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WEATHERING PROPERTIES

WEATHERING PROPERTIES. PERMANENCE PROPERTIES. The property of a plastic which describes its resistance to deterioration and change in characteristics with time and environment comes under permanence properties. WATER ABSORPTION & SOLUBILITY. DEFINITION

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WEATHERING PROPERTIES

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  1. WEATHERING PROPERTIES

  2. PERMANENCE PROPERTIES The property of a plastic which describes its resistance to deterioration and change in characteristics with time and environment comes under permanence properties. Corporate Training & Planning

  3. WATER ABSORPTION & SOLUBILITY DEFINITION • Ability of plastics to absorb the water when immersed in water, it is directly related to the square root of the immersion time. SIGNIFICANCE • Test results indicates the effect of exposure of plastics to water or humid condition where the moisture content of a plastic is very intimately related to properties such as electrical insulation resistance, dielectric losses, mechanical strength, appearance, and dimensions etc. • Selection of material for specific applications. • The test results can be used as a database for the development of new materials/products. Corporate Training & Planning

  4. WATER ABSORPTION & SOLUBILITY TEST METHOD • ASTM D 570: Standard test method for Water Absorption of Plastics • ISO 62: Determination of water absorption of plastics. • JIS K 7209: Testing Methods for Water and Boiling Water Absorption of Plastics. • DIN 53495: Testing of Plastics; Determination of water absorption Corporate Training & Planning

  5. TEST SPECIMEN A minimum of three specimens shall be tested for each sample; the specimen shall be prepared according to the given dimension (Table 1) to the nearest 0.025 mm Table 1: Specimen dimension as per the product WATER ABSORPTION & SOLUBILITY Corporate Training & Planning

  6. WATER ABSORPTION & SOLUBILITY CONDITIONING : • Specimen shall be dried in an oven for 24 h at 50 ± 30 C, cooled in desiccators and immediately weigh to the nearest 0.001 g. Note: In case of phenolic laminated plastics and other plastics whose water absorption value not affected up to 1100C, shall be dried in an oven for 1 h at 1100C. INSTRUMENTS/ APPARATUS • Weighing machine: up to 0.001 g precision • Dimension Measuring instrument: up to 0.025 mm precision • Oven: up to 150 0 C with ± 10C precision REAGENTS : • Anhydrous calcium chloride (dried at 2000C) and distilled water. Corporate Training & Planning

  7. WATER ABSORPTION & SOLUBILITY PROCEDURE The standard conditions of immersion of test specimens are as follows: • Twenty four Hour Immersion: the conditioned specimen shall be placed in a container of distilled water maintained at a temperature 23 ± 10C. At the end, the specimen shall be removed from the water and all surface water wiped off with dry cloth, and weighed to the nearest 0.001g immediately. • Two Hours Immersion at 23 ± 10C for the material having higher water absorption. • Repeated Immersion at 23 ± 10C: specimens may be weighed to the nearest 0.001g after for 2h immersion, re-immersed in water and weighed again after 24 h. Corporate Training & Planning

  8. WATER ABSORPTION & SOLUBILITY PROCEDURE • Long Term Immersion: repeat the procedure (a) in a sequence of 24 h, one week, two weeks up to saturation (until the increase in weight per two week, until the average increase in weight is less than 1% of the total increase in weight or 5 mg) • Two Hours boiling water Immersion: at the end of 120 ± 4 minutes specimen shall be removed from water and cooled in distilled water maintained at room temperature. • Half an hour boiling water immersion for the material having relatively high rate of absorption. • Immersion at 50 ± 10C for 48 ± 1h, cooled in water before weighing shall be omitted. Corporate Training & Planning

  9. WATER ABSORPTION & SOLUBILITY PROCEDURE RECONDITIONING : • When the materials are known and contain any appreciable amount of water soluble ingredients, the specimens after immersion shall be weighed and then reconditioned for the same time & temperature as used in the original drying period. Then this shall be cooled in desiccators and reweighed immediately. If the reconditioned weight is lower than the conditioned weight, the difference shall be considered as water soluble matter lost during the immersion test. For such materials the water absorption value shall be taken as the sum of the increase in weight on immersion and of the weight of the water soluble matter. Corporate Training & Planning

  10. WATER ABSORPTION & SOLUBILITY CALCULATION : % Water absorption = % increase in weight during immersion. In the case of plastics having water soluble ingredient % Water absorption = % increase in weight during immersion + % soluble matter Where, Conditioned weight – just after conditioning of specimen Wet weight – Specimen weigh after Immersion in water Corporate Training & Planning

