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Which of the following levels is responsible for the physical properties of materials?
Which of the following levels is responsible for the physical properties of materials?
The chemical changes in packaging materials do not involve breaking of chemical bonds.
The chemical changes in packaging materials do not involve breaking of chemical bonds.
False
What is the major type of atom commonly found in plastics?
What is the major type of atom commonly found in plastics?
Carbon
In the aseptic carton for milk, layers consist of ______, aluminum, and polyethylene.
In the aseptic carton for milk, layers consist of ______, aluminum, and polyethylene.
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Which material is known to provide gas and light barriers in packaging?
Which material is known to provide gas and light barriers in packaging?
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Match the following packaging materials with their characteristics:
Match the following packaging materials with their characteristics:
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The bond type primarily found in plastics is ______ backbone.
The bond type primarily found in plastics is ______ backbone.
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Intermolecular forces do not influence the behavior of materials under heat or pressure.
Intermolecular forces do not influence the behavior of materials under heat or pressure.
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Which material has the highest surface tension at 25°C?
Which material has the highest surface tension at 25°C?
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Surface tension increases with temperature.
Surface tension increases with temperature.
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What is tacticity in relation to molecular arrangement?
What is tacticity in relation to molecular arrangement?
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Polyethylene terephthalate has a surface tension of _____ dyne/cm at 25°C.
Polyethylene terephthalate has a surface tension of _____ dyne/cm at 25°C.
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Match the following materials with their respective surface tensions at 25°C:
Match the following materials with their respective surface tensions at 25°C:
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Which process is needed to improve the surface tension of plastics for operations like printing?
Which process is needed to improve the surface tension of plastics for operations like printing?
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The methyl groups in isotactic polypropylene are arranged alternately on both sides of the chain.
The methyl groups in isotactic polypropylene are arranged alternately on both sides of the chain.
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Name one additive used to lower the surface tension of liquids in plastic applications.
Name one additive used to lower the surface tension of liquids in plastic applications.
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Which type of bond has the highest bond energy?
Which type of bond has the highest bond energy?
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Intermolecular forces are stronger than intramolecular forces.
Intermolecular forces are stronger than intramolecular forces.
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What is the bond dissociation energy?
What is the bond dissociation energy?
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What is one consequence of too fast oxidation in food packaging materials?
What is one consequence of too fast oxidation in food packaging materials?
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Covalent bonds are _____ times stronger than intermolecular forces.
Covalent bonds are _____ times stronger than intermolecular forces.
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All types of polyethylene have the same density and gas permeability.
All types of polyethylene have the same density and gas permeability.
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What type of forces hold molecules together loosely?
What type of forces hold molecules together loosely?
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Name one main material that can be affected by oxidation.
Name one main material that can be affected by oxidation.
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Match the types of intermolecular forces with their bond energy range:
Match the types of intermolecular forces with their bond energy range:
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Packaging materials are primarily degraded by __________ when exposed to atmospheric oxygen.
Packaging materials are primarily degraded by __________ when exposed to atmospheric oxygen.
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What happens to the covalent bonds in a punctured PE film?
What happens to the covalent bonds in a punctured PE film?
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Metals are composed of individual molecules held together by covalent bonds.
Metals are composed of individual molecules held together by covalent bonds.
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Match the types of behavior with their respective materials:
Match the types of behavior with their respective materials:
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Which property is important for food packaging materials to prevent degradation?
Which property is important for food packaging materials to prevent degradation?
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Cellulosic materials are not susceptible to chemical reactions during food contact.
Cellulosic materials are not susceptible to chemical reactions during food contact.
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Identify one factor that affects the chemical properties of food packaging.
Identify one factor that affects the chemical properties of food packaging.
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What happens during a redox reaction?
What happens during a redox reaction?
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Combustion reactions are endothermic processes.
Combustion reactions are endothermic processes.
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What is one example of a bleaching agent?
What is one example of a bleaching agent?
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The burning behavior of polyethylene produces a _____ flame with weak smoke.
The burning behavior of polyethylene produces a _____ flame with weak smoke.
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Match the following polymers with their burning characteristics:
Match the following polymers with their burning characteristics:
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What is a notable characteristic of bleaching agents?
What is a notable characteristic of bleaching agents?
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All bleaching processes are environmentally safe.
