Processing and Characterization of Thermoplastic Starch / Polypropylene Blends (original) (raw)
Related papers
Tensile, water absorption and biodegradable properties of potato starch filled polypropylene blends have been investigated. Polypropylene grafted maleic anhydride (PP-g-MA) was used as compatibilizer. It was observed that the tensile strength and elongation at break are inversely related to the starch content but Young’s modulus followed a direct relationship with the starch content. However, the addition of PP-g-MA to the blends improved the tensile strength and elongation at break even though they were still lower than the neat polymer but the Young’s modulus increased progressively. This is as a result of the enhanced interfacial bonding between the starch and matrix which can be proved by the SEM images. The tensile strength and elongation at break of the compatibilized blends increased by 30.59%; 42.62% and 23.36%; 24.62% in comparison with the uncompatibilized blends at 10 wt.% and 50 wt.% respectively. The percent water absorbed and weight loss of the PS/PP were higher than the CPS/PP blends due to poor interfacial bonding. Biodegradation products of the blends showed no deleterious effects on the growth of plants.
Blends of plasticized cassava starch (PCS) plasticized compatibilized cassava starch (PCCS) and polypropylenes (PP) were prepared using an injection molding process. Tensile, water absorption and biodegradable properties of the blends have been investigated. Here, variable amounts of cassava starch were processed in the presence of glycerol as plasticizer. The incorporation of PCS reduced the tensile strength and elongation at breaks but with an increase in Young's modulus of the blends. However, on addition of PP-g-MA to the blends, tensile properties were found to improve due to enhanced interfacial adhesion between PCS and PP, which can be proved by the scanning electron microscopy (SEM) observations. The percentage of water absorbed and weight loss of the PCS/PP were higher than the PCCS/PP blends due to poor interfacial adhesion. Biodegradation products of the various blends had no adverse effects on the growth of plants.
EFFECT OF SOIL BURIAL ON PROPERTIES OF POLYPROPYLENE (PP)/ PLASTICIZED POTATO STARCH (PPS) BLENDS
The effect of potato starch on the mechanical properties and biodegradability of polypropylene was investigated using the soil burial test method. Polypropylene and plasticized potato starch with and without compatibilizer were produced through melt blending for soil burial that lasted for 90 days. The results showed that tensile properties of the various PP blends decreased progressively with the increase in starch content and burial time for PP/PPS blends. Similarly, tensile properties of PP/PCPS blends followed the same trend but with less decrease in tensile properties than PP/PPS blend due to compatibilizing effect of maleic anhydride-graft- polypropylene which offered an improved interfacial adhesion between starch and matrix. The tensile properties however, for both PP/PPS and PP/PCPS decreased with increased in starch content and burial period. KEYWORDS: Plasticized potato starch, polypropylene, soil burial, mechanical properties, compatibilizer.
Polypropylene (PP) biodegradable blends were prepared by the incorporation of native potato starch (NPS) powder at filler content in the range of 0-50 wt. % into an injection moulding machine. The native starch has a particle size of 0.075mm. The biodegradation of the native potato starch filled polypropylene blends were investigated as a function of filler content and compatibilizing agent (PP-g-MA). A soil burial test was conducted for 90 days, and the degradation of NPS/PP blends was evaluated through tensile testing. The results showed that the tensile strength, elongation at break and Young's modulus all decreased after soil burial testing due to the microbial attack on the samples. Tensile properties improvement was seen on addition of PP-g-MA due to better adhesion between the native potato starch filler and polypropylene matrix.
ANALYSIS OF THE MECHANICAL AND DEGRADATION PERFORMANCES OF SELECTED STARCH/POLYPROPYLENE BLENDS
Effects of starch content and compatibilizing agent on the tensile, water absorption and biodegradability properties of starch blended polypropylene (PP) have been investigated. The starches used in this study were native cassava and sweet potato starch. Dried cassava or sweet potato starch with particle size of 0.075 mm was used at 0-50 wt. % of PP, while polypropylene graft maleic anhydride was used as a compatibilizer at 10 wt. % based on starch content. The various starch/PP blends were prepared in an injection molding machine and injected as sheets. Tensile tests were carried out using Instron tester. The water absorption test and biodegradability of the blend samples by soil burial test were investigated for a period of 90 days. Results showed that the tensile properties of the compatibilized starch/PP blends were greater than the uncompatibilized starch/PP blends particularly at higher starch content. The water absorption of the various starch/PP blends increased with increase in starch content and immersion time, and decreased on addition of PP-g-MA to the blends. The percent weight loss due to degradation of the blends was observed to increase with increase in starch content and burial period, and decreased with the incorporation of PP-g-MA into the blends. The effects biodegradation of the various starch blended PP buried in the soil on the growth of wheat and soy bean plants studied indicated that plants grow normally in the soil containing the degraded blends. The interfacial properties between starch filler and PP matrix were improved after the addition of PP-g-MA as it is evident from the fracture micrographs using SEM.
