Preparation and characterization of thermoplastic starch/zein blends
01 Sep 2007-Materials Research-ibero-american Journal of Materials (Materials Research)-Vol. 10, Iss: 3, pp 227-231
TL;DR: The use of zein in thermoplastic starch compositions causes a decrease in the water sensitivity of these materials and lower its melt viscosity during processing making zein a suitable and very promising component in TPS compositions as mentioned in this paper.
Abstract: Blends of starch and zein plasticized with glycerol were prepared by melting processing in an intensive batch mixer connected to a torque rheometer at 160 °C. The resulting mixtures were compression molded and then characterized by scanning electron microscopy, differential scanning calorimetry, wide-angle X ray diffraction and water-absorption experiments. The blends were immiscible, showing two distinct phases of starch and zein. The water uptake at equilibrium and its diffusion coefficient were determined. The water uptake at equilibrium decreased with increasing zein content. The diffusion coefficient fell sharply on addition of 20% zein and remained constant as zein content was increased. No appreciable effect of zein on starch crystallization was observed by X ray diffraction. The use of zein in thermoplastic starch compositions causes a decrease in the water sensitivity of these materials and lower its melt viscosity during processing making zein a suitable and very promising component in TPS compositions.
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TL;DR: In this article , the authors compared the preparation and characterization of polymer blends containing two types of polystyrene (HIPS) and general-purpose poly styrene (GPPS)) and thermoplastic corn starch (TPS) as a natural resource.
3 citations
TL;DR: In this article, thermal decomposition temperatures and mechanical properties of TPS and TPS/wheat gluten composites were investigated using scanning election microscopy (SEM), thermal gravimetric analysis (TGA), and tensile testing, respectively.
Abstract: Thermoplastic starch (TPS) and TPS/wheat gluten composites were prepared using compression molding. The wheat gluten contents ranged from 0 wt% to 20 wt%. The morphology of the fractured surfaces, thermal decomposition temperatures and mechanical properties of the TPS and TPS/wheat gluten composites were investigated using scanning election microscopy (SEM), thermal gravimetric analysis (TGA) and tensile testing, respectively. The maximum tensile strength of TPS/wheat gluten composites (1.1 MPa) was obtained when 10 wt% of wheat gluten was used. The crosslinking between wheat gluten protein chains caused an increase in the tensile strength of the TPS/wheat gluten composites. The temperature at the maximum weight loss of the TPS/wheat gluten composites was higher than for TPS. Moreover, wheat gluten decreased the water absorption.
3 citations
TL;DR: In this article, a mixture of zein and polyvinyl alcohol (PVAl) was processed in an internal mixer (150oC, 50 rpm) for 5-8 minutes and the mixtures obtained were then compression molded and further characterized by Fourier transform infrared spectroscopy (FTIR), water-absorption experiments, mechanical tests, and scanning electron microscopy (SEM).
Abstract: Blends of zein and poly(vinyl alcohol) (PVAl) were processed in an internal mixer (150oC, 50 rpm) for 5-8 minutes. Glycerol and oleic acid were used as plasticizers. The mixtures obtained were then compression molded and further characterized by Fourier transform infrared spectroscopy (FTIR), water-absorption experiments, mechanical tests, and scanning electron microscopy (SEM). FTIR analysis indicated the existence of hydrogen bonding interactions between zein and PVAl. Tensile tests showed that the addition of PVAl increased the flexibility of the blends. The tensile strength ranged from 1.7 to 5.7 MPa, elongation at break ranged from 2.7 to 32% and Young’s modulus ranged from 433 to 7371 MPa. Water absorption at equilibrium decreased with increasing zein content, which favored a brittle behavior in the zein/PVAl. The blends were immiscible in the composition studied and the presence of voids indicated poor interfacial interaction between the polymers.
3 citations
Cites background from "Preparation and characterization of..."
...The literature reports on several studies about blends of zein with conventional synthetic polymers, such as polyethylene, nylon[16] and polyvinylpyrrolidone (PVP)[17], and with biodegradable (natural or synthetic) polymers such as starch[18-20], chitosan[21] poly(ε-caprolactone) (PCL)[22], poly(vinyl alcohol) (PVAl) [23], and poly(propylene carbonate)[24], Poly(butylene adipateterephthalate) (PBAT)[9]....
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TL;DR: In this article, the synthesis of starch-graft-poly(-caprolactone) copolymers (St-g-PCL) was achieved under vacuum by employing low doses of 60Co γ-radiation.
Abstract: Synthesis of starch-graft-poly(-caprolactone) copolymers (St-g-PCL) was achieved under vacuum by employing low doses of 60Co γ-radiation. Irradiation synthesis was carried out by using glass vials containing gelatinized starch suspension and e-caprolactone (-CL) monomer. Two starch:-CL mass ratios were employed 1:0.1 and 1:10. Irradiated samples were exhaustively treated with chloroform in order to remove homopolymer traces. Fourier transform infrared spectra of extracted samples showed a characteristic band associated to stretching vibration of carbonyl group, an indicative that PCL was grafted onto starch backbone. A grafting degree between 9 and 12% was achieved according to thermogravimetric analysis. Thermoplastic starch/PCL blends (TPS/PCL) with different amounts of St-g-PCL copolymers were prepared in order to test their thermal and mechanical properties. The addition of the synthesized copolymer did not show substantial changes over thermal properties, meanwhile significantly increased their maximum tensile strength and Young’s modulus since St-g-PCL enhances the interfacial adhesion between starch and PCL chains.
