超声对不同粒径二氧化硅改性热塑性木薯淀粉的影响

通过熔融共混模压法制得了热塑性木薯淀粉(TPS)/SiO₂复合材料。采用DSC、偏光(PLM)、水接触角、TG、SEM、FTIR、XRD考察了超声作用下不同粒径(0.02、0.2、23μm)SiO₂对热塑性木薯淀粉的回生熔融焓、回生速率、回生指数及球晶形态结构、水接触角、热稳定性的影响。结果表明,超声作用使TPS/SiO₂复合材料的熔融焓增加、回生速率提高、回生指数降低,且添加粒径0.02μm SiO₂制得TPS/SiO₂复合材料的回生速率提升幅度最大;超声作用使TPS/SiO₂复合材料球晶变得明显、水接触角提高;超声作用使复合材料的水分容易挥发,甘油与淀粉的结合能力增强,淀粉的分子结构稳定性增加;超声作用使SiO₂粒子在基体中聚集减少、分散更好;复合材料的回生程度增加,双螺旋结构减少;复合材料呈现出A+V晶型,超声作用后,复合材料V晶型增加、A晶型减少。     

二氧化硅粒子对热塑性木薯淀粉稳定性能的影响

通过添加二氧化硅(SiO2)到木薯淀粉(TPS)中,采用熔融共混法制备热塑性TPS/SiO2复合材料,研究复合材料的吸水性、生物降解性和熔融行为。结果表明,随着SiO2添加量的增加,TPS吸水率呈下降趋势,且添加经过硅烷偶联剂(KH550)表面处理后的纳米SiO2比未处理的吸水率低。随着生物降解时间的增加,TPS/SiO2复合材料的生物降解率提高;随着SiO2用量的增加,TPS的生物降解率呈下降变化,且SiO2表面处理后能明显提高TPS的生物降解性。随着SiO2用量的增加,TPS的熔融峰增加,且添加SiO2表面处理后的TPS熔融峰比未经表面处理的SiO2高。     

热塑性木薯淀粉/SiO2复合材料回生过程的稳定性研究

通过熔融共混法制备热塑性木薯淀粉/二氧化硅(TPS/SiO_2)复合材料,通过差示扫描量热仪(DSC)研究回生过程中TPS/SiO_2复合材料的熔融焓和熔融峰变化,通过X射线衍射(XRD)和偏光显微镜(POM)研究晶型和球晶形态大小的变化规律,通过热重仪(TG)分析TPS/SiO_2复合材料的热降解行为,并进行自然降解测试。结果表明:随着回生时间增加,TPS/SiO_2复合材料的熔融焓增大、回生程度增加,热降解温度降低、自然降解率增加;球晶大小和晶型随着回生时间变化发生改变。在短期回生过程中,TPS/SiO_2复合材料以淀粉直链分子链结晶为主;在长期回生过程中,部分淀粉分子链发生断裂,有利于淀粉的回生程度提高,但随着回生时间进一步增加,淀粉分子链继续发生断裂降解,使得球晶结构完善程度下降。     

不同表面性质SiO2对热塑性木薯淀粉/LDPE复合材料的稳定性影响

通过熔融法制备热塑性木薯淀粉(TPS)/低密度聚乙烯(LDPE)/二氧化硅(SiO2)复合材料,研究不同表面性质SiO2对复合材料的熔融、结晶行为、亲疏水性及热稳定性变化规律.研究结果表明添加疏水SiO2后TPS/LDPE/SiO2复合材料的熔融峰、结晶峰温度及结晶度高于添加亲水SiO2;添加疏水SiO2后复合材料的接...     

