Thermoplastic Extrusion- a Method to Produce Starch-Based Loose Fill Packaging

Bioplastic materials, where starch-based loose fill packaging can also be included, play an important role in the evolution of modern science and civilisation. As they have unbeatable benefits as compared to classical synthetic plastic materials, they are more and more used. This paper presents some aspects of producing loose fill packaging based on starch by means of thermoplastic extrusion, putting an emphasis on the working diagram describing the extrusion mechanism with direct expansion of a partially crystalline polymer and the mechanism of extrudate expansion in its five steps: order-disorder changes, nucleation, extrudate swelling, development of voids and void breaking

Screening for Resistance to Artificial Infection by Common Bunt (Tilletia caries and Tilletia Foetida) in F2 Populations of Wheat (Triticum Aestivum L.)

The species of Tilletia which cause common bunt of wheat (Tilletia caries and Tilletia foetida) can cause major yield losses in common wheat (Triticum aestivum L.) and durum wheat (Triticum turgidum L.). The aim of this study was to test resistance to Tilletia spp. of eight F2 populations of wheat consisting of progenies derived from resistant x susceptible crosses. Tests were carried out in the field by artificial inoculation of wheat seeds with a mixture of spores of T. caries and T. foetida. Analysis of variance for the percentage of infected plants showed that there were statistically significant differences between tested F2 progenies (between the progenies derived from crosses) regarding percentage of infection with Tilletia spp. (varying between 18.4 and 63%). The progenies of four crosses were tested comparatively using two different doses of inoculum, in order to find out the infection degree. Significant differences were observed between the bunt incidence after inoculation with the two doses. Characterization of the resistance in F2 progenies allowed us to perform a genetic analysis on the inheritance of resistance to Tilletia spp. in F2 population. The chi-square (χ2) analysis showed that inheritance of resistance to Tilletia spp. in progenies of F2 segregating populations fit a 3:1 (resistant:susceptible) ratio for the segregation of a single major resistance gene. The exception is represented by the segregation of resistance in F2 progenies of five crosses that do not fit the expected ratio of 3:1, which is possible because of the small number of plants that could be evaluated in tested population

Contributions for Producing Biodegradabile Shock Absorbent Packaging

Making biodegradable plastics is a concern of recent years, research in this field from universities, research institutes and enterprises are continuously developing. Biodegradable loose fill shock absorbent packaging are also part of the large class of biodegradable plastics and it is necessary for them to ensure, besides biodegradability, a number of technical requirements deriving from their utilization purposes: protection of breakable products during handling and transport. Packaging properties depends on both the type and proportion of materials that are part of the formula and the technology used in its manufacture, process characterized by certain technological parameters. This paper presents some results obtained making a biodegradable loose fill packaging by corn-starch extrusion in the presence of plasticizers

STRUCTURAL INVESTIGATION OF SOME NATIVE BIODEGRADABLE PACKAGING MATERIALS

The IR, Raman and NMR methods are used to investigate the structural effects of water and glycerol (plasticizers) on biodegradable packaging materials proceeding from native corn starch. The IR and Raman methods not give a clear response on the amorphous/crystalline content in the investigated starch samples because the origin of vibrational bands is in the same atomic groups of the major starch components (amylose, amylopectin). The nuclear magnetic relaxation data show that the amorphous/crystalline ratio depends not only by the amylose/amylopectin content but also of the mobility and the place of theirs polymer chain segments. The shapes of 13C CP/MAS NMR spectra show clearly the presence of A, B, V-types crystalline structures and also amorphous phase which prevails with the increasing of plasticizers content and also in the extruded starch samples. The composition having starch/glycerol/water 68/17/15 mass % ratio was found to have a dominant amorphous character and very similar features with a commercial specimen (USA) used for the package. It was also found that this best package is extremely degraded after just one day under water absorption

The Role of Water On Structure Formation to Extrusion of Corn Starch Based Plastic Foams

Foaming extrusion has been used to produce loose-fill starch-based packaging materials, in a similar way to the production of extruded expanded snack foods. Native starches are non-plastic due to the intra- and intermolecular hydrogen bonds between the hydroxyl groups in starch molecules, which represent their crystallinity. Thermal processing is used to disrupt and transform the semi-crystalline structure of starch granules to form a homogeneous and amorphous material. This transformation is usually accomplished using small amounts of molecular substances commonly known as gelatinization agents or plasticizers. This paper presents some results obtained during researches conducted in order to obtain a biodegradable starch-based loose-fill by thermoplastic extrusion, when using in different ratios between starch and plasticizers in the formula. Increasing the levels of water in the formula leads to lower viscosity value of the mixture and changing structure of the finished product

