By: Matthew Tabassi
Biodegradable Films
Biodegradable film technologies have enjoyed a tremendous increase in demand from the marketplace. This is largely due to an increased awareness of the environmental and performance attributes and benefits that these technologies bring to their users. Recent developments in polymer technology, manufacturing processes and complementary chemistries have provided possibility of the future generation of Biodegradable products to enter the marketplace. These products Include agriculture films, anti-static films, stretch films, masking films and films for other high technology applications. As these products become available globally, a much larger range of industries can effectively realize the environmental, economic and performance benefits of biodegradable technologies.
What is Biodegradable?
According to the FTC’s Green Guides, a product is biodegradable as long as it “will completely break down and return to nature (i.e., decompose into elements found in nature) within a reasonably short period of time after customary disposal.” In other words, the item will continue to disintegrate into small pieces until micro-organisms consume it.
The U.S. Federal Trade Commission (FTC)
Biodegradable polymers
• Process by which organic substances are broken down by the environmental effects and by the living organisms.
• Organic material can be degraded aerobically or anaerobically .
• Biodegradable matter is generally organic material such as plant and animal matter and other substances originating from living organisms, or artificial materials that are similar enough to plant and animal matter to be put to use by microorganisms.
• Biodegradable polymers are a kind of materials which degrades biologically.
• The biodegradability of plastics is dependent on the chemical structure of the material and on the constituent of the final product, not just on the basic materials used in the production.
Biodegradable Range
• Starch based products including thermoplastic starch, starch and synthetic aliphatic polyester blend, and starch and PVOH (polyvinyl alcohol) blends.
• Naturally produced polyester including PVB (polyvinyl butadiene).
• Renewable resource polyesters such as PLA (poly lactic acid).
• Synthetic aliphatic polyesters including PCL (poly caprolactone).
• Aliphatic-aromatic (AAC) co polyester.
• Hydro-biodegradable polyester such as modified PET.
• Water-soluble polymers such as polyvinyl alcohol and ethylene vinyl alcohol.
• Photo-biodegradable plastics.
• Controlled degradation additive master batches.
Classes of Biodegradable
• Compostable
• Hydro-biodegradable
• Photo-biodegradable
• Bioerodable
• Biodegradable
Starch-Based Polymers
• Our work relates to a biodegradable film prepared by chemical bonding of starch and polyethylene.
• Polyethylene is polyolefin having the most widest general application, coupling agent such as maleic anhydride, methacrylic anhydride or maleimide which bonds with starch and polyethylene, and Lewis acid catalyst and to a process for preparing thereof.
Cornstarch
Common cornstarch has 25% amylose. The two remaining corn starches are high-amylose corn starches; one has 50% to 55% amylose, while the second has 70% to 75%.
Their size ranges between 5 microns and 20 microns
Mazie Starch
Maize starch has irregularly shaped granules. High-amylose starches also have an irregular shape, but tend to be smooth. Some of these are even rod-shaped. High-amylose starches have a narrower size range: 5 to 15 microns, or even 10 to 15 microns, depending on the variety.
Potato Starch
Potato starch has about 20% amylose. Potato starch granules are large with a smooth round oval shape. Of the starches commonly used for food, potato starch is the largest; its granules range in size from 15 to 75 microns.
Rice Starch
Common rice starch has an amylose: amylopectin ratio of about 20:80, while waxy rice starch has only about 2% amylose. Both varieties have small granule sizes ranging from 3 to 8 microns.
Tapioca Starch
Tapioca starch has 15% to 18% amylose. Tapioca granules are smooth, irregular spheres with sizes ranging from 5 to 25 microns.
Wheat starch
Wheat starch has an amylose content of around 25%. Its granules are relatively thick at 5 to 15 microns with a smooth, round shape ranging from 22 to 36 microns in diameter.
Soya Bean Starch
Soya bean starch has irregular shaped granules. Common Soya bean starch has 7% amylose. Its granules range in size from 10 to 90 microns.
Variety of Starch by Percentage
CATEGORIES OF STARCH BASED POLYMERS
• Thermoplastic starch products.
• Starch synthetic aliphatic polyester blend
• Starch PBS/PBSA polyester blends
• Starch PVOH blends.
Thermoplastic Starch Products
• Thermoplastic starch biodegradable plastics (TPS) have a starch (amylose) content greater than 70%.
• It is based on vegetable starch, and with the use of specific plasticizing solvents, can produce thermoplastic materials with good performance properties and inherent biodegradability.
• This can be overcome through blending, as the starch has free hydroxyl groups, which readily undergo a number of reactions such as acetylation, esterification and etherification.
Starch Synthetic Aliphatic Polyester Blends
• Blends of biodegradable synthetic aliphatic polyesters and starch are often used to produce high quality sheets and films for packaging by flat-film extrusion using chill-roll casting or by blown film methods
• Approximately 50% of the synthetic polyester (at approximately $4.00/kg) can be replaced with natural polymers such as starch (at approximately $1.50/kg), leading to a significant reduction in cost.
• Furthermore, the polyesters can be modified by incorporating a functional group capable of reacting with natural starch polymers.
Starch and PBS/PBSA Polyester Blends
• Polyesters that are blended with starch to improve material mechanical properties are Polybutylene succinate (PBS) or polybutylene succinate adipate (PBSA).
• At higher starch content (>60%), such sheets can become brittle.
• Plasticizers are often added to reduce the brittleness and improve flexibility.
• Starch and PBS or PBSA blends are used to produce biodegradable plastic sheet, which can be thermoformed into products such as biscuit trays or film products.
PVOH (PVA)
Starch-PVOH Blends
• Polyvinyl alcohol (PVOH) is blended with starch to produce readily biodegradable plastics.
MAJOR DISPOSAL ENVIRONMENTS FOR BIODEGRADABLE PLASTICS
• Composting facilities or soil burial
• Anaerobic digestion
• Wastewater treatment facilities
• Plastics reprocessing facilities
• Landfill
• Marine and freshwater environments
• General open environment as litter.
WASTE WATER TREATMENT PLANTS
• Activated sewage sludge will convert approximately 60% of a biodegradable polymer to carbon dioxide.
• The remaining 40% will enter the sludge stream where, under anaerobic digestion, it will be converted to methane.
• Any biodegradable polymer that meets the composability criteria will degrade even faster in a sewage environment.
MARINE AND FRESHWATER ENVIRONMENTS
• The rate of biodegradation in marine environments is affected by the water temperature.
• In cold waters, the plastic material may still be in a form that could endanger marine life for an extended period of time. It is found that plastic is fully degraded in 20-30 days in a compost environment .
• Thus seasonal and climatic effects on biodegradation rates need to be considered in relevant applications.
LITTER
• Plastic litter causes aesthetic problems as well as danger to wildlife resulting from entanglement and ingestion of plastic packaging materials and lightweight bags. Wildlife losses are an issue for the conservation of biodiversity, and losses due to litter have caused public concern.
Future of Biodegradable plastics
• It is estimated that plastic waste generation will grow by 15% per year for the next decade.
• There is room for growth and expansion in many areas of the biodegradable plastic industry.
• Researchers worldwide are interested in the area of biopolymer development.
• Organic recovery (composting spent materials) is the most commonly applied waste reduction method.
• The nature of natural materials requires different considerations than those for synthetic materials.
• The biopolymer industry has a positive future, driven mainly by the environmental benefits of using renewable resource feedstock sources.
• The ultimate goal for those working in development is to find a material with optimum technical performance, and full biodegradability.
TEST FORMULATION
Material PHR
• LDPE 100
• Maize Starch 5-400
• Maleic Anhydride 0.01-10
• Stearic Acid 0.01-6
• Di-Cumyl Per Oxide 0.01-1.0
• Manganese Stearate 0.01-10
• Viton 0.01-10
Polymers Chemically Bonded by Starch
FOOD PACKAGING
Wide ranges of food packaging can use Biodegradable film. More and more companies are switching to biodegradable and compostable films to help facilitate their sustainability initiatives.
AGRICULTURE MULCH FILM
These low-density polyethylene mulch films help vegetable producers achieve early, more lucrative markets by enhancing soil warming and earliness of crops. Biodegradable mulches of interest are those made from plant starches (corn or wheat) and are completely biodegrade in the soil.
SHOPPING BAGS
Biodegradable shopping bags can be made "oxo-biodegradable" by being manufactured from a normal plastic polymer (i.e. polyethylene) or polypropylene incorporating an additive which causes degradation and then biodegradation of the polymer (polyethylene) due to oxidation.
Liquid Detergents
This application hinges on the principle of using biodegradable water soluble packaging to deliver unit dosage amounts of liquid detergent products. Active concentrate of liquid detergent ingredients is packaged in biodegradable water soluble films.
Toilet Blocks
The biodegradable water-soluble film can be used to pack all toilet blocks which helps in storing the toilet cleaning detergents safely in hospitals, hotels and in individual homes thereby ensuring that all toilets remain germ-free and smell clean.
Biodegradable water-soluble film for powdered detergent pouches usually contains powdered ingredients that effectively dissolve in water.
Conclusion
• The nature of natural materials requires different considerations than those for synthetic materials.
• The biopolymer industry has a positive future, driven mainly by the environmental benefits of using renewable resource feedstock sources.
• The ultimate goal for those working in development is to find a material with optimum technical performance, and full biodegradability.
No comments:
Post a Comment