View
237
Download
0
Category
Preview:
Citation preview
7/29/2019 Swelling Behavior
1/13
Click to edit Master subtitle style
3/24/13
Sorption PropertiesEnhancement of
Composites: HygroscopicThickness Swelling
Aileen Grace M. OngkikoMS Materials Science & EngineeringDepartment of Mining, Metallurgical &Materials EngineeringCollege of EngineeringUP Diliman
28 March 2011
National Engineering CenterUP Diliman
MSE 282
Composite
7/29/2019 Swelling Behavior
2/13
3/24/13
Wood fiber/polymer composites
Wood fiber/polymer composite ismanufactured by dispersing woodparticles into molten plastic with
coupling agent or additives to form
composite material through varioustechniques of processing such asextrusion, compression or injection
moulding.Better dimensional stability and
durability against bio-deterioration as compared to
wood.
As compared to polymers, highermechanical properties, thermalstability and more resistance to
ultraviolet light and degradation.
7/29/2019 Swelling Behavior
3/13
3/24/13
Thickness Swelling Stages of WoodComposites
7/29/2019 Swelling Behavior
4/13
3/24/13
Shi and Gardner(2005)
Relative swelling rate DECLINESlinearly;
INCREASE in board thickness
T
T
Thickness swelling (TS) = f(specimen
thickness)
7/29/2019 Swelling Behavior
5/13
3/24/13
Fabrication of Wood fiber/polymer composite& Hygroscopic Thickness Swelling TestShi and Gardner (2005)
Thermomechanical fibers pulping (TMP): 75% aspen & 25% otherhardwoodsPolymer fluff: polyurethane, polypropylene, poly(vinyl chloride),acrylonitrile, butadiene/styrene (ABS); processed from reclaimedautomobile polymer mixturespMDI Polymeric diphenylmethane diisocyanate
7/29/2019 Swelling Behavior
6/13
3/24/13
Effect of ambient environment on thehygroscopic thickness swelling rateShi and Gardner (2005)
1. The swelling model fits the experimental dataquite well for most of the cases.
7/29/2019 Swelling Behavior
7/13
3/24/13
Effect of ambient environment on thehygroscopic thickness swelling rateShi and Gardner (2005)
2. The thickness swelling of wood fiber/polymercomposites was about 30% lower than that of thewood fiberboard.
7/29/2019 Swelling Behavior
8/13
3/24/13
Effect of ambient environment on thehygroscopic thickness swelling rateShi and Gardner (2005)
3. The higher the temperature, the greater theswelling rates of the composites.
0
0
0
0
0
00
00
00
0 00 00 00 00 00 00 00 00 00
KSR
Temperature (C)
Relationship of temperature and swelling rate of the wood fiberboard and wood
fiber/polymer composites.
Woodfiberboard
Woodfiber/PolymerComposite
Activation energyWood fiberboard: 14.91KJ/moleWood fiber/polymer composite:
13.33 KJ/mole
Temperature have less effect on theswelling rate for wood fiber/polymer
composites than that for neat woodfiberboard.
ff f bi i h
7/29/2019 Swelling Behavior
9/13
3/24/13
Effect of ambient environment on thehygroscopic thickness swelling rateShi and Gardner (2005)
4. RH has a significant effect on the hygroscopicthickness swelling process of the woodfiber/polymer composites.
EMC RH
Actual RHs in the experimentalenvironment can possibly deviate
from the target RHs;
EMC was used to describe how RHaffects the TS or the swelling rate
Linear relationship between TS and EMC
Eff f bi i h
7/29/2019 Swelling Behavior
10/13
3/24/13
Effect of ambient environment on thehygroscopic thickness swelling rateShi and Gardner (2005)
5. Hygroscopic thickness swelling rate has a poorrelationship with RH for both samples.
RH; greater concentration gradientfor the moisture diffusion in the
materialRH; Thickness swelling rate
RH; water vaporSpecimens may be equilibrated in
moisture quicker & less time isneeded for the specimen to attain the
equilibrium thickness.
As the RH INCREASES, the swellingrate DECREASES
Eff t f bi t i t th
7/29/2019 Swelling Behavior
11/13
3/24/13
Effect of ambient environment on thehygroscopic thickness swelling rateShi and Gardner (2005)
6. Higher RH and lower swelling rate the better theprediction obtained from the swelling model.
Higher RH, more water molecules arepresent in the environment & the
more hygroscopic aspect contributedto the hygroscopic thickness swelling
process
The specimens with a higherswelling rate would have more
potential to have more innerdebonding or damage changingthe mode of moisture uptake.
Change in pure diffusion
controlled swelling to a swellingincluding fracture inside the
specimen which may induce moreerror in the swelling model
prediction.
7/29/2019 Swelling Behavior
12/13
3/24/13
Characteristics of Shi and Gardner Model
7/29/2019 Swelling Behavior
13/13
3/24/13
ReferenceShi, S.Q. and D.J. Gardner. 2006. Hygroscopic
thickness swelling rate of compression moldedfiberboard and wood fiber/polymer composites.Composites: Part A, 37, pp. 1276-1285.
Recommended