effect of temperature sintering on density, bending
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EFFECT OF TEMPERATURE SINTERING ON DENSITY, BENDING
STRENGTH AND WATER ABSORPTION
OF COMPOSITE ORGANIC WASTESHDPE MATERIAL
Heru Sukanto1), Wijang Wisnu Raharjo2)
1)
Mechanical Engineering Department Sebelas Maret University, Indonesia2)Mechanical Engineering Department Sebelas Maret University, Indonesia
email: [email protected]
Abstract
The purpose of the research is to investigate the change of composite
characteristics of HDPE plastic and organic wastes because of sintering
temperatures elevation. The characteristics would be found including water
absorption, density, bending strength.
The organic wastes used in the research were leaves and twigs or branches
and then they were bound by HDPE plastic. The pressured sintering methodwas selected for making the specimens. The change of process parameters
investigated in the resaerch were sintering temperature elevation of 105oC,
112oC, 120oC and 127oC refferred to melting temperature of HDPE. The
composite consite of 30%wt HDPE powder with particles size of -20 mesh
and the remaining procentage of ornagic wastes. The testing specimens
method reffered to ASTM standard. The result depicts that the increasing
temperature of 105oC to 127oC will make the bending strength to be stronger
and the density to be higher as well.
Key words: HDPE-organic wastes composite, water absorption, density, sintering
1. IntroductionManufacturing of composite products sawdust and recycled plastic is one of the
alternative utilization of waste wood and plastic, in order to improve the efficiency of
wood utilization, reduce environmental loading of waste plastics and producing
innovative products as a wood substitute building materials. The development of this
product in the future will hopefully provide a positive impact, not just limited to
industrial development and foreign exchange savings, but also improve the
environmental quality of life (Setyawati, 2003).
The usage of composite porous aims to obtain a composite that has a low
density but has a relatively high strength. In the health sector, for example, a porouscomposite applications usually used for bone replacement. A study of porous
composite states with controlled temperature, the composite porous / solid titanium
structure can show buckling strength exceeds that of human bones yet still provide the
porosity and pore size of the conditions necessary for the growth of skin tissue
(Pitkin, 2007).
Amal, 2008, made preparation of composites of HDPE, used tires and polyester
matrix with sintering time variations of 10, 15 and 20 minutes. On the variation of
sintering time 10 minutes have 0.391% volume, the variation within 15 minutes have
a volume of 0.413%, and the variation within 20 minutes have a volume of 0.530%.
Sintering time increasing the tensile strength decreased, the variation within 10
minutes had a tensile strength of 13.1 MPa, the variation within 15 minutes has a
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tensile strength of 10,603 MPa, and the variation within 20 minutes has a tensile
strength of 7.92 MPa (Amal, 2008).
Research conducted by Purnama (2008) with pressured sintering method states
that the composite powder HDPE plastic-rubber tires have a flexural strength far
below the flexural strength of HDPE material. The quality of the composite board-
polyetylene cocopeat best form on the volume ratio of 30:70 with a clamptemperature 170 C, because this board has a value of low water absorption and the
highest value of MOR. Providing treatment temperature felts no effect on the quality
of the resulting composite board (Prasetyawan, 2009).
Teak (2008) conducted a study on the influence of sintering temperature
variations on the composite HDPE - rubber tires. The result showed that increasing
the sintering temperature of 110 C to 140 C will increase the density up to 10:18%,
71.52% the impact strength, and flexural strength of 12:28%. The greatest increasing
density occured when the temperature rises from 120 C to 130oC that is equal to
6.20%, the biggest impact increases when the temperature is raised from 110 C to
120 C that is equal to 55.01%, and an increase in flexural strength was greatest when
the temperature rises from 110 C to 120 C that is equal to 6.91%. At faultobservation after tensile and impact testing on composite HDPE-PET-rubber can be
seen that the fault that occurred is brittle fracture, where the direction of crack
propagation is perpendicular to the direction of tensile stress that work and produce a
relatively flat surface (Huda, 2009) .
