Podcast
Questions and Answers
What is the primary factor that allows microbes to enter a package?
What is the primary factor that allows microbes to enter a package?
The permeability ratio between two gases is affected by the type of polymer used.
The permeability ratio between two gases is affected by the type of polymer used.
False
Which gas penetrates approximately six times faster than O2?
Which gas penetrates approximately six times faster than O2?
CO2
The permeability coefficient of _____ is highest due to its solubility coefficient being significantly higher than that of O2 and N2.
The permeability coefficient of _____ is highest due to its solubility coefficient being significantly higher than that of O2 and N2.
Signup and view all the answers
What happens to selectivity ratios as the temperature decreases?
What happens to selectivity ratios as the temperature decreases?
Signup and view all the answers
What effect does pressure have on the permeability coefficient of permanent gases?
What effect does pressure have on the permeability coefficient of permanent gases?
Signup and view all the answers
Match the gases with their respective penetration rates relative to each other:
Match the gases with their respective penetration rates relative to each other:
Signup and view all the answers
When temperature rises from 0 to 20°C, the CO2:O2 ratio for LDPE varies from _____ to _____ .
When temperature rises from 0 to 20°C, the CO2:O2 ratio for LDPE varies from _____ to _____ .
Signup and view all the answers
What is the primary mechanism used in the extrusion process?
What is the primary mechanism used in the extrusion process?
Signup and view all the answers
Monolayer extrusion involves using multiple types of polymers.
Monolayer extrusion involves using multiple types of polymers.
Signup and view all the answers
What are the two methods through which films can be produced in the extrusion process?
What are the two methods through which films can be produced in the extrusion process?
Signup and view all the answers
Coextrusion combines multiple polymers through several ________.
Coextrusion combines multiple polymers through several ________.
Signup and view all the answers
Match the following types of extrusion with their characteristics:
Match the following types of extrusion with their characteristics:
Signup and view all the answers
Which of the following is a disadvantage of monolayer extrusion compared to coextrusion?
Which of the following is a disadvantage of monolayer extrusion compared to coextrusion?
Signup and view all the answers
The flat film process provides higher optical properties than the tubular film process.
The flat film process provides higher optical properties than the tubular film process.
Signup and view all the answers
Which process offers greater control over thickness and surface finish, extrusion or calendering?
Which process offers greater control over thickness and surface finish, extrusion or calendering?
Signup and view all the answers
What is the main purpose of annealing films?
What is the main purpose of annealing films?
Signup and view all the answers
Stretch films can generally stretch up to 1000%.
Stretch films can generally stretch up to 1000%.
Signup and view all the answers
What temperature range do most shrink films require to shrink?
What temperature range do most shrink films require to shrink?
Signup and view all the answers
The __________ process uses a tube that is inflated and stretched to produce thermoplastic films.
The __________ process uses a tube that is inflated and stretched to produce thermoplastic films.
Signup and view all the answers
Match the following film types with their key properties:
Match the following film types with their key properties:
Signup and view all the answers
Which of the following factors affects the final properties of thermoplastic films?
Which of the following factors affects the final properties of thermoplastic films?
Signup and view all the answers
Balanced shrinkage is essential for printed films to avoid print distortion.
Balanced shrinkage is essential for printed films to avoid print distortion.
Signup and view all the answers
What are some common materials used to make stretch films?
What are some common materials used to make stretch films?
Signup and view all the answers
Which test method is considered quantitative for measuring the strength of heat seals?
Which test method is considered quantitative for measuring the strength of heat seals?
Signup and view all the answers
Thermoplastic polymers are impermeable to small molecules such as gases and water vapor.
Thermoplastic polymers are impermeable to small molecules such as gases and water vapor.
Signup and view all the answers
What effect describes the movement of gases through tiny cracks or pores in the polymer?
What effect describes the movement of gases through tiny cracks or pores in the polymer?
Signup and view all the answers
The primary mechanism for true permeability is the ______________ Effect.
The primary mechanism for true permeability is the ______________ Effect.
Signup and view all the answers
Match the following factors to their effect on permeability:
Match the following factors to their effect on permeability:
Signup and view all the answers
What is the ASTM F 88-00 standard test method used for?
What is the ASTM F 88-00 standard test method used for?
Signup and view all the answers
Polarized light can provide a visual guide to the consistency of heat seals.
Polarized light can provide a visual guide to the consistency of heat seals.
Signup and view all the answers
Which gas permeates polymers much faster than O2 and N2?
Which gas permeates polymers much faster than O2 and N2?
Signup and view all the answers
What property of ECCS makes it more suitable for protective coatings compared to tinplate?
What property of ECCS makes it more suitable for protective coatings compared to tinplate?
