Preparation,characterization and performances of biodegradable thermoplastic starch

A biodegradable thermoplastic starch (TPS) was successfully prepared from plasticizer ethanolamine and native cornstarch. The hydrogen bonding interaction between starch and ethanolamine was investigated using Fourier transform infrared (FT‐IR). When the ethanolamine mass content was 30%, after the ethanolamine‐plasticized thermoplastic starch (ETPS) was stored at RH 50% for 14 days, the mechanical testing showed that the maximum tensile stress of the ETPS reached 5.98 MPa, the tensile strain reached 106.52%, Young's modulus increased from 38.14 MPa of glycerol‐plasticized thermoplastic starch (GTPS) to 75.32 MPa of ETPS, and the breaking energy increased from 1.921 N·m to 2.305 N·m, which indicated that the mechanical properties of ETPS evidently excelled those of the GTPS. The effects of water contents on the mechanical properties of ETPS and GTPS were studied. A differential scanning calorimetry (DSC) analysis revealed that the low‐temperature transition and the glass transition temperature (T_g) of the ETPS were ?58 and 22°C respectively, which were lower than that of the GTPS. The ETPS effectively restrained the re‐crystallization of traditional GTPS, which was proved by the X‐ray diffraction (XRD). The scanning electron microscopy (SEM) images presented that ethanolamine made starch uniform. Copyright © 2007 John Wiley & Sons, Ltd.     

Effect of Plasticizer Type and Concentration on Dynamic Mechanical Properties of Sugar Palm Starch–Based Films

In the quest for biodegradable and environmentally friendly packaging materials, starch-based films have been considered as a potential alternative to address ecological problems that emerged from the use of nonbiodegradable petroleum-based plastics. Thus, this article presents a new biopolymer (sugar palm starch) for the preparation of biodegradable packaging films using the solution-casting technique. The effects of different plasticizer types (glycerol [G], sorbitol [S], and glycerol-sorbitol [GS] combination) with varying concentrations (0, 15, 30, and 45, w/w %) on the dynamic mechanical properties of sugar palm starch (SPS) films were evaluated. It was observed that the storage (E′) and loss modulus (E″) of the plasticized SPS films decrease as plasticizer concentration increases from 15 to 45%. S-plasticized films showed higher storage modulus (1000 MPa) than G (880 MPa) and GS (920 MPa) plasticized films, irrespective of plasticizer concentration.     

Correlation between mechanical adhesion and interfacial properties of starch/biodegradable polyester blends

Biopolymers are preferred ingredients for the manufacture of materials because they are based on abundantly available and renewable raw materials that have benign environmental problems associated with their production, fabrication, use, and disposal; however, the wide use of biopolymers in engineering applications has not been achieved, mainly because of the inferior quality of many biopolymer‐based products. To overcome this limitation, studies have been initiated on blends of biopolymers and biodegradable synthetic polymers. We used the contact angle of probe liquids to measure the surface energy of polystyrene, the biodegradable polyesters polycaprolactone, poly(hydroxybutyrate‐co‐hydroxyvalerate), polylactic acid, polybutylene adipate terephthalate, and adipic poly(hydroxy ester ether), and normal starch. The surface energies were used to estimate the starch/polymer interfacial energy and work of adhesion. The calculated starch/polyester work of adhesion showed mixed correlation with published starch/polyester mechanical properties, indicating that factors other than interfacial properties might be dominant in determining the mechanical properties of some starch/polyester blends. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 920–930, 2001     

Influence of various starch types on PCL/starch blends anaerobic biodegradation

Research concentrated on the biodegradable capability of PCL blends with various types of starch in an anaerobic aqueous environment of mesophilic sludge from a municipal wastewater treatment plant. For blend preparation, use was made of a native starch Meritena from maize, another from Waxy – a genetically modified type of maize, as well as Gel Instant, a gelatinized starch, and an amaranth starch. Additional PCL/starch blends were prepared from the same starch types, but these were initially plasticized with glycerol. The biodegradability tests were supplemented with thermo gravimetric analysis (TGA), and differential scanning calorimetry (DSC); morphology was identified using scanning electron microscopy (SEM), plus mechanical properties were also tested. While mixtures of PCL with starches plasticized with glycerol exhibited improved mechanical properties and a higher degree of biodegradation in the anaerobic environment, mixtures of PCL with pure forms of starch were ascertained as rather resistant to the anaerobic aqueous environment. TGA and DSC analysis confirmed the removal of starch and glycerol from the PCL matrix. SEM then proved these results through the absence of starch grains in the samples following anaerobic biodegradation.     

