effect of temperature sintering on density, bending

8/12/2019 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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effect of temperature sintering on density, bending

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