Composites Lab Reports 9, 10, 12, 13 PDF

# Lab# 9 - To Determine the Molecular Weight of Nylon (Polyamide) ## Objective: - To measure the molecular weight of nylon using magnetic stirrer. ## Introduction: Nylon, a synthetic polymer, has revolutionized industries due to its exceptional properties, including strength, durability and ve...

# Lab# 9 - To Determine the Molecular Weight of Nylon (Polyamide) ## Objective: - To measure the molecular weight of nylon using magnetic stirrer. ## Introduction: Nylon, a synthetic polymer, has revolutionized industries due to its exceptional properties, including strength, durability and versatility. Its applications range from packaging and textiles to automotive and engineering materials. To fully understand the behavior and optimize the performance of nylon-based materials, a comprehensive characterization of critical parameters is essential. One of the significant parameters is molecular weight, which directly impacts the fundamental properties such as mechanical strength, thermal resistance, and processability. Molecular weight refers to the average mass of the molecule. It is typically translated to improved mechanical strength and enhanced processability. A higher molecular weight may result in increased degradation, while a lower molecular weight may provide improved processability and solubility. ## Procedure: 1. Prepare a solution of nylon with different concentrations in a suitable solvent. 2. Measure the viscosity of each solution using viscometer. 3. Plot a reduced viscosity against the concentration. 4. Extrapolate the graphs to zero concentration to obtain the mark-homwink intrinsic viscosity (n) based on the known values for the polymer solvent system. ## Formula Mn = Sample weight x 1000 / mt of HCl x molarity ## Observation and Calculation: - Weight of sample= 5.1g - Molarity = 36M - Amount of HCl = 37ml - Mn = 5.1 x 1000 / 37 x 36 - Mn = 3.82g/mole ## Result: We use the technique of viscosity to find the average molecular weight of polyamide (nylon) which is 3.82 g/mol. ## Discussion: To determine the molecular weight of nylon sample is crucial for understanding its properties and performance. The choice of method and accuracy depends on the specific properties of the nylon sample. GPC, viscosity and end group analysis are common techniques that can be used to characterize the molecular weight. The result obtained can be used for optimization of processing conditions and develops new nylon-based materials. # Lab Report No. 10 - To Fabricate a Polymer Sheet by Hot Pressing Technique ## Objective: - We experimentally fabricate a polymer sheet by hot pressing technique. ## Principle: Hot pressing is a manufacturing process that involves applying heat and pressure to a polymer material within a mold to form a desired shape. The underlying principles of this technique can be summarized as follows: - Thermoplastic properties (Softening, reversible process) - Mold design (cavity shape, vent holes) - Pressure application (compression, density increase) ## Background: **Hot pressing:** Hot pressing consists in applying pressure with a hot punch on the metal powder placed in a heated die, usually under a protective atmosphere. The main problem with hot pressing is to find a suitable die material, which has to withstand the applied pressure without any reaction with the powder. Although the total amount of deformation of the compact is relatively limited compared to hot extrusion or hot forging, complete densification is generally achieved. This process is used to induce (thermomechanical) sintering and creep, leading to the consolidation and densification of the polymer material. The heat is usually provided by induction or resistance heating, and temperatures can reach up to 2400 °C (4350 °F) with pressure up to 500 MPa (300 psi). **Heating Method:** - Induction Heating - Resistance Heating - Field Assisted Sintering Technique (FAST) - Direct Hot pressing ## Procedure: 1. Prepare the materials: Gather the materials, including the powder to be pressed, the mold, and the heating element. 2. Measure out the desired amount of powder and place it into the mold. 3. Carefully position the mold on the hot press, ensuring it’s centered and secure. 4. Adjust the temperature of the heating element to the desired level, based on the properties of the material. 5. Gradually reduce the temperature and pressure to allow the sheet to cool down. 6. Examine the sheet for quality, uniformity, and any defects. Conduct any necessary tests or measurements to evaluate its properties. ## Results: Hot pressing is a manufacturing process that involves simultaneously applying heat and pressure to a polymer material to form a sheet. - **Polymer type**: Different polymers have varying melting point, flow properties, and thermal stability. - **Temperature**: The temperature must be high enough to soften the polymer but not so high as to cause degradation. - **Pressure**: The pressure applied during hot pressing determines the thickness and density of the sheet. - **Mold designs**: The shape and size of the mold dictate the dimensions and geometry of the sheet. ## Discussions: Hot pressing is a versatile technique used to produce polymer sheets with various properties and applications. # Lab# 12 - To Determine Tensile Properties of Polymethyl Methacrylate (PMMA), Bakelite, and PVC Using a Monsanto Tensometer/Universal Testing Machine ## Objective: - We experimentally determine tensile properties of polymethyl methacrylate (PMMA), bakelite and PVC using a Monsanto tensometer/universal testing machine. ## Principle: - **Stress-strain relationship**: The tensile test is based on the relationship between stress (force per unit area) and strain (deformation per unit length). - **UTS**: The UTS is the maximum stress that a material can withstand before failure. It corresponds to the highest point on the stress-strain curve. ## Apparatus: - Universal Testing Machine - Head specimen/Vernier scale - Scale etc. - Sample (PMMA, bakelite, PVC) ## Theory: Tensile testing is used to measure the force required to break the specimen and the extent to which the specimen stretches or elongates to the breaking point. Tensile tests produce a stress-strain diagram which is used to determine tensile modulus. The data is often used to specify a material to design parts to withstand applied forces and as a quality control check of materials. Since the physical properties of many materials can vary depending on ambient temperature, it is sometimes appropriate to test materials at temperatures that simulate the intended end-user environment. A standardized test specimen is machined from a sample of the material, typically in the form of a dogbone-shaped piece. The specimen has a reduced section in the middle mounted on to a testing machine (UTM) equipped with grips. The tensile testing machine is designed to elongate the specimen at a constant rate and to continuously measure the instantaneous applied load and the resulting elongations. - σ = F/A - E = ΔL/L ## Procedure: 1. **Preparation of Specimens:** - Choose reliable specimens: Make sure both PMMA (Polymethyl methacrylate) and Bakelite materials are sourced from reliable suppliers. - Cut the specimens: Cut the specimen according to the required size and shape. - Ensure smooth surface: Make sure the surfaces of the specimen are smooth and free from defects; any contaminants could affect testing. 2. **Equipment Setup:** - Calibrate the UTM according to the manufacturer's specifications. - Securely mount each specimen to the grips of the UTM, ensuring they are aligned properly to avoid bending during testing. 3. **Testing:** - Test according to a standard testing speed; this is around 5 mm/min for polymers. ## Results: - The typical tensile strength range from 60 to 70 MPa. Elongation at break can range from 5% to 10%. - The typical tensile strength from 80 to 50 MPa. Elongation at break is generally lower than PMMA, often around 1-3%. ## Conclusion: This experiment successfully demonstrated the tensile properties of PMMA and Bakelite using a Universal testing Machine. The results indicated that PMMA has superior tensile strength and elongation compared to bakelite, which aligns with their material properties. This difference can be attributed to their microstructure. PMMA is an amorphous polymer with greater flexibility, while Bakelite is a thermosetting resin characterized by its rigidity and brittleness. # Lab# 13 - To Produce a Fiber Glass Composite Sheet with Woven Mat and Chopped Fiber ## Objective: - The main objective of this experiment is to produce a fiber glass composite sheet with woven mat and chopped fiber sheet. ## Principle: The principle of this experiment is to show that it is possible to make a fiber glass composite sheet with the appropriate properties by methodically integrating woven mat, chopped fiber shell, and a win matrix. We want to optimize the production process via extensive testing and testing, in order to fulfill specified mechanical and structural criteria. ## Background: **Fiber-Reinforced Polymers:** Fiber glass composites are a type of FRP, combining fibers (glass) with a polymer matrix (polyester resin). ## Composite Properties: The composite mechanical, thermal, and electrical properties are determined by the fiber-matrix interaction. **Woven Mat and Chopped Fiber Sheet:** - **Woven Mat:** A 2D fabric with intersecting warp and weft yarns, providing bidirectional reinforcement. - **Chopped Fiber Sheet:** A random orientation of short fibers, providing multi-directional reinforcement. **Polyester Resin:** - **Thermosetting Polymer:** Cures irreversibly when mixed with hardener. - **Cross-linking:** Temperature and time dependent. ## Mechanical properties: - Tensile strength - Flexural strength - Impact Resistance ## Procedure: 1. First cut the required size and shape. To make composite like, we use a tissue form, needle fiber, or other object. 2. Clean the glass fiber sheet. 3. Prepare the mixture. The resin will be prepared with the help of a brush and then add some hardener. 4. The glass fiber sheet is placed on the plate surface according to instruction. 5. Place the glass fiber sheet one by one, and after every layer wed it with the next sheet. 6. Join easily until full strength is achieved. ## Results: The composite produced using woven fibers exhibited a smooth surface and elasticity due to the reduced tissue fibers. The tensile strengths were slightly harmed due to the surface defects. The woven mat fiber demonstrated a multi-dimensional reinforcement. The composite, with a combination of these three types of fibers, resulted in a composite with a favorable balance of strength, low weight, and good surface finish, making it suitable for applications where both mechanical performance and aesthetics are important. ## Discussion: The woven fibers with good impact resistance, combined with a good surface finish, make it suitable for applications where both mechanical performance and aesthetics are important.