.TheSorptionSolution.com
The Surface Energy Solution
Flame IonizationDetector (FID):Adjustable gain.
iGC - inverse Gas Chromatography - the founding principle
The iGC Surface Energy Analyzer continues SMS’s pioneering history with inverse gas chromatography, which now spans more than fifteen years.
iGC is a gas-phase technique for characterizing surface and bulk properties of powders, particulates, fibers, films and semi-solids. An experiment consists of a series of vapor pulses or frontal injections eluting through a column packed with the sample under examination.
The vapor’s retention time is measured by a Flame Ionization Detector (FID). Varying the vapor probe molecule, flow rate, temperature, or column conditions elucidates a wide range of surface and bulk properties of the sample.
SEA - the next generationThe Surface Energy Analyzer (SEA) represents a huge advance in iGC technology.
The heart of the SEA’s innovation is its unique injection manifold system*, which generates solvent pulse sizes of the greatest precision and range - accurately producing isotherms at unprecedentedly high and low sample surface coverages. This allows for the accurate determination of surface energy heterogeneity distributions. *patent pending
About theTechnique
ANALYTICAL GAS CHROMATOGRAPHY
Sample gas pulse Standard analyticalcolumn packing
Separated sample peaks
inverse GAS CHROMATOGRAPHY (iGC)
Simple probegas pulse
Packed sample column(particulate or fiber)
Single peaks(retention time measured)
Front panel LEDs:Provides at-a-glance information including data saving, FID ignition, system status and leak detection.
Fully integrated design: Provides easy access to the
sample column oven and solvent reservoirs.
12 solvent reservoirs:Easy access drawers.
Temperature-controlledfor vapor stability.
2-sample column design:Higher throughput.
Sample column oven:20ºC to 150ºC
Fully integrated.
Optional:Film/monolithic sample holder.
Optional:Background humidity control.
Unique variable injection system with a 1:4000 injection volume ratio.
SMS operates a continuous product improvement policy and specifications and content are subject to change without notice. E&OE.
Optional:Gas delivery manifold.
Minimized bench requirements:System Dimensions: W: ~490mm; H: ~650mm;D: ~564mm System Weight: 80kg
Dispersive surface energy values for milled and unmilled paracetamol vs. particle size. The data shows a strong dependence of surface energy on particle size for the milled sample. Unmilled paracetamol shows a much weaker correlation.
Surface energy , is the principle characteristic measured by the iGC SEA. For a solid to exist, it must be energetically favorable (of lower energy) for its molecules to form bonds with each other. It follows that the molecules at the solid’s surface are in a less favorable state (ie; of higher energy), as they are not surrounded by other bulk molecules.
The surface energy of a solid is analogous to the surface tension of a liquid and quantifies the excess energy at the sample’s surface relative to its bulk. If a solid sample has a high value, its surface molecules are in a high-energy state and it is energetically favorable for them to form intermolecular bonds.
It is these intermolecular forces which are responsible for the attraction between powder particles and other solid surfaces. Thus, surface energy values (dispersive and polar) correlate to several key solids properties including powder flowability, agglomeration, process-induced disorder, adhesion, static charge and surface chemistry.
The SEA simulates the interface between a solid surface and other molecules by exposing the solid sample to vapor probes of known properties. The intermolecular forces that result from this interaction can be analyzed to quantify the total surface energy of the sample.
Surface Energy
Molecules at the surface are in a higher-energy state as they form fewer bonds with moleculesin the bulk. These surface molecules have regionsof different energy levels, giving rise to surface energy heterogeneity.
Molecules in the bulk bond with each other in three dimensions and are energetically more stable.
Intermolecular forces between the surfaces of powder granules contribute greatly to the powder’s physical properties.
30.0
32.0
34.0
36.0
38.0
40.0
42.0
0 100 200 300 400 500 600 700 800
Particle Size (m)
Dis
per
sive
Su
rfac
e En
erg
y (m
J/m
2)
Milled Paracetamol
Unmilled Paracetamol
Heterogeneity Mapping
Additional Surface Properties measured by the iGC SEA
Most materials are energetically anisotropic ie; they have regions of different surface energy. Therefore it is important to characterize the entire sample surface and not simply calculate average values, as liquid-based techniques do.
The SEA is the only commercial iGC system that provides detailed dispersive and polar (acid-base) component energetic heterogeneity analysis, with the ability to produce ‘mapping’ graphs, as shown below:
Surface energy heterogeneity profiles (left) and distributions (right) for micronized and crystalline budesonide powders. Micronized samples show broader surface energy distributions and higher average surface energies.
Dispersive Surface Energy ProfilesBudesonide Samples
Dispersive Surface Energy Distributions Budesonide Samples
Heats of sorption (∆H) plots for Amyl Acetate on cotton fabric at 0%RH (∆H = 56.54kJ/Mol) and 40%RH (∆H = 50.20kJ/Mol). Background humidity has a larger effect on ∆H for hydrophilic probe molecules.
