the starch in degradable plastics blend biodegradable plastics as an example, introduces the process of its degradation. Degradation of starch in plastic particles is first fungi or bacteria, all send the starch degradation, first of all be removed from the Soviet union blend, the rest of the general plastic parts for the mesh, mesh or fragmented material, weaken the strength of plastic, increasing its surface area.
surface area larger residual by plastic parts in contact with the soil or the salt in the water, in some one's own or with the effect of oxidant, the formation of peroxides, triggering macromolecular oxidative degradation, make plastic molecular weight decreased, until can be microbial metabolism, and finally even form small molecular substances, this process is slow, cycle is long, so people often say long starch blend biodegradable plastic not completely biodegradable plastics. Can be used in the design of biodegradable plastics formula composition is not a lot, there are mainly biodegradable polymer. In addition, the degradation of promoter can also be added.
compared with synthetic resin, natural polymer material has the following disadvantages: 1. Processing is difficult, most natural polymer materials do not have heating thermoplastic characteristics of fusible, so it is difficult to use conventional injection molding processing; And need to be modified or added processing AIDS can use skeens, sintering and other methods for processing, it is biodegradable plastics hinder its large-scale application of the main factors. 2. Strength is not high, most of the natural polymer material physical and mechanical properties of hard and brittle, as synthetic resin with high intensity, generally need to join plasticizer and strengthening agent can be used. The strength of the intensity and is influenced by the environment of natural polymer materials in the dry and wet environment vary widely. In the moist environment intensity is greatly reduced and even lost its original strength.
Hu Hua modification also known as the gelation modification. Its purpose is to make the starch granules and textile starch crystal, which increase with the compatibility of resin. To promote starch Hu Hua, prevent Hu Hua after recrystallization, sometimes join Hu Hua promoter. Grafting modification is in the starch graft hydrophilic macromolecular main chain, the starch with hydrophobic and hydrophilic.
cellulose type of natural polymer material is a kind of natural polysaccharide polymer, is also a kind of ideal biodegradable plastics. As with starch, pure cellulose polymers workability is bad, hard to use method of plasticizing injection molding processing. Although its dry good mechanical strength in the starch, but moist degree drop. Cellulose kind of polymer material is rarely used alone, it is often a thermoplastic starch blend, starch can be used as the reinforcing agent.
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