Polymer Lab Reports 3, 4, & 5 PDF

# Polymeric and Composite Materials (Lab) ## Lab Report No.03 **Session:** 2021-2025 **Submitted to:** Dr. Hafiz Kabeer Raza **Submitted by:** - M. Aaliyan Ijaz 21MME-S1-321 - Bilal Iqbal 21MME-S1-312 - Azan Khaliq 21MME-S1-305 - Usman Farooq 21MME-S1-325 **Institute of Metallurgy and Materia...

# Polymeric and Composite Materials (Lab) ## Lab Report No.03 **Session:** 2021-2025 **Submitted to:** Dr. Hafiz Kabeer Raza **Submitted by:** - M. Aaliyan Ijaz 21MME-S1-321 - Bilal Iqbal 21MME-S1-312 - Azan Khaliq 21MME-S1-305 - Usman Farooq 21MME-S1-325 **Institute of Metallurgy and Material Engineering** **University of the Punjab Lahore** ## To determine the Swelling Index of a given sample of Hydrogel ### Objective: - To measure the swelling capacity of the given hydrogel sample. - To determine the swelling index of the hydrogel under specific conditions. - To analyze the factors influencing swelling behavior of the hydrogel. ### Principle: - **Swelling Index:** A measure of the ability of a hydrogel to absorb and retain water or other solvents. It is calculated as the ratio of the weight of the swollen hydrogel to the weight of the dry hydrogel. - **Hydrogels:** Cross-linked polymeric networks that can absorb and retain large amounts of water or other solvents. The swelling behavior is influenced by the nature of the polymer, cross-linking density, and environmental conditions. - **Equilibrium Swelling:** The point at which the swelling of the hydrogel reaches a steady state, where the rate of water uptake equals the rate of water loss. ### Background: - **Swelling Index:** The ability to absorb water or other fluids, growing in volume but not dissolving. This property is critical in the study of polymers, hydrogels, and other materials, appearing in drug delivery systems, wound dressings, and other good products. - **The Swelling Index** affects the rate of active pharmaceutical ingredient release, the properties of food product, and the overall properties of hydrophilic materials as a whole. - **The swelling index** is the amount of space that a substance takes up after it has soaked up water or any other liquid. It is a quantitative description of the swelling of this material, on hydration but without dissolving. ### Preparation: - Using the material, start a process with precisely weighed amounts of the dried and powdered plant matter. - The standard weight used is 1g, but this can be different due to the variation of density. ### Hydration: - After powdering the material, using a graduated cylinder or other container of your choice, transfer it into the container. - Then add a known volume of distilled water, for instance 25ml or 50ml, depending on the size of the swelling expected from the sample. ### Formula: - **Swelling Index:** (Volume of swollen material - original volume of dry material) / (Weight of dry material) x 100 - **Swelling Index:** (WF - WI) x 100 / WI ### Procedure (Lab): - **Different polymeric samples** were provided. - The **weight of empty crucible** was noted using a digital weighing balance. - **The weight of sample** was noted. - The sample was added to an empty crucible. - The crucible was placed in a jar containing water and left, the weight was noted again. - After 15 minutes, the crucible with the sample inside was removed from the bottle, the weight of the crucible was noted, the water was put in, and again the crucible was left in air for 15 minutes. Then after 15 minutes, the water was taken again. - This procedure was adopted until the constant weight was achieved. This helps in the observation and calculation of water absorption of hydrogel films. ### Observation and Calculation: | No. | Initial Weight (Wi) (g) | Final Weight (Wf) (g) | Time (mins) | Wf - Wi (g) | Water Absorption (%) | Wf/Wi | |---|---|---|---|---|---|---| | 1 | 0.0259 | 0.0259 | 0 | 0 | 0 | 0 | | 2 | 0.0259 | 0.0891 | 15 | 0.0632 | 2.44 | 3.44 | | 3 | 0.0259 | 0.0617 | 30 | 0.0358 | 1.382 | 2.38 | **Maximum percentage water absorption = 2.44** ### Results: At first attempt, the percentage of water absorption was 0%. Then it was 2.44%. In the second attempt, the percentage of water absorption was 138.2%. Hence, the maximum water absorption was 244%. In figure no. 1, a sample of hydrogel, the water absorption can be seen. The water absorption