Polyurethane AloneAs ReceivedMulti-walled NanotubeOxidized Multi-walledNanotubeAs Received NanoclayFunctionalized Nanoclay
----0.55
0.49
0.470.86
61 ± 460 ± 7
56 ± 6
54 ± 1171 ± 7
Tensile Strengthat Break (MPa)
Wad / WcohSample
Work of adhesion and work of cohesion values for different nanofiller-polyurethane composites correlate directly with composite mechanical strength.
30.0
35.0
40.0
45.0
50.0
55.0
0.00 0.03 0.06 0.09 0.12 0.15
Fractional Surface Coverage
Dis
per
sive
Surf
ace
Ener
gy
(mJ/
m²)
Micronized
Crystalline
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
35.0 38.0 41.0 44.0 47.0 50.0 53.0
Dispersive Surface Energy (mJ/m2)
Are
a In
crem
ent
(%)
Micronized
Crystalline
-3.8
-3.7
-3.6
-3.5
-3.4
-3.3
-3.2
-3.1
-3
-2.9
-2.8
0.00312 0.00316 0.0032 0.00324 0.00328 0.00332
1/T (1/K)
lnV
/T
Amyl Acetate, 0%RH
Amyl Acetate, 40%RH
P-SEA-001 v1.0 22NOV2010
Gutmann acid (Ka) and base (Kb)values for different polymers
along with their relative ranking on the triboelectric series.
Bulk Properties measured by the iGC SEA
Competitive sorption: Dispersive surface energy values for different proton exchange membranes as a function of background relative humidity conditions.
using optional Analysis Software Modules
Polymethyl methacrylate PolycarbonateAcrylonitrileButadiene StyrenePolypropylene Polyvinylchloride
1.331.101.09
0.630.02
Kb / KaTriboelectricSeries Order
Glass transition temperatures for maltose as a function of relative humidity. The plasticizing effect of water vapor is clearly observed by the drop in Tg.
Degree of crosslinking as a function of film depth for a UV-cured automobile top coat. Crosslinking decreases at the surface as oxygen inhibits curing.
Hildebrandt solubility parameter for polymethyl methacrylate. Value of 19.08 MPa½ agrees with literature values (17.4-21.3 MPa½).
Van Deemter Plot: Diffusion coefficient(0.0034 cm2/sec) for cyclohexane on a catalyst sample at 250°C.
2600
2800
3000
3200
3400
3600
3800
4000
4200
0 10 20 30 40 50 60
Distance from top of film (m)
Cro
ssli
nk
Den
sity
(m
ol/
g)
40000
70000
100000
130000
160000
190000
220000
250000
15000 17000 19000 21000 23000 25000 27000
1 (Pa)½
1
² /(R
*T)-
1In
f/V
1 (
Mol/
m³)
linear fit
Polymethyl Methacrylate
330
335
340
345
350
355
360
365
0 2 4 6 8 10 12 14 16
%RH
Gla
ss T
ransi
tion,
Tg (
K)
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.1
0.11
0.12
0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55
Linear Flow Rate (cm/sec)
Pla
te H
eight
(cm
)
Cyclohexane
Van Deemter fit
0.00
5.00
10.00
15.00
20.00
25.00
30.00
10 50 90
%RH
Dis
per
sive
Surf
ace
Ener
gy
(mJ/
m2)
BPSH Nafion
Special features include:• Intelligent, wizard-based experiment and sample set-up.• Wide range of Method variables: surface coverage, solvents, temperatures and flow rates.• Real-time display of experiment progress.• Easy set-up, saving and restoring of Methods.• Batch running of up to 10 Methods.• Advanced system status diagnostics.
Standard features:• Isotherm determination/BET/ Henry Constant.• Surface Energy analysis.• Surface Heterogeneity mapping.• Work of Adhesion/ Cohesion determination.• Competitive sorption measurement.• Heats of Adsorption/ Sorption measurement.• Acid-Base Chemistry analysis.
SEA Control Software: CIRRUS
SEA Data Analysis Software: CIRRUS PLUS
SMS continues to be the world leader in stable, flexible and intuitive system software. Designed entirely in-house with extensive customer participation and feedback,SMS software provides stable, flexible and easy-to-use sorption solutions.
Cirrus makes experimental sophistication easy. With its intuitive, windows-based user interface, Cirrus experimental methods can be flexibly designed, edited and run in real-time.
Cirrus Plus harnesses the experimental flexibility of the iGC SEA. Delivering extensive and user-friendly data analysis alongside one-click report generation, Cirrus Plus helps you make the most of your iGC data.
Optional Bulk Analysis….The SEA’s capabilities can be extended even further by adding extra analysis modules for the calculation of bulk properties such as solubility parameters, diffusion coefficents and Tg.
Software
Head Office [email protected] • www.TheSorptionSolution.com
