热塑性淀粉中氢键及其对性能的影响

热塑性淀粉中的氢键对热塑性淀粉的性能有决定性的作用．本文利用红外光谱分析甘油或甲酰胺塑化热塑性淀粉中塑化剂和淀粉间的氢键形成情况，发现在淀粉中，与塑化剂形成氢键的主要是C-O-C基团中的氧原子和C-O-H基团中的氢原子；而且过量的塑化剂之间会形成氢键，减弱塑化剂与C-O-C中氧原子的氢键作用．与甘油相比，甲酰胺可以和淀粉形成更稳定的氢键．X-ray衍射研究了氢键对两种热塑性淀粉在不同湿度环境下的回生性能的影响．结果表明甲酰胺可以有效抑制淀粉回生．热动态力学分析(DMTA)研究发现，氢键使甲酰胺塑化热塑性淀粉的玻璃化转变温度更低．氢键使甲酰胺塑化热塑性淀粉强度和杨氏模量低，但伸长率和断裂能大．     

甲酰胺塑化热塑性淀粉的性能研究

用甲酰胺作为塑化剂制备了热塑性淀粉 (TPS) ,扫描电镜显示甲酰胺可以使淀粉塑化 ,形成均一的连续相 ;流变性能说明在加工温度范围内 ,甲酰胺塑化淀粉 (FPTPS)的剪切应力对温度变化敏感性要小于甘油塑化淀粉 (GPTPS) ;用热重和DSC研究了热稳定性和玻璃化转变 ;FPTPS在 13%～ 2 3%的水含量时有较好的力学性能 ,水含量为 13%时 ,FPTPS有最大的断裂强度 3 9MPa ;水含量为 17%时 ,FPTPS最大的伸长率为 95 % ;与GPTPS相比 ,在RH(Relativehumidity) =0 5 0 %and 10 0 %环境下 ,FPTPS有良好的耐回生性能 ,这主要是因为甲酰胺可以和淀粉羟基形成更稳定的氢键     

热塑性淀粉/蒙脱石复合材料性能研究

用柠檬酸活化蒙脱石(CMMT),用尿素和甲酰胺塑化热塑性淀粉(UFTPS),制备了热塑性淀粉/蒙脱石(UFTPS/CMMT)复合材料.广角X-ray衍射(WAXD)、透射电子显微镜(TEM)表明,UFTPS和CMMT形成复合材料.CMMT质量分数2%~10%时,将复合材料在相对湿度50%(RH=50%)的环境下保存10 d,力学测试得出,复合材料的最大拉伸应力达到24.86 MPa,应变为134.50%,杨氏模量和断裂活化能分别由UFTPS的87.25MPa,1.87 N.m上升到复合材料625.25 MPa,2.45 N.m;可以看出,和纯UFTPS相比,复合材料强度明显提高;流变行为研究得出,通过改变加工温度和螺杆挤出机速度可以调整复合材料的流变行为;与传统的甘油体系相比,复合材料很好的抑制了材料长时间放置的结晶行为;并且该材料比纯UFTPS具有很好的耐水性能和热稳定性.     

新型热塑性淀粉的制备和性能

以二甲基亚砜(DMSO)为增塑剂, 通过熔融共混法制备了一种新型热塑性淀粉(TPS), 研究不同增塑剂含量对材料结构和性能的影响, 并与甘油及甘油/水复合增塑淀粉体系进行了比较. FTIR结果显示, DMSO能够与淀粉产生强烈而稳定的氢键相互作用. WAXD和SEM的研究结果表明, DMSO的加入破坏了淀粉的有序结构, 实现了淀粉的塑化, 形成均一的非晶连续相. 同甘油及甘油/水增塑体系相比, DMSO与淀粉的羟基形成更为稳定的氢键, 能够有效抑制淀粉的重结晶. 动态力学和拉伸力学性能测试结果表明, 经过DMSO的增塑, 有效降低了淀粉的玻璃化转变温度, 改善了材料的韧性, 增塑效率要好于甘油及甘油/水复合增塑体系.     

