MECHANICAL PROPERTIES AND MORPHOLOGY OF POLY … · absence of natural biodegradable tapioca...

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International Journal of Mechanical Engineering and Technology (IJMET) Volume 10, Issue 01, January 2019, pp. 745–754, Article ID: IJMET_10_01_076 Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=01 ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

MECHANICAL PROPERTIES AND MORPHOLOGY OF POLY

(LACTIC ACID) (PLA) WITH DIFFERENT FLEXIBLE

COPOLYMERS

B Ramanjaneyulu

Research scholar, Department of mechanical engineering, Jawaharlal Nehru technological university ananthapur, A.P. India

N.Venkatachalapathi

Department of mechanical engineering, Annamacharya institute of technology and sciences (Autonomous) Rajampet, A.P. Kadapa

G.Prasanthi

Department of mechanical engineering, Jawaharlal Nehru technological university ananthapur, A.P. India

ABSTRACT

Poly (lactic acid) (PLA) blended with acrylonitrile-butadiene styrene (ABS) and

natural biodegradable tapioca cassava starch powder (NBTCSP) the weight ratios on the

properties of blends, the blends films were prepared by using a twin-screw extruder and

semi-automatic compression molding machine. The mechanical and morphological

properties of samples were investigated by tensile test, flexural, compressive , impact test

and scanning electron microscope (SEM), respectively.it was found that the tensile

strength of PLA/ABS (45/45/ wt %) blend composite was about 31.50 MPa the in the

absence of natural biodegradable tapioca cassava starch (NBTCSP), and it increased to

28.66 –32.90 MPa in presence of natural biodegradable tapioca cassava starch powder

(NBTCSP) at 10 wt% .The flexural value of PLA/ABS (45/45/ wt %) blend composite was

about 31.50 MPa the in the absence of natural biodegradable tapioca cassava starch

Powder (NBTCSP), and it increased to 28.66 –32.90 MPa in presence of natural

biodegradable tapioca cassava starch powder (NBTCSP) at 10 wt% . The SEM images

showed good interface and distribution for PLA containing 47.5 wt% ABS, 5 wt%

(NBTCSP) and 45 wt% ABS 10 wt% (NBTCSP)

KEY WORDS: Poly (lactic acid) (PLA) blended with acrylonitrile-butadiene styrene (ABS) and natural biodegradable tapioca cassava starch powder (NBTCSP) and SEM analysis.

Cite this Article: B Ramanjaneyulu N.Venkatachalapathi and G.Prasanthi, Mechanical Properties and Morphology of Poly (Lactic Acid) (Pla) with Different Flexible Copolymers, International Journal of Mechanical Engineering and Technology, 10(01), 2019, pp.745–754 http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&Type=01

B Ramanjaneyulu N.Venkatachalapathi and G.Prasanthi


1. INTRODUCTION

The word composite can be defined as a material composed of two or more different materials, with the properties of the resultant material being superior to the properties of the individual materials that make up the composite. Composite material is a lightweight, strong, and low thermal expansion material used in different application due to their good properties. The raw materials are much less expensive. Its bulk strength and weight properties are very favorable when compared to metals, and it can be easily formed using molding processes. Now a day’s natural and partial biodegradable polymer blend composites materials are replacing the plastics and this natural and partial biodegradable polymer composites doesn’t create any environmental issues. By using natural biodegradable blend polymer materials, and partial and natural biodegradable blend polymer composites is improved remarkably due to the fact that the field of application is improved day by day in different field of applications 1-2. Several researches have been taken place in this direction. Most of the studies on natural biodegradable polymer composites are concerned with and without reinforcement and the addition of biodegradable polymer matrix material to the ABS can make the composite hybrid which is comparatively cheaper and easy to use. In the present study the mechanical properties PLA matrix composite materials is studied. The PLA matrix composite materials are manufactured by semi-automatic compression molding process. The properties such as tensile, compression, flexural and impact are studied and presented in detail. The results indicated that the addition of PLA and NBTCSP material makes the composite hybrid and it improves the properties

