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Questions and Answers
How many C=C bonds are broken in the formation of one polyester unit?
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.
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?
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?
How much net energy is generated during the polymerization process?
What is the mass of a single polyester unit in grams per mole?
What is the mass of a single polyester unit in grams per mole?
What is the energy generated from forming C-C bonds for 3.446 moles?
What is the energy generated from forming C-C bonds for 3.446 moles?
Given the heat capacity of polyester is 0.25 cal/g/oC, what is the increase in temperature of polyester assuming no heat loss?
Given the heat capacity of polyester is 0.25 cal/g/oC, what is the increase in temperature of polyester assuming no heat loss?
What is the total number of moles of C=C and C-C bonds involved in the formation of polyester from 122.4 g?
What is the total number of moles of C=C and C-C bonds involved in the formation of polyester from 122.4 g?
What is a key property that nanoclay enhances in epoxy materials?
What is a key property that nanoclay enhances in epoxy materials?
Which application is NOT typically associated with carbon nanotubes in composites?
Which application is NOT typically associated with carbon nanotubes in composites?
How does the conductivity of epoxy composites change with increasing carbon nanotube (CNT) weight fraction?
How does the conductivity of epoxy composites change with increasing carbon nanotube (CNT) weight fraction?
What testing machine is typically used to create composite epoxy materials with well-dispersed nanotubes?
What testing machine is typically used to create composite epoxy materials with well-dispersed nanotubes?
Which of the following is an application for nanoclay-enhanced epoxy materials?
Which of the following is an application for nanoclay-enhanced epoxy materials?
Which type of amine generates the most energy per mole during the reaction?
Which type of amine generates the most energy per mole during the reaction?
In the reaction sequence, how many primary amines participate in the initial stage?
In the reaction sequence, how many primary amines participate in the initial stage?
What happens to the heat generated as more amines are consumed in the reaction?
What happens to the heat generated as more amines are consumed in the reaction?
What is the energy associated with a secondary amine?
What is the energy associated with a secondary amine?
During the reaction, which of the following amines can participate when the temperature is sufficiently high?
During the reaction, which of the following amines can participate when the temperature is sufficiently high?
What is the minimum number of secondary amines that can participate in the reaction at the second stage?
What is the minimum number of secondary amines that can participate in the reaction at the second stage?
What is the characteristic of the energy associated with tertiary amines compared to primary and secondary amines?
What is the characteristic of the energy associated with tertiary amines compared to primary and secondary amines?
What role does heat play in the participation of amines in the reaction?
What role does heat play in the participation of amines in the reaction?
What is one of the main reasons for using diluents in resin systems?
What is one of the main reasons for using diluents in resin systems?
How do diluents potentially interact with resin?
How do diluents potentially interact with resin?
What effect does adding diluents have on the shelf life of resins?
What effect does adding diluents have on the shelf life of resins?
Which amine curing agent has the lowest viscosity at 25°C?
Which amine curing agent has the lowest viscosity at 25°C?
What is the equivalent weight range of Diethylenetriamine (DETA)?
What is the equivalent weight range of Diethylenetriamine (DETA)?
What does the stoichiometric ratio determine in resin formulation?
What does the stoichiometric ratio determine in resin formulation?
Which of the following is NOT a characteristic of amine curing agents?
Which of the following is NOT a characteristic of amine curing agents?
What is the primary purpose of using anhydrides in curing processes?
What is the primary purpose of using anhydrides in curing processes?
What is the main purpose of lowering the exotherm in resin curing?
What is the main purpose of lowering the exotherm in resin curing?
What is meant by 'amine hydrogen' in the context of curing agents?
What is meant by 'amine hydrogen' in the context of curing agents?
What is the primary resin used for advanced composites?
What is the primary resin used for advanced composites?
What property is NOT associated with Diglycidyl ether of bisphenol A (DGEBPA)?
What property is NOT associated with Diglycidyl ether of bisphenol A (DGEBPA)?
Which component is used in the formation of epoxy resin?
Which component is used in the formation of epoxy resin?
What is one of the properties of specialty epoxy resins?
What is one of the properties of specialty epoxy resins?
Which of the following is an example of Epoxy Novolac?
Which of the following is an example of Epoxy Novolac?
What is the molecular structure that combines multiple epichlorohydrins in epoxy resin formation?
What is the molecular structure that combines multiple epichlorohydrins in epoxy resin formation?
What is the maximum operating temperature stated for DGEBPA?
What is the maximum operating temperature stated for DGEBPA?
Which among the following is a characteristic of epoxy resins?
Which among the following is a characteristic of epoxy resins?
What is the purpose of diluents in resin formulation?
What is the purpose of diluents in resin formulation?
Tetraglycidylether of Tetrakis (Hydroxyphenyl) Ether is associated with which brand?
Tetraglycidylether of Tetrakis (Hydroxyphenyl) Ether is associated with which brand?
What type of chemical reaction predominantly leads to the formation of epoxy resins?
What type of chemical reaction predominantly leads to the formation of epoxy resins?
Which structure is crucial for the characteristic properties of epoxy resins?
Which structure is crucial for the characteristic properties of epoxy resins?
What characteristic does the structure of DGEBPA impart to the resin?
What characteristic does the structure of DGEBPA impart to the resin?
In resin formulation, what is a potential disadvantage of using too many diluents?
In resin formulation, what is a potential disadvantage of using too many diluents?
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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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