All bleaching processes are environmentally safe.
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What can the flame color of a burning polymer help identify?
What can the flame color of a burning polymer help identify?
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What is one consequence of microbial biofilms on material surfaces?
What is one consequence of microbial biofilms on material surfaces?
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Biodeterioration applies mainly to fragile and easily damaged materials.
Biodeterioration applies mainly to fragile and easily damaged materials.
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What term describes the ability of a material to resist changes when exposed to chemically aggressive substances?
What term describes the ability of a material to resist changes when exposed to chemically aggressive substances?
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The process of removal of matter from the surface of packaging materials by dissolution or scraping is known as __________.
The process of removal of matter from the surface of packaging materials by dissolution or scraping is known as __________.
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Which factor does NOT influence the adhesion of microbial cells on surfaces?
Which factor does NOT influence the adhesion of microbial cells on surfaces?
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What is microbiologically-triggered corrosion?
What is microbiologically-triggered corrosion?
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Match the following terms with their definitions:
Match the following terms with their definitions:
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Controlled exposure tests are used to objectively measure changes in properties after weathering.
Controlled exposure tests are used to objectively measure changes in properties after weathering.
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Study Notes
Chemical Structure & Properties of Packaging Materials
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Packaging material properties depend on four levels of atomic and molecular structures.
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Level 1: Chemical Constituents identifies the atoms composing the materials. -Four basic material types for food packaging: plastics, paper, glass, and metals. -Examples: plastics and paper are carbon-based organic materials, which can be lighter and weaker and may interact with food; glass and metal materials are inorganic and more resistant to chemical reactions. -Various complex materials are combinations of two or more materials to improve functions. -Example: an aseptic carton for milk and juices is made from layers of 70% paper, 6% aluminum and 24% polyethylene (PE).
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Level 2: Chemical Bonding describes the forces holding atoms together to form molecules. -Transferring electrons creates ionic bonds. -Sharing electrons forms covalent or metallic bonds, which are stronger bonds called primary bonds. -Examples: -Ionomers (packaging polymers) consist of covalent and ionic bonds, which leads to unique properties like heat seal strength. -Covalent bonds are the most common type in plastics, paper, and glass, frequently using atoms like C, O, N, and Cl.
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Level 3: Intermolecular Forces explains the forces attracting molecules together to form materials. -Weaker than primary bonds, these forces create loosely-associated groups. -Types include dispersion forces (weakest), dipole-dipole interactions, ion-dipole interactions, and hydrogen bonding (strongest). -Examples: -These forces explain properties like surface tension, which may be useful in coating, printing, and adhesion (lamination, wetting). -Typical values of the bonds' strengths are given (dispersion forces, 0.04-4 kJ/mol; Dipole-dipole forces, 0.15-15 kJ/mol; hydrogen bonds, 4-40 kJ/mol). -Covalent bonds have much greater strength than intermolecular bonds (10-100 times stronger).
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Level 4: Spatial Arrangement (Tacticity) describes the ordering of molecules in three dimensions within a material. -Tacticity or stereochemistry defines the placement of groups in molecules, influencing properties. -Structures can be crystalline (orderly, predictable units) or amorphous (random molecular arrangement). -Crystalline structures are stronger and stiffer than amorphous structures. -Degree of crystallinity is a measure of crystalline organization within a material, including plastics and ceramics. A higher percentage of crystallinity results in greater strengths and reduced transparency. -Examples: -Different types of polymers can exhibit different levels of crystallinity based on the processing and composition.
Chemical Reactivity & Susceptibility of Packaging
- Chemical properties are crucial for packaging's protective function.
- Packaging materials' reactivity depends on atomic and molecular level interactions . -Examples: -The structure of polyethylene, for example, strongly affects its gas permeability.
- Chemical properties important for food packaging: -Oxidation (e.g., through combustion, corrosion or bleaching). -Resistance to corrosion and chemical substances (e.g., acids or solvents). -Biodegradation/Biodeterioration (e.g., through microbial action). -Specific standards (e.g., ASTM standards) are used to measure the chemical resistance.
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Description
Test your knowledge on the physical and chemical properties of packaging materials. This quiz covers topics such as intermolecular forces, surface tension, and the composition of various packaging materials. Perfect for students in material science or packaging technology courses.