2. MATERIALS AND METHODS

2.1. Materials

Poly 3052D (lactic acid) (PLA) (NATURE TECTMA-1001) [density =1.25g/cm3 (21.5˚C), MFI=g/10min (210˚C/2.16kg)] was supplied by India Industrial Company. Pvt.Ltd. (Chennai, India), the selected grade is an extrusion material; it was must be driedat60˚Cfor6hours before using. Acrylonitrile-butadiene styrene (ABS) (AADILAKSHMI PLASTIC TRDERS-ABS) [density =1.05 g/cm3, MFI= 21.3g/10 min (220˚C/10 kg, MFR= 50 g/10min (200˚C/21.6 kg)].Was supplied by AADILAKSHMI PLASTIC TRDERS Pvt.Ltd (Hyderabad India) the selected grade is extrusion material Acrylonitrile-butadiene-Styrene; it was must be driedat80-85˚Cfor2-5hours before using. TAPIOCA CASAVA STRACH extracted from cassava tubers (TAPIOCA CASSAVA STRACH FOOD GRADE) which was purchase from ANGEL STARCH&FOOD Pvt.Ltd (Chennai INDIA).It has a particle size of 0.075mm.

2.2. Blending

The blends were processed in a Twin-screw extruder (ZV20-High Torque, L/D= 40, NEO PLAST) at 1960c (die) and 300 rpm. The extrusion rate was 10kg / hr. And the accumulation time was approximately 2 min. Seven hundred and fifty six gram PLA and 313 g ABS were mixed in a 1-l beaker and then 62.5 g NBTCSP was added. In the same manner other blends were prepared with different proportion as show in table .1 the mixed pellets were collected from the granulator and dried for 6 h at 600c in a hot air oven. Twin-screw extruder and hot air oven shown in fig.1

Mechanical Properties and Morphology of Poly (Lactic Acid) (Pla) with Different Flexible Copolymers


A b

Figure1. (a) Twin Screw Extruder Machine NEOPLAST (b) Hot air Oven with Dimensions Model HOS-5 605 mm X 605 mm X 605 mm

2.2. Samples Preparation

Table1. PLA formulations and blend compositions.

Samples formulation PLA (wt %)

(g)

ABS (wt %)

(g)

NBTCSP (wt %)

(g)

neat PLA 100

neat ABS 100

PLA70/ABS30 70 30

PLA50/ABS 50 50 50

PLA30/ABS70 30 70

PLA47.5/ABS47.5/NBTCSP5 47.5 47.5 5

PLA45/ABS45 / NBTCSP10 45 45 10

PLA25/ABS60/ NBTCSP15 25 60 15

PLA60/ABS25/ NBTCSP15 60 25 15

The prepared granules were Compression molded at 190˚C- 210˚C using NEO PLAST ENGINEERING (NP30) Compression machine (NEOPLAST ENGINEERING PVT.LTD, GUJARATH (INDIA)). The tensile samples were prepared according to the following Compression conditions, cooling time in the mold was15sec, the mold temperature was room temperature with water-cooling (25˚C) and injection pressure was 9MPa.Themoldedsamples were dog bone-shaped sampleswithathicknessandwidthof4mmand10mm respectively. The gauge length ofthesamplewas80mm (Fig 2).The obtained products were immediately packed in plastics bags and stored in a dark cool surrounding.

2.3 Experimental test specimens



Figure. 2: Tensile test specimens type 1A and 1B

3 MECHANICAL AND MORPHOLOGICAL TEST

3.1. Tensile test

The polymer composite material fabricated is cut into required dimension using a CNC contour cutting and the edges finished by using emery paper for mechanical testing. The tensile test specimen is prepared according to the ASTM D 638standard. The dimensions, gauge length and cross-head speeds are 50 mm and 5mm/min respectively. The tests are conducted on four identical specimens for each type of compounded separately. The Universal Testing Machine with Flexural and Compression Set-Up are shown in Fig. 3 and Fig. 4, respectively. The testing process involves placing the test specimen in the testing machine and applying tension to it until it fractures. The tensile force is recorded as a function of the increase in gauge length. During the application of tension, the elongation of the gauge section is recorded against the applied force. Experimental tests to sort out the tensile strength of partial biodegradable polymer prepared blends material were conducted in Static Mechanical Properties Testing Laboratory of G.Pullareddy Engineering College Autonomous by using Universal Testing machine INSTRON 3969 USA (Fig3). Group is the world’s leading supplier of static materials testing machines, developed by experts for use in demanding testing situations and in a wide range of applications. Their static testing machines have been specially designed for tensile, compression and flexure tests, as well as shear and torsion tests, making them ideal for the most rigorous materials and component testing requirements. Max. Test load 10kN, work space height 1050mm, work space width 440mm, Max. Crosshead speed 1000 mm/min

Figure 3.Universal Testing Machine model (INSTRON -3369)



3.2. Compression test

The compressive test specimen is prepared according to the ASTM D638 standard. The dimensions, width, height, and Length and cross-head speeds are 13 mmx13 mmx10 mm and 5mm/min respectively.

