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.
TL;DR: The biodegradability and biocompatibility of zein and other inherent properties associated with zein’s structure allow a myriad of applications of such materials with great potential in the near future.
Abstract: Zein is a biodegradable and biocompatible material extracted from renewable resources; it comprises almost 80% of the whole protein content in corn. This review highlights and describes some zein and zein-based materials, focusing on biomedical applications. It was demonstrated in this review that the biodegradation and biocompatibility of zein are key parameters for its uses in the food-packing, biomedical and pharmaceutical fields. Furthermore, it was pointed out that the presence of hydrophilic-hydrophobic groups in zein chains is a very important aspect for obtaining material with different hydrophobicities by mixing with other moieties (polymeric or not), but also for obtaining derivatives with different properties. The physical and chemical characteristics and special structure (at the molecular, nano and micro scales) make zein molecules inherently superior to many other polymers from natural sources and synthetic ones. The film-forming property of zein and zein-based materials is important for several applications. The good electrospinnability of zein is important for producing zein and zein-based nanofibers for applications in tissue engineering and drug delivery. The use of zein’s hydrolysate peptides for reducing blood pressure is another important issue related to the application of derivatives of zein in the biomedical field. It is pointed out that the biodegradability and biocompatibility of zein and other inherent properties associated with zein’s structure allow a myriad of applications of such materials with great potential in the near future.
Cites background from "Preparation and characterization of..."
...Several studies involving zein and starch blends are reported in the literature [2,59,60]....
TL;DR: In this paper, the authors developed packaging bags from thermoplastic corn starch containing talc nanoparticles (0, 1, 3, 3 and 5% w/w) and evaluated the properties of these bags by tensile tests and quasi-static assays.
Abstract: Packaging bags from thermo-compressed films of thermoplastic corn starch containing talc nanoparticles (0, 1, 3 and 5% w/w) were developed. Mechanical properties of films were studied by two different techniques (tensile tests and quasi-static assays) revealing starch films reinforcement by talc addition. Strength improvement of thermoplastic starch films with talc concentration higher than 3% w/w was reflected in an increase in both Young's modulus and yield stress. Talc particles modified failure mode of thermo-seal of thermoplastic starch films giving another bags opening possibility. Usually, bags based on starch films could be only opened by tearing while those of starch-talc bionanocomposites could be torn or peeled off. Finally, in order to evaluate packaging bags tightness, films barrier properties were determined. Water vapor and oxygen permeability were reduced 54 and 26%, respectively, by talc addition (3% w/w) to thermoplastic starch.
TL;DR: In this paper, a review of various processing techniques used to produce starch based polymers and composites with their properties to address the poor properties of starch is presented, including low toxic and good compatibility natural plasticizers are of great interest in the processing of thermoplastic starch.
Abstract: In recent years, interest in agro polymers has created great interest among researchers and industry alike, as these materials are found to be biodegradable and eco-friendly. Since the fossil fuel based polymers have created greater environmental concern, these bio-based polymers are addressing the concerns in some of impactful areas such as food packaging and contribute significantly to the sustainable development with minimum ecological problems. Among agro polymers, starch based polymers have made major stride to marketable products in food packaging field. It is estimated that by the year 2020, the biocomposite materials demand will touch 20% of total plastic utilization. This review enlightens various processing techniques used to produce starch based polymers and composites with their properties to address the poor properties of starch. Low toxic and good compatibility natural plasticizers are of great interest in the processing of thermoplastic starch (TPS). Further emphasis is also given on essential packaging film properties such as barrier, biodegradation, mechanical, and thermal properties for TPS based materials. The overview of literature indicates that, Final properties of the thermoplastic starch can be improved by using different fillers, as well as by changing the source of the starch. Since the quest to produce better, cheaper, and eco-friendly materials never stops, a multidisciplinary approach is required to achieve further improvement in the existing materials and to produce new class of materials that are eco-friendly which can extend smarter and efficient services to customers. POLYM. COMPOS., 2016. © 2016 Society of Plastics Engineers
TL;DR: Stress relaxation measurements indicated that the bioelastomers have strain energy dissipation factors that are lower than those of conventional rubbers, rendering them as promising green substitutes for plastic mechanical energy dampeners.
Abstract: Designing starch-based biopolymers and biodegradable composites with durable mechanical properties and good resistance to water is still a challenging task. Although thermoplastic (destructured) starch has emerged as an alternative to petroleum-based polymers, its poor dimensional stability under humid and dry conditions extensively hinders its use as the biopolymer of choice in many applications. Unmodified starch granules, on the other hand, suffer from incompatibility, poor dispersion, and phase separation issues when compounded into other thermoplastics above a concentration level of 5%. Herein, we present a facile biodegradable elastomer preparation method by incorporating large amounts of unmodified corn starch, exceeding 80% by volume, in acetoxy-polyorganosiloxane thermosets to produce mechanically robust, hydrophobic bioelastomers. The naturally adsorbed moisture on the surface of starch enables autocatalytic rapid hydrolysis of polyorganosiloxane to form Si–O–Si networks. Depending on the amount...
TL;DR: In this paper, three different types of amphiphilic molecules (Tween 60, linoleic acid, and zein) were used as additives for the production of thermoplastic starch (TPS).
Abstract: Three different types of amphiphilic molecules — Tween 60, linoleic acid, and zein were used as additives for the production of thermoplastic starch (TPS). The addition of those amphiphiles resulted in: (i) improved plasticization and processability, (ii) enhanced extensibility, (iii) increased crystallinity, and (iv) decreased stiffness, strength and rigidity of the TPS materials. Zein facilitated more effective plasticization, melting and processability of TPS material than did linoleic acid and Tween 60, respectively. However, Tween 60 allowed greater reduction of Tg and produced softer TPS material than did linoleic acid and zein, respectively. Binary blends of those TPS materials and poly(lactic acid) (PLA) were also fabricated by varying PLA content, i.e. 30, 50 and 70% (w/w). The melt flow index, tensile strength and elastic modulus of the TPF-PLA blends increased significantly with increasing PLA content. In addition, amphiphiles facilitated processability, flowability and extensibility of the blends. Linoleic acid was a more effective additive to enhance flowability of the TPS–PLA blends than were Tween 60 and zein, respectively.
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
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.
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.
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.