Plastics Testing and Failure Analysis - Lab Report Example

no Lab Section) CHARACTERISATION, TESTINGS AND IDENTIFICATION OF VARIOUS PLASTICS Partner(s Full s) Experiment: TA: (Full Name) Abstract A series of experiments were performed on six samples of unknown plastic in order to characterize and identify the unknown plastics samples according to the results obtained from the experiment. Physical properties of the samples were examined through test 1 for general characteristics, test 2 for density, test 3 for water uptake percentage, test 4 for burning characteristics, test 5 for indentation, test 6 for indentation creep and finally test 7 for strength. The major aim of the experiment is to identify and characterize the unknown plastic samples through the use of the earlier mentioned tests. Given the considerable differences in plastic properties brought about by such factors as composition, chemical structure, manufacturing conditions and thermal history, the series different tests were necessary in order to completely distinguish the samples. The general characteristic test distinguished most of the samples by color given that most of the other properties tested such as transparency were the same in almost all the samples. The results of the burning test however, outlined the major differences among the sample in terms of flame color, melting and dripping manner. Introduction Background A plastic can be generally defined as a macromolecular substance formed from linking up of monomers through the use of covalent bonds. Using two or more monomers in the linking process leads to the formation of co-polymer. Thermoplastics and thermosets make up the wider classification of plastics. Thermoplastics are those that exist as single discrete long-chained molecules as opposed to thermosets which exists as cross linked network structure. The manufacture of plastic products using different processing techniques and materials makes their identification through visual inspection practically impossible. Among the many reasons that necessitate the identification of plastics is the need to identify plastic materials used in competitive products. Scope of the lab The lab session aimed at characterizing, testing and identifying various plastics given that plastic properties are considerably different and are dependent on various factors like composition, thermal history, chemical structure and manufacturing condition. It conducts a series of tests such as general characteristics: color and texture, transparency, rigidity and the crystalline nature, Density measurement: direct method and Archimedes, Water absorption, Burning test, Indentation test, Indentation creep test and strength test on six samples of different plastics. The plastic samples included: Teflon, polypropylene, cellulose fibre reinforced epoxy composite PMMA, polyvinyl chloride, polyethylene Aim • Characterise the physical properties of six common plastics • Fabrication of plastics and composites • Evaluate the hardness, strength and creep properties of various plastics or composites • Establish the identity of six common plastics General characteristics of the samples Polypropylene Light weight and rigid High tensile strength Low moisture absorption Opaque with an intermediate level of crystalline Teflon Completely insoluble at temperature below 300oc Excellent thermal stability Does not embrittle at either high or low temperatures Cellulose fibre reinforced epoxy composite anisotropic PMMA Low surface hardness Low heat resistance Poor impact strength Polyvinyl chloride It is brittle with high hardness properties White in colour Insoluble in alcohol but soluble in tetrahydrofuran Low heat stability Polyethylene Low density Good toughness i.e can deform without breaking Excellent elongation Viscoelasticity in polymers can be defined as the polymer property that exhibits both viscous and elastic behaviours as well as time dependant strain when undergoing deformation. Experimental Procedure Six unknown plastic samples numbered from 1 to 6 were provided for a series of tests including the following. The data collected were then recorded in the following tables. Test 1: General Characteristics This test was generally done based on visual