Figure .4. UTM with compressive test set-up

3.4. Flexural test

The flexural specimens are prepared as per the ASTM D790 standard. The 3-point flexural bending test is the most common flexural test for polymer composite blend materials. Specimen deflection is measured by the crosshead position. Test results include flexural strength and displacement. The testing process involves placing the test specimen in the universal testing machine and applying force to it until it fractures and breaks. The specimen used for conducting the flexural test. The tests are carried out at a condition of an average relative humidity of 50%.

5 (a) Specimen for under the Flexural bending test condition. 5 (b) Specimens for flexural test

FIGURE 5. Physical appearance of Specimens for flexural 5 (b) (i) neat PLA,( ii) neat ABS (iii) PLA30/ABS70 wt%, (iv) PLA50/ABS50 wt%, (v)PLA70/ABS30 wt%, (vi)

PLA47.5/ABS47.5/NBTCSP5 wt%, (vii) PLA45/ABS45/NBTCSP10 wt%, (viii) PLA60/ABS25/NBTCSP15 wt%, (ix) PLA25/ABS60/NBTCSP15 wt%,

3.5. Impact test The impact test specimens are prepared according to the required dimension following

the ASTM-D-256 standard. During the testing process, the specimen must be loaded in the testing machine and allows the pendulum until it fractures or breaks. Using the impact test, the energy needed to break the material can be measured easily and can be used to measure the toughness of the material and the yield strength



Figure 6. Impact test rig

4. RESULTS AND DISCUSSION

The use of polymer composite blend materials in the different fields is increasing day by day due to their improved properties. Engineers and Scientists are working together for number of years for finding the alternative solution for the high solution materials. In the present study partial biodegradable composites are added to the thermo plastics, composite materials and their effect on mechanical properties is evaluated and tensile fractured surfaces morphology properties are investigated.

4.1. Tensile properties and SEM of Specimens

The modulus, tensile strength and elongation at break were displayed in table 2. The tensile properties such as tensile strength and modulus increasing with increasing of ABS percentage, the increases tensile strength resulted from the presence copolymers inserted in PLA matrix [9-10]. The increase in elongation at break probably resulted from the samples were some ductile nature. PLA added 60 wt% ABS showed the highest elongation at break value. It also appeared necking phenomenon which demonstrated the ductile behavior of the polymer blends.

Table 2. Tensile properties of PLA and the blends containing different copolymers.

Sample Modulus

(MPa) Tensile Strength(MPa)

Elongation at

break [%]

neat ABS 1873.52 29.59 19.80

neat PLA 1102.56 56.39 19.68

PLA70/ABS30 1315.69 28.66 13.37

PLA50/ABS 50 1331.80 28.38 12.57

PLA30/ABS70 1399.96 31.50 13.37

PLA47.5/ABS47.5/NBTCSP5 1707.51 31.05 13.04

PLA45/ABS45/NBTCSP10 1714.14 32.90 11.55

PLA25/ABS60/NB TCS P15 1732.17 31.97 14.70

PLA60/ABS25/NBTCSP15 1512.55 24.03 10.98



From figure 7, it was demonstrated that complete breakage could be obtained with samples a), b),c), d), e), and f) Stress whitening near the notched tip was observed due to crazing or micro cracks, and it showed that the matrix could bear most of the stress [17]. It is common that the continuous transfer of energy is an important factor for impact resistance. In adding dispersed phases into the polymer matrix, the good distribution of the dispersed phase, smaller particle sizes and good interfacial adhesion are key factors to determining the optimum performance of materials. Fractured surface of impact specimens corresponding to the same concentration of copolymers are shown in figures 5(a) and 5 (f). The tensile fractured surface micrographs of neat

PLA and PLA/ABS/NBTCSP blends are displayed in Figure7. It can be confirmed from Figure 7 (d) that PLA45/ABS45/NBTCSP5 undergoes a little brittle failure, whereas the fractured surface of PLA25/ABS60/NBTCSP15 wt% was smooth and a homogenous microstructure can be seen, indicating that no phase separation took place. No agglomerates or brittle crack behavior were observed in Figure 7(f), which evidences good interfacial adhesion between the two phases of PLA matrix and with copolymers of ABS and NBTCSP. This was indirectly reflected in the more efficient load transfer under stress conditions, which was apparent from the improved tensile, flexural and impact properties of the blend [4 and 6].