  11. WATER ABSORPTION & SOLUBILITY RESULT • Results can be expressed in terms of • % Water absorption • % Water soluble matter • Dimension of specimen before and after if required • Warping, cracking or change in appearance of specimen FACTORS INFLUENCING • Thickness of the specimen • Test condition: Temperature, Time (with in saturation) Corporate Training & Planning

  12. WATER ABSORPTION & SOLUBILITY • CASE STUDY 1: Water absorption of different grade of Nylon in investigated at 50 % relative humidity and at saturation.

  13. WATER ABSORPTION & SOLUBILITY CASE STUDY 1: Water absorption of different polymers at 24 hr and saturation is compared below

  14. CHEMICAL RESISTANCE Definition • The resistance of plastics to chemical reagents (acids, bases, solvents, fuels), measured in terms of change in weight, dimension, appearance and strength properties after exposure to reagents at specified temperature and stress conditions for a stipulated period of time. Significance • The result obtained provides basis for standardization and serve as a guide to compare the relative resistance of various plastics to typical chemical reagents. • Selection of plastics for specific applications. Corporate Training & Planning

  15. CHEMICAL RESISTANCE TEST METHOD • ASTMD 543: standard practice for evaluating the resistance of plastics to chemical reagents. • ASTM D 4398: Standard Test Method for Determining the Chemical Resistance of glass Fibre-Reinforced Thermosetting Resins by One-Side Panel Exposure. • ASTM C581: Standard Practice for Determining Chemical Resistance of Thermosetting Resins Used in Glass-Fibre-Reinforced Structures Intended for Liquid Service. • ASTM D1239: Standard Test Method for Resistance of Plastic Films to Extraction by Chemicals • ISO 175 Plastics: Determination of resistance to liquid chemicals • JIS K 7114: Testing Method for Evaluation of Resistance of Plastics to Chemical Substance. Corporate Training & Planning

  16. TEST SPECIMEN Table 2: Specimen dimension as per the products For the effect of chemicals on specific properties (e.g. mechanical), specimen dimension shall be taken as per the standard related to the properties. CONDITIONING : Specimen shall be conditioned for a minimum period of 40 h at 23 ± 20C and 50 ± 5% Relative Humidity. CHEMICAL RESISTANCE Corporate Training & Planning

  17. CHEMICAL RESISTANCE INSTRUMENTS / APPARATUS : • Weighing balance:up to 0.001 g precision • Dimension Measuring instrument: up to 0.025 mm precision • Strain Jig: capable of supplying known amount of strain to the test specimen. • Testing devises: to check the change in mechanical or other required properties. REAGENTS : • Required Chemicals as per end use applications and distilled water. Corporate Training & Planning

  18. CHEMICAL RESISTANCE PROCEDURE : A. Weight & Dimension changes • Weigh the each conditioned specimen and measure its thickness at the center, length and width or two diameters at right angles to each other to the nearest 0.025 mm. • Place the specimens in a container and allow the specimens to be totally immersed in a fresh reagent for seven days at the standard laboratory environment. • Stir the reagents every 24 h by suitable means. • After 168 hours, remove the specimens from the reagents and weigh immediately. • After weighing, wash with running water, wipe and dry with filter paper carefully, then recondition the specimen. • Then re-measure its dimensions and weight. Corporate Training & Planning

  19. CHEMICAL RESISTANCE B. Changes in Mechanical Property • Immerse the test specimens in reagent as per the above procedure. Carryout the required mechanical test of non-immersed and immersed specimens, prepared from the same sample, in the same manner. Calculation Percentage weight loss or gain = [(W2- W1) / W1] x 100 Percentage weight loss or gain = [(W3- W1) / W1] x 100 where: • W1: Weight of the specimen before immersion in reagent • W2: Weight of the specimen after immersion • W3: Weight of the specimen after drying and reconditioning Corporate Training & Planning

  20. CHEMICAL RESISTANCE RESULT : Shall be expressed in terms of • Percentage weight loss or gain. • Percentage change in mechanical properties. • Changes in dimension of specimen before and after. • Warping, cracking or change in appearance of specimen FACTORS INFLUENCING : • Temperature and time of exposure • Surface area of exposure • Nature (basic, acidic etc.) and concentration of chemicals Corporate Training & Planning