Signup and view all the answers
ECCS is more resistant to corrosion than tinplate due to its sacrificial tin layer.
ECCS is more resistant to corrosion than tinplate due to its sacrificial tin layer.
Signup and view all the answers
What must be done to ECCS before welding?
What must be done to ECCS before welding?
Signup and view all the answers
Aluminum foil is produced from aluminum ingots by a series of __________ operations.
Aluminum foil is produced from aluminum ingots by a series of __________ operations.
Signup and view all the answers
Match the materials with their characteristics:
Match the materials with their characteristics:
Signup and view all the answers
Which of the following is NOT a use of ECCS?
Which of the following is NOT a use of ECCS?
Signup and view all the answers
Lacquer must be applied to aluminum alloy for most applications due to its high corrosion resistance.
Lacquer must be applied to aluminum alloy for most applications due to its high corrosion resistance.
Signup and view all the answers
What types of products are often packaged in aluminum foil?
What types of products are often packaged in aluminum foil?
Signup and view all the answers
What is the primary purpose of lacquering the outside of a can?
What is the primary purpose of lacquering the outside of a can?
Signup and view all the answers
Internal coatings in cans can prevent acidic soft drinks from corroding the metal.
Internal coatings in cans can prevent acidic soft drinks from corroding the metal.
Signup and view all the answers
What type of cans are typically used for carbonated beverages?
What type of cans are typically used for carbonated beverages?
Signup and view all the answers
The method of applying lacquers that involves using a brush is called _____ lacquers.
The method of applying lacquers that involves using a brush is called _____ lacquers.
Signup and view all the answers
Match the type of can with its description:
Match the type of can with its description:
Signup and view all the answers
Which of the following is NOT a method for applying lacquers?
Which of the following is NOT a method for applying lacquers?
Signup and view all the answers
Metal lids used on jars provide easy access but do not contribute to preserving freshness.
Metal lids used on jars provide easy access but do not contribute to preserving freshness.
Signup and view all the answers
What type of can is commonly used for packaging items like canned whipping cream?
What type of can is commonly used for packaging items like canned whipping cream?
Signup and view all the answers
Study Notes
Introduction
- Food packaging materials traditionally rely on non-renewable resources.
- There's a growing focus on sustainable, renewable packaging such as plant-based products and fermentation by-products.
Edible Films and Coatings
- These are used to extend the shelf life of food items and protect them from environmental factors.
- Benefits include consumption with the product, reduced residual packaging, enhancement of food's organoleptic properties, nutritional value enhancement, individual food portion packaging, application in heterogeneous foods, functioning as carriers for antimicrobial and antioxidant agents, microencapsulation of flavoring and leavening agents, and use in multilayer packaging materials with nonedible films.
- Advantages over traditional synthetic materials are prominently highlighted.
Polysaccharide-Based Coatings
- Polysaccharides and their derivatives (alginate, pectin, carrageenan, starch, etc.) are used as edible films or coatings.
- These polymers have limited moisture-barrier properties due to their hydrophilic nature.
Lipid-Based Coatings
- Derived from lipids (fats), used as protective barriers in food packaging.
- Effective in preventing water movement.
- However, they aren't ideal for strong structural support.
Protein-Based Coatings
- Made from animal and plant proteins (collagen, gelatin, milk proteins, cereal proteins).
- Good barrier properties against oxygen and moisture.
- Susceptible to proteolytic enzymes, especially in high humidity conditions.
Multicomponent Films
- Combination of different materials for structural strength and protective properties.
- Typically composed of a lipid layer for moisture resistance and a polysaccharide or protein layer for structural integrity and functionality.
- Often compared to synthetic films (LDPE) but with varying water and oxygen barrier properties.
- Combining edible waxes or fatty acids significantly improves their water vapor and oxygen barrier traits.
Biobased Packaging Materials
- First-generation materials: synthetic polymers (LDPE) with 5 to 20% starch fillers
- Second-generation materials: synthetic polymers (40 to 75% gelatinized starch) and addition of hydrophilic copolymers (partially biodegradable).
- Third-generation materials: fully biobased and biodegradable materials (PHAs).
First, Second, and Third Generation Biobased Polymers
- First generation polymers: 5% to 20% starch with LDPE and additives. Biofragmentation, not biodegradation.
- Second generation polymers: 40% to 75% gelatinized starch with LDPE and copolymers. 40-day starch degradation, 5-year total degradation.
- Third generation polymers: entirely biobased, broken down into three categories from extracted biomass or produced from biomass monomers.
Food Packaging Applications of Biobased Polymers
- Limited use in general, despite significant research and various studies.
- PLA (polylactic acid) most viable commercial polymer, suitable for food wrapping, thermoformed goods for bakery, and biodegradable food service containers.
