**5. Conclusions**

The analysis of thermal properties of water-free TPS materials prepared in a TSE showed that granular starch was completely disrupted and that TPS shows a thermal transition below room temperature corresponding to the glass transition temperature and this Tg is dependent on glycerol content. As was observed for the thermal properties, the rheological properties were also highly dependent on glycerol content. of TPS36 at shear rate ~ 130 s-1 decreases by 20% when the glycerol content is increased from 36 to 40%. In the same way, G' and G" also decrease as glycerol content increases. However, a particularly dramatic variation is observed when the glycerol content is varied from 29 to 33%. These latter results suggest a phase inversion from a hard elastic network matrix to a soft amorphous one. The glycerol plasticization threshold thus occurs at a content of approximately 30%. This result concerning a critical plasticization threshold is very important for morphology control strategies.

The PE/TPS blends prepared using the one-step process demonstrated levels of ductility and modulus similar to the virgin polyethylene even at very high loadings of TPS without the addition of any interfacial modifier. The excellent properties are a combination of both the melt blending process and a sophisticated morphology control. Through a control of the glycerol content and thermoplastic starch volume fraction, the above process can result in morphological structures, which run the full range of those observed in classical blends of synthetic thermoplastics. Spherical, fiber-like and co-continuous morphologies are observed. Control of the glycerol content of the starch allows one to control the properties of starch from that of a solid filler through to that of a highly deformable thermoplastic material. A wide range of potential properties can be exploited for this type of material.

This material has the added benefit of containing large quantities of a renewable resource and hence represents a more sustainable alternative to pure synthetic polymers. Since the starch can be fully interconnected through morphology control, it is also completely accessible for biodegradation as opposed to the case of starch particles dispersed in a synthetic polymer matrix.

Melt Blending with Thermoplastic Starch 21

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**1. Introduction** 

of plastic waste.

2003; Thompson, 2003, Wang et al, 2003).

material useful for packaging applications.

**2. Cassava** 

**2** 

**Thermoplastic Cassava Flour** 

*1Universidad de San Buenaventura Seccional Cali* 

*2Universidad del Cauca* 

*Colombia* 

Diana Paola Navia1 and Héctor Samuel Villada2

Stocks of oil in the world are limited and most synthetic plastics can not be degraded by the environment, whereby people are investigating other sources of raw materials aimed at the production of materials less aggressive to the environment, to serve to decrease the amount

The food industry plays an important role in the use of plastic for protection before, during and after food harvest to ensure the integrity of these (Weber, 2001; De Graff et al, 2003; Tharantahan, 2003, Halley, 2005 ); for example the common consumer products such as plates, cups, spoons, knives, disposable, film or coating films and bags (Wang et al, 2003; De Graff et al, 2003; Averous & Boquillon, 2004; Bastioli, 2001, Garcia et al, 2000, Shogren et al,

The plastics produced from fossil sources have contributed significantly to increasing environmental pollution caused by the accumulation of solid waste that can not degrade in landfills, so that has prompted the search for new biodegradable materials not only in the food, but also in the medical, automotive, among others. Renewable natural raw materials become an important alternative, including flour, starch, natural fibers, proteins, and others prominent in developing options for bioplastics (Tharantahan, 2003). Currently there is growing interest to use raw materials and agricultural byproducts in obtaining biodegradable plastics, such as from corn and cassava and potato tubers. However, plastics developed from these sources have certain drawbacks of structural stability compared to conventional plastics, caused by its stiffness or weakness due to its high hygroscopicity and rapid aging (Villada, 2005). Therefore, the research efforts must be maintained and increased in this field, taking into account the use of local products in the region such as cassava, which are being studied in research projects, through which it is intended that the methodology production of biodegradable plastics is reproducible on an industrial scale,

taking into account the specific functional requirements for various applications.

This document presents some excerpts related to thermoplastic cassava flour as a raw

Cassava (*Manihot esculenta* Crantz), also known as mandioca, is a starchy root belonging to the Euphorbiaceae family and is one of the most important energy sources for tropical areas