乙酰化淀粉的塑化和性能研究

以乙酰化改性淀粉为基体,甘油为增塑剂,利用哈克旋转流变仪密炼制备热塑性乙酰化淀粉.实验结果表明制备热塑性乙酰化淀粉的甘油/乙酰化淀粉配比应大于30/100(W/W),且随甘油含量增加,热塑性乙酰化淀粉的脆性降低.动态机械热分析(DMTA)显示热塑性乙酰化淀粉包含富甘油和富淀粉两相,乙酰化淀粉和甘油为部分互溶.流变学分析显示淀粉分子间作用力非常强,表现为类固态行为.同时本文对材料的热稳定性进行了初步研究.     

热塑性淀粉/聚乙烯醇/蒙脱土三元纳米复合材料

用熔融挤出的方法制备了甘油塑化热塑性淀粉（TPS）/聚乙烯醇（PVA）/蒙脱土（MMT）纳米复合材料,添加蒙脱土和聚乙烯醇用以提高热塑性淀粉材料的力学性能。 在相对湿度50%的条件下,复合材料的XRD衍射谱图和透射电子显微镜测试表明,MMT以剥离状态均匀分布在TPS/PVA基体中;力学测试表明,当MMT的质量分数从0％增至5％时,复合材料的力学性能明显提高。 当蒙脱土的质量分数为3%时,复合材料最大抗张强度达到13.24 MPa,杨氏模量达到61.46 MPa。 这说明蒙脱土在复合材料中可以起到物理交联点的作用,提高了复合材料的力学性能。     

热塑性甲壳素衍生物N,O-苄基壳聚糖的合成及表征

天然高分子的热塑化一直引起人们的极大关注．由于存在大量的分子内和分子间氢键,一般天然高分子都不能加热塑化,从而限制了其应用．纤维素和淀粉的热塑化改性已有了许多研究．典型的热塑性纤维素衍生物有乙基纤维素、醋酸纤维素和经丙基纤维素等[1,2],有些纤维素衍生物还具有热致液晶性．淀粉的某些衍生物也已有热塑性[3]．在分子结构上,甲壳素／壳聚糖比纤维素或淀粉多了乙酰氨基和氨基,更易形成氢键,分子间作用力更强．迄今,国内外已报道了大量甲壳素／壳聚糖衍生物,但均无热塑性．我们曾合成具有热塑性的氰乙基经丙基壳聚糖,但熔点与分解温度之间只有27℃E4J．热塑性甲壳素的研究不仅为甲壳素的加工利用开辟了新途径,而且也将为热致性甲壳素液晶的研究奠定基础,从而进一步丰富和深化目前以纤维素衍生物为主的热致胆舀液晶研究[5,6]．为此,本文研究了一种新的热塑性甲壳素衍生物,并从结构上讨论了其具有热塑性的原因．     

石墨烯在甘油/尿素剥离液中的稳定行为的分子动力学模拟研究

现有的实验方法很难实时观测到石墨烯在液相剥离溶剂中的结构演变, 尤其是石墨烯稳定的微观机理尚不明确. 本工作通过分子动力学方法, 模拟了多层石墨烯和U型石墨烯在不同的物质的量比下的甘油/尿素溶剂中的结构变化, 研究剥离液对石墨烯稳定性的影响. 结果表明, 多层石墨烯在不同溶剂体系中的稳定性差异不显著; 而U型石墨烯在各溶剂体系的稳定性有明显差异, 且稳定能力为: 纯甘油>甘油/尿素(2/1)>甘油/尿素(3/1)>甘油/尿素(1/1). 这说明石墨烯在剥离溶剂中的稳定性与石墨烯的剥离状态有关. 通过溶剂分布发现, 尿素能够进入石墨烯层间, 增加石墨烯层间距; 同时, 甘油能够与尿素形成氢键, 随尿素进入石墨烯层间, 进一步增大层间距, 从而形成稳定的单层或多层受限二元溶剂分子层. 受限溶剂分子层对剥离的石墨烯存在排斥作用, 从而为石墨烯在甘油/尿素二元剥离液中的长期稳定提供了保障.     

