Effect of Starch on the Mechanical and Rheological Properties of Polypropylene

Abstract

Abstract:Blends of starch (tapioca) and polypropylene were prepared in various wt/wt concentrations ranging from 100% polypropylene resins to 5:95, 10:90, 20:80, 30:70, 40:60, and 50:50 wt% starch to wt% polypropylene blends. Then the rheological and mechanical properties of the resulting blends were determined using Plastometer and Universal Testing Machine respectively. Tensile strength, percentage elongation, flexural modulus, Izod impact, vicat softening temperature and melt flow index tests were carried out according to American standard for testing and materials procedure. The melt flow index was found to decrease linearly with increasing starch concentrations up to 30 wt% starch to wt% plastic, beyond which no flow was observed. The presence of starch in polypropylene was found to have positive effect on some of the mechanical properties like flexural modulus and Izod impact strength, whereas a negative impact was obtained on the tensile strength and percentage elongation. It was observed that higher starch loadings above 30% reduced the mechanical properties while lower starch loadings below 30% improved some mechanical properties. In addition, higher starch loadings above 30% does not favor the melt flow index and the Izod impact strength since there was no flow due to lower vicat softening temperature. Thus, with the aid of controlled incorporation of the starch additive, several properties of the modified polypropylene specimen could be enhanced.

Fabrication and Characterization of Biocomposite Membranes from Polycaprolactone and Native Arrowroot (<i>Maranta arundinacea</i> L.) Extracted Starch

“…The data also show a trend of increasing film flexibility as PCL to starch ratio was reduced, unlike with a previous study [3]. Tensile strength is inversely proportional to starch content, similar to past research [12,13]. The amorphous structure created by gelatinized starch may explain these findings.…”

Inspecting the properties of polypropylene/ poplar wood flour composites with microcrystalline cellulose and starch powder addition

“…Aspect ratio is the most effective on the strength and stiffness of WPCs made of WF and PP (Stark and Rowlands 2003). Pure starch has high bending strength and is flexible; hence, by entering a PP matrix material, increases the bending properties thereof and behaves as a stiffening agent (Oduola and Akpeji 2015). Mousavi et al (2015) obtained different results and found that by increasing the weight percentage of starch in produced composites, the bending properties decreased, while contrary to their finding.…”

“…By the entrance and increase in SP in the composition, the composite tensile strength was reduced, because the pure starch tensile strength is 90% lower than that of pure PP (Oduola and Akpeji 2015), therefore, a decrease in PP weight percentage in composite structure and replacing it with starch, the final tensile strength of the composites containing starch would reduce. The tensile modulus is increased because pure starch is very flexible (Oduola and Akpeji 2015) and may increase the flexibility by entering the composite, consequently increasing the tensile modulus. Mousavi et al (2015) obtained different results that might be due to differences in the composition of the composites and the different volumes of materials used.…”

Avaliação Da Biodegradação Da Blenda Poli(butileno Adipato Co-Tereftalato)/Amido Termoplástico Em Diferentes Condições De Solo Simulado

“…A concentração do amido na blenda também é um fator de grande importância, pois quando adicionados em altas concentrações há perda das propriedades (MARTINS, 2015). Oduola (2015) estudou o efeito da adição de diferentes concentrações de amido (de 5% a 50%) em blendas com PP. Observou-se que, em relação ao amido, quanto maior sua concentração nas blendas, menor é o índice de fluidez, devido ao aumento da viscosidade, e menor é o valor da resistência de tração, devido a redução dos valores de tensão no escoamento e na ruptura.…”