Preparation and properties of thermoplastic pea starch using N,N‐bis(2‐hydroxyethyl)formamide as the plasticizer

N,N‐bis(2‐hydroxyethyl)formamide (BHF) was synthesized efficiently and used as a new plasticizer for pea starch to prepare thermoplastic starch (TPS). The hydrogen bond interaction between BHF and pea starch was proven by Fourier‐transform infrared (FT‐IR) spectroscopy. As detected by scanning electron microscope (SEM), pea starch granules were completely disrupted, and the homogeneous materials were obtained. The crystallinity of pea starch and BHF‐plasticized thermoplastic pea starch (BTPS) was characterized by X‐ray diffraction (XRD). Rheological properties of TPS were analyzed. The water resistance of BTPS was better than that of glycerol‐plasticized thermoplastic pea starch (GTPS). At RH 33%, the tensile strength of BTPS was higher than that of GTPS for TPS containing 30% plasticizer. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Thermoforming starch‐graft‐polycaprolactone biocomposites via one‐pot microwave assisted ring opening polymerization

A thermoformable starch‐graft‐polycaprolactone biocomposite was prepared by initiating ring‐open polymerization of caprolactone monomer onto starch under microwave irradiation. In this case, the thermoplastic and hydrophobic modification of starch could be realized by one‐pot grafting PCL, where the grafted PCL chains acted as the “plasticizing” tails of thermoforming and as the hydrophobic species of water‐resistance. The resultant biocomposites were injection‐molded as the sheets and their structure and properties were investigated by Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, differential scanning calorimetry, dynamic mechanical analysis, contact angle measurement, and tensile testing. In this case, the grafted PCL chains entangled each other, and hence contributed to the strength and elongation of biocomposites. This work provided a simple strategy of one‐pot thermoplastic and hydrophobic modification of starch, and may be applied in a continuous process of modification, compounding, and molding. Meanwhile, the resultant biocomposites containing starch are believed to have a great potential application as an environment‐friendly and/or biomedical material. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Ageing of soft thermoplastic starch with high glycerol content

In this study, a soft and thermoplastic starch with an improved ageing‐resistant property was prepared by melt blending method for a biodegradable biomaterial. The glycerol content varies from 30 to 60 wt %. The aging temperature and humidity of the glycerol‐plasticized thermoplastic starch (GTPS) was 37°C and 50 ± 5 RH %, respectively. The retrogradation was characterized by X‐ray diffraction (XRD), dynamic mechanical thermal analysis (DMTA), Fourier transform infrared (FTIR), and the stress‐strain mechanical properties. The XRD results suggest that high content of glycerol promotes the formation of single helix structure of V‐type, but inhibits double helix structure of B‐type. Changing of the tan δ, storage modules (E′), and the glass transition temperatures as a function of glycerol content and ageing time was detected by DMTA. FTIR result shows that the shifting speed of the peak of hydroxyl group stretching fell as the glycerol content increased. The glycerol content has no obvious effect on the mechanical properties when it is high enough. Results from all characterizations demonstrate that the ageing speed is closely relative to the plasticizers content. The higher content of glycerol possesses an obviously inhibitory effect on the ageing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 574–586, 2007     

D‐isosorbide and 1,3‐propanediol as plasticizers for starch‐based films: Characterization and aging study

In the present work, D‐isosorbide and 1,3‐propanediol are proposed as alternative plasticizers obtained from renewable resources. Plasticized starch films were prepared by solvent casting method. The influence of using different “green” plasticizers in the final properties of starch‐based films was analyzed. Besides, the characterization of the films was also performed after storage time in order to evaluate the effect of the plasticizer on aging. UV‐spectrophotometry results showed better optical properties for both glycerol and D‐isosorbide films with higher transparency. The thermal and mechanical properties resulted influenced by the nature of the plasticizer. It was demonstrated that water vapor permeability was governed by the starch‐water interactions, whereas the oxygen permeability depended on the plasticizer's nature. The storage time affected the surface, mechanical, and thermal properties of the plasticized starch films. Atomic force microscopy results concluded that the topography of the films changed due to aging. The use of D‐isosorbide as plasticizer reduced the evolution of the mentioned properties and enhanced the reliability of the material. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44793.     