- Offers key benefits in reducing reliance on fossil fuels and CO2 emissions compared to petrochemical alternatives.
- Fully compostable.
Properties of Biobased Packaging Materials
- Poor barrier properties under high humidity.
- Starch-based films have WVTRs (water vapor transmission rates) that are 4-6 times higher than conventional films.
- Polyhydroxyalkanoates (PHA) have WVTRs similar to Low-Density Polyethylene (LDPE).
Food Packaging Applications of PLA
- Beverage cups (used in major Olympic Games)
- Niche market for PLA trays and films (especially for vegetables and fruits).
- Potential use for short-life food packaging items (such as salads, eggs).
- Products that are minimally processed and fruits/vegetables.
Environmental Aspects of Biobased Packagings
- Biobased materials have lower environmental impacts than their petrochemical counterparts.
- Energy needed for PHA production is high (2.39 pounds of fossil resources vs. 2.26 pounds).
Permeability of Thermoplastic Polymers
- Packages are permeable to small molecules (gases, water vapor, organic vapors).
- Two mechanisms for permeation: pore effect (gaps and holes) and solubility-diffusion effect (dissolution and diffusion).
- Factors influencing permeability: pressure, temperature, and sorption (absorption).
Migration
- Release of initial compounds from packaging.
Measurement of Permeability
- Several methods for measuring gas permeability.
- Pressure and volume increase methods.
- Concentration increase method.
- Detector film methods.
Factors Affecting Diffusion & Solubility Coefficients
- Pressure increase with permeated gas.
- Temperature has a significant effect on solubility coefficients.
- Sorption is a process used in combination of both adsorption and absorption.
Processing and Converting of Thermoplastics
- Extrusion: primary method for producing sheets and films.
- Monolayer extrusion: single polymer type.
- Coextrusion: multiple polymers for layered films.
- Calendering: processes plastic between rollers for thin uniform sheets or films.
- Coating: applying liquid/melted substances to a substrate (surface treatment)
- Laminating: bonding multiple layers (e.g., plastic to paperboard).
- Metallization: adding a metal layer (e.g., aluminum) to a substrate.
- Orientation: aligns polymer chains for enhanced strength and properties.
Shrink Films
- Made of polyolefins, PVC, or PVdC.
- Shrinking requires heat.
Stretch Films
- Introduced in the 1970s, for wrapping large items.
- Common materials include LDPE, LLDPE, PVC, EVA copolymer, and PP.
Cross-Linking
- Chemical bonding to improve strength, heat resistance, and durability.
Microperforation
- Creates breathable films (especially for products with high respiration rates).
Injection Molding
- Process for shaping thermoplastics into products (e.g., containers, caps, preforms).
- Three main steps: feeding, melting, and injecting.
Blow Molding
- Creates hollow objects (e.g., bottles).
- Molten plastic (parison) expands inside a mold.
Stretch Blow Molding
- Biaxial orientation to produce high strength bottles (e.g., for carbonated beverages).
Foamed Cellular Plastics
- Plastics with reduced density due to numerous cells.
- Common materials include polystyrene.
Heat Sealing
- Process to bond materials using heat and pressure.
- Different sealing methods include conductance, impulse, induction, and ultrasonic.
Dielectric Sealing
- Using high-frequency current for bonding.
Hot-Wire Sealing
- Uses a heated wire for sealing (especially polyethylene bags).
Testing of Heat Seals
- Methods to evaluate the strength of heat seals. (Dynamic and static load tests).
Glass
- Amorphous (non-crystalline) structure that exhibits varying properties.
- Types: soda-lime, borosilicate.
- Applications: food, lab, and other products based on its special properties.
- Impact resistance and thermal shock resistance are crucial for glass containers.
Paper and Paperboard
- Raw material: pulp (fibrous).
- Types: Kraft, bleached.
- Processes: pulping, forming, pressing, drying, calendering, coating.
- Applications: folding cartons and boxes.
Molding Pulp Containers
- Made from aqueous slurry of cellulose fibers to create various containers (especially for foods).
Important Points in Printing Processes
- Relief (letterpress and flexography).
- Gravure (rotogravure).
- Lithography (offset litho and letterset).
- Screen printing
- Digital (Ink-jet and electrophotography (EP)).
Inks
- Different types of inks for various processes.
- Paste based: better for offset lithography and letterpress.
- Liquid based: faster drying, suitable for most processes
Adhesives
- Water-based, hot melt, solvent-based.
- Important materials in packaging, bonding parts together, and ensuring structural integrity.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge on the factors influencing microbial entry in packages and the properties of gases permeating through polymers. This quiz covers concepts such as permeability coefficients, selectivity ratios, and the extrusion process used in film production. Dive into the intricate details of polymer science and gas behavior!
