一种新型热塑性淀粉衍生物的制备方法

由于淀粉及其衍生物一般都具有可生物降解,无毒或毒性小,原料易得等方面的优势,以淀粉及其衍生物单独,或作为添加剂与塑料等其它材料复合开发可降解等功能性材料的研究愈来愈受到重视。以淀粉衍生物作为添加剂与非降解性塑料等复合制备可降解材料时,淀粉衍生物的热生是一项非常重要的指标。我们介绍一种平均分子量为50万左右,具有良好的热塑性的新型羟丙羟乙基改性淀粉的制备方法,该产品有望单独,或作为添加剂之一与塑料等混炼,开发出可降解性功能材料。     

热塑性淀粉耐水性的化学与物理作用机制

石油资源的短缺以及减轻石油基聚合物所产生的环境负担的必要性,推动了生物可降解材料的开发和生产。近几十年来天然聚合物由于无毒性、可生物降解性和生物相容性正在某些领域取代目前的合成聚合物。淀粉由于其可再生性、可生物降解性、低成本和易获得性已经被广泛研究用于制造可生物降解的复合材料,应用于农业、食品、医药和包装行业。但淀粉的多羟基结构赋予其很强的亲水性,这种湿度敏感性限制了它们的机械性能并影响到其应用。本文主要从提高热塑性淀粉耐水性的物理与化学作用机理的角度出发,总结和归纳了近年来国内外以提高热塑性淀粉材料的耐水性能和降低其对环境湿度敏感性为目的的研究工作,介绍了影响耐水性能的相关因素以及改善方法,并指出今后研究工作的发展方向。     

热塑性淀粉的制备、性质及应用研究进展

淀粉由于可降解、来源广泛、价格低廉、可再生而被认为是最具发展前景的生物降解材料之一,因此,热塑性淀粉材料的研究与开发备受关注。本文综述了近年来热塑性淀粉材料的研究进展情况,内容主要涉及了热塑性淀粉的制备、性质和应用。     

热塑性淀粉的制备及其结构与性能

热塑性淀粉的制备及其结构与性能;流变性能;生物降解     

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.     

热塑性淀粉力学性能的提升途径及作用机理

以可再生资源(如淀粉、纤维素和蛋白质等)为基础发展而来的生物可降解塑料受到人们越来越多的关注,是可降解塑料行业发展的重要方向之一。天然淀粉由于来源广、低成本和可生物降解的特点,广泛用于制备淀粉塑料,并用于农业、食品、医药和包装等行业,有望取代石油基衍生聚合物。淀粉大分子具有结晶结构,所含大量羟基可形成较强的分子间和分子内氢键,使其不能热塑加工,而当加入增塑剂后可破坏其结晶结构,从而用于制备热塑性淀粉。目前,热塑性淀粉的力学性能差,是影响其使用性能的首要问题。近年来国内外开展了大量的研究以试图增强其力学性能。本文主要以不同类型的热塑性淀粉为基础,以淀粉自身改性和外加组分改性两种提高其力学性能的途径为主线,以其力学性能的提升方法和作用机理为重点,系统总结了近年来国内外以提高热塑性淀粉材料的力学性能为目的的研究工作,归纳了影响力学性能的相关因素以及提升途径,并对该领域重点研究的内容进行了总结和展望。     

尿素和甲酰胺塑化热塑性淀粉

用甲酰胺和尿素作为塑化剂制备了热塑性淀粉 (TPS) .扫描电镜显示甲酰胺和尿素混合物可以使淀粉塑化 ,形成均一的连续相 ;根据FT IR谱图可以确定 ,与甘油相比 ,甲酰胺可以使热塑性淀粉体系在保存时更稳定 ,各基团的化学环境变化更小 ,这是由于甲酰胺可以和淀粉羟基形成更稳定的氢键 .X ray衍射说明甲酰胺和尿素 (重量比为 10 % 2 0 % )作为混合塑化剂可以有效抑制淀粉的回生 ,同时防止尿素结晶析出 .在RH=33%的湿度环境保存 1周 ,这种热塑性淀粉有良好的拉伸强度、伸长率和断裂能 ,分别达到 4 83MPa ,10 4 6 %和 2 17N·m .水含量对热塑性淀粉的力学性能的影响也被研究 .另外 ,热失重实验和吸水实验说明这种热塑性淀粉的热稳定性和耐水性也要优于常用的甘油塑化热塑性淀粉     

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.     