热塑性木薯淀粉/剑麻纤维复合材料在回生过程中的性能

通过熔融共混法制备了热塑性木薯淀粉(TPS)/剑麻纤维(SF)复合材料,研究了TPS/SF复合材料在回生过程中的热行为、拉伸性能、透光率、球晶大小等。结果表明:随着回生时间的增加,TPS/SF复合材料的熔融焓、拉伸强度和透光率增加,外延起始分解温度、质量损失50%时的温度、外延终止分解温度、最大分解速率对应的温度升高;TPS/SF复合材料的球晶随着回生时间增加变得更细密。     

二氧化硅作用下木薯淀粉/聚乙烯醇复合材料的回生行为研究

通过熔融混合法制备了热塑性木薯淀粉(TPS)/聚乙烯醇(PVA)/二氧化硅(SiO_2)复合材料。利用差示扫描量热仪(DSC)、扫描电镜(SEM)、傅里叶红外仪(FTIR)研究SiO_2用量、表面改性前后对TPS/PVA/SiO_2复合材料回生动力学和结构的影响。结果表明:随着回生时间的增加,TPS/PVA/SiO_2复合材料的氢键作用增强,回生程度增加。利用Avrami方法进行回生动力学分析发现,当SiO_2用量为2和7份时可抑制TPS/PVA/SiO_2复合材料回生;而当SiO_2为5份时则促进TPS/PVA/SiO_2复合材料回生。表面改性后的SiO_2与木薯淀粉分子之间形成更强的氢键作用,比未改性SiO_2能起到抑制木薯淀粉回生作用。改性后SiO_2在基体材料均匀分散,且与基体材料具有较好的界面黏结力。     

不同树脂对热塑性淀粉改性的影响

通过对添加不同的树脂改性热塑性淀粉进行X射线衍射XRD图象分析;对添加不同的树脂和不同添加量的改性热塑性淀粉材料的力学性能分析得到实验结果热塑性淀粉和树脂之间的混合只限于物理相的混合,随着树脂加入量的增加,混合从热塑性淀粉的连续相向树脂的连续相、淀粉的分散相转变.拉伸强度、断裂伸长率也经历一个从大到小再变大的过程.     

氨基表面改性二氧化硅/热塑性淀粉复合材料的制备与性能

为了进一步提高热塑性淀粉(TPS)的力学性能,用硅烷偶联剂KH-550对二氧化硅微球(SM)表面进行氨基化改性(SM-NH₂),并且,添加至热塑性淀粉基体中,得到SM-NH₂/TPS复合材料,研究了添加量对拉伸强度、冲击强度、动态力学性能、热稳定性和流变加工性能的影响。研究发现,当SM-NH₂的添加量为2.0%时,复合材料的拉伸强度由3.25 MPa增大至9.28 MPa,冲击强度由6.222 kJ/m²增大至14.635 kJ/m²;玻璃化转变温度T_α达到最大,其值为53.67℃;微商热重曲线中最大分解速率对应的温度为321.8℃,热稳定性最佳;扭矩峰值和平衡扭矩分别为47.23 N·m和10.86 N·m,流变加工性能下降。     

热塑性木薯淀粉/PVA/SiO_2共混材料的稳定性能研究

通过添加聚乙烯醇(PVA)、二氧化硅(SiO2)到木薯淀粉中,采用熔融密炼法制备热塑性木薯淀粉(TPS)/PVA/SiO2共混材料,研究共混材料的吸水性、生物降解与熔融行为。研究结果表明:随着SiO2用量的增加,TPS/PVA/SiO2共混体系的吸水率增加,TPS/PVA(1799)/SiO2共混材料的吸水率高于TPS/PVA(1788)/SiO2共混物。表面改性后SiO2的TPS/PVA/SiO2共混物的吸水率低于未改性SiO2。随着SiO2用量的增加,TPS/PVA/SiO2共混物的生物降解降低,共混物的熔融峰增高,而熔融焓降低。     

超声波处理对木薯氧化淀粉性质的影响

将超声技术应用于木薯淀粉的氧化改性中,对制得的氧化淀粉的性质进行了考察,并将其与木薯原淀粉、非超声法制得的氧化淀粉的性质进行比较和分析。结果表明:与原淀粉相比,超声法制备的氧化淀粉的溶解度、透明度分别增加了4.55、3.38倍,白度增加了1.23%,凝沉性降低了99.05%;同时,氧化淀粉所成的膜性能良好、均匀有韧性,而原淀粉难以成膜;超声法制备的氧化淀粉的糊化焓与原淀粉相比降低了45.79%。其他条件相同时,采用超声处理可以使氧化淀粉的溶解度、透明度分别提高97.23%、33.68%,白度增加0.26%(在显著水平α=0.05具有显著差异),凝沉性最大可降低78.80%,糊化焓降低了24.13%。因此,超声技术可以有效地应用于木薯淀粉的氧化改性。     

