Aliphatic Amidediol and Glycerol as a Mixed Plasticizer for the Preparation of Thermoplastic Starch

The synthesis of 2‐hydroxy‐N‐[2‐(2‐hydroxy‐propionylamino)‐ethyl]propionamide (“aliphatic amidediol”) is described. Aliphatic amidediol and glycerol were used as a novel mixed plasticizer for corn starch to prepare thermoplastic starch. Fourier transform infrared (FT‐IR) spectroscopy proved that the mixture of aliphatic amidediol and glycerol could form more stable and strong hydrogen bonds with starch molecules than glycerol alone. By scanning electron microscopy (SEM) and X‐ray diffraction (XRD) it was proven that native starch granules and crystalline structures were broken and starch was plasticized. Tensile testing revealed that TPS plasticized by aliphatic amidediol and glycerol (AGPTPS) showed a better mechanical properties than TPS plasticized by glycerol (GPTPS). Furthermore, the water resistance of AGPTPS was better than that of GPTPS. In addition, dynamic mechanical thermal analysis (DMTA) showed that both storage modulus and glass transition temperature (T_g) of AGPTPS were higher than those of GPTPS.     

N,N‐Bis(2‐hydroxyethyl)formamide as a New Plasticizer for Thermoplastic Starch

N,N‐Bis(2‐hydroxyethyl)formamide (BHF) was synthesized efficiently and used as a new plasticizer for corn starch to prepare thermoplastic starch (TPS). The hydrogen bond interaction between BHF and starch was proven by Fourier‐transform infrared (FT‐IR) spectroscopy. As detected by scanning electron microscopy (SEM), starch granules were completely disrupted and a continuous phase was obtained. The crystallinity of corn starch and BHF‐plasticized TPS (BTPS) was characterized by X‐ray diffraction (XRD). The thermal behavior of glycerol‐plasticized TPS (GTPS) and BTPS was investigated by differential scanning calorimetry (DSC). The water resistance of BTPS was better than that of GTPS. Generally, at low relative humidity (RH), the tensile strength of BTPS was higher than that of GTPS. At high RH, the elongation at break of BTPS was higher than that of GTPS.     

Retrogradation of Ethylenebisformamide and Sorbitol Plasticized Corn Starch (ESPTPS)

Several thermoplastic starches (TPSs), i.e. ethylenebisformamide, sorbitol and ethylene‐sorbitol plasticized (EPTPS, SPTPS and ESPTPS) were prepared and their retrogradation was investigated by X‐ray diffraction, Fourier‐transform infrared spectroscopy (FT‐IR) and scanning electron microscopy (SEM). These studies revealed that the mixture of ethylenebisformamide (E) and sorbitol (S) was a good plasticizer for corn starch, restraining the retrogradation of the TPSs. The mechanical properties were also investigated of the TPSs after conditioning for 150 days at ambient atmosphere. It indicated that TPS produced by mixed plasticizer possessed better mechanical properties than TPS produced using a single plasticizer (ethylenebisformamide or sorbitol). From the analysis of X‐ray, FT‐IR and SEM data it was hypothesized that some interaction between ethylenebisformamide and sorbitol occurred, which could prevent the plasticizer form separating out of the TPS matrix. As a result, the retrogradation of ESPTPS was limited, resulting in better mechanical properties compared with those of EPTPS and SPTPS.     

Reinforced Thermoplastic Acetylated Starch with Layered Silicates

Montmorillonite (MMT) and organically modified montmorillonite (OMMT) were utilized to reinforce the thermoplastic acetylated starch (TPAS) composite prepared with glycerol as a plasticizer. After the addition of layered silicates, the restriction of the motion of the intercalated acetylated starch molecular chains by the clay layer sheets led to an increase in melt viscosity and equilibrium torque. As expected, the tensile strength and storage modulus of the TPAS composite were remarkably enhanced due to the interaction of layered silicates with the TPAS matrix, but the thermal stability of the TPAS composite was not obviously improved. The greater reinforcing effect of OMMT than that of MMT could be attributed to the better dispersion of OMMT in the TPAS matrix, resulting from the larger distance between OMMT layers after the modification by organic ammonium cations with long alkyl chains.     