MODELLING OF THE SUGAR BEET PULP DRYING PROCESS

The paper presents the drying model proposed for sugar beet pulp in the presence of hydrated lime within a range temperature of 333 and 368 K. The experimental results were used to identify the coefficients in the two-term exponential model, choose as the most appropriated model for our case. The relationships for the variation of the coefficients with temperature were determined. The equations of the mathematical model were used to establish the optimal drying time

WATER ABSORPTION AND DEGRADATION OF PACKAGES BASED ON NATIVE CORN STARCH WITH PLASTICIZERS

The starch in native forms or chemically modified is found as the main component of biodegradable packaging materials. Regarding this the water can produce a fast degradation, of the order of days, of such materials. Four types of packaging materials, one witness and three with different starch, glycerol and water ratios were subjected to natural degradation after absorption of distilled water. The degradation process was monitored by various NMR relaxometry methods based on the measurement of CPMG (Carr-Purcell-Meiboom-Gill) decays with a T1 filter to exclude the signal from free water. The analysis of NMR signal decays was performed using a Laplace inversion algorithm and the dynamic components were identified from the T2 transverse relaxation times distributions. We found that the best package with 68/17/15 ratios between starch/glycerol/water is extremely degraded after just one day forming a colloid substance. After that in time we observe a quasi-solid precipitation at the bottom of NMR tube. The reduction of dynamics is observed also in the T2–distributions measured for 5 days. The most resistant package (78/19.5/2.5) was that with a large content of starch but which was also reaching the swallow limit in five days and start to be decomposed

THE INFLUENCE OF TEMPERATURE AND DOLOMITE ADDITION ON THE DRYING KINETICS OF SUGAR BEET PULP (BETA VULGARIS L.)

The aim of this study is to investigate the hot air drying kinetics of sugar beet pulp, without and with dolomite addition, in order to establish the drying mechanism. The influence of temperature and dolomite addition on the drying rates is observed. The drying constant rates and the activation energies for different working conditions are determined. The obtained results show that the drying took place in falling rate period. The obtained activation energy values correspond to the mechanism mass transfer at low amount of dolomite addition and combined mechanism, mass transformation (evaporation process) – mass transfer, at higher amount

WATER ABSORPTION AND DEGRADATION OF PACKAGES BASED ON NATIVE CORN STARCH WITH PLASTICIZERS

The starch in native forms or chemically modified is found as the main component of biodegradable packaging materials. Regarding this the water can produce a fast degradation, of the order of days, of such materials. Four types of packaging materials, one witness and three with different starch, glycerol and water ratios were subjected to natural degradation after absorption of distilled water. The degradation process was monitored by various NMR relaxometry methods based on the measurement of CPMG (Carr-Purcell-Meiboom-Gill) decays with a T1 filter to exclude the signal from free water. The analysis of NMR signal decays was performed using a Laplace inversion algorithm and the dynamic components were identified from the T2 transverse relaxation times distributions. We found that the best package with 68/17/15 ratios between starch/glycerol/water is extremely degraded after just one day forming a colloid substance. After that in time we observe a quasi-solid precipitation at the bottom of NMR tube. The reduction of dynamics is observed also in the T2–distributions measured for 5 days. The most resistant package (78/19.5/2.5) was that with a large content of starch but which was also reaching the swallow limit in five days and start to be decomposed

Thermoplastic Extrusion- a Method to Produce Starch-Based Loose Fill Packaging

Bioplastic materials, where starch-based loose fill packaging can also be included, play an important role in the evolution of modern science and civilisation. As they have unbeatable benefits as compared to classical synthetic plastic materials, they are more and more used. This paper presents some aspects of producing loose fill packaging based on starch by means of thermoplastic extrusion, putting an emphasis on the working diagram describing the extrusion mechanism with direct expansion of a partially crystalline polymer and the mechanism of extrudate expansion in its five steps: order-disorder changes, nucleation, extrudate swelling, development of voids and void breaking.</jats:p