热塑性淀粉/聚丁二酸丁二醇酯合金的制备和结构性能表征

制备了高填充的甘油塑化淀粉（GTPS）/聚丁二酸丁二醇酯（PBS）合金,并对其结构性能进行了表征。结果表明：GTPS/PBS在合金加工过程中其扭矩以及力学性能随PBS质量分数的增加及甘油质量分数的减小而增大;扫描电镜（SEM）显示甘油可提高合金的相容性;动态力学分析（DMA）表明合金在玻璃态时的储存模量高于纯PBS,黏流态时则相反;合金的热稳定性随PBS和甘油质量分数的增加而有所提高;PBS的加入将合金的吸水率由100%以上降低到10%以下;淀粉和甘油的存在则均可提高PBS的降解率。     

蔗糖酯和尿素对淀粉改性的协效作用

蔗糖酯是一种对环境无害的表面活性剂,含有与淀粉相容的极性头.将不同比例蔗糖硬脂酸酯加入到玉米淀粉或20％尿素增塑的玉米淀粉中,在热水中煮浆后浇铸成膜.采用X-射线衍射法表征淀粉膜的结晶结构,并测定了浆膜在不同相对湿度下的吸湿性以及浆膜的拉伸性能.结果表明,蔗糖酯可与淀粉形成V-型包合配合物,并影响淀粉的B-型结晶,因此改变淀粉的吸湿性和力学性能.添加0.5％蔗糖酯使淀粉的吸湿率提高,随着蔗糖酯进一步增加,淀粉的吸湿率下降.含尿素20％的淀粉混合物中添加不同比例的蔗糖酯,对淀粉材料的结晶度、结晶形态,以及吸湿率和力学性能产生了不同的影响.蔗糖酯与尿素对淀粉材料改性具有协效作用.含蔗糖酯0.5％的尿素增塑淀粉膜显示出非晶特征,且具有较高的断裂伸长.     

A Mixed Plasticizer for the Preparation of Thermoplastic Starch

In this paper, formamide was firstly used as plasticizer to prepare thermoplastic starch (TPS), which could suppress the retrogradation of TPS by X-ray diffractometry (XRD) and show a good flexibility, but was weaker than conventional glycerol-plasticized TPS (GPTPS). When urea was introduced into plasticizer, both the retrogradation and mechanical properties were ameliorated. The tensile stress, strain and energy break of TPS plasticized by urea (wt. 20%) and formamide (wt.10%), respectively, reached 4.83 MPa, 104.6 % and 2.17 N-m (Newton-meter) after it had been stored at relative humidity (RH) 30% for one week.     

Synthesis of aliphatic amidediol and used as a novel mixed plasticizer for thermoplastic starch

In this paper,aliphatic amidediol was synthesized and mixed with glycerol used as a plasticizer for preparing thermoplastic starch（AGPTPS）.The yield of aliphatic amidediol was 91%.FF-IR expressed that the mixture of aliphatic amidediol and glycerol formed stronger and stable hydrogen bond with starch molecules compared to the native cornstarch.By scanning electron microscope（SEM）native cornstarch granules were proved to transfer to a homogeneous continuous system.After being stored for a period time at room temperature,the mechanical properties of AGPTPS were also studied.As a mixed plasticizer,aliphatic amidediol and glycerol would be practical to extend TPS application scopes.     