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．     

Thermoplastic Starch

The thermoplastics processing of native starch in the presence of water is a recent development with very wide possible applications. Eventually, oil-based polymer materials have to be replaced in many applications by sustainable, inexpensive, natural materials from renewable resources. The present contribution focuses on the injection moulding of starch. The bases of the processing and the thermal and molecular changes occurring are described. In addition, the rheological behaviour of starch-water melts during processing is analysed quantitatively to give apparent melt viscosities. The dimensional, thermal and mechanical properties of moulded thermoplastic starch polymer (TSP) materials and the products presently being produced from them are discussed.     

热塑性淀粉材料的表面疏水化反应

用反应性试剂 (TDI/蓖麻油预聚体 )对热塑性淀粉材料 (TPS)表面进行了疏水化处理。研究了预聚体与 TPS表面的反应性、涂层的疏水性能以及涂层的形貌。红外光谱 (IR)分析结果表明 ,预聚体与 TPS之间发生了反应 ,为反应性涂层 ;样品表面的接触角变化速率由原来的 3 .90°/ min变为 0 .3～ 0 .4°/ min,表明 TDI/蓖麻油体系涂层样品表面的疏水性能与 TPS相比有了很大的改善。涂层液的粘度及 n(— NCO) / n(— OH)比例对材料厚度等性能有很大的影响 ,n(—NCO) / n(— OH)为 2时 ,涂层表面光滑透明 ,韧性好 ,具有良好的综合性能 ;n(— NCO) / n(— OH)大于 2时 ,涂层表面粗糙且脆。涂层厚度可以通过改变涂层预聚体的粘度来进行调节。     

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.     

The Influence of Pair Spiral Extrusion Equipment on Thermoplastic Potato Starch

Owing to contain a great deal of hydroxyl in Potato Starch, between the molecules and inside of molecules have very strong hydroxyl action. Thus, the liquate temperature is higher than disintegrate temperature, so it is difficult to process. Under the microscope, the microcosmic construction is a polar crystal molecule, and it appears globe predicament.To make the original potato starch into possession thermoplastic, we must make molecule of starch to change construct into amorphous state to form thermoplastic starch colophony. Besides auxiliary agent, shearing stress, temperature, time, pressure and hydrous quantity can affect the quality of starch thermoplastic too. The pair spiral extrude machine is used widely as the machines that are based of the pressure difference, and this extrude course may suffice require.Using the machine of pair spiral extrude of specific combination in the test of thermoplastic starch, the potato starch can be turned into thermoplastic starch of denaturalization preferably under auxiliary agent, shearing stress, temperature, pressure and the certain hydrous quantity.By the action of the technology process condition and the spiral combination, potato starch grains expand and fragmentate; hydroxyl bond cleave between and inside of molecules. Thus, crystallize state is changed into amorphous state. The transmutation of starch molecule property may be seen clearly from X diffraction chart and analyses of the construction property,By means of the denaturation, the crystal area of potato starch is broken,its crystallization degree is decreased,and its molecular chains are in amorphous state. The hydrogen bond among the molecular chain is broken or removed so that the starch structure is changed, making the starch thermoplastic.The processing of thermoplastic starch advances a higher requirement of ingredient water content, and technical conditions. A remodeled twin-screw extruder is used to create an environment to realize the condition of denaturalizing and plasticizing reactions. After the continuous probing, we have successfully developed three types of thermoplastics starch plastic from the potato starch (starch content of all of them is greater than 90%). The fluidity of the thermoplastics starch will be better if the processing is performed under the condition of 4.0-6.0Mpa (pressure) and 80-110℃ (temperature). By doing so, it is shown that there is the possibility of further thermoplastic fabrication upon it.     

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。     

Use of Thermoplastic Starch in Continuous Pharmaceutical Process

Controlled release formulations of thermoplastic starch (TPS) matrix were prepared by extrusion granulation and injection molding of tablets. The compositions contained glycerol, water and on occasion urea plasticizers, glycerol-monostearate; Ca-stearate lubricants and Na-benzoate drug representing component, in addition to the starch. The lubricants and especially the urea reduce the complex viscosity of the TPS considerably facilitating the injection molding process-ability. DSC thermal analysis demonstrated, the urea is in a molecular dispersed form in the extruded granules and Raman microscopic mapping showed an under micron sized dispersion of Na-benzoate in injection molded tablets. Both the extrusion and the injection molding processing resulted retard release character of the active component.