after first, second, and third attempts was given, and then the maximum water absorption was seen. On table no. 1, the point of inflection can be seen. The point of inflection is being labeled. The onset of degradation is the point where the curve changes its position first time, and in the first attempt, it was seen as point of inflection. # Lab Report No.04 **Session:** 2021-2025 **Submitted to:** Dr. Hafiz Kabeer raza **Submitted by:** - M. Aaliyan Ijaz 21MME-S1-321 - Bilal Iqbal 21MME-S1-312 - Azan Khaliq 21MME-S1-305 - Usman Farooq 21MME-S1-325 **Institute of Metallurgy and Material Engineering** **University of the Punjab Lahore** ## To Determine The Crosslinking Density of the given Polymeric Sample ### Objective: The objective of this experiment is to quantify the cross-linking density of a given polymer sample which will provide valuable insights into the material's mechanical properties, thermal stability. ### Principle: The experiment will be considered using sol-gel technique. The principle behind this is as follow: - **Sol Formation:** The polymer material is dissolved in a suitable solvent. - **Sol to Gel Transformation:** The solution is subjected to conditions that induce cross-linking between the polymer chains. This transforms the sol into a gel-like network. - **Swelling:** The gel is immersed in a solvent to allow it to swell. - **Measurement of Swelling:** The swelling behavior of the gel is measured by determining its weight or volume increase. ### Theory: - **Cross-link density**: Crosslinking refers to the bonds between the chains of a polymer. Usually, cross-linking is done in order to achieve better mechanical properties. By reducing the level of unsaturation, the polymer can be saved from degradation. A polymer is immersed in a solvent at a specified temperature, and the change in mass or volume is measured correspondingly. - **By using the Flory-Rehner equation, cross-linked density is measured:** $Ve = - (ln(1-Vi)+Vr+XVi^2) / V(Vr^{1/3}-Ve^{1/2})$ **Where:** - **X:** Rubber toluene interaction parameter - **Vi:** Molecular volume of solvent = 1.06 x 10^-4 m^3/mol - **Ve:** Effective number of chains in real network per unit volume (cross-linked density) - **Vr:** Volume fraction of polymer in a swollen network, in equilibrium with pure solvent (0.19) - **XI:** Polymer-Solvent interaction parameter ### Explanation: The crosslinking density greatly affects the mechanical properties of rubber. Low cross-linking densities decrease the viscosities of polymer melts. Intermediate cross-linking densities transform gummy polymers into materials that have elastomer properties. Very high cross-linking densities can cause material to become very rigid or glassy. The polymer is instantly observed to gain weight and swell as it absorbs toluene, but as the number of cross links increased, the absorption rate decreased. ### Procedure: - Different samples of polymeric materials were provided. - First, the weight of these samples was taken in air using a weighing balance. - Then their weight was taken in water by lying them in water and weighing them on the weighing balance. - The samples were then dipped into toluene for a given time. - After that, the samples were taken out and dried in an oven at 80°C for a week. - Then the samples were weighed again. - The sample was dried in an oven at 80°C for a week, until the constant weight was achieved. - After that, the weight of the sample was calculated with the given solvent and the cross-linking density was also calculated. ### Observation and Calculation: - **V1:** molecular volume of solvent = 1.069 x 10^-4 m^3/mol - **X:** (for rubber) = 0.4 - **Density of toluene:** 0.86 g/cm^3 - **V1 = Volume** fraction of polymer in equilibrium with pure solvent. - **V =** calculated by following equation. $V= (Weight\ of\ dry\ rubber\ + \ Weight\ of\ solvent\ absorbed\ by\ sample) / \ (Density\ of\ rubber\ + \ Density\ of\ solvent)$ ### Observation: | Sample | Crosslinking density of rubber (mol/cm^3) | |---|---| | 1 | 3.35 x 10^-3 | | 2 | 6.25 x 10^-3 | | 3 | 5.65 x 10^-3 | | 4 | 11.2 x 10^-3 | | 5 | Dissolved completely. | | 6 | Dissolved completely. | ### Discussion: The crosslinking density of the given samples (3.35 x 10^-3 mol/cm^3, 6.25 x 10^-3 mol/cm^3, 5.65 x 10^-3 mol/cm^3) is very low. As crosslinking density is the