增塑剂对淀粉浆料性能的影响

针对淀粉浆膜脆硬,柔韧性差的缺点,将甘油、尿素、柠檬酸氢二铵等增塑剂分别以不同量加入淀粉中,并对浆膜的吸湿率、断裂强力、断裂伸长率、耐屈曲性及浆液粘附性等进行了测试分析。结果表明,使用增塑剂能改善淀粉浆膜的脆硬性能,且提高了淀粉对纯棉粗纱的粘附性;其中柠檬酸氢二铵对淀粉质量分数为1％时,对改善淀粉浆膜各项性能及纯棉粗纱粘附性的效用最大。     

一种新型两性淀粉的制备方法

研究了在低温条件下,采用同一醇与水的混合溶剂使淀粉与3-氯-2-羟丙基三甲基氯化铵和氯乙酸进行醚化反应,制得一种新型的两性淀粉.并探讨了反应温度、反应时间以及阳离子醚化剂、阴离子醚化剂用量对其取代度的影响.     

The Effects of Citric Acid on the Properties of Thermoplastic Starch Plasticized by Glycerol

The effects of citric acid on the properties of glycerol‐plasticized thermoplastic starch (GPTPS) were studied. In the presence of citric acid and glycerol, native cornstarch granules are transferred to a continuous phase as shown by scanning electron microscopy (SEM). As shown by thermogravimetric analysis (TGA), the improvement in thermal stability confirms that the adhesion between citric acid, glycerol, water and starch in TPS was enhanced with the addition of citric acid. It was proven by Fourier transform infrared (FTIR) spectroscopy that citric acid can form stronger hydrogen‐bond interactions with starch than glycerol. Both FTIR spectroscopy and X‐ray diffractometry of citric acid‐modified GPTPS (CATPS) revealed that citric acid can effectively inhibit starch re‐crystallization (i.e. retrogradation), because of the strong hydrogen‐bond interaction between citric acid and starch. Rheology studies revealed that citric acid can obviously decrease the shear viscosity and improve the fluidity of TPS. Citric acid can also improve the elongation of GPTPS and ameliorate the water resistance of GPTPS at high relative humidities, but decreased the tensile stress.     

Green Nanocomposites from Renewable Resources: Effect of Plasticizer on the Structure and Material Properties of Clay‐filled Starch

Nanocomposites of starch were prepared via different addition sequences of plasticizer and clay by the solution method. The extent of dispersion of the filler was evaluated by wide angle X‐ray diffractometry (WAXD) in the resulting composites. Thermal stability, mechanical properties and water absorption studies were conducted to measure the material properties whereas FT‐IR spectroscopy was used to study the microdomain structure of composites. The sequence of addition of components (starch /plasticizer (glycerol) / clay) had a significant effect on the nature of composites formed and accordingly properties were altered. Glycerol and starch both have the tendency to penetrate into the silicate layers but penetration of glycerol is favored owing to its smaller molecule size. The filler dispersion becomes highly heterogeneous and the product becomes more brittle when starch was plasticized before filling with clay due to the formation of a bulky structure resulting from electrostatic attractions between starch and plasticizer. It was concluded that best mechanical properties can be obtained if plasticizer is added after mixing of clay in the starch matrix.     

The Effects of Plasticizers Containing Amide Groups on the Properties of Thermoplastic Starch

Several amide groups‐containing plasticizers for thermoplastic starch (TPS), such as formamide, acetamide, and urea, were studied in this paper with glycerol as reference. The hydrogen bond interaction between starch and plasticizers in TPS was tested by Fourier transform infrared (FT‐IR) spectroscopy. Both the oxygen of the C‐O‐H group and the oxygen of the C‐O‐C group in starch could form hydrogen bonds with these plasticizers. The order of the hydrogen bond‐forming abilities is as follows: urea > formamide > acetamide > polyols. The retrogradation of formamide‐plasticized TPS (FPTPS), acetamide‐plasticized TPS (APTPS) and urea‐plasticized TPS (UPTPS) was investigated at three levels of relative humidity (RH=0, 50 and 100%) using X‐ray diffractometry. Urea and formamide could effectively improve the resistance of TPS towards retrogradation. The studied mechanical properties demonstrated that FPTPS had a good breaking strain but poor breaking stress, while UPTPS had opposite characteristics. The properties of TPS mainly relied on the hydrogen bond‐forming abilities between plasticizers and the starch matrix. On the other hand, the water resistance of TPS mainly depended on the plasticizer. The higher the water absorption of the plasticizer was, the better was the water resistance of the TPS.     

