Polyester and Epoxy Resins Quiz
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Questions and Answers

How many C=C bonds are broken in the formation of one polyester unit?

  • 4
  • 3
  • 1
  • 2 (correct)

    • Calculate the total number of C-C bonds formed for 122.4 g of polyester.

  • 3.446 moles (correct)
  • 2.076 x 10^24 bonds
  • 1.038 x 10^24 bonds
  • 1.724 moles

    • What is the energy required to break one mole of a C=C bond?

  • 680 kJ/mole (correct)
  • 500 kJ/mole
  • 370 kJ/mole
  • 435 kJ/mole

    • How much net energy is generated during the polymerization process?

    <p>102.7 kJ</p> Signup and view all the answers

    What is the mass of a single polyester unit in grams per mole?

    <p>142 g/mole</p> Signup and view all the answers

    What is the energy generated from forming C-C bonds for 3.446 moles?

    <p>1275.02 kJ</p> Signup and view all the answers

    Given the heat capacity of polyester is 0.25 cal/g/oC, what is the increase in temperature of polyester assuming no heat loss?

    <p>3.51 °C</p> Signup and view all the answers

    What is the total number of moles of C=C and C-C bonds involved in the formation of polyester from 122.4 g?

    <p>4.15 moles</p> Signup and view all the answers

    What is a key property that nanoclay enhances in epoxy materials?

    <p>Barrier properties</p> Signup and view all the answers

    Which application is NOT typically associated with carbon nanotubes in composites?

    <p>Flammability resistance</p> Signup and view all the answers

    How does the conductivity of epoxy composites change with increasing carbon nanotube (CNT) weight fraction?

    <p>It increases exponentially</p> Signup and view all the answers

    What testing machine is typically used to create composite epoxy materials with well-dispersed nanotubes?

    <p>Three-roll milling machine</p> Signup and view all the answers

    Which of the following is an application for nanoclay-enhanced epoxy materials?

    <p>Flammability resistance</p> Signup and view all the answers

    Which type of amine generates the most energy per mole during the reaction?

    <p>Tertiary amine</p> Signup and view all the answers

    In the reaction sequence, how many primary amines participate in the initial stage?

    <p>20 primary amines</p> Signup and view all the answers

    What happens to the heat generated as more amines are consumed in the reaction?

    <p>Heat generation decreases over time</p> Signup and view all the answers

    What is the energy associated with a secondary amine?

    <p>131 kJ/mole</p> Signup and view all the answers

    During the reaction, which of the following amines can participate when the temperature is sufficiently high?

    <p>All three types of amines</p> Signup and view all the answers

    What is the minimum number of secondary amines that can participate in the reaction at the second stage?

    <p>20 secondary amines</p> Signup and view all the answers

    What is the characteristic of the energy associated with tertiary amines compared to primary and secondary amines?

    <p>It is higher than both primary and secondary amines</p> Signup and view all the answers

    What role does heat play in the participation of amines in the reaction?

    <p>It raises the temperature, allowing more amines to participate</p> Signup and view all the answers

    What is one of the main reasons for using diluents in resin systems?

    <p>To reduce the viscosity of the resin</p> Signup and view all the answers

    How do diluents potentially interact with resin?

    <p>They may react and become part of the cured resin system</p> Signup and view all the answers

    What effect does adding diluents have on the shelf life of resins?

    <p>It improves the shelf or pot life</p> Signup and view all the answers

    Which amine curing agent has the lowest viscosity at 25°C?

    <p>Diethylaminepropylamine (DEAPA)</p> Signup and view all the answers

    What is the equivalent weight range of Diethylenetriamine (DETA)?

    <p>20 g/eq</p> Signup and view all the answers

    What does the stoichiometric ratio determine in resin formulation?

    <p>The ratio of amine to epoxy components</p> Signup and view all the answers

    Which of the following is NOT a characteristic of amine curing agents?

    <p>They do not react with epoxies</p> Signup and view all the answers

    What is the primary purpose of using anhydrides in curing processes?

    <p>To act as a curing agent for epoxies</p> Signup and view all the answers

    What is the main purpose of lowering the exotherm in resin curing?

    <p>To prevent cracking and warping in cured resins</p> Signup and view all the answers

    What is meant by 'amine hydrogen' in the context of curing agents?

    <p>Hydrogen atom attached to nitrogen</p> Signup and view all the answers

    What is the primary resin used for advanced composites?

    <p>Diglycidyl ether of bisphenol A (DGEBPA)</p> Signup and view all the answers

    What property is NOT associated with Diglycidyl ether of bisphenol A (DGEBPA)?

    <p>High toxicity</p> Signup and view all the answers

    Which component is used in the formation of epoxy resin?

    <p>Epichlorohydrin</p> Signup and view all the answers

    What is one of the properties of specialty epoxy resins?

    <p>Enhanced adhesive strength</p> Signup and view all the answers

    Which of the following is an example of Epoxy Novolac?

    <p>DOW DEN 438</p> Signup and view all the answers

    What is the molecular structure that combines multiple epichlorohydrins in epoxy resin formation?

    <p>Cross-linked network</p> Signup and view all the answers

    What is the maximum operating temperature stated for DGEBPA?

