Download - Teknologi Partikel
-
Nanopharmaceutical Research Group Department of Pharmaceutical Science
Faculty of Pharmacy USB
-
More than 75 % all materilas are in particulate form
The particles may be solid, liquid and gaseous
-
Micromeritics is the science of small particles. It is the study of a number
of characteristics, including
paRticle size and size distribution,
shape, angle of repose, porosity, true
volume, apparent density ANd
bulkiness.
Size and surface area can be related
1. The physical, chemical and
pharmacologial of a drug
2. The partile size of a drug can affect
its release from dosage forms
3. The viewpoints a both physical
stability
-
Size range and number or
weight particles
Shape and surface area
Polydisperse
-
The sphere thats very easy
Diameter
The degree of asymmetri particles increases
equivalent spherical diameter
ds, dv, dp, dst
-
n : the number of particle, d : The equivalent diameter p : index size (p 1 = the particle length, p 2 = surface, p 3 = volume. The value of index : p positive ( arithmetic), p negative (harmonic) and p zero ( geometric)
Edmundson Equation
Arithmetic, Geomteric and Harmonic
Average Particle Size
For a colletion particle : ndf, f : frequency index has value 0, 1,2 and 3
The size frequency distribution is expresed total number, length, surface
and volume particle
-
Particle Size Distribution
The number or weight vs the size range or mean particle size, so called frequency distribution curve. For example (Sinko (2006), Martins Physical Pharmacy and Pharmaceutical Science, p 444)
-
The following data at above, we can calculate the average diameter of the particles i.e dln, dsn, dvn, dsl dvs and dwm
Mode
-
Other method to representing the data is to plot cumulative percentage over or under particular size with particle size
-
Cont..
-
When the data in Figure 18-2 (taken from Table 18-6) are plotted as frequency versus the logarithm of the particular diameter, a typicall bell-shaped curve. A size distribution fitting this pattern is spoken as a log normal distribution, in contrast to the normal distribution show in Figure 18-1
-
The logarithm of the particle size vs the cumulative percent frequency on a probability scale
dg/50 : geometric mean diameter
g : geometric standart deviation
g : 50 %
16 % .
g : 50 %
84% .
-
Number and Weight Distribution
Hatch and Choate Equation
The number distribution can be convert to a weight distribution and vice versa
-
0,8791
-
Particle Number
The number of particles per unit weight (N) or therm dvn
-
Microscopy, sieving, sedimentation , LD, PCS, SEM, TEM and the determination of particle volume
Methods for Determining Particles Size
-
Cont.. MICROSCOPIC METHOD(OPTICAL MICROSCOPY)
Uses an ordinary microscope for particle measurement in the range of 0.2 m to 100 m.
Presence of agglomeration and particles of more than one component may be detected
The diameter is obtained only from two dimensions: length and breadth, the thickness/depth in not measured.
The microscopic method can include counting not fewer than 200 particles in a single plane using calibrated ocular on a microscope.
-
Cont..
-
SIEVING - uses standard sieves; generally used for grading coarser particles. May be employed for screening materials as fine as 44 m (No. 325 sieve)
A carefully weighed sample of the powder is paced on the top sieve, and after the sieves are shaken for a predetermined period of time. The powder retained on each sieves is weighed
Sieving errors can arise : sieve loading, duration and intensity of agitation
-
US Sieve Standart
-
Sedimentation Stokes Law
v :
=
2 0
18 0 or dst =
18 0
Spheres fallin freely and at a constant rate
Irregularly shaped particle s as long as diameter is relative particle size equivalent to that of sphere
The particles mus not be aggregated or clumped
Flow of medium dispersion laminar / streamline
-
MICROMERITICS FACTORS AFFECTING FLOW PROPERTIES
1. PARTICLE SIZE AND SHAPE 250-2000m = free flowing
75 250 m = flow freely or cause problem depending on shape
Very fine particles (less than 10 m) = do not flow freely as large particles
Particle shape and flow properties
Spherical shape flow better than needle particles
Elongated or flat particles tend to pack resulting to high porosity powders
2. POROSITY AND DENSITY High density, low porosity = FREE FLOWING
3. SURFACE ROUGHNESS Leads to poor flow characteristics
-
BENTUK PARTIKEL DAN LUAS PERMUKAAN
1. BENTUK PARTIKEL Sferis luas permukaan minimum persatuan volume
Luas permukaan = . d2 dan Volume = 3
6
Dengan konstanta perbandingan maka : luas permukaan = s . dp
2 = . ds2
(s : faktor luas permukaan, ds : diameter permukaan ekivalen)
volume = v . dp3 =
2
6
(v : faktor volume, ds : diameter volume ekivalen)
Jadi sferis s = .ds2/dp2 = 3,142 dan v = .dv3/6dp3 = 0,524
-
2. LUAS PERMUKAAN SPESIFIK
Permukaan spesifik : luas permukaan per satuan volume (Sv) atau persatuan berat (Sw)
Persamaan diturunkan dari persamaan luas permukaan dan volume, untuk partikel asimetris maka :
Sv =
=
. 2
.3
Sv =
n : jumlah partikel
Sw =
: densitas partikel
substitusi Sv pada Sw , maka Sw =
dvs : diameter volume permukaan
Jika sferis atau mendekati sferis, maka Sw = 6
karena bentuk sferis s / v = 6
-
Contoh.
