Biodegradable plastics are those that, under natural conditions such as soil and sand, and under specific conditions such as composting conditions or anaerobic digestion conditions or in aqueous medium, are degraded by the action of microorganisms present in nature. And eventually completely degrade into carbon dioxide (CO2) or/and methane (CH4), water (H2O) and mineralized inorganic salts of the elements they contain, as well as new biomass plastics. Biodegradable plastics, because they can biodegrade under certain conditions and do not increase environmental load, are an effective way to solve white pollution. Today we will focus on polybutylene succinate (PBS).
Introduction to polybutylene succinate
Polybutylene succinate (PBS)is formed by condensation polymerization of succinic acid and butanediol. The resin is milky white, odorless and tasteless, and is easy to be decomposed and metabolized by various microorganisms in nature or enzymes in animals and plants, and eventually decomposed into carbon dioxide and water, making it a typical biodegradable polymer material. Good biocompatibility and bioabsorbability; The density is 1.26g/cm3, its melting point is 114℃, and its crystallinity can be between 30 and 45% according to the molecular weight and the molecular weight distribution.
PBS entered the field of material research in the 1990s, and quickly became one of the research hotspots of general-purpose biodegradable plastics that can be widely promoted and applied. It has good heat resistance, and the thermal deformation temperature and product use temperature can exceed 100℃. Its synthetic raw material source can be either petroleum resources, or can be obtained by fermentation of biological resources, PBS is the leader in biodegradable plastic materials.
Excellent performance of PBS
1. PBS polyester has good comprehensive properties. PBS polyester can not only meet the requirements of the use of general plastics in terms of mechanical properties, but also PBS polyester can only be degraded under the conditions of contact with microorganisms such as compost, and the performance is very stable during normal storage and use.
2. The processing performance of PBS is very good, and it can be used for all kinds of molding processing on general processing equipment. It is the best processing performance of general degradable plastics at present, which is crucial for the application of degradable plastics. The excellent processing properties of PBS make it highly inclusive, and it can be blended with starch, calcium carbonate, etc., to achieve cost reduction while maintaining good material properties.
3. PBS series polyester has excellent heat resistance. PBS is fully biodegradable polyester in the best variety of heat resistance, thermal deformation temperature close to 100℃, after modification can exceed 100℃, to meet the heat demand of daily supplies, can be used to prepare hot and cold drink packaging and lunch boxes. This has an advantage over PLA, whose processing stability and heat resistance of the product are not ideal.
4. PBS polyester has a price advantage. It uses aliphatic dibasic acid and dibasic alcohol as the main raw materials, and after large-scale production, the price can reach the level of PET polyester. Related raw materials can also be produced by means of whey, by-product of cheese manufacturing, natural polysaccharide glucose, fructose, lactose, maltose, mannitol, mannose, sucrose, xylose and cellulobiose and other natural products through biological fermentation, succinate, butanediol, not only can realize the green cycle production from nature and return to nature. Moreover, the raw materials produced by biological fermentation process can also greatly reduce the cost of raw materials, thus further reducing the cost of PBS.
5. PBS polyester production equipment has been localized. PBS polyester can be produced by slightly reforming PET and PBT polyester equipment. At present, the production capacity of polyester equipment in China is seriously excess, and the transformation and production of PBS provide a new opportunity for excess polyester equipment.
6. PBS polyester has a wide range of uses. It can be used in packaging fields, such as packaging film, lunch boxes, cosmetic bottles and medicine bottles, electronic device packaging, etc. It can also be used for disposable utensils, such as disposable dining utensils, disposable medical supplies, etc. In addition, it can also be used in agricultural fields, such as agricultural film, pesticide and fertilizer slow-release materials; Finally, it can also be used in medical fields, such as biomedical polymer materials.
Synthesis method of PBS
At present, there are two kinds of synthesis methods of PBS: chemical polymerization and enzyme polymerization. Enzymatic polymerization method has high production cost and low molecular weight, and only has academic research value. The direct esterification method is the most widely used production method in industry. The transesterification method uses dimethyl succinate and the same amount of butanediol under the action of high temperature, high vacuum and catalyst to carry out transesterification reaction and remove methanol. In order to further increase the molecular weight of the product, the active group of the chain extender reacts with the end hydroxyl group of the polyester.
Application areas of PBS
At present, the demand for disposable tableware and packaging materials in food, daily necessities and other aspects is increasing, and most of the degradable plastic bags sold on the market are still difficult to degrade polyethylene components, only 1/3 to 1/4 are degradable components. In order to seek a degradable material that can replace polyethylene, PBS has become one of the key materials that people chase because of its completely biodegradable performance. In order to better degrade PBS, more and more reports have been made about the use of natural biodegradable polymers to modify PBS. In starch, bamboo powder, tapioca flour, plant fiber these natural polymers, the most used is starch filling.
In biomedicine, PBS, as a non-toxic, biodegradable and biocompatible polymer material, also has broad application prospects. In recent years, a new fiber material has been applied in the fields of drug controlled release, artificial skin, wound healing, tooth enhancement, bone tissue engineering, etc. The PBS fiber material is a polymer nanofiber prepared by electrostatic textile method.
PBS can also be used in cosmetics bottles, medicine bottles, disposable medical supplies, agricultural films, pesticide and fertilizer slow-release materials, biomedical polymer materials and other fields.