  21. CHEMICAL RESISTANCE SAFETY PRECAUTIONS Safety precautions should be taken to avoid personal contact, to eliminate toxic vapours, and to guard against explosion hazards in accordance with the hazardous nature of the particular reagents being used. Corporate Training & Planning

  22. CHEMICAL RESISTANCE OF THERMOPLASTICS Corporate Training & Planning 22

  23. STAINING RESISTANCE DEFINITION • Ability of plastics materials to resist the staining during the contact with external sulfide source in the form of matter. SIGNIFICANCE • Plastics composition containing salts of lead, cadmium, copper, antimony, and certain other metals (as stabilizer, pigments, driers or fillers) may stain due to the formation of a metallic sulfide when in contact with external materials that contain sulfide. The external sulfide source may be liquid, solid or gas. This provides a means of estimating the relative susceptibility of plastics to sulfide staining. • Selection of plastics for specific applications. Corporate Training & Planning

  24. STAINING RESISTANCE TEST METHOD • ASTM D 1712: Standard Practice for Resistance of Plastics to Sulfide Staining • ASTM D 2299: Recommended Practice for Determining Relative Stain Resistance of Plastics Corporate Training & Planning

  25. STAINING RESISTANCE TEST SPECIMEN • Plastics test specimens 100 ± 25 mm in length by 13 ± 6 mm in width by thickness suitable for the testing. CONDITIONING • Specimen shall be conditioned for a minimum period of 40 h at 23 ± 2 0C and 50 ± 5 % Relative Humidity. INSTRUMENTS / APPARATUS • 250 ml glass beaker, watch glass cover or aluminum foil. REAGENTS • Hydrogen sulfide solution - Prepare a solution by rapidly bubbling hydrogen sulfide gas through water. Five minutes of bubbling is sufficient for 100 to 150 mm of water at room temperature. Corporate Training & Planning

  26. STAINING RESISTANCE PROCEDURE • Immerse approximately half of each conditioned specimen in 250 ml beaker containing saturated hydrogen sulfide solution. • Cover the beaker with watch glass or aluminum foil for 15 minutes. • Remove the specimen, wipe dry and examine for discoloration of the immersed section by comparing unexposed part. • Compare the relative degree of staining for each material being tested in a series, and establish their relative order of stain resistance. Corporate Training & Planning

  27. STAINING RESISTANCE RESULT • Shall be expressed in terms of discolouration and physical changes along with relative degree of sulfide staining. FACTORS INFLUENCING • Temperature and time of exposure. • Surface finish of specimen. • Concentration of hydrogen sulfide solution. SAFETY PRECAUTION • Hydrogen sulfide is a highly toxic gas and must be handled only in suitable ventilated area such as a hood. Avoid breathing of vapour. Corporate Training & Planning

  28. ENVIRONMENTAL STRESS CRACKING RESISTANCE DEFINITION • Environmental stress cracking resistance is defined as an external or internal rupture in plastics in presence of reagents such as soap, wetting agents, oils or detergents under tensile stress less than its short-time mechanical strength. SIGNIFICANCE • Selection of material for specific application where the material is exposed to crack accelerating agents. • Test results can be used for direct application to engineering problems. TEST METHOD • ASTM D 1693: Standard test method for environmental stress-cracking of Ethylene Plastics. Corporate Training & Planning

  29. ENVIRONMENTAL STRESS CRACKING RESISTANCE TEST SPECIMEN • Test specimen shall be 38 ± 2.5 mm by 13 ± 0.8 mm, thickness range of the specimens is given in Table 2. CONDITIONING • Test specimens should be conditioned at 23 ± 20C and 50 ± 5% Relative Humidity for a minimum period of 40h & maximum of 96h. Table 3: Standard test conditions, specimen thickness & notch depth Corporate Training & Planning 29

  30. ENVIRONMENTAL STRESS CRACKING RESISTANCE INSTRUMENTS / APPARATUS : • Blanking die: A rectangular die for cutting specimens as per required dimension. • Nicking jig: a jig for making a controlled imperfection on specimen of the notch dimension given in Table 2, parallel to the long edge of specimen and centered on one of the board face. • Specimen holders • Test tubes: Hard glass tube with outside diameter 32mm and 200 mm long. • Aluminum foil: Approximately 0.08 to 0.13 mm thick, for wrapping the glass tube. • Constant temperature bath: up to 100°C • Test tube rack • Bending clamp • Transfer tool Corporate Training & Planning