Twin‐screw extrusion production and characterization of starch foam products for use in cushioning and insulation applications

Cylindrical starch foam shapes were produced on a small scale (～11–12 kg/hr) Werner Pfleiderer ZSK‐30 twin‐screw extrusion (TSE) process using water, which functions as a plasticizer as well as a blowing agent. The properties of the starch foams depend on the type of starch used (hydroxypropylated high amylose corn starch, 70% amylose), the amount of water and additives (poly(hydroxyamino ether)) (PHAE) used, and extrusion conditions such as temperature and the screw configuration. PHAE offers the adhesion and durability of epoxy resins with the flexibility and processibility of thermoplastic resins. PHAE was successful in imparting mechanical strength and toughness, cell integrity, weather and water resistance to the foam structure. The purpose of this work was to study the effects of the extrusion (melt) temperature, amount of water added and the screw configuration on the density of starch foams. The water externally added was varied from 3% to 12%, while the PHAE content was varied from 3% to 15% of the starch used (on a wet basis). The foaming was carried out at melt temperatures in the range from 85 to 145°C. A match of material properties with process engineering conditions was achieved to facilitate the control of expansion to a structure with valuable commercial properties. The effects of processing conditions on the foaming process were studied using a Werner Pfleiderer ZSK‐30 twin screw extruder. The optimum temperature, blowing agent content, and PHAE content were determined. The density of the cylindrical foam extrudates obtained was 22–25 kg/m³. The screw configuration, temperature and pressure profiles, and additives affected the morphology, expansion ratio (ER), resilience, and compressibility of the product. These results were then employed on an industrial scale (410–420 kg/hr) twin‐screw food extruder, a Wenger‐80, to manufacture foam sheets. The density of the foam sheets was 27–30 kg/m³. The cushioning and insulation properties were studied and are reported. POLYM. ENG. SCI., 46:438–451, 2006. © 2006 Society of Plastics Engineers     

Preparation and properties of biodegradable thermoplastic starch/poly(hydroxy butyrate) blends

The vital differences using three types of thermoplastic starches (TPS), including potato starch, corn starch, and soluble potato starch, with two different gelatinization degrees to blend with poly(hydroxy butyrate) (PHB) are thoroughly discussed in this study. For blends containing a certain amount of PHB, thermal stability remains in a certain degree. In all cases of this study, mechanical properties of TPS blended with PHB confer higher performance than those of pristine TPS. In particular, a significant increase on tensile strength and tear strength is observed for TPS (potato starch) blended with PHB at low gelatinization degree. A suitable degree of gelatinization of starch is critical to achieve optimum performance. The investigation on the morphological observation partly features the supporting evidence of the above findings. The assessment of biodegradability indicates that the values of water absorption and weight loss increase with increasing treatment period and glycerol content, but decrease with increasing amount of PHB content. Among three types of starches investigated, the TPS (soluble starch)/PHB blend gives the highest level of water absorption and weight loss. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2371–2379, 2006     

Thermoplastic starch blends with a poly(ethylene-co-vinyl alcohol): Processability and physical properties

We investigated the effect of poly(ethylene-co-vinyl alcohol) (EVOH) concentration on the processability and physical properties of thermoplastic starch plasticized with glycerine and water. Waxy maize starch (Amioca), native corn starch (Melogel), and a treated high amylose corn starch (Hylon VII) were employed to explore the effect of starch type on blend properties. All the starches exhibited similar changes in properties with increasing EVOH content. The minimum injection pressure required for filling a standard test specimen (a measure of processability) decreased with increasing EVOH concentration and provided an indication of improved processability. Blends with high amylose corn exhibited higher injection pressures than the corresponding waxy maize or native corn starch blends. The ductility of all the thermoplastic starches was significantly increased upon the addition of EVOH. The waxy maize blends were stiffer and the high amylose corn blends exhibited higher elongation at low EVOH concentrations, but all the starch/EVOH blends exhibited similar physical properties when the EVOH concentration was ≥ 50 wt%. An investigation of physical properties of this blend series after long term aging from 10% to 90% relative humidity is in progress. Future studies include rheology, electron microscopy, and thermal analysis to more fully elucidate phase behavior in these binary blends.     