处理工艺对热塑性淀粉粘度特性的影响

通过双螺杆挤压工艺,分析甘油/淀粉质量比、Ⅲ区温度和螺杆转速3因素的不同处理水平热塑性淀粉粘度特性。结果表明,热塑性淀粉的糊化起始温度随甘油含量的提高而提高,随机腔Ⅲ区温度和螺杆转速的提高而先升高,后降低;峰值粘度及恒温阶段开始、冷却阶段开始、冷却阶段结束、最终恒温阶段结束,粘度和回生值则随甘油含量的提高而降低,随机腔Ⅲ区温度和螺杆转速的提高而先降低,后升高。     

Impact of Pre‐Processing of Montmorillonite on the Properties of Melt‐Extruded Thermoplastic Starch/ Montmorillonite Nanocomposites

A simple and environmentally‐friendly processing method was used to prepare thermoplastic starch (TPS)/ montmorillonite (MMT) nanocomposites. X‐ray diffraction (XRD) and transmission electron microscopy (TEM) demonstrated that glycerol could enlarge the d‐spacing and destruct the layered structure of MMT effectively during the pre‐processing of MMT. So the enlarged d‐spacing and fragmentized platelets of glycerol activated‐MMT were a precondition to form intercalated or exfoliated TPS‐based nanocomposites during the melt extrusion processing. These highly dispersive and compatible TPS/activated‐MMT nanocomposites had increased thermal stability and tensile properties as compared with non‐activated composites. Especially, the tensile strength of nanocomposites could be enhanced to 8.6 MPa, the improvement was about two times the initial tensile strength of TPS.     

Degradability of Different Phosphorylated Starches and Thermoplastic Films Prepared from Corn Starch Phosphomonoesters

Different starch types (corn, rice, potato, corn amylose and corn amylopectin) were phosphorylated to varying degrees of substitution (DS) and tested both for acid hydrolysis during 3 h in a boiling bath and for enzymatic hydrolysis with a thermostable bacterial α‐amylase (Bacillus licheniformis) for 30 min at 95 °C. Generally, phosphorylated starches showed a reduced degree of acid hydrolysis during the entire time of hydrolysis (3 h) as well as reduced susceptibility to α‐amyIase hydrolysis. The enzyme action was inhibited by the presence of phosphate groups in the modified starch molecules and the extent of inhibition increased with increasing degree of phosphate substitution, regardless of the starch type. Thermoplastic films were fabricated by blending modified corn starches of different DS with polyacrylate, urea and water at a ratio of 4:5:1:50, heating for 30 min at 95 °C before casting and allowing to cool, stand and dry at room temperature. The plastic films prepared from phosphorylated corn starch showed both higher disintegration rate and a greater degradability by thermostable bacterial α‐amylase than the ones prepared from non‐phosphorylated starch. These new acquired properties can meet the increasing demand for biodegradable disposable plastic bags.     

Fully Biodegradable Lubricated Thermoplastic Wheat Starch: Mechanical and Rheological Properties of an Injection Grade

Pellets of lubricated and fully biodegradable thermoplastic wheat starch formulations were produced by extrusion. The lubricants used were a vegetable oil or an internal biodegradable release agent such as magnesium stearate. After being conditioned for one week at 20 °C at 65% of relative humidity, (HR), the pellets were injected to produce ISO/R 527 standardised samples for tensile tests. These samples were conditioned in the same way as the pellets, before determining the mechanical properties and the moulding shrinkage of these fully biodegradable materials. The automatic injection mode for production of samples was only possible with pellets lubricated with magnesium stearate. This formulation is considered hereafter as the reference injection grade. The rheological study in this paper emphasises, all other factors being equal, that the injection parameters depend on the relative humidity of the conditioning atmosphere of the pellets.     