Plasticizing effects of epoxidized sun flower oil on biodegradable polylactide films: A comparative study

Polylactide (PLA) is one of the most promising materials among the renewable source-based biodegradable plastics. However, high inherent stiffness and brittleness of the pure PLA is often insufficient for wide range of engineering applications. One of the best ways to improve the processability, toughness and flexibility of PLA is to plasticize with epoxidized plant oils. In this work, epoxidized sun flower oil (ESFO) was incorporated into PLA matrix. The thermal, mechanical, biodegradation, optical transmission properties and fracture morphology of ESFO plasticized PLA were investigated to make a comparison with that of PLA plasticized by commercial epoxidized soya bean oil (ESO). Results show that a remarkable improvement of elongation at break was observed in the case of ESFO incorporated PLA. Although a slightly decrease the T _g of PLA was resulted from the plasticizing effects of ESFO, the thermal stability of the plasticized PLA was improved. On the other hand, the ESFO plasticized PLA showed a higher level of UV adsorption but a lower level of biodegradation ratio. After all, ESFO exhibited similar effects on the biodegradable PLA films to ESO, which is anticipated to be a good candidate for plasticizing biodegradable polymer materials.     

Properties of Starch Blends with Biodegradable Polymers

Abstract

Starch, one of the most inexpensive and most readily available of all natural polymers, can be processed into thermoplastic materials only in the presence of plasticizers and under the action of heat and shear. Poor water resistance and low strength are limiting factors for the use of materials manufactured only from starch, and hence the modification of starch is often achieved by blending aliphatic polyesters. In this review, the literatures concerning the properties of various blends of starch and aliphatic polyesters have been summarized. The biodegradable rates of blends can be controlled to a certain extent depending on the constitutions of blends, and the mechanical properties of blends are close to those of traditional plastics such as polyethylene and polystyrene. The reduction of their sensitivity to humidity makes these materials suitable for the production of biodegradable films, injection-molded items, and foams.     

Preparation and characterization of corn starch/soy protein biocomposite film reinforced with graphene and graphene oxide nanoplatelets

Corn starch (CS) and soy protein isolate (SPI), as inexpensive, abundant, and biodegradable materials, can chemically interact well with each other to produce biofilms. However, to overcome some of their physical and mechanical limitations, it is preferred to use their composite form, employing reinforcing materials. In this study, initially, graphene (G) and graphene oxide (GO) were synthesized by a green method. Then, to enhance the polymer blend final properties, the effects of adding G and GO in the range of 0.5 to 2 wt% on physical and mechanical properties of starch/protein blend were investigated. The results showed that the presence of 0.5‐wt% G and 2‐wt% GO significantly increased the modulus of starch/protein film from 252 to 578 and 449 MPa, respectively. In addition, the thermal stability of CS/SPI/GO (2 wt%) composite film was 50°C to 60°C more than that of the pure starch/protein film. On the other hand, G‐reinforced composite films tended to decline water diffusion compared with the pure polymer film. In addition, the composite film with 2‐wt% GO content had the lowest oxygen permeation rate (3.48 cm³ μm/m²d kpa) among the other composite films.     

A New Approach to Use Arenga Pinnata as Sustainable Biopolymer: Effects of Plasticizers on Physical Properties

The motivation of this research is to develop a new biopolymer derived from sugar palm tree (Arenga pinnata) which can lead to solve non degradable polymer waste disposal problems. Therefore, this paper presents the development of alternative biodegradable material developed by using locally available sugar palm starch (SPS) in presence of biodegradable glycerol as a plasticizer. The environmental friendly plasticized SPS were successfully prepared using 15, 20, 30 and 40% w/w of glycerol. The samples were characterized for density, moisture content, water absorption and thickness swelling. The results showed that the physical properties i.e. density, moisture content, water absorption and thickness swelling of the plasticized SPS become lower with the increasing of glycerol content.     