-
SIFAT TURUNAN SERBUK
1. POROSITAS
Volume bulk (ruahan) =Vb
Vb Vb
Serbuk tanpa pori-pori internal atau ruang-ruang kapiler, volume ruahan adl vol sebenarnya + vol ruang antara
partikel (vol kosong= v)
v = Vb - Vp
Vp : volume sebenarnya
-
Porositas/kekosongan () : rasio volume kosong (V) dengan volume ruahan (Vb), dinyatakan dlm persen x 100. Persamaan :
=
= 1 -
-
2. PENGATURAN SUSUNAN
Serbuk sferis
terapat/rhombohedral = 26%
renggang/kubik/terbuka = 48%
Serbuk sejati/umumnya serbuk farmasi : 30-50%
Serbuk flokulat/agregat : 30-50%
Serbuk kristalin dg tekanan 100.000 lb/inci2 = < 1%
-
3. DENSITAS PARTIKEL
Densitas () = massa / volume
Volume partikel padat cukup sulit ditentukan karena
1. partikel mengandung retakan mikroskopis
2. pori-pori dalam
3. ruang kapiler
-
Ada 3 jenis densitas yaitu :
1. Densitas sebenarnya (). Densitas bahan padat sesungguhnya
dimana terdapat pori-pori intrapartikel dan rongga partikel
yg lebih besar dari dimensi molekuler, atom dan kisi kristal.
Alat : densitometer helium
-
2. Densitas granul (g). Densitas bahan padat yg ditentukan
dengan pemindahan merkuri yg tidak berpenetrasi ke dalam
pori-pori yang lebih kecil dari 10 m.
Alat : densitometer merkuri
-
3. Densitas ruahan (b). Massa suatu serbuk dibagi dengan
volume ruahan. Volume ruahan diukur dengan gelas ukur
100 ml tanpa diketuk (untapped volume).
Alat : Tap density tester
densitas ruahan dipengaruhi : PSD, bentuk partikel, agegrasi
-
Jika volume ruahan dihitung setelah dilakukan ketukan (tapped) disebut densitas mampat/Bj mampat/ tapped density. Standar ketukan adalah 10, 500 dan 1250 ketukan
Tapped density (Bj mampat) =
Porositas intrapartikel (ip). Dihitung dengan mengetahui
densitas sebenarnya dan densitas granul.
inrapartikel = 1 -
= 1-
Porositas antarruang/porositas kosong (k). Vol relatif bagian kosong antarruang terhadap vol ruahan serbuk. Dihitung jika densitas ruahan dan densitas granul diketahui
antarruang= 1 -
= 1-
-
Porositas total (total). Serbuk berpori tersusun dari bagian kosong antara partikel dan juga pori-pori. Sehingga total :
total =
= 1 -
(Vb : vol bulk, Vp : vol bhn padat)
Dimana Vp = w/ dan Vb = w / b (w : berat/massa serbuk) Substitusi kedua persamaan diatas diperoleh porositas total sbb:
total = 1 -
atau total 1 -
-
4. KERUAHAN
Merupakan ukuran volume ruahan dan kebalikan densitas
ruahan. Keruahan meningkat dengan bertambahnya ukuran
suatu partikel.
5. SIFAT ALIRAN
Dipengaruhi : ukuran partikel, bentuk partikel, tekstur suatu
partikel dan densitas.
Partikel fine dg ukuran 1-10 m sifat aliran jelek karena gaya
kohesi antara partikel besar atau sama dengan gaya gravitasi.
Kelembaban juga menyebabkan sifat aliran berkurang.
Serbuk dgn densitas tinggi dan porositas dalam rendah akan
lebih mudah mengalir
Tekstur permukaan yg tdk rata /kasar menyebabkan terjadi
gesekan dan perlekatan shg serbuk tdk mengalir bebas.
-
6. SUDUT DIAM/SUDUT ISTIRAHAT ( = phi)
Sudut maksimum antara permukaan gundukan serbuk dan bidang horisontal. Sebagai fungsi gaya gesek antar partikel yg menghasilkan permukaan dengan sudut berada dala kesetimbangan dg gaya gravitasi .
Tangen sudut diam = koefisien gesekan ()
tan = atau tan = h/r
(h tinggi serbuk, r : jari-jari gundukan serbuk) Sudut diam kecil serbuk mudah mengalir dan sebaliknya.
Semakin kasar/tidak beraturan permukaan partikel , semakin
besar sudut istirahat maka sifat aliran semakin menurun.
-
Thank you Dreams and Endeavors