3 citations
TL;DR: In this article , the authors assessed agar-containing thermoplastic sago starch (TPSS) properties at various loadings, and found that adding agar to starch-based thermoplastics significantly improved their tensile, flexural, and impact properties.
Abstract: Thermoplastic starch is a material that has the potential to be environmentally friendly and biodegradable. However, it has certain drawbacks concerning its mechanical performance and is sensitive to the presence of moisture. The current study assessed agar-containing thermoplastic sago starch (TPSS) properties at various loadings. Variable proportions of agar (5%, 10%, and 15% wt%) were used to produce TPSS by the hot-pressing method. Then, the samples were subjected to characterisation using scanning electron microscopy (SEM), mechanical analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), and moisture absorption tests. The results demonstrated that adding agar to starch-based thermoplastic blends significantly improved their tensile, flexural, and impact properties. The samples’ morphology showed that the fracture had become more erratic and uneven after adding agar. FT-IR revealed that intermolecular hydrogen bonds formed between TPSS and agar. Moreover, with an increase in agar content, TPSS’s thermal stability was also increased. However, the moisture absorption values among the samples increased slightly as the amount of agar increased. Overall, the proposed TPSS/agar blend has the potential to be employed as biodegradable material due to its improved mechanical characteristics.
3 citations
References
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Book•
01 Jan 1956
TL;DR: Though it incorporates much new material, this new edition preserves the general character of the book in providing a collection of solutions of the equations of diffusion and describing how these solutions may be obtained.
Abstract: Though it incorporates much new material, this new edition preserves the general character of the book in providing a collection of solutions of the equations of diffusion and describing how these solutions may be obtained
20,495 citations
3,755 citations
TL;DR: The combination of bio-fibers such as kenaf, hemp, flax, jute, henequen, pineapple leaf fiber, and sisal with polymer matrices from both nonrenewable and renewable resources to produce composite materials that are competitive with synthetic composites requires special attention as discussed by the authors.
Abstract: Sustainability, industrial ecology, eco-efficiency, and green chemistry are guiding the development of the next generation of materials, products, and processes. Biodegradable plastics and bio-based polymer products based on annually renewable agricultural and biomass feedstock can form the basis for a portfolio of sustainable, eco-efficient products that can compete and capture markets currently dominated by products based exclusively on petroleum feedstock. Natural/Biofiber composites (Bio-Composites) are emerging as a viable alternative to glass fiber reinforced composites especially in automotive and building product applications. The combination of biofibers such as kenaf, hemp, flax, jute, henequen, pineapple leaf fiber, and sisal with polymer matrices from both nonrenewable and renewable resources to produce composite materials that are competitive with synthetic composites requires special attention, i.e., biofiber–matrix interface and novel processing. Natural fiber–reinforced polypropylene composites have attained commercial attraction in automotive industries. Natural fiber—polypropylene or natural fiber—polyester composites are not sufficiently eco-friendly because of the petroleum-based source and the nonbiodegradable nature of the polymer matrix. Using natural fibers with polymers based on renewable resources will allow many environmental issues to be solved. By embedding biofibers with renewable resource–based biopolymers such as cellulosic plastics; polylactides; starch plastics; polyhydroxyalkanoates (bacterial polyesters); and soy-based plastics, the so-called green bio-composites are continuously being developed.
1,921 citations
TL;DR: In this paper, the composites were conditioned at various moisture contents in order to evaluate the effect of amylopectin on the composite structure, and the resulting films were characterized using scanning electron microscopy, differential scanning calorimetry, water absorption experiments, and wide-angle X-ray scattering.
Abstract: Nanocomposite materials were obtained using glycerol plasticized starch as the matrix and a colloidal suspension of cellulose whiskers as the reinforcing phase. The cellulose whiskers, prepared from tunicin, consisted of slender parallelepiped rods with a high aspect ratio. After mixing the raw materials and gelatinization of starch, the resulting suspension was cast and evaporated under vacuum. The composites were conditioned at various moisture contents in order to evaluate the effect of this parameter on the composite structure. The resulting films were characterized using scanning electron microscopy, differential scanning calorimetry, water absorption experiments, and wide-angle X-ray scattering. An accumulation of plasticizer in the cellulose/amylopectin interfacial zones was evidenced. The specific behavior of amylopectin chains located near the interface in the presence of cellulose probably led to a transcrystallization phenomenon of amylopectin on cellulose whiskers surface.
622 citations
TL;DR: In this article, a review of the early literature on zein is presented, which reexamines the old literature and reconciles it with new zein research to illustrate some of the unique properties of and opportunities for zein.
Abstract: Corn is the largest and most important agricultural commodity in America. Zein, one of the components in corn, has long been investigated for uses other than food and feed. Zein is a unique and complex material, and it is one of the few cereal proteins extracted in a relatively pure form. Today, because of environmental concerns, interest in zein utilization is again growing. Some of the more important research on zein is more than 50 years old. Most of this work has been either forgotten, lost, or difficult to locate. Much of this work was done at the USDA laboratory in Peoria, IL. Since most early zein literature is still easily accessible at that laboratory, this review on zein has been prepared making use of this old literature. This review reexamines the old literature and reconciles it with new zein research to illustrate some of the unique properties of and opportunities for zein.
461 citations