Research conducted by Suyanto (2007) stated that with the variation of sintering
time from 10 to 20 minutes will reduce the mechanical properties (impact strength
and flexural strength) of the material. Widya T (2007) in study of experimental
research on the influence of sintering time on the physical and mechanical properties
of plastic-rubber composite materials concluded that, given sintering time from 10 to
20 minutes will improve the physical properties of materials that is shrinkage and
density.
2. Research MethodThe process of preparing the base material is a collection of plastic, HDPE
plastic kind that cames from the plastic garbage collectors while the use of organic
waste came from the environment around campus and housing.
The materials were then cleaned from the remnants of oil and dirt. The next process
was the manufacturing of basic materials into powder which made the process of
milling (crushing). For the selection of the size of HDPE powder was done by sieving
using size of 30 mesh and 40 mesh, while for organic waste used 6 mesh and 10
mesh.Powder mixing process carried out to uniform composition, as well as reducing
segregation commonly occur due to movement or vibration to the powder. Powder
mixing was done in the dry state. HDPE and organic waste were mixed with
composition of volume fraction of 30:70. The use of volume fraction in mixing the
two materials was to facilitate for estimating the amount of each ingredient each the
mix. The mixing was done in a cylindrical tube which was rotated by speed of 85 rpm
with a tube diameter of 14 cm with a maximum volume of powder in the tube is 40%
of the volume of the tube.]
Specimens were make by pressured sintering method. Pressured sintering is
intended to form bonds between the powder particles using thermal energy at
temperature of below the melting point material, in this case was HDPE. Pressuredsintering was done inside the mold with air-free environment. Sintering temperatures
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were varied 105, 112, 120C and 127oC, while the sintering time of detention carried
out for 10 minutes. Way of cooling the specimen after sintering is muted in the mold
to cool (ambient temperature). Tests performed included testing specimens flexural
strength (ASTM D1037), density testing (ASTM D-1037) and water absorption
(ASTM D1037).
3. Research Results and Analysis
A. The Effect of Temperature Sintering on DensityGraph the results of testing the density of HDPE plastic-waste composite with
variation oganik sintering temperature 105, 112, 120, and 127oC done can be seen in
Figure 1. At a temperature of 120C an increase in density is higher, amounting to 0.86%
compared to the temperature of 112oC. The increasing density occurs because the
viscosity of the plastic become low, as a result, plastic flow ability become increase and
to be able to fill the voids between the particles of waste.
Figure 1 shows the increase in density at each sintering temperature rises. At a
temperature of 105oC plastic viscosity is still very high, because most of plastic
powder do not melt yet. Plastics have not been able to fill the empty spaces between
particles of organic waste, thereby forming pores large enough. The increase in
temperature from 105oC to 112oC powder plastic viscosity only slightly decrease,
because the plastic has not melted enough. So the ability of plastic flow at atemperature of 112C is almost equal to the temperature of 105oC. At a temperature of
112C an increase in density is not higher that is 0.65% than the temperature of
105oC. The increase was greatest density at a temperature of 127C which is worth
1.79% over the temperature of 120C, because at 127oC temperature of HDPE plastic
that is already close to its melting point at a temperature of 130oC (Corneliusse,
2002). But the ability of plastics to withstand the load from the outside goes down.
If the sintering temperature continues to rise, the viscosity of HDPE will be higher.
HDPE will be more melting and mass transfer that occurs will be greater. With a
greater mass transfer will result in HDPE easy move to find an empty space,
especially the pores between particles of the composite. So that the resulting
composite has pores smaller and has a greater density (German, 1994).Temperature variations in the sintering process will affect the density of the
Figure 1.The graphic of correlation between sinteringtemperature and composite density
R2 = 0.9512
440
445
450
455
460
465
470
475
100 105 110 115 120 125 130
Sintering Temperature ('C)
Density(Kg/m3)
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composites are made. Evident from the research that increasingly produce density
increased with increasing sintering temperature. The value of the density of the
composites according to the sintering temperature is 452.49 kg / m at a temperature
of 105oC; 455.44 kg / m at a temperature of 112oC, and then sequentially 459.35 kg /
m and 467.56 kg / m at a temperature of 120oC and 127oC.