(a) PLA50/ABS50 wt%, (b) PLA70/ABS30 wt% (c) PLA47.5/ABS47.5/NBTCSP5

wt%,

(d) PLA45/ABS45/NBTCSP10 wt%, (e) PLA60/ABS25/NBTCSP15

wt%, (f) PLA25/ABS60/NBTCSP15

wt%,



4.2 Compressive properties

The specimen size for compression test is 13x13x11mm.The results generated directly from the machine for compression test with respect to load and displacement for partial biodegradable polymer composites. That the results show that the maximum compressive strength is 84.9MPa the respective elongation at break is 25.08 %. [7]

Table 3. Compressive properties of PLA and the blend

Sample Modulus

(MPa)

Compressive

Strength(MPa)

Elongation at

break [%]

neat ABS 11246.08 126.4 5.56

neat PLA 5198.219 37.90 5.28

PLA70/ABS30 4721.231 89.9 25.08

PLA50/ABS 50 7088.841 84.80 8.56

PLA30/ABS70 6741.882 67.14 8.99

PLA47.5/ABS47.5/NBTCSP 5 11312.91 28.19 3.03

PLA45/ABS45 /NBTCSP10 9051.129 68.33 4.97

PLA25/ABS60/NBTCSP 15 6278.662 76.00 8.75

PLA60/ABS25/NBTCSP 15 10590.88 67.24 4.97

4.3. Flexural properties

The flexural specimens Prepared as for ASTMD 638.The results generated directly from the machine for three point bending test with respect to load and displacement for partial biodegradable polymer composites. That the results show that the maximum flexural strength is 84.9MPa the respective elongation at break is 25.08 %. [7]

Table 4. Flexural properties of PLA and the blend.

Sample Modulus(MPa) Flexural Strength(MPa) Elongation at break

[%]

neat ABS 3790.28 98.26 50.06

neat PLA 3331.22 75.48 50.04

PLA70/ABS30 3445.92 64.35 42.26

PLA50/ABS 50 3032.09 51.28 28.02

PLA30/ABS70 3063.83 43.63 26.86

PLA47.5/ABS47.5 /NBTCSP5 2937.09 53.53 32.81

PLA45/ABS45 /NBTCSP10 3537.20 62.46 30.10

PLA25/ABS60/NBTCSP 15 4118.99 61.89 25.46

PLA60/ABS25/NBTCSP15 2922.86 57.27 35.27

4.4. Izod Impact properties

The impact test un-necked specimens are prepared according to the required dimension following the ASTM-D638 standard. The dimension length width and thickness are 67.5mmX 12.75mm X 4mmduring the testing process, the specimen must be loaded in the testing machine and allows the pendulum until it fractures or breaks. Using the impact test, the energy needed to break the material can be measured easily and can be used to measure the impact resistance of the material and the absorbed energy ,the obtain results are shown in the table.5 [5and 7]



Table 5. Impact properties of PLA and the blend

sample Izod impact strength (IS) (KJ/m2)

neat ABS 57.74

neat PLA 89.23

PLA70/ABS30 68.24

PLA50/ABS 50 57.74

PLA30/ABS70 78.74

PLA47.5/ABS47.5 /NBTCSP5 68.24

PLA45/ABS45 / NBTCSP10 62.99

PLA25/ABS60/ NBTCSP15 68.40

PLA60/ABS25/NBTCSP15 62.99

5. CONCLUSION

In this study, the partial biodegradable polymer blend composite samples have been fabricated successfully by the compression molding technique. The tensile strength, impact strength and flexural strength of the fabricated composite material have been evaluated satisfactorily. The following conclusions are drawn from this experimental investigation

• The partial biodegradable polymer based polymeric matrix composites has been fabricated.

• The tensile strength, compressive strength flexural, and impact strength of the fabricated materials have been found by different tests.

• The average tensile strength of fabricated specimen is 29.26 MPa, which make it suitable for medium tension applications such as agricultural high tunnel poly house or green house applications

• In flexural test, the specimens show their higher durability under higher load. The average flexural strength of fabricated composite laminates is 63.12 MPa.

• The average impact strength of specimens was 68.25K J/m2.

• SEM results evidence good interfacial adhesion between the two phases of the PLA matrix and their copolymers

ACKNOWLEDGMENTS

The authors would like to gratefully thank institution of engineers, India (IEI) and this work was supported by a grant from IEI R&D Cell Technical Department The institution of engineers (India)

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MECHANICAL PROPERTIES AND MORPHOLOGY OF POLY … · absence of natural biodegradable tapioca...

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