New breathable films using a thermoplastic cross‐linked starch as a porogen

Breathable films, which find in variety of product applications, are conventionally made using mineral porogens such as calcium carbonate (CaCO₃). This article addresses a novel biodegradable and highly breathable film without inorganic porogens. Unexpectedly, a thermoplastic cross‐linked natural polymer (corn starch) was used successfully to create tortuous passages for film breathability. This concept was demonstrated using two types of thermoplastic cross‐linked corn starches as porogens and contrasted to control samples: native corn and chemically cross‐linked starches, respectively. The films discussed had increased breathability and mechanical properties relative to the control samples. The film morphology reveals that filler was irregular when thermoplastic starch or CaCO₃ was used. The difference in filler from chemically modified cross‐linked starch and thermoplastic cross‐linked starch was observable as well. It is believed that spherical particles provided by thermoplastic cross‐linked starch helps film debonding and porosity during the film stretch processes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41016.     

Aging and moisture effects on the tensile properties of starch/poly(hydroxyester ether) composites

The effects of starch and aging on the mechanical properties of starch/poly(hydroxyester ether) (PHEE) composite materials were characterized. Native or modified cornstarches were extruded with PHEE. Composites were aged for up to 20 months at either 23°C and 50% relative humidity (RH) or over calcium sulfate to keep the composites dry. The tensile strength (TS) of the composites was affected by the type of starch filler that they contained. Composites containing native or crosslinked starch had significantly greater TS than composites containing octenylsuccinated starch. It was thought that the octenylsuccinate modification of the starch granule affected the adhesion between the starch and PHEE. Aging the composites at 50% RH had a significant effect on the mechanical properties of the composites, with TS and Young's modulus (YM) significantly decreasing and the elongation to break significantly increasing after 20 months of storage. Composites stored at 50% RH absorbed water, which caused changes in the mechanical properties by plasticizing PHEE. Composites containing poly(lactic acid) and PHEE did not experience large reduction in TS and YM when aged at 50% RH, even though they also absorbed water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3332–3339, 2006     

Urea and formamide as a mixed plasticizer for thermoplastic starch

Mixtures of urea and formamide were tested as plasticizers for thermoplastic starch (TPS). The hydrogen bonding interactions between urea/formamide and starch were investigated by using Fourier‐transform infrared spectroscopy (FT‐IR). The thermal stability, mechanical properties and starch retrogradation behavior were also studied by thermogravimetric analysis (TGA), tensile testing and X‐ray diffraction (XRD), respectively. TPS plasticized by urea (20 wt%) and formamide (10 wt%) showed better thermal stability and water resistance than conventional TPS plasticized by glycerol. Moreover, the tensile stress, strain and energy at break, respectively, reached 4.83 MPa, 104.6 % and 2.17 N m after storing in an atmosphere of relative humidity (RH) of 33 % for one week. At the same time, this mixed plasticizer could effectively restrain the retrogradation of starch. Copyright © 2004 Society of Chemical Industry     

Micromechanical properties of injection‐molded starch–wood particle composites

The micromechanical properties of injection‐molded starch–wood particle composites were investigated as a function of particle content and humidity conditions. The composite materials were characterized by scanning electron microscopy and X‐ray diffraction methods. The microhardness of the composites was shown to increase notably with the concentration of the wood particles. In addition, creep behavior under the indenter and temperature dependence were evaluated in terms of the independent contribution of the starch matrix and the wood microparticles to the hardness value. The influence of drying time on the density and weight uptake of the injection‐molded composites was highlighted. The results revealed the role of the mechanism of water evaporation, showing that the dependence of water uptake and temperature was greater for the starch–wood composites than for the pure starch sample. Experiments performed during the drying process at 70°C indicated that the wood in the starch composites did not prevent water loss from the samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4893–4899, 2006     

Preparation and characterization of thermoplastic starch–kaolinite nanocomposite films

In this work, the thermoplastic starch–kaolinite (KAO) nanocomposite films were first prepared via solution‐casting method using chitosan‐modified KAO (CKAO) and Na⁺–KAO (NKAO). The structure was investigated by X‐ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy techniques. The results showed that the well‐dispersed KAO layers were delaminated in the starch matrix attesting to anexfoliated nanocomposite and formed strong interaction with starch molecules. According to thermogravimetric analysis, differential scanning calorimetric study, and water absorption testing, the starch–CKAO–urea nanocomposites have the greatest enhancements compared with those of starch–urea film and starch–NKAO–urea nanocomposites. These results provide the important information with using CKAO to obtain the exfoliated starch nanocomposites with high performance. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Properties of extruded starch–poly(methyl acrylate) graft copolymers prepared from spherulites formed from amylose–oleic acid inclusion complexes