Effect of PHB on the properties of biodegradable PLA blends

Blends of biodegradable polymers polylactic acid/thermoplastic starch/polyhydroxybutyrate (PLA/TPS/PHB) were prepared using a twin-screw extruder. The TPS content was constant (50 %) and the PHB content in the blends was gradually changed from 0 mass % to 20 mass %. TPS was prepared by melting, where a mixture of native starch, water and glycerol was fed into the twinscrew extruder. Average temperature of extrusion was 180°C and the concentration of glycerol was 40 mass %. Influence of the PHB concentration in the blend and that of the processing technology on the mechanical and rheological properties of the PLA/PHB composition containing TPS were studied. Mechanical properties were measured 24 h after the film and monofilament preparation and also after the specific storage time to study the effect of storage on the properties. The results indicate that differences in morphology strongly influence the mechanical properties of the studied materials with identical material composition.     

A Novel Plasticizer for the Preparation of Thermoplastic Starch

TPS was a biodegradable material based on starch. Starch was an inexpensive and natural renewable polysaccharide, which was widely investigated as the substitute of petroleum-derived plastics. Native starch commonly existed in granule structure with about…     

Preparation and Characterisation of Thermoplastic Starches from Cassava Starch,Cassava Root and Cassava Bagasse

Summary: Thermoplastic starches (TPS) based on cassava starch have been produced by extrusion at 120 °C, using glycerol as plasticizer. Three forms of cassava starch were employed, viz: cassava root (CR), cassava bagasse (CB) and purified cassava starch (PCS). The main differences between these are the presence of sugars and a few fibres in CR and high fibre concentration in CB. Conditions of processing and characteristics such as amylose and fibre content, crystallinity, water absorption and mechanical behaviour in the tension x deformation test were evaluated. The results demonstrated that the PCS and CR had amylose contents consistent with literature values (14–18%) and that CB is a material constituted mainly by amylopectin. It was found that fibres in high proportions (as in the bagasse) can confer reinforcement properties and are thus able to generate natural composites of TPS with cellulose fibre. The sugars naturally found in the root reduce the elongation of the TPS under tension. The PCS and CR TPS were stable with respect to indices of crystallinity after processing; and during a period of 90 d in a relative humidity of 53%, while the CB TPS tended to vary its crystallinity, probably because its amylose chain had low degree of polymerization.     

Reducing water absorption in compostable starch-based plastics

To improve the mechanical and physical properties of corn starch-based bioplastics the addition of natural polymers was investigated. Thermoplastic starch (TPS) was made of 70 g corn starch and 30 g glycerol. To this mixture 10–10 g of cellulose, hemicellulose and zein (protein) were added. Mechanical strength, water absorption and enzymatic degradation of composite materials were measured. Unfilled TPS and 10 w/w% polycaprolactone filled TPS were used as controls in the experiments. All the samples were biodegradable by enzymes. The tensile strength of unfilled and biopolymer filled TPS samples were significantly higher than that of the polycaprolactone filled one. Hemicellulose and zein composites had the best mechanical strength (10.4 and 11.5 MPa). Water uptake of each sample was measured using five different relative humidities. There were slight differences in water uptake of polycaprolactone, hemicellulose and zein filled TPS, however unfilled and cellulose filled samples absorbed more moisture than the polycaprolactone control in all the relative humidities used.     

尿素/乙醇胺复配增塑聚乙烯醇性能的研究

采用尿素/乙醇胺为复合增塑剂,利用流延法制备了增塑改性的PVA膜.通过FTIR法研究了尿素/乙醇胺复合体系与PVA的相互作用,采用XRD、DSC考察了增塑改性PVA膜的结晶性能和热性能.研究结果表明,乙醇胺作为尿素的良溶剂,能有效抑制尿素从PVA基体中析出.由尿素、乙醇胺组成的复合增塑剂能破坏PVA分子中的氢键作用、降低PVA的结晶度和熔点,对PVA的增塑作用显著.增塑改性后的PVA膜在水中的溶胀率(DS)下降,溶失率(S)增加.力学性能测试表明增塑改性后的PVA膜拉伸强度(TS)降低,断裂伸长率(E%)提高.含30phr尿素/乙醇胺的PVA膜的拉伸强度、断裂伸长率分别为23.89MPa和542.88%.     

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.