木薯淀粉纳米晶的结构研究

将木薯淀粉进行H2SO4酸解后制备淀粉纳米晶。用X射线衍射、电子显微镜、红外光谱仪(FTIR)和差示扫描量热仪(DSC)表征酸解后淀粉颗粒的结构,并对其热稳定性进行研究。研究结果表明,木薯淀粉经H2SO4酸解后,淀粉颗粒粒径减小至50～100nm之间;结晶度比原淀粉提高了41%。     

Studies on the properties of Montmorillonite-reinforced thermoplastic starch composites

Montmorillonite (MMT), a kind of reinforced additive and glycerol-plasticized thermoplastic starch (GTPS) were used in the preparation of Montmorillonite-reinforced themorplastic starch composites (MTPSC) with the method of melt extrusion. Scanning electron microscope (SEM) revealed that MMT were uniformly dispersed in GTPS. Fourier Transform infrared (FT-IR) patterns showed that in the MTPSC the C-O groups of starch molecules shifted to the higher wavenumber, while the reactive hydroxyl groups of MMT shifted to the lower wavenumber. That was caused by the cooperation of the strong absorption that existed between MMT and starch molecules and hydrogen bonds that formed between the reactive hydroxyl groups of MMT and the hydroxyl groups of starch molecules. MMT was on the submicron filling transition state and acted as an obstructor. When MTPSC was stored for 14 days at RH (relative humidity)=39%, the tensile strength, Young's modulus and breaking energy of MTPSC were 27.34, 206.74 MPa and 1.723 N m, respectively. It was obvious that the mechanical properties of MTPSC were greatly improved. At the same time, the effect of water content on the mechanical properties was studied. X-ray diffraction revealed that MMT restrained the crystallization of GTPS effectively. Differential thermal analysis (DTA) and water absorption testing showed that the thermal stability and water-resistant properties of MTPSC were better than those of GTPS.     

超临界CO2处理对木薯淀粉结构和性质的影响

采用超临界二氧化碳萃取技术在不同条件下处理木薯淀粉,利用扫描电镜(SEM)、X射线衍射仪(XRD)、布拉班德(Brabender)黏度仪等分析手段,考察超临界处理对木薯淀粉颗粒形貌、膨胀度、结晶结构以及淀粉糊黏度、凝沉性、冻融稳定性等的影响。结果表明,随超临界压力、温度、处理时间的变化,样品颗粒外貌无明显改变,但膨胀度降低,结晶度增大;淀粉糊的凝抗性增强,淀粉凝胶冻融稳定性却降低;Brabender黏度分析显示经超临界处理后的淀粉样品糊化温度小幅度升高,糊峰值黏度降低、热稳定性变化不明显。以上结果说明:木薯淀粉经超临界CO₂处理,存在淀粉分子部分降解,直链淀粉与支链淀粉比例增大等现象,从而导致淀粉的微观结构及凝胶特性等发生改变。     

Effect of graft-copolymerization with poly(acrylamide) on rheological and thermal properties of cassava starch

Graft copolymers of different grafting levels were synthesised by the free radical initiated reaction of cassava starch with acrylamide in presence of ceric ammonium nitrate. The viscosity properties of the native granular starch and the grafted starches were determined using a Rapid visco analyzer (RVA) and rheological properties by frequency sweep test under different conditions using a rheometer. Some of the grafted starches exhibited significantly higher and some others exhibited drastically reduced peak viscosity values irrespective of the percentage grafting. All the grafted starches exhibited very good viscosity stability as evidenced from the highly reduced breakdown and higher final viscosity values in comparison to native cassava starch. Thermal analysis of the pure granular cassava starch and grafted starches was carried out using a differential scanning calorimetry (DSC) and thermogravimetry. DSC studies showed that in comparison to native starch, the grafted starches showed lower temperatures of transition. The thermal stability of cassava starch was enhanced by grafting as observed from the thermogravimetric data. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