effective number of chains in a network of polymer per unit volume, the samples have to be put in toluene for a week. The given sample was almost completely dissolved after a week. That's why crosslinking density was very low. ## Lab Report No. 05 **Session:** 2021-2025 **Submitted to:** Dr. Hafiz Kabeer Raza **Submitted by:** - M. Aaliyan Ijaz 21MME-S1-321 - Bilal Iqbal 21MME-S1-312 - Azan Khaliq 21MME-S1-305 - Usman Farooq 21MME-S1-325 **Institute of Metallurgy and Material Engineering** **University of the Punjab Lahore** ## To Perform Izod and Charpy Impact Test on a given polymer. ### Objective: The objective of this experiment is to determine the impact resistance of a given polymer material using both Izod and Charpy impact tests. This will involve understanding the principles behind these tests and evaluating the material's toughness and brittleness. ### Principle: Both Izod and Charpy impact tests relate a sudden, dynamic load to a known height, allowing it to strike a specimen. The energy absorbed by the specimen during the impact is measured and converted into the material's impact strength. - **Izod Test:** The specimen is held vertically with a notch at the bottom. The pendulum strikes the opposite side of the specimen. - **Charpy Test:** The specimen is hold horizontally with the notch at the middle. The pendulum strikes from above. ### Background: The **Izod** test has become the standard testing procedure for comparing the toughness of materials. The **Izod** test is most commonly used to evaluate the relative toughness or impact toughness of materials, and as such, is often used in quality control applications where it is fast and economical. The **Charpy** impact test, also known as the Charpy V-notch test, is a standardized high strain-rate test. It determines the amount of energy absorbed by a material during fracture. These tests measure the total amount of energy that a material is able to absorb. This energy absorption is directly related to the brittleness of the material. ### Procedure: - **Different polymeric materials** were provided to determine the toughness. - **Izod test:** For **acrylic**, the testing machine was used freely by selecting the option of load, selecting the option of friction on the screen, and selecting the mode. The machine was placed vertically between the jaws, and the testing machine was raised to the maximum height and locked. - **Charpy test:** For **acrylic**, a sample was provided by selecting the option of load and selecting the desired mode (0,1, and 2). The procedure was performed for testing the acrylic sample, the testing machine was performed for the fibreglass sample, and the testing machine was performed for melamine sample. The testing machine was raised to the maximum height and was locked. - **Izod test:** For **fibreglass**, the sample was placed horizontally with the jaws and the testing machine was raised to the maximum height and was locked. - **Charpy test:** For **melamine**, the testing machine was placed horizontally with the jaws, and the testing machine was raised to the maximum height and was locked. ### Observation and Calculation: **Charpy Impact (length=80mm, Width=11mm, Thickness=3.5mm)** | Mode | Speed | Toughness (kj/m^2) | |---|---|---| | 0 | 3.2 | 40.7 | | 1 | 3.5 | 28.79 | | 2 | 3.8 | 37.33 | **Impact Toughness of Acrylic = 35.6 KJ/m^2** ### Impact Toughness of Glass Fibre: - **Length:** 79mm - **Width:** 11mm - **Thickness:** 4mm - **Area of glass fibre:** L x W = 79 x 11 = 869 mm^2 - **Energy:** E = 8.89 J - **Impact Toughness:** Energy / Area = 8.89 J / 869 mm^2 = 0.0102 J/mm^2 - **Impact Toughness of glass fibre:** Impact Toughness x 1000 KJ/m^2 = 0.0102 x 1000 KJ/m^2 = 10.23 ### Discussion: The impact toughness of acrylic is 35.6 kJ/m^2, and the impact toughness of glass fibre is 10.23 kJ/m^2. Impact tests of acrylic and glass fibre were performed and their toughness were shown on table no. 1 and table no. 2. The impact toughness of acrylic was measured on the impact testing machine, and the impact toughness of glass fibre was measured on the Charpy impact testing machine. Observations were taken on three different modes, 0, 1, and 2, and three different impact toughness were measured. The average of different toughness of Acrylic after measuring them was taken, which is shown in the result.