  31. ENVIRONMENTAL STRESS CRACKING RESISTANCE Figure 1: Nicking Jig Figure 2: Test sample Figure 3: Specimen Holder Figure 4: Test Assembly Corporate Training & Planning

  32. ENVIRONMENTAL STRESS CRACKING RESISTANCE REAGENTS : • Igepal (10% by volume) or Solvents as per requirements. PROCEDURE : • Prepare 10 specimens as per the required thickness as given in Table – 2, condition it. • Make the notch on each conditioned specimen, with the sharp blade, mounted in the jig. In no case shall a blade be used for more than 100 specimens • Place the notched specimens in specimen holder with the help of bending clamp and transfer tool with in 30 to 35 sec. • Insert the holder in the test tube within 10 min after the specimen have been bent in to the holder. Corporate Training & Planning

  33. ENVIRONMENTAL STRESS CRACKING RESISTANCE PROCEDURE : • Fill the test tube, approximately 13 mm above the top specimen with fresh reagent. • Stopper the tube with a foil- wrapped cork and immediately place it in the constant temperature bath at the preselected test temperature. • Inspect the specimen at indicated elapsed times and record the percentage of failure at the time (on the basis of ten specimens). Convenient suitable inspection times have been found to be 0.1, 0.25, 0.5, 1.0, 1.5, 2, 3, 4, 5, 8, 16, 24, 32, 40, and 48 hour. Extended test are inspected every 24h thereafter. • If the test duration is specified, measure the percentage of failure and stop the test, otherwise continue the test up to more than 50 % failure. Corporate Training & Planning

  34. ENVIRONMENTAL STRESS CRACKING RESISTANCE CALCULATION : • Graphical method of determining failure points: • Plot the data on logarithmic graph paper, by taking percentage failure on probability scale and time on logarithmic scale. • Calculate the time required for 50 % failure from the graph. RESULT : • Shall be expressed in terms of % failure at given time or the time (hours) required for 50% failure. FACTORS INFLUENCING : • Specimen thickness, Notch depth • Igepal or other solvents concentration • Internal stress of the specimen • Test temperature (Water bath) Corporate Training & Planning

  35. ENVIRONMENTAL STRESS CRACKING RESISTANCE CASE STUDY: ESCR resistance of HDPE cross linked and HDPE linear Polymer is analyzed in 10 % Igepal solution. As per the result the cross linked HDPE is showing better ESCR resistance. Corporate Training & Planning 35

  36. GAS PERMEABILITY DEFINITIONS • Gas transmission rate: The quantity of a given gas passing through a unit of the parallel surface of a plastics film in unit time under the condition of test. • Gas permeance: The ratio of gas transmission rate to the difference in partial pressure of the gas on the true site of the film. • Gas permeability: The product of the permeance and the thickness of a film. The permeability is meaningful only for homogeneous materials, in which it is a property characteristic of the bulk material. SIGNIFICANCE • Test data helps in selection of materials for gas packaging. Corporate Training & Planning

  37. GAS PERMEABILITY TEST METHOD • ASTM D 1434: Standard Methods for determining characteristics of plastics films and sheeting. • ISO 2556: Plastics. Determination of the gas transmission rate of films and thin sheets under atmospheric pressure. Manometric method. • DIN 53380: Testing of Plastic Films; Determination of the Gas Transmission Rate. Corporate Training & Planning

  38. GAS PERMEABILITY TEST SPECIMEN • The test specimen shall be cut to an appropriate size (generally circular) to fit the test cell. CONDITIONING • Specimen shall be conditioned in a desiccator for a minimum period of 48 h at 23 ± 20C. INSTRUMENTS / APPARATUS • Weighing balance: up to 0.001 g precision • Dimension Measuring instrument: up to 0.025 mm precision • Desiccator • Materials: Anhydrous calcium chloride (dried at 2000C), test gas, mercury. • Gas transmission equipment. Corporate Training & Planning

  39. GAS PERMEABILITY Figure 5: Gas Permeability test instruments Corporate Training & Planning 39

  40. GAS PERMEABILITY PROCEDURE • Place the filter paper in the lower plate cavity. • Apply a light coating of vacuum grease on a flat metal that the surface of specimen will contact. Avoid excess grease. • Place the conditioned specimen on the greased plate by covering the filter paper and entire exposed face of the lower plate. Then close and tighten the cell. • Check the mercury level and pore mercury from reservoir in to manometer system of the cell by carefully tripping the cell till the mercury level in reservoir leg and capillary leg become same. Corporate Training & Planning