淀粉基高分子材料的研究进展

概述了近5年国内外在淀粉的化学、物理改性及其作为一种材料使用方面取得的最新研究进展.淀粉的化学改性主要介绍了淀粉的酯化、醚化、氧化、交联、接枝共聚等,而物理改性主要介绍了淀粉分别与黏土、脂肪族聚酯、聚乙烯醇以及纤维素等天然大分子的共混改性,同时还介绍了通过酸化制备淀粉纳米晶.淀粉基材料除了用于制备可生物降解塑料、吸附材...     

Effects of chemical modification on the structure and mechanical properties of starch-based biofilms

Abstract  

In this work, chemically modified corn starch and plasticized corn starch biofilms were obtained and characterized in four steps: (1) preparation of corn starch microparticles, (2) preparation of malic acid-modified corn starch microparticles (MA–SM), (3) preparation of corn starch biofilms and MA–SM-plasticized corn starch biofilms, and (4) characterization of the biofilms. The effects of MA–SM concentration (4, 8, and 12% based on the amount of corn starch) on the structural characteristics and mechanical properties of the biofilms were investigated. Changes in the starch granules after chemical modification were studied by X-ray diffraction, FT-IR spectroscopy, and scanning electron microscopy. The presence of ester carbonyl group stretching vibration at 1,720 cm⁻¹ in FT-IR spectra was evidence of reaction of the starch microparticles with malic acid. The tensile yield strength and Young’s modulus of the films increased with increasing MA–SM content. Water uptake decreased from 69.8% for biofilm without MA–SM to 52.7% for biofilm with MA–SM. The improvement of these properties in the plasticized product could be attributed to the good interaction between the MA–SM filler and the corn starch.     

Structure and properties of clay nano‐biocomposites based on poly(lactic acid) plasticized with polyadipates

The use of nano‐biocomposites based on plasticized poly(lactic acid) (PLA) has been proposed as a way to improve the polymer ductility and to expand PLA applications window. Novative nano‐biocomposites were elaborated with PLA plasticized by polyadipates (15 wt%) with different molar masses (from 1500 to 2500 Da), with 2.1 wt% of an organo‐modified montmorillonite (O‐MMT). These materials showed enhanced ductility and barrier properties. The clay was swelled in liquid polyadipates prior to their blending with PLA to facilitate chains intercalation and nanofiller exfoliation during melt‐blending. In certain processing conditions, quite homogenous and exfoliated structures were obtained, as shown by X‐ray diffraction (XRD) and transmission electronic microscopy (TEM) results. Irrespective of the average molar mass of the polyadipate, the clay addition induced a reduction in around 25% in oxygen transmission rate (OTR) without an important detriment in tensile properties. Nano‐biocomposites prepared with higher molar masses polyadipates showed the highest thermal stability as well as the lowest OTR, resulting in very promising and novative materials for different applications such as soft packaging. Copyright © 2010 John Wiley & Sons, Ltd.     

Structure and properties of degradable polyolefin-starch blends

The structure, mechanical properties and susceptibility to degradation of blends of low density polyethylene (PE) or isotactic polypropylene (PP) and glycerol plasticized starch (GS) was investigated. Monoethers of glycerol and fatty alcohols (GA) and in some cases epoxidized rubbers (ER) were used as compatibilizers for the investigated systems. It was found that mechanical properties and ageing susceptibility of blends depend strongly on their composition, i.e. the content of plasticized starch in the blend and the content of glycerol in the starch. In some cases an increased susceptibility to biodegradation during soil or fungus ageing not only of the starch phase but also of the polymer phase was observed. The susceptibility of these systems to accelerated artificial weathering was also investigated.     