木薯淀粉/天然橡胶复合材料制备工艺研究

以木薯淀粉和天然胶乳为主要原料,将木薯淀粉和天然胶乳共混共沉制备木薯淀粉/NR复合材料。研究了制备工艺对复合材料力学性能的影响。结果表明:当木薯淀粉浓度为20%,搅拌速度为450r·min~(-1),搅拌时间为30min和木薯淀粉用量为20份时,木薯淀粉/NR复合材料具有较好的力学性能。     

木薯淀粉废水混凝预处理试验

在对木薯淀粉生产过程中产生的2种主要废水进行混凝试验的研究中,探讨了pH值、混凝剂的种类及混凝剂、助凝剂的投加量对混凝反应的影响.试验表明,2种废水混凝反应最佳pH值范围均为7.0～7.5.一次废水最佳混凝剂为聚铁(PFS),COD去除率约45%,剩余浊度仅为500度;二次废水最佳混凝剂为聚铝(PAC),COD去除率最高可达62%,剩余浊度仅为210度.混凝过程中的沉淀物含有大量的蛋白质和氨基酸,可回收做饲料添加剂.广西年排放淀粉废水约2000万m3,回收的沉淀物按1 000元/t计,每年可获得约3 200万元的产值.     

偶联剂KH-570对木薯淀粉/天然橡胶复合材料性能的影响

采用偶联剂KH-570对木薯淀粉/NR复合材料进行改性,研究了偶联剂KH-570对复合材料结构和性能的影响.结果表明:加入KH-570后,木薯淀粉/NR复合材料的定伸应力、拉伸强度和撕裂强度提高;当KH-570用量为3％时,复合材料的综合力学性能最佳.SEM分析表明,KH-570增强了木薯淀粉与天然橡胶间的界面结合;加...     

Rheological behavior of reactive blending of epoxidized natural rubber with cassava starch and epoxidized natural rubber with natural rubber and cassava starch

Epoxidized natural rubbers (ENR‐25 and ENR‐45) were prepared using the performic epoxidation method. Two‐component (ENR–cassava starch) and three‐component (ENR–NR–cassava starch) blends were prepared. ENR‐25 and ENR‐45 were blended with various quantities of gelatinized cassava starch in the latex state. The pure ENR exhibited lower shear stress and shear viscosity than those of the blends with cassava starch. Furthermore, the shear stress and shear viscosity were increased with an increase in the cassava starch concentration. The chemical interaction between the epoxide groups in the ENR and the hydroxyl groups in the cassava starch molecules might be the reason for the increasing trends of the shear stress and shear viscosity. The blends are classified as compatible blends because of the strong chemical bonding between different phases. SEM micrographs were used to clarify the compatibility. Power law behavior with pluglike flow profiles was observed for all sets of ENR–NR–cassava starch blends. Very low power law index values (<0.34) and highly pseudoplastic fluid behavior were also observed. The log additive rule was applied to plots of zero shear viscosity (consistency index) and the shear viscosity versus the concentration of ENR‐25. Positive deviation blending was observed, which indicates compatible blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1752–1762, 2004     

Effect of potassium persulfate on graft copolymerization and mechanical properties of cassava starch/natural rubber foams

The aim of this study was to improve the mechanical properties of thermoplastic starch foams prepared from cassava starch blended with natural rubber latex by reactive blending. Potassium persulfate was used as an initiator for graft copolymerization between the starch and natural rubber during baking. The starch–natural rubber graft copolymer (starch‐g‐NR copolymer) was successfully produced during both suspension and melt blending based on ¹H‐NMR and FTIR characterization. Natural rubber increased the flexural modulus of starch/natural rubber foams without potassium persulfate, thus indicating the compatibility of the blends. The starch‐g‐NR copolymer, acting as a compatibilizing agent, enhanced the impact strength of foams, but it did not improve the flexural modulus. This may be due to the potassium persulfate decreasing the molecular weight of the natural rubber. Relative humidity also played an important role on the mechanical properties. Foams became more ductile at higher relative humidities. Since foam density increased with an increasing natural rubber content, the specific impact strength was also considered. A soil burial test showed that the cassava starch foams and foams containing 15 pph of natural rubber were fully biodegraded within 8 and 18 weeks, respectively. The starch‐g‐NR copolymer delayed biodegradation of foams and foams containing high natural rubber content, i.e., 35 pph, showed a low ability to be biodegraded. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010