Influence of Citric Acid on the Properties of Glycerol‐plasticized dry Starch (DTPS) and DTPS/Poly(lactic acid) Blends

In the presence of citric acid (CA), one‐step extrusion processing is used to prepare poly(lactic acid)/thermoplastic dry starch (PLA/DTPS) blends (50/50, %, w/w) in a single‐screw extruder. The rheological study proves that CA decreases the viscosity of both DTPS and of DTPS/PLA blends. The low viscosity increases the dispersion and decreases the interfacial tension between DTPS and PLA, as shown by scanning electron microscopy (SEM). In the presence of CA, the tensile strength of DTPS/PLA reaches 41 MPa—similar to that of pure PLA—because of improved dispersion and compatibility. At the same time, CA increases not only the degradation of starch, but also the interaction between DTPS and PLA, as detected by Fourier transform infrared (FTIR) spectroscopy. The blend containing CA has a higher thermal stability. The water absorption of DTPS and DTPS/PLA blends is also studied.     

糯玉米交联羧甲基淀粉的制备

以糯玉米淀粉为原料，采用乙醇溶剂法，在碱性条件下，合成了交联羧甲基复合变性淀粉，并对制备条件进行探索。研究表明，最佳工艺条件为n（淀粉）：n（氯乙酸）：n（氢氧化钠）=0．3：0．2：0．9，按此条件可制备出取代度0．86的糯玉米交联-羧甲基（CCMS）复合变性淀粉。     

Preparation and Evaluation of Some Cationic Starch Derivatives as Flocculants

Six types of cationic starch derivatives bearing different types of amino groups, i.e., primary, secondary and tertiary or quaternary ammonium salt, were prepared and evaluated as flocculants. Native and hydrolyzed maize starches were used as parent materials for these derivatives. The different factors affecting flocculation were studied. These factors include (a) flocculant dose, (b) pH of the flocculation medium, (c) chemical formula of the flocculant and (d) type of cationic starch, its molecular weight and nitrogen content.     

柠檬酸甘油共混热塑性淀粉的制备及性质研究

以糯米淀粉为原料,加入甘油、柠檬酸制备热塑性淀粉。通过试验得到热塑性淀粉制备的最佳工艺条件,即反应时间60 min、反应温度120℃、柠檬酸与糯米淀粉质量比为0.4∶1、甘油与糯米淀粉质量比为0.3∶1,热塑性糯米淀粉达到最高取代度0.118。并通过红外图谱分析和差示扫描量热检测,证明柠檬酸甘油共混制备的热塑性糯米淀粉与原糯米淀粉相比透明度明显提高,黏度显著降低。处理后的淀粉发生了部分酯化反应,其热稳定性明显提高,增强了热塑性糯米淀粉的生产加工能力。     

淀粉聚氨酯增强剂的合成与应用

以淀粉作为软段,与甲苯-2,4-二异氰酸酯（TDI）反应合成聚氨酯预聚体,然后用咪唑作为封端剂,再进行乳化,最后进行湿部添加实验。结果表明,纸张的抗张强度和耐破度随淀粉聚氨酯添加量增加而提高,随pH的升高而下降,但纸张的耐折度随淀粉聚氨酯的加入而降低。     

Study of the Thermoplastic Wheat Starch Cationisation Reaction under Molten Condition

This paper deals with the functionalization of thermoplastic wheat starch with cationic groups under the action of thermo‐mechanical energy. Two reagents, leading to the same reactive species, are used: 3‐chloro‐2‐hydroxypropyltrimethylammonium chloride and 2‐epoxypropyltrimethylammonium chloride. An experimental study and a theoretical approach for reactive extrusion operations were carried out in a bench‐top twin‐screw microcompounder. The theoretical model developed is in satisfactory agreement with the experimental results obtained in the molten state, with low water content. Reaction kinetic studies, performed at different temperatures between 100 and 140°C, show that starch cationisation follows a second order reaction, with rate constants following the Arrhenius law. The obtained results allow calculation of the values of activation energy. The analysis of the thermoplastic unmodified and modified cationic starches by size exclusion chromatography (SEC) shows a decrease of the excluded fraction, which is attributed to the effect of the thermo‐mechanical melting process. The X‐ray diffraction spectra typical of molten starches were obtained.