Mixtures of high‐amylose corn starch and oleic acid were processed by steam jet cooking, and the dispersions were rapidly cooled to yield amylose–oleic acid inclusion complexes as micron‐ and submicron‐sized spherulites and spherulite aggregates. Dispersions of these spherulite particles were then graft polymerized with methyl acrylate, both before and after removal of uncomplexed amylopectin by water washing. For comparison, granular, uncooked high‐amylose corn starch was also graft polymerized in a similar manner. Graft copolymers with similar percentages of grafted and ungrafted poly(methyl acrylate) (PMA) were obtained from these polymerizations. The graft copolymers were then processed by extrusion through a ribbon die, and the tensile properties of the extruded ribbons were determined. Although extruded ribbons with similar tensile strengths were obtained from the three starch–PMA graft copolymers, much higher values for % elongation were obtained from the spherulite‐containing systems. Also, the tensile properties were not significantly affected by removal of soluble, uncomplexed amylopectin by water washing before graft polymerization. These results are consistent with the observation that these PMA‐grafted starch particles did not melt during extrusion, and that continuous plastic ribbons were formed by fusing these particles together in the presence of small amounts of thermoplastic PMA matrix. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40381.     

Assessment of aged biodegradable polymer‐coated nano‐zero‐valent iron for degradation of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX)

BACKGROUND: This study reports on the effects of aging on suspension behavior of biodegradable polymer‐coated nano‐zero‐valent iron (nZVI) and its degradation rates of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) under reductive conditions. The polymers investigated included guar gum, potato starch, alginic acid (AA), and carboxymethyl cellulose (CMC). Polymer coating was used to mitigate nZVI delivery hindrance for in situ treatment of RDX‐contaminated groundwater. RESULTS: The RDX degradation rates by bare nZVI and starch‐coated nZVI suspensions were least affected by aging although these suspensions exhibited the least favorable dispersion behavior. CMC, AA, and guar gum coating improved nZVI rates of degradation of RDX but these rates decreased upon aging. The best suspension stability upon aging was achieved by CMC and AA. Guar gum with loadings rates one order of magnitude lower than that of CMC and AA achieved good iron stabilization but significantly higher RDX degradation rates. CONCLUSION: It is demonstrated that both migration and reactivity of polymer‐stabilized nZVI should be explicitly evaluated over a long period before application in the field. Guar gum coated nZVI appeared best suited for in situ application because it maintained good suspension stability, with RDX degradation rates least affected by aging compared with the other polymers tested. © 2012 Society of Chemical Industry     

Effect of starch on thermal,mechanical, and barrier properties of low density polyethylene film

Low‐density polyethylene (LDPE) with different quantities of starch was compounded using a twin screw extruder and blown into films by a Konar K, blow‐film machine. Mechanical properties, namely percent elongation, tensile, bursting, and tear strength, as well as barrier properties, such as water vapor and oxygen transmission rate, of the filled LDPE film were studied. Thermal properties of the films were studied using DSC and DMA. Master curves at reference temperature of 30°C were obtained using software linked to DMA. Incorporation of 1% starch in LDPE has marginally affected the thermal, barrier, and mechanical properties; however, that of 5% starch filled LDPE has affected the properties to a great extent. The mechanical properties, such as percent elongation, tensile, tear, bursting, and seal strength, decreased by 19.2, 33.6, 3.60, 10.8, and 22.12%, respectively. Similarly, water vapor and oxygen transmission rate increased to 32.5 and 18.3%, respectively. Other physical properties, namely migration and thermal properties, were also affected in 5% starch filled LDPE; however, the film can still be used as packaging material. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3355–3364, 2006     

Clay–starch composites and their application in papermaking

Clay–starch composites with different aggregate sizes and starch to clay ratios were prepared by a simple precipitation method. The aggregates of the composites were used as fillers to improve the paper properties. The experimental results showed that the paper strengths increased more than 100% for starch‐modified clay compared to untreated clay at 20–30% clay loading. The increase in paper strengths of clay–starch composite‐filled handsheets was mainly due to two reasons, i.e., the relatively large aggregate size and the improved internal bonding. The optical properties compared at same mechanical strength were also improved. The water solubility of starch in the clay–starch composite was less than 3% at 50°C for 30 min, and it could be further reduced by adding crosslinker. Bonding sites between composite and fiber were investigated by scanning electron microscope. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1032–1038, 2006     

