The development of sustainable bioplastics for new applications in packaging industry

The constantly increasing demand for new, original products increases amounts of packaging waste. The need for recycling enforces new, environmentally responsible approach to the problem of plastics. The solution may be packaging manufactured from biodegradable polymers, especially those that are susceptible to organic recycling.The common plastic material is composed of synthetic polymers. Most of them aren't found in nature, so are not biodegradable. Progress in the study of the relation between structure and properties of the polymers and their degradation mechanisms led to the development of new polymeric materials that retain the characteristics and usefulness of traditional plastics, but biodegradable. Biodegradable polymers are subject to degradation in the environment such as sea water, compost, as well as under atmospheric conditions [1-16] to the products which are safe for health and the environment. About the real advantages of bioplastics, we can say if, after a period of use such materials are disposed of under conditions that allow their biological decomposition and introduction of degradation products to the natural cycle. Susceptibility of polymers and plastics on biodegradation process depends primarily on their chemical structure. For this reason, the origin of polymers, whether they are derived from renewable resources (biomass) or non-renewable (fossil sources), does not refer to the notion of biodegradability. The chemical structure of the polymers determines their degradation possibility, so the biodegradable polymers can be obtained from both of these sources. There is a common misconception that all biodegradable polymers are derived from renewable resources. 

According to the European Bioplastics Association polymer materials can be divided in accordance with the scheme that takes account of their origin and susceptibility to biodegradation, as shown in Figure 1.

 The vertical axis of the Scheme indicates the origin of plastic (renewable resources (biomass) or non-renewable (fossil sources)), and the horizontal axis determines their biodegradability: 

1) Conventional plastics (non-biodegradable polymeric materials derived from petrochemical sources) 

2) Bioplastics

 a. non-biodegradable, derived from renewable resources, bio-PE/PP/PVC, Bio-PET;

 b. biodegradable, derived from non-renewable resources, PBTA, PBS, PCL;

 c. biodegradable, derived from renewable resources, PLA, PHA, starch.

Now the market offers a biodegradable plastic more and more manufacturers. The most common commercially produced materials can be classified into the following groups:

  The starch-based materials 

 PLA-based materials 

 PHA-based materials (PHB, PHBV, etc.) 

 Materials based on aliphatic-aromatic polyesters  Cellulose-based materials (e.g., cellophane, etc.) 

 Materials based on lignin. 

The plastics, in addition to the polymer materials also contain other materials and/or additives, what determines their processing opportunities, and thus the properties of the final product. Plastics may include: stabilizers, lubricants, dyes, fillers, etc. In the case of bioplastics is important that these additives were also biodegradable. There are also various composites containing natural components (biocomposites). The composite is a mixture of polymers or plastics and fillers are added in order to improve their mechanical or chemical properties or to reduce the price of the material. Biocomposites very often contain natural fibers (eg hemp) or sawdust. [17-21] 

There are two main aspects, under which, the consumer decides on the choice of plastic: economic/commercial and environmental aspect. Although aspects of the environmental and economic/commercial should not be treated separately, but in practice the predominant aspect is the final price of the product. 

Within the framework of research the susceptibility on the composting process of commercial PLA rigid package, in the form of disposable cups, as well as the correlation between structure and functional properties of packaging material was determined.