    <p>140 oC</p> Signup and view all the answers

    Which among the following is a characteristic of epoxy resins?

    <p>Good thermal and chemical resistance</p> Signup and view all the answers

    What is the purpose of diluents in resin formulation?

    <p>Modify flow characteristics</p> Signup and view all the answers

    Tetraglycidylether of Tetrakis (Hydroxyphenyl) Ether is associated with which brand?

    <p>SHELL EPON 103</p> Signup and view all the answers

    What type of chemical reaction predominantly leads to the formation of epoxy resins?

    <p>Addition reactions</p> Signup and view all the answers

    Which structure is crucial for the characteristic properties of epoxy resins?

    <p>Epoxide groups</p> Signup and view all the answers

    What characteristic does the structure of DGEBPA impart to the resin?

    <p>Enhanced durability</p> Signup and view all the answers

    In resin formulation, what is a potential disadvantage of using too many diluents?

    <p>Reduced chemical resistance</p> Signup and view all the answers

    Study Notes

    Crosslinking Process

    • For every polyester unit, 2 C=C bonds are broken
    • 4 C-C bonds are formed
    • The mass of a polyester unit is 142 g/mole
    • 122.4 g of polyester results in 1.724 moles or 1.038 x 10^24 C=C bonds broken
    • 122.4 g of polyester results in 3.446 moles or 2.076 x 10^24 C-C bonds formed

    Polymerization Energy

    • 680 kJ/mole is required to break a C=C bond
    • 370 kJ/mole is released when a C-C bond forms
    • Energy needed to break all C=C bonds is 1172.32 kJ
    • Energy released when all C-C bonds are formed is 1275.02 kJ
    • Net energy generated during polymerization is 102.7 kJ

    Polyester Properties

    • The heat capacity of polyester is 0.25 cal/g/oC

    Epoxy Resin

    • Diglycidyl ether of bisphenol A (DGEBPA) is an epoxy resin
    • Epoxy resins form by reaction of the following:
      • Epichlorohydrin
      • Bisphenol-A
    • Epoxy Novolac is another epoxy resin
    • Tetraglycidylether of Tetrakis (Hydroxyphenyl) Ether is an epoxy resin example
    • Tetraglycidylmethylene Dianiline (TGMDA) is an epoxy resin example

    Epoxy Resin Diluents

    • Diluents reduce the viscosity of epoxy resins
    • Diluents improve the shelf or pot life of epoxy resins
    • Diluents lower the exotherm of epoxy resins
    • Diluents may react with the resin and become an integral part of the cured system
    • Butyl glycidyl ether, Cresyl glycidyl ether, and Phenyl glycidyl ether are common dilutents

    Epoxy Resin Curing Systems

    • Amine curing agents are a curing system for epoxy resins
    • Anhydrides are a curing system for epoxy resins
    • Tertiary amines and accelerators are curing systems for epoxy resins

    Amine Curing Agents

    • Diethylenetriamine (DETA) is an amine curing agent
    • Triethylenetetramine (TETA) is an amine curing agent
    • Diethylaminepropylamine (DEAPA) is an amine curing agent

    Stoichiometric Ratio

    • Parts by weight of amine to be used is calculated by the following equation:
      • (Molecular weight of amine)/(Number of available amine hydrogens per molecule)*100/(Epoxy equivalent weight)
    • Epoxy equivalent weight = (Molecular weight of epoxy)/Number of epoxy groups in the molecule)
    • Amine hydrogen equivalent weight = (Molecular weight of amine)/(Number of amine hydrogen atoms in the amine molecule)

    Anhydride Curing Agent

    • Phthalic anhydride (PA) is an anhydride curing agent

    Tertiary Amines and Accelerators

    • EMI accelerator is an example of a tertiary amine
    • Boron Trifluoride Methyl Amine (BF3-MEA) is an accelerator example

    Nature of Reactions and Heat Generation

    • Primary amines (RNH2) have an associated energy of 83 kJ/mole
    • Secondary amines (RNH) have an associated energy of 131 kJ/mole
    • Tertiary amines (RN) have a higher associated energy

    Possible Applications

    • Barrier properties: obstruction to diffusion of small particles, such as CO2, leading to flammability resistance
    • Fracture resistance

    Carbon Nanotube Configurations

    • Variations exist for carbon nanotube configurations

    Three-Roll Milling Machine

    • Three-roll milling machines exist

    Electrical Conductivity and Nanotubes

    • Increasing the CNT content in a composite increases the electrical conductivity
    • Conductivity of composites with CNTs can vary based on the CNT content

    Possible Applications

    • Enhance electrical conductivity:
      • Lightning strike resistance
      • Conductive adhesives
    • Strain measurements
    • Defect detection in composite structures

    Aggregately Conductive Materials

    • Electrical resistance can be measured between two points in a plate
    • The electrical resistance in composite materials is largely dependent on the configuration and distribution of the conductive agent

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    Manufacturing of Composites - MECH 415/6521 PDF

    Description

    Test your knowledge on the polymerization processes of polyesters and epoxy resins. This quiz covers the chemical reactions involved, energy changes, and properties associated with these materials. Challenge yourself and understand the intricacies of these essential polymers.

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