Processing and Properties of Low Cost Corn Gluten Meal/Wood Fiber Composite

Abstract

Corn gluten meal (CGM)/wood fiber composites, plasticized by glycerol, water and ethanol, were extruded into pellets, and then the pellets were compression-molded into sheets for evaluation of water resistance, thermal stability and morphology. Pellets were also injection-molded to prepare plant pots for developing low cost, biodegradable containers used in agriculture. Ethanol played an important role for preparing homogeneous pellets under a condition of low specific mechanical energy. Extrusion, compression and injection-molding showed a similar trend that melt viscosity increased with the increasing wood fiber content and with decreasing water content. The trend led to a decrease in melt fluidity. The acceptable injection molding temperature range is from 125 to 160 °C, depending on the water content and wood fiber content in the pellets. Flexural strength of molded sheets was improved by 10-30% wood fiber but reduced by 40-50% wood fiber, which was a result of a change in the breaking mechanism. Visual observations showed that fracture occurred in matrix for sheets with low fiber content but in the interface for high fiber content composite. The former breaking mechanism can improve composite strength but the latter cannot. Compression-molded sheets and injection-molded pots showed a medium water resistance, suggesting possible commercial potential.

Physico-Chemical, Functional and Rheological Characterization of Biodegradable Pellets and Composite Sheets

“…Moreover, the increased hardness measured by texture analyser is due to more resistance to compression [7]. Plasticizers are important to maintain dimensional stability, hardness and flexibility of protein-based polymer due to its high boiling temperature [9]. The hardness was found to be directly correlated with the density of the pellets.…”

“…The flexural test was conducted at different storage conditions (relative humidity-RH and temperature) mentioned below [9] Maximum flexural stress (σ m ) was calculated as following equation: (5) where P is the maximum stress, 'L' is the support span, 'B' is the width and 'd' is the thickness of the pellet.…”

“…The water resistance of injection-molded pots was measured by using the method as described by Wu et al [9] with slight modifications. The experiment was carried out in triplicates.…”

“…The effect of extrusion on the properties of pellets, using rice husk as filler was analyzed by Simone [8]. Zein based pellets were also developed by Wu et al [9]. Till date, research is scanty on properties of pellets developed from deoiled rice bran and potato peel, the agro industrial byproducts and wastes along with plasticizers such as cashew nut shell liquid and glycerol using extrusion technology.…”

Absorção de água, solubilidade em água, propriedades mecânicas e morfológicas de compósitos de glúten de milho e poli(hidroxibutirato-co-valerato) (PHBV) reforçados com fibras de coco verde

“…O glúten pode ser processado na presença de plastificante, similarmente aos polímeros sintéticos convencionais [5] . No entanto, o glúten apresenta pobre processabilidade comparado a outros polímeros biodegradáveis [6] ; além disso, a sua baixa resistência mecânica e elevada sensibilidade à umidade são outras características que limitam a sua aplicação [7,8] . Nesse sentido, algumas pesquisas têm sido realizadas para melhorar as propriedades do glúten, tais como: modificação química [9] , blendas com polímeros sintéticos [10,11] , uso de cargas inorgânicas [12] e uso de fibras vegetais como reforço [13,14] .…”