Biodegradable Nanocomposites Based on the Polyester Poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) and Layered Silicate or Expanded Graphite

Novel nanocomposites based on the biodegradable polymer poly(3‐hydroxybutyrate‐co‐3‐hydroxyhexanoate) (PHBHx) and layered fillers, specifically layered silicate (clay25A) and expanded graphite (EG), were prepared by melt intercalation. The dispersion of the fillers in the PHBHx was characterized by wide‐angle X‐ray diffraction (WAXD) and transmission electron microscopy (TEM). The effects of the fillers on the polymer structure, thermal stability and mechanical properties of the nanocomposites were also studied, by differential scanning calorimetry, thermogravimetric analysis, and strain‐stress measurements in elongation, respectively. The WAXD and TEM results showed that the clay25A and EG was exfoliated into well‐dispersed sheets in the polymer matrix, especially when the filler concentration were relatively low. This gave rise to considerable improvements in Young's modulus, and resulted in increases in the thermal degradation. It should be possible to convert the EG dispersions obtained thus far to ones yielding filler‐filler networks that show electrical conductivity.     

Synthesis and nuclear magnetic resonance analysis of starch‐g‐poly(1,4‐dioxan‐2‐one) copolymers

A new biodegradable starch graft copolymer, starch‐g‐poly(1,4‐dioxan‐2‐one), was synthesized through the ring‐opening graft polymerization of 1,4‐dioxan‐2‐one onto a starch backbone. The grafting reactions were conducted with various 1,4‐dioxan‐2‐one/starch feed ratios to obtain starch‐g‐poly(1,4‐dioxan‐2‐one) copolymers with various poly(1,4‐dioxan‐2‐one) graft structures. The microstructure of starch‐g‐poly(1,4‐dioxan‐2‐one) was characterized in detail with one‐ and two‐dimensional NMR spectroscopy. The effect of the feed composition on the resulting microstructure of starch‐g‐poly(1,4‐dioxan‐2‐one) was investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3417–3422, 2004     

Solid-state NMR study of biodegradable starch/polycaprolactone blends

Abundant literature exists on starch or modified starch blended with biodegradable polyesters to achieve good performance with cheap compost plastics. The level of miscibility in these blends is one of the most relevant parameters. In the present study, solid-state ¹H and ¹³C NMR spectra, as well as carbon spin-lattice relaxation times T₁(C) and proton spin-lattice relaxation times T₁(H) and proton spin-lattice relaxation times in the rotating frame T_1ρ(H) of biodegradable starch (or starch formate)/polycaprolactone (PCL) (or polyester (PE) oligomers) blends and samples of the neat components were measured. From the T_1ρ(H) and T₁(H) relaxation times it follows that blends starch/PCL, starch/PE-oligomers and starch formate/PE-oligomers are phase separated even on the scale of 20-110 nm. On the contrary starch formate/PCL blend is phase separated on the scale 2.5-12 nm but homogeneously mixed on the scale 20-90 nm. Moreover, shorter T₁(C) and especially T_1ρ(H) values found for the starch or starch formate component in all these blends in comparison with neat samples show that molecular mobility of starch and starch formate segments is affected by blending. This indicates some miscibility also in phase separated blends which can happen in amorphous channels of starch.     

谷朊粉/淀粉/甘油混合体系的流变行为与力学性能

研究了甘油增塑谷朊粉/淀粉混合体系的动态流变行为与单轴拉伸力学性能,考察了淀粉与水含量的影响.研究结果表明,含水量10%的混合体系储能模量(G′)随淀粉含量增大而增大,并在100℃出现橡胶平台.增塑谷朊粉在30℃呈现凝胶特性,在80℃出现交联网络结构.淀粉粒子可与小麦蛋白质形成复杂相互作用,阻碍蛋白质链段运动,导致模量与强度增加,断裂伸长率降低.含水量为20%与25%时,水份在淀粉粒子与蛋白质网络间起稀释和润滑作用,拉伸强度与断裂伸长率随淀粉含量的增高而降低.     