B. The Effect of Temperature Sintering on Bending Strength
Figure 2 shows that the bending strength of plastic-organic wastes composite increase
proportionally to sintering temperature upward. The increasing of bending strength composite
is contributed by decreasing porous size in the composite material because ofthe porous is
the location for initiating the crack. Sintering temperature effect on the mass transferof HDPE. The higher the sintering temperature of the HDPE will be more easy to melt
and move to find a place that has a smaller pressure (pores). With the movement of
molten HDPE into the pores, it will cause the pores of the composite has narrowed.
With the addition of the sintering temperature of the HDPE will be more easily
infiltrate and surrounding organic waste. The behaviour results the bonding between
particles become better besides the burden imposed on the composite can also be
transferred to better the HDPE into the organic waste. Organic wastes also are not
easily separated from the HDPE bonding. The composites flexural strength values in
a sequence according to the sintering temperature of 105C, 112C, 120C and 127C
are 1.97 Mpa; 2.66 Mpa; 3.96 MPa and 5.37 MPa. The highest increasing in the
strength of the composite are at temperature 105C to 127C that is 171.6%.
C. Effect of Sintering Temperature on Water AbsorptionFigure 3 shows the reducing value of water absorption due to the increasing
sintering temperature. At the sintering temperature of 105C the uptake of water from
organic waste-HDPE composite has the highest value compared with another
temperatures. The value of water absorption at this temperature is still high because
there are many pores in the composite. The composite with so many pores formed
makes the water stored in the composite reaching 71.9%. The value of water uptake of
composite at a temperature of 112C is equal to 66.2% or a decline of 8%. Decliningthe value of the composite water absorption is not too big because at this temperature
Figure 2.The graphic of the effect temperature sinteringon com osite bendin stren th ro ert .
R2 = 0.9805
0
1
2
3
4
5
6
7
8
100 105 110 115 120 125 130
BendingStrength(MPa)
Sintering Temperature ( 'C )
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of HDPE is almost the same conditions with a temperature of 105C. At a temperature
of 120C water uptake value of the composites decreases at the amount of 54.3%. The
biggest decreasing in the value of water absorption occurs at the sintering temperature
of 127 C which is a decrease of 28%. The value of water uptake at this temperature
is 39.1%. The reason of the result is that at the temperature the HDPE plastic is
approaching its melting point, so that HDPE has begun to be soften. With thesoftening of HDPE there will be a process of filling the pores of composite by the
HDPE resulting in decreasing pore size of the composite.
From some of the statements above can be concluded that the higher of sintering
temperature the water that could seep in and stored in the composite will decrease. So
that will reduce the value of water absorption of composite.
D. Scanning Electron Micrograph( SEM ) Immages
Figure 4 shows that the bond between HDPE and organic waste is not too
strong. It can be seen from the organic waste which does not coverred by HDPE
entirely. Figure 5 shows the bonding between the HDPE with organic waste at a
temperature of 127 C. Figure 5 shows clearly that the strong binding HDPE or
surrounding organic waste so much better. The reason is that at temperature of 127Cwill increase the mass transfer of HDPE in the composite.
Figure 3.The graphic of the composite water absorption
property as sintering temperature increased
porous
HDPE
wastes porousHDPE
wastes
R2 = 0.9647
20
30
40
50
60
70
80
90
100 105 110 115 120 125 130
SinteringTemperature('C)
WaterAbsorptio
n(%)
Figure 4. SEM immage ofsample at 105
oC sintering
Figure 5. SEM immage ofsample at 127
oC sintering
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The phenomenon shown in Figure 4 and 5 occurs because the higher the sintering
temperature will tend to HDPE become softened. The softening of HDPE plastic will
increase the infiltration to the pores and the surrounding organic waste and causing
the pores of the composite will become smaller.
Conclusiona. Increasing sintering temperature tends to raise the density composite up to
3.33% from temperature of 105oC to 127oC.
b. Increasing sintering temperature from 105oC to 127C will increase the
flexural strength of composites by 171.6%.
c. Increasing sintering temperature from 105oC to 127C causes the water
absorption of composite down organic that is equal to 84.23%
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