Upload
others
View
2
Download
0
Embed Size (px)
Citation preview
Development of Wood Fiber-
Polypropylene Laminates with Layer-
By-Layer Assembly of Kraft Pulp Hand-
Sheets and Polypropylene Films
Todd Shupe and Chung Hse
SWST International Convention
June 7-12, 2015
Grand Teton National Park, WY
Objective
This study examined the effects of
polypropylene (PP) film thickness, hand-
sheet fiber content in layer (FC), and weight
ratio of total fiber content (TFC) on tensile
properties and dimensional stability of
wood-plastic laminates.
Experiment Design
CRD design with factorial treatment
3 levels of plastic layer (1, 2, and 3 ply)
3 levels of fiber content (50, 50, and 70%)
Each treatment had 3 reps
27 total samples
Materials
SYP Kraft obtained from a local paper mill
(avg. fiber length of 3.0 mm and aspect
ration of 58.2)
Polypropylene films (0.75 mil)
Handsheet Preparation
500 g of pulp added to 1 gal. water > slurry
Excess water removed with a deckle box.
Mat had a water to OD pulp ratio of 4:1
Wood Fiber-PP Laminate
Assemblies (5in. x 5in.) were hot pressed at
400◦ F.
10 min. total press time
Pressed to 1/8 in. stops in 15 sec.
Testing
• Dimensional Stability: 2 hr. boil
• Handsheet porsity: image analysis
• Tensile strength (ASTM D 638): MORt, MOEt
ELONG - % of elongation at break,
• SEM – fracture surface of tensile samples
EFFECT OF LAYER ON MOR OF
WOOD FIBER-PP LAMINATES
4000
5000
6000
7000
8000
1 2 3
Number of PP Films Between Two Handsheets
Ten
sil
e M
OR
(p
si)
A AB B
EFFECT OF FIBER CONTENT ON MOR
5500
5700
5900
6100
6300
6500
50 60 70
Fiber Content (%)
Ten
sil
e M
OR
(p
si)
B
AA
INTERACTION OF LAYER AND FIBER
CONTENT ON MOE
100
150
200
250
300
1 2 3
50
60
70
Number of PP Films Between Two Handsheets
Ten
sil
e M
OE
(1
03
psi)
EFFECT OF FIBER CONTENT ON
DIMENSIONAL STABILITY
EFFECT OF PLASTIC LATER ON
DIMENSIONAL STABILITY
1 layer
2 layers
3 layers
More layers
allows the
plastic to
better melt
and flow into
the voids.
HANDSHEET
POROSITY
SEM Micrograph of Tensile
Fracture for Fiber-PP Laminate
Note: fiber breakage,
not pulled out
SEM Micrograph of Inner Surface
NOMFC = 50, LAYER =1
Interpenetration of
PP films to fiber
network, mechanical
anchor
SEM Micrograph of Outer Surface
NOMFC = 50, LAYER =1
Thin handsheets
allowed PP to
migrate to the
outer surface
SEM Micrograph of Inner Surface
NOMFC = 70, LAYER =3
Less interpenetration,
less plastic, thicker
handsheets
SEM Micrograph of Outer Surface
NOMFC = 70, LAYER =3
Less PP on the surface
Conclusions (1)Experimental results show that laminates of
LAYER 1 had better MORt than those of LAYER 3,
due to better interpenetration of plastic, as
evidenced in SEM observation.
With proper control of LAYER, wood fiber-
polypropylene laminates with fiber loading as high
as 70% could be fabricated with favorable
mechanical properties.
Conclusions (2)
Dimensional stability of wood fiber-polypropylene
laminates were appreciably affected by both NOMFC and
LAYER. An increase in NOMFC and LAYER led to an
increase in WA, LE and TS.
Without surface treatment, lower NOMFC and LAYER
showed best dimensional stability.
Conclusions (3)SEM micrographs showed that the major failure mode of
wood fiber-polypropylene laminates was fiber breakage.
Voids existed inside and on the surface of the laminates;
therefore, precautions should be taken to avoid the
enclosure of air bubbles and the excess shrinkage of PP
in order to improve the strength properties.
(225) 578-6432