New biodegradable polymers from renewable sources: Polyester‐carbonates based on 1,3‐propylene‐co‐1,4‐cyclohexanedimethylene succinate

α,ω‐Dihydroxy‐terminated copolymeric oligomers of a 1,3‐propylene/1,4‐cyclohexanedimethylene succinate structure were obtained by the thermal polycondensation of 1,3‐propanediol/1,4‐cyclohexanedimethanol/succinic acid mixtures. They were subsequently chain‐extended via phosgene synthesis to high molecular weight aliphatic/alicyclic copolyester‐carbonates. These new polymers, besides having a biodegradable backbone, originate from two monomers, namely, 1,3‐propanediol and succinic acid, which can be obtained by renewable sources. Therefore, they have a potential as environmentally friendly materials. All synthesized materials were characterized in reference to their molecular structure by ¹H NMR and ¹³C NMR. Their molecular weights and molecular weight distributions were determined by size exclusion chromatography, and their main thermal properties were measured by DSC. Spectroscopic characterizations were in full agreement with the proposed structures. 1,4‐Cyclohexanedimethanol was used as a diol comonomer to improve the overall thermal properties of poly(1,3‐propylene succinate). The results of the characterization performed show that the initial expectations were only partially satisfied. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2508–2519, 2001     

Characterizations of modified cassava starch with long chain fatty acid chlorides obtained from esterification under low reaction temperature and its PLA blending

In contrast to typical starch esterification in an aqueous solution, which are carried out at elevated to ambient reaction temperatures, a low reaction temperature was applied in this study to minimize the starch chain hydrolysis. The physical properties of the modified starch, obtained from an esterification of cassava starch with long-chain fatty acid chlorides carried out in aqueous media at 4°C, were characterized using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and contact angle measurements. The modified starches show improvement in thermal stability and hydrophobicity, which can be further optimized by varying the types of acid chlorides and the reaction conditions. The starch products have high potential for use as fillers for biodegradable polymers, especially polylactic acid (PLA), as their tunable hydrophobicity can impose strong effect on controlling of the PLA's hydrolytic degradation rate for specific applications. Results on mechanical properties of the blends between the modified starch and PLA show an improvement in modulus of the polymer.     

高速搅拌对淀粉/聚乙烯醇共混物溶液成膜性能的影响

淀粉与聚乙烯醇（ＰＶＡ）溶液在高速搅拌下共混,可大大改善淀粉／ＰＶＡ共混薄膜的力学性能、透明性与耐水性,对其生物降解性有明显的影响．淀粉／ＰＶＡ共混体系在高速搅拌前后的光谱分析、显微观察、分子量及流变性能的测定表明,这些变化起因于高速搅拌增加了淀粉中直链淀粉的含量,同时提高了淀粉与ＰＶＡ共混溶液的稳定性,改善了淀粉／ＰＶＡ共混物薄膜的使用性能．     

Novel fluorinated stabilizers for ring‐opening polymerization in supercritical carbon dioxide

Ring‐opening polymerization (ROP) in supercritical carbon dioxide (scCO₂) has been the subject of much recent interest, although few publications describe the development of stabilizers to produce biodegradable particles of poly(L ‐lactide) (PLLA) and polyglycolide (PGA). Here we describe the synthesis of a series of novel fluorinated diblock copolymers by the acid‐catalyzed esterification of well‐defined blocks of polycaprolactone (PCL) with Krytox 157FSL, a carboxylic acid terminated perfluoropolyether. These diblock copolymers were then tested as stabilizers in the ROP of glycolide and L ‐lactide, or a mixture of the two, in scCO₂, and this resulted in the corresponding homopolymers or random copolymers. In the absence of stabilizers, only aggregated solids were formed. When the reaction was repeated with a stabilizer, PGA and PLLA were obtained as discrete microparticles. The stabilizer efficiency increased as the length of the polymer‐philic PCL block increased. One optimized stabilizer worked at loadings as low as 3% (w/w) with respect to the monomer, demonstrating these to be extremely effective stabilizers. It was found that to produce microparticles with this process, the product polymers must be semicrystalline; amorphous polymers, such as poly(lactide‐co‐glycolide), are plasticized by scCO₂ and yield only aggregated solids rather than discrete particles. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6573–6585, 2005