Electron‐beam processing of destructurized allylurea–starch blends: Immobilization of plasticizer by grafting

Allylurea (AU) was used as a reactive additive with poor aptitude to homopolymerization for obtaining grafted plasticized starch films with stabilized physical properties. Potato starch was mixed with AU (30–50 parts per hundred/pph) in a mixer operating at 125°C. Upon storage in well‐defined hygrothermal conditions, the resulting thermoplastic material shows strong plasticizer migration revealed by AU crystals blooming at the samples surface and exhibits strong opacity assigned to phase separation of the organic additive inside the material. Freshly prepared thermoplastic films of appropriate thickness were exposed to a 175‐kV electron beam (EB) radiation for inducing covalent grafting of AU by a free radical process. FTIR monitoring of the resulting chemical changes in thin films of AU–starch blends indicates unambiguously the transformation of AU allylic bond. High irradiation doses are required for achieving complete conversion of AU in the blend. However, no detectable AU migration was observed for intermediate AU conversion, probably as a consequence of higher plasticizer solubility in the grafted polysaccharide. Examination of the viscoelastic properties by dynamic mechanical thermal analysis shows that artificial aging by placing the films alternatively in high and low relative humidity (RH) atmosphere does not significantly alter the thermomechanical spectrum of the material reconditioned in a cell at 58% RH. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 409–417, 1999     

Thermal,mechanical, and morphological characterization of biobased thermoplastic starch from agricultural waste/polypropylene blends

The thermal, mechanical, and morphological properties of biobased thermoplastic starch (TPS) obtained from agricultural waste seed (AWS) and agricultural waste tuber (AWT) blended with polypropylene (PP) were investigated in this article. The grounded (pulverized) AWS and AWT were different in amylose/amylopectin ratios and contained relatively low starch content (≤50%). The commercial grade of TPS (CS) and native tapioca starch blended PP (NTS/PP) were also prepared for comparison. The performances of the TPS/PP blends were dependent on the starch composition (e.g., amylose‐to‐amylopectin ratio), particle size, dispersion, and interfacial adhesion with matrix. The high‐amylopectin starch blend (i.e., AWS/PP) was more susceptible to thermal degradation than the amylose‐rich material (i.e., NTS/PP). The addition of starch to PP not only led to a stiffening effect (i.e., increase in storage modulus), but it also affected the relaxation of polymer matrix by shifting the thermal transition (i.e., glass transition temperature) to a higher temperature. POLYM. ENG. SCI., 54:1357–1365, 2014. © 2013 Society of Plastics Engineers     

Improving the physical and chemical functionality of starch‐derived films with biopolymers

The physical and chemical properties of composite starch‐based films containing cellulosic fiber, chitosan, and gelatin were investigated. Films containing both cellulosic fibers and chitosan demonstrated tremendous enhancements in film strength and gas permeation. The water absorbency of composite films could be greatly reduced in film composites containing cellulosic fibers and gelatin, but the inclusion of chitosan into these films provided a higher hydrophilicity, increasing water absorbency. Film transparency was not noticeably affected in the composite films that were made. These films may have wide application in the food packaging, agricultural mulching, and the medical industries. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2542–2548, 2006     

Impact strength of recycled thermoplastic composites subjected to corrosive environment

The objective of the present study is to investigate the effect of hygrothermal aging on the impact strength of virgin and recycled commercial polyphenylenesulfide (PPS) matrix composites reinforced with 40% by weight of short glass fibres after water absorption at different pH and temperature environments. This study is part of a long‐term strategy for developing a sound methodology for reusing short fiber‐reinforced thermoplastic materials. Hygrothermal aging has been conducted so as to represent actual service conditions identified for the components made from these recycled materials. Taking into account the corrosive nature of the service environment in which the aforementioned components are required to operate, a study of the recycled material impact strength as a function of the environmental conditions to which they are subjected, is deemed indispensable before using them for the manufacturing of new products. The results of the present study showed a great effect of the various parameters studied such as, water temperature, alkaline or acidic nature of the environment, andtype of the coupling agent used on the impact behavior of the PPS‐glass fiber composites investigated. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers