Introduction-Definition-Development History-Five General Plastics-Biodegradable Materials-Degradation Product Classification
Lead
Since the beginning of the 21st century, energy and environmental issues have become the most concerned topic in the world. Petrochemical energy such as coal, oil and weather, as the most used non-renewable energy source, has always played an important role in the development of human society in the world economy, especially after the industrial revolution. However, as the use of time continues and usage increases year by year, the ability of this non-renewable petrochemical energy to sustainably supply in the future has caused concern. Moreover, the use of carbon dioxide produced by petrochemical energy has caused serious environmental problems, such as global warming, melting glaciers, rising sea levels, etc., which are closely related to the increase in the amount of carbon dioxide in the atmosphere. Therefore, how to protect the environment and reduce the excessive dependence of economic development on petrochemical energy has become a topic of common research in all countries of the world.
Plastics, a polymer material that appeared more than a hundred years ago, has brought tremendous convenience to people's production and life. With this rapid development of this kind of petroleum-based products, human beings have faced two difficult problems: environmental pollution and resource shortage. At present, the total output of plastics in the world has exceeded 230 million tons / year, and waste plastics have 100 million tons / year, and it is still increasing. Most of these wastes are derived from packaging materials, agricultural films, medical materials, plastics for people's daily life, etc. Since most synthetic polymer materials have good corrosion resistance, they are difficult to decompose in nature and cause serious pollution. The main treatment methods for waste plastics are soil burial and incineration. Soil is a waste of land, which is difficult for some countries with high population density. Incineration produces a large amount of carbon dioxide and other harmful compounds such as nitrogen, sulfur and phosphorus, which contribute to the greenhouse effect and acid rain. In order to solve the problems of the land department, countries are using legal means and technological advancement to recycle and reuse the waste plastics on the one hand, and to develop new materials that can be naturally degraded on the other hand. In theory, recycling and recycling of plastics can solve both environmental pollution and resource shortages. However, in the implementation process, plastic materials themselves, technologies and costs are often limited, while research and development of naturally degradable materials It became an important topic after the 1970s and was widely regarded by all countries in the world.
Naturally degradable materials have not been widely promoted due to limitations in technology and cost. Until recently, people have become more aware of the serious pollution and destruction of the environment and the scarcity of resources. Naturally degradable materials have become a must. European countries have introduced plastic restrictions and passed legislation to restrict the production and entry of plastics. During the “plastic limit” imposed by China on June 1, 2008, and during the “two sessions” in 2011, the “Proposal on Legislation to Promote Biodegradable Plastic Garbage Bags” submitted by CPPCC member Yang Lan has received national attention.
Definition of degradation:
In a broad sense, after the material is discarded, it will automatically decompose and disappear under certain conditions.
Strictly speaking, degradable plastics are materials that undergo significant changes in their chemical structure under certain environmental conditions and cause some degradation in performance that can be degraded or metabolized by organisms.
The definition of the United States:
Biodegradable materials refer to degradation by the action of natural microorganisms (bacteria, fungi, etc.).
The definition of China:
The properties of plastics and their products can meet the requirements of use, and the properties in normal use are unchanged. After use, they can be degraded into environmentally friendly substances in the natural environment.
Definition of Japan: biodegradable plastics that can degrade during biological and biochemical processes or in biological environments
Completely biodegradable plastics: mainly made from natural polymers (such as starch, cellulose, chitin) or agricultural by-products by microbial fermentation or synthesis of biodegradable polymers, such as thermoplastic starch plastics, aliphatic polyesters, poly Lactic acid, starch/polyvinyl alcohol, etc. are all such plastics.
Destructive biodegradable plastics: Currently mainly include starch modified (or filled) polyethylene PE, polypropylene PP, polystyrene PS, polyvinyl chloride PVC, and the like.
The development of biodegradable plastics
foreign:
The study of degradable plastics began in the 1970s, when British scientist GJLGriffin proposed the idea of adding cheap biodegradable natural starch as a filler to the polymer and published the first starch-filled vinyl. Patent, developed a "biodegradable" polyethylene obtained by blending starch with polyethylene and then rolling it into a film. It was buried in the soil, and after a while the material became powdery. At that time, the researchers believed that the polyethylene had been biodegraded. The emergence of this new material has aroused people's attention to biodegradable plastics, and has entered the wave of research and development based on starch-based plastics. Many patents and literatures have been published, and a series of products have been launched. Some have been in the late 1980s. Commercialization. However, studies in the early 1990s pointed out that C-C bonds cannot be enzymatically hydrolyzed and hydrolyzed. In order to break bonds, unless photolysis and oxidation, polyethylene is actually only a fragment that remains in the soil and is not really a fully degradable material. Really good biodegradability and similar to the traditional plastic polyethylene, polypropylene, polystyrene and other physical properties, only polycaprolactone (PCL), polylactic acid (PLA), polyhydroxybutyl ester and its amyl ester copolymerization (PHB/PHV) and partially modified starch plastic
foreign:
• The main foreign manufacturers of biodegradable plastics are: fat-aromatic copolyester produced by BASF in Germany under the trade name Ecoflex;
v Polylactic acid produced by NatureWorks, USA;
• PVA (PCL)/starch alloy produced by Novamont Company of Italy is called Mater-Bi, starch-based plastic, trade name is Novon, polycaprolactone PCL trade name is BionolleTone Polymer; starch-based plastic, trade name is Novon;
• Japanese Showa Polymer Polybutylene succinate PBS, trade name Bionolle.
• Polyhydroxyalkanoate (PHB) produced by Mitsubishi Chemical, trade name Biopol;
domestic:
• 70s - China's biodegradable materials originated in 1978
• 80s - Starch Addition (Concept)
• 90s - CO2 degradation concept
• After 2000 - began granulation and a group of companies emerged
Starch-based companies - Shangjiu, Su Shi, Biage, etc.
Calcium carbonate-based companies - gorgeous, Chinese, Hua Dan, blonde, etc.
Biodegradable material
vPLA
Polylatic acid, abbreviated as PLA, is also known as polylactide. It is a thermoplastic polymer obtained by artificial chemical synthesis of lactic acid produced by biological fermentation, which has good biocompatibility and biodegradability.
Physical properties: great mechanical properties, good biodegradability and compatibility, good tensile strength and ductility, good gas permeability, oxygen permeability and dioxane permeability. Isolation of odor characteristics. It is the only biodegradable plastic with excellent antibacterial and antifungal properties.
Lack of limitation: low melting point, strength, transparency and resistance to climate change are not as good as ordinary plastics.
The membranes are comparable to membranes made from PS.
vPCL
Polyvsptolsvton is a semi-crystalline polymer (aliphatic linear polyester).
Physical properties: low melting point and glass transition temperature, respectively, only 60 ° C -60 ° C, crystallization temperature is 22 ° C; its fiber strength and polyamide 6 fiber is almost equivalent, tensile strength can reach 70.56 cN / tex or more, nodule strength Also above 44.1cN/tex. It has good biodegradability, good shape memory function, good solubility in various solvents, good compatibility with various plastics/rubbers, and is a low temperature plastic profile.
Defect: Strong crystallinity, slow biodegradation, and hydrophobic polymer.
vPBS
Polybutylene succinate (poly butylene surcinate) is a crystalline polymer synthesized by polycondensation reaction using aliphatic and diol as raw materials.
Physical characteristics: 1. Density 1.26g/cm3, melting point 114°C, 2. Crystallinity is 30% to 45% depending on the molecular weight and molecular weight distribution
3. Good heat resistance, heat distortion temperature is close to 100 °C, and the temperature after modification is close to 100 °C.
Excellent overall performance, good heat resistance, good processing and mechanical properties. Processability is currently the best of general-purpose degradable plastics, and heat resistance is the best in heat resistance of fully biodegradable materials.
Its derivatives are: PBSA, PBST, PBAT.
vPHB
Poly-β-hydroxybutyrate (PHB) is a carbon source storage that is a lipid-like property found in many bacterial cytoplasms.
Physical properties: insoluble in water, but soluble in chloroform, can be stained with Nile Blue or Sudan black, with storage energy, carbon source and reduce intracellular osmotic pressure.
vPVA
Polyvinyl alcohol
Physical properties: PVA is soluble in water. The higher the water temperature, the greater the solubility, but it is almost insoluble in organic solvents. The solubility of PVA varies with the degree of alcoholysis and degree of polymerization. Partial alcoholysis and low degree of polymerization of PVA dissolve very quickly, while full alcoholysis and high degree of polymerization PVA dissolve slowly. Performance is between plastic and rubber, its use can be divided into fiber and non-fiber two purposes. PVA has unique strong adhesion, film flexibility, smoothness, oil resistance, solvent resistance, protective colloid, gas barrier, abrasion resistance and water resistance after special treatment.
vCarbon dioxide copolymer
valiphatic/aromatic copolymer
Classification of degradable plastics
vPhotodegradable plastics: A photosensitizer is added to the plastic to gradually decompose the plastic under sunlight. It belongs to the earlier generation of degradable plastics. The disadvantage is that the degradation time is difficult to predict due to sunshine and climate change, and thus the degradation time cannot be controlled.
vBiodegradable plastic: A plastic that can be completely decomposed into low molecular compounds under the action of microorganisms.
vLight / biodegradation
we offer patented full biodegradable film and PVA bag, all products are made by casting equipment, It is different from traditional blow molding products, all blow molding products are non full biodegradable. We can produce pva films and bags in all transparent and various colors.
we also offer organic material full biodegradable film and bags with patented raw material and production Process.
For more PVA film and bags products please visit us:
http://www.joyful-printing.net/pva-bag/
http://www.joyful-printing.com/pva-bag/ eng only