observation and the following properties were recorded on each of the six samples. Results 1 2 3 4 5 6 Colour clear Light white Grey Light grey white Brown Texture smooth smooth smooth Smooth Transparent/opaque Transparent opaque opaque opaque opaque opaque Flexible/rigid rigid rigid Rigid rigid rigid rigid Semicrytalline/Amorphous Amorphous Semicrytalline Semicrytalline Semicrytalline Semicrytalline Semicrytalline Test 2: Density Measurements Density of the samples were measured using two methods A. Direct Method The samples were weighted and volume measured then the data were used to calculate the density of each sample using the following formula. Density =D=Mass /Volume The corresponding density values were recorded in the following table. No M (gm) L (mm) W (mm) H (mm) V=L.W.H (mm)3 D= (gm/cm3 ) 1 3.1092 26.18 10.00 10.2 2670.36 1.1643 2 2.5035 27.26 10.00 9.8 2671.48 9.371210-1 3 3.3957 24.52 10.36 10.00 2540.27 1.3367 4 2.1570 21.88 10.00 10.9 2384.27 9.044310-1 5 5.4519 25.90 10.02 9.98 2589.99 2.10499 6 1.0137 20.62 12.60 3.92 1018.46 9.9532610-1 B. Archimedes method The samples were weighted three times and the corresponding masses M1 M2 M3 Density is then calculated using the following formula Density =D=(Ml /M2 -M3 )D1 M1 = mass of dried specimen Di = density of immersion liquid M2 = mass of specimen, saturated with liquid and suspended in air M3 = mass of specimen, saturated with and suspended in liquid Sample M2 (gm) M3 (gm) D=( M1/ M2- M3)D 1 3.1289 0.4687 1.169205 2 2.5139 0 0.995926 3 3.4122 0.9160 1.360333 4 2.1716 0 0.993323 5 5.5519 2.9466 2.092619 6 1.1741 0.1700 1.009460 Test 3: Water Absorption To test for water absorption, each plastic sample was submerged in liquid and the weight measured before and after. The weight of the dry sample and the one saturated with liquid were then recorded and used to calculate the water uptake percentage as follows. Water uptake (%) = (M2−M1 /M 1 ) ×100 M2 = mass of specimen saturated with liquid M1 = mass of dried specimen Study Week NO. Time (Week) M2 (gm) Water Uptake (%) = 100 1 2 3 4 5 6 1 2 3 4 5 6 4 0 3.1092 2.5035 3.395 2.1570 5.4519 1.0137 0 0 0 0 0 0 5 1 3.1289 2.5139 3.4122 2.1716 5.5519 1.1741 0.624 0.411 0.486 0.672 1.834 15.833 6 2 3.1619 2.6225 3.4634 2.1858 5.4905 1.2307 1.685 0.799 0.518 8 4 3.1635 2.5481 3.483 2.1982 5.4990 1.2249 1.737 1.785 0.957 1.905 0.864 20.835 9 6 3.2081 2.5742 3.4742 2.229 5.5330 1.2264 3.1808 2.8240 2.311 3.370 1.487 20.982 Test 4: Burning Test: Each of the 6 plastic samples were placed under burning test and the observations such as the color of the flame melting or non-melting dripping and the rate of burning recorded as below Sample Colour Of Flame Melting Dripping Self - extinguishing Fast or slow burning Note 1 Yalow Y Y N F 2 Y Y N S 3 Orange N N Y S Black smock 4 Yalow Y Y N F 5 N N N S Very Slow melting 6 Dark Orange N N Y F Black smock Test 5: Indentation test Sample Hardness The average hardness 1 72 72.67 73 73 2 19 21.67 23 23 3 46 44 41 45 4 51 51.33 50 53 5 9 10.67 11 12 6 40 40.33 40 41 Test 6: Indentation Cree test Sample Time(Sec) 20 60 120 240 1 73 62 57 45 2 9 3 2 -2 3 41 35 28 25 Test 7: Strength Test Sample Name W (mm) T (mm) A=W x T (m2) Θ2 Δθ= θ1-θ2 E= Δθ x C (J) Impact strength= E/A (J/m2) Pure Epoxy 6.6 10.9 6.93 x 10-5 134 11 0.187 2698.412698 Epoxy + Aluminium 6.2 9.2 5.70 4 x 10-5 140 5 0.085 1490.182328 cellulose fibre reinforced epoxy composite 11.2 10.4 1.648 x 10-4 106 39 0.663 4023.058252 Identification/Conclusion Comparing the obtained values and the observations made to the literal values using the plastic and elastomers identification chart provided the unknown samples were identified and summarized in the table below. Sample Number Thermoplastics or thermoset Identity of plastic Chemical structure 1 Thermoplastic Polyethylene 2 Thermoplastic Polypropylene 3 Thermoplastic polyvinyl chloride 4 Thermoplastic PMMA 5 Thermoplastic Teflon 6 Thermoset Cellulose fibre reinforced epoxy composite References Shah, Vishu. Handbook of plastics testing and failure analysis. 3rd ed., Expanded ed. Hoboken, N.J.: Wiley-Interscience, 2007. Print. Lever, Rhys. The Properties and Testing of Plastic Materials, Temple Press, Feltham, England, 1968 Top of Form Bottom of Form Read More