  41. GAS PERMEABILITY PROCEDURE • Make the vernier to the required height and measure the initial height of mercury in capillary leg (h0). • Maintain the required pressure difference on specimen with the help of Vacuum pump and gas cylinder pressure (approx 26 Pa or less). • After suitable estimated time for attaining steady state condition, record the height of the mercury in the capillary leg and elapsed time. Corporate Training & Planning

  42. GAS PERMEABILITY Figure 6: Ray diagram for gas permeability test setup Corporate Training & Planning 42

  43. GAS PERMEABILITY CALCULATION : The permeance “P” in SI unit from the following equation where: Corporate Training & Planning

  44. GAS PERMEABILITY Where, ac = Area of capillary AB, mm2 A = Area of transmission in mm2 H0 = Height of mercury in the capillary leg at the start of the actual transmission run, after steady-state condition have been attained, mm. h = Height of Mercury in cell capillary leg at any given time, mm hB = Maximum height of mercury in the cell manometer leg from the datum plane to upper calibration line B, mm. hL = Height of mercury in cell reservoir leg from the datum plane to top of mercury meniscus, mm. Pu = Upstream pressure of gas to be transmitted, mm Hg. R = Universal Gas constant = 8.3143 x103 L Pa / (moI.K) To = Time at the start of the actual transmission run, h, after steady -state conditions have been attained. t = time T = absolute temperature, K VBC = volume from B to C, µL. VCD = Void volume of depression, µL Vf = (VBC +VCD) Corporate Training & Planning

  45. GAS PERMEABILITY RESULT : • Shall be expressed in terms of • Gas transmission rate in mol/ m2.s • Gas permeance in mol/ m2.s. Pa • Gas permeability in mol/ m.s. Pa FACTOR INFLUENCING : • Uniformity in Film thickness • Surface finish, should be free from wrinkles and pinholes. • Gas pressure and type of gas used. Corporate Training & Planning

  46. GAS PERMEABILITY CASE STUDY: Gas permeability testing is performed on different polymer with N2 (30°C), O2 (30°C) and CO2 (30°C) as a permeable gas. The test result compared data is tabulated in Table 8. Corporate Training & Planning 46

  47. WATER VAPOUR TRANSMISSION / PERMEABILITY DEFINITIONS • Water vapour transmission rate: The steady water flow in unit time through unit area of a body, normal to specific parallel surfaces, under surface conditions of temperature and humidity at each surface. • Water vapour permeability: the rate of water vapour transmission through unit area of flat material of unit thickness induced by unit vapour pressure difference between two specific surfaces, under specified conditions of temperature and humidity. SIGNIFICANCE • Selection of material in packaging applications. • Test values are useful in design, manufacturing and marketing. Corporate Training & Planning

  48. WATER VAPOUR TRANSMISSION / PERMEABILITY TEST METHODS • ASTM E 96: Standard Test Methods for Water Vapour Transmission of Materials • ASTM D1653: Standard Test Methods for Water Vapor Transmission of Organic Coating Films • ISO 1663: Rigid cellular plastics -- Determination of water vapour transmission properties Corporate Training & Planning

  49. WATER VAPOUR TRANSMISSION / PERMEABILITY TEST SPECIMEN • The test specimen shall be cut to an appropriate size (generally circular) to fit the test dish. CONDITIONING • Specimen shall be conditioned for a minimum period of 40 h at 23 ± 20C and 50 ± 5% Relative Humidity. INSTRUMENTS / APPARATUS • Weighing balance: up to 0.001 g precision • Oven: up to 1500C with ± 10C precision • Test Chamber:Temperature: 21 - 230C & 50 ± 2% Relative Humidity. • Test dish: Test dish shall be of impermeable to water or water vapour. The mouth of the dish shall be as range as practical and 4.65 inch. The desiccant or water area shall be not less mouth area. Corporate Training & Planning

  50. Figure 7: Test setup for WVTR WATER VAPOUR TRANSMISSION / PERMEABILITY REAGENTS • Anhydrous calcium chloride (dried at 2000C) and distilled water. • Sealant: For attaching the specimen to the dish e.g. Asphalt or wax, must be highly resistant to the passage of water vapour. Corporate Training & Planning

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