Effect of Soil Burial on Tensile Properties of Polypropylene/Plasticized Cassava Starch Blends
Polypropylene (PP)/plasticized cassava starch (PCS) blended with and without compatibilizer (polypropylene-graft-maleic anhydride (PP-g-MA)) via melt blending were prepared for soil burial which lasted for 90 days. Plasticized starch loadings of 0, 10, 20, 30, 40, and 50 wt.% were used, while pp-g-ma was used at 10 wt.% based on starch weight. The PP/PCS and PP/PCS/PP-G-MA blends were evaluated for their tensile properties. It was observed that the tensile strength, elongation at break, and young's modulus decreased with increases in soil burial time as well as starch content for PP/PCS blends. Similar treads for the tensile properties were observed for PP/PCS/PP-g-MA, but with higher properties as compared to uncompatibilized blends. However, the tensile properties for both PP/PCS and PP/PCS/PP-g-Ma decrease with increases in starch loading and also as the burial period progressed.
This study presents the utilization of starch from botanical resources for the development of biodegradable materials. A thermoplastic starch obtained from cassava starch and potato starch was successfully prepared using glycerol as a plasticizer. Polypropylene matrix filled with starch along with a compatibilizer was prepared by a melt-mixing technique, using an injection molding machine at different starch contents (0 to 50 wt. %) whereas compatibilizer was used at 10 wt. % based on starch content. The effects of starch content, plasticizer and compatibilizer on the tensile, water absorption, and biodegradable properties of starch/PP blends have been investigated. Results showed that plasticized starch content exhibited an inverse relationship with the tensile strength, elongation at break and directly related to Young's modulus, water absorption index and weight loss of the starch/PP blends. However, the addition of PP-g-MA to the blends improved all the properties under study; though tensile strength and elongation at break were still lower than the neat PP. On comparison, potato starch/PP blends exhibited higher tensile, lower biodegradable and higher water absorption properties than cassava starch/PP blends due to fibre, amylose-amylopectin ratio and phosphorus contents. Biodegradation products had no adverse effects on the growth of soya bean and wheat plants. The morphology of the blends was studied using SEM and compatibilized blends showed better results.
International Journal of Advanced Science and Engineering, 2022
In this study, potato starch (PS) was physically mixed with low-density polyethylene (LDPE) through twin screw extruder to form LDPE/PS composites. Glycerol was added to the mixture as a plasticizer to increase the compatibility of PS and LDPE, which subsequently reduced the brittleness of the composite. The effect of thermoplastic potato starch (TPS) content and two different compatibilizers on the melt flow index (MFI), mechanical properties, morphology, thermal properties, and biodegradability of LDPE/TPS composites were investigated. The results show that the MFI of LDPE/TPS composite with or without compatibilizer decreased as the content of TPS increased. The mechanical properties such as tensile modulus, flexural strength, and modulus of the uncompatibilized composites begin to increase, but the tensile strength and impact strength gradually decrease as the TPS content increases. The addition of compatibilizer further enhances the mechanical properties of the composite. Morphological observations have shown that compatibilized composites can form a good bond between TPS and LDPE, and that starch particles are evenly dispersed in the polymer matrix. In addition, DSC, thermal stability, and biodegradability were performed for dissimilar LDPE/TPS composites. Besides, water absorption of LDPE/TPS composites was reduced through the addition of compatibilizers.
Study of the Physical Properties and Biodegradability of Potato-Starch Based Plastics
Due to the exceptional growth of environmental menace pollution caused by the disposal of used plastics in the world today, there exist the needs to produce biodegradable plastics from cheap and renewable feed stocks. This research work focuses on the synthesis and characterization of potato starch based plastics (biodegradable) using polyvinyl alcohol (PVA) as cross linker. PVA was varied in mass ratios of 15, 30, 45 and 80% in the thermoplastic starch (TPS)/PVA blend. Mechanical properties (such as tensile strength, percentage elongation, young modulus) and specific gravity of the blends were studied. The results showed that 80% PVA plastic had the highest tensile strength, elongation and lowest young modulus of 384.47kPa, 347.27%, and 310.10kPa respectively. The specific gravity of the whole blends was 1.2. The elongation at break increases with increasing concentration of PVA, having the least value of 0% and highest value of 481.82% for 15 % and 80 % PVA plastic respectively. In addition, the results obtained showed increase in the values of the properties of the samples with respect to thermal conductivity, acid, base and water resistance with increase in composition of PVA. Biodegradability test was done via soil-burial method and the PVA/TPS blend was noted to be biodegradable.
Native starches have an outstanding potential as a biodegradability promoter in thermoplastics. This study deals with the preparations of native cassava starch blends by a melt blend injection process. Good interfacial adhesion is generated between polypropylene matrix and native cassava starch filler by modifying with Polypropylene-graft-maleic anhydride as new covalent bonds are formed. The resultant blends were prepared for biodegradability and mechanical tests. Tests on tensile strength, elongation at break and Young's modulus, of the samples were performed and the findings reported. These results are discussed in view of the improved adhesion at the polypropylene/native cassava starch phase boundaries.