纳米二氧化硅/淀粉/聚乳酸三元复合材料力学性能研究

主要是对淀粉进行增韧改性,研究共混改性后对力学性能的影响。首先是制备不同含量的淀粉/聚乳酸共混材料,通过双螺杆挤出机进行挤出、造粒,在通过注塑机将共混材料注塑成样条,对注塑的样条进行力学性能测试,检测其拉伸强度、断裂伸长率。选出性能做好的一组材料,得到最佳的加工工艺。研究结果表明:在淀粉/聚乳酸共混体系中,随着偶联剂与纳米二氧化硅的增加,共混体系出现了曲线形的变化,随着聚乳酸含量的增加断裂伸长率升高再降低,由此得到了偶联剂、纳米二氧化硅的最佳配比,淀粉与甘油含量的最佳配比。由力学性能得到淀粉材料通过改性后的力学性能优于没有改性前,有明显的断裂伸长率,缓解了全淀粉断裂伸长率低的特点。     

聚乳酸/羟丙基淀粉复合降解型材料的制备和表征

羟丙基改性淀粉作为填充剂,在偶联剂作用下与聚乳酸共混、挤出制备聚乳酸/羟丙基淀粉复合降解型材料。随着羟丙基改性淀粉含量的增加,共混材料的硬度略有增加、拉伸强度和断裂伸长率都先减小后增大,材料的吸水率和降解速率增加,且改性淀粉取代度的增加有利于提高材料的韧性。     

聚丁二酸丁二醇酯/淀粉共混物改性研究进展

综述了国内外制备聚丁二酸丁二醇酯(PBS)/淀粉共混物改性的研究进展,主要包括直接共混体系,增塑改性体系,增容改性体系以及淀粉纳米晶对于PBS的改性作用。增容改性体系中,通过不同的增容方法,基体与淀粉之间产生较强的界面作用力,力学性能得到了大幅提高。并对PBS/淀粉共混物改性存在的问题进行了总结,展望了其发展趋势。     

聚羟基烷酸酯共混改性研究进展

介绍了聚羟基烷酸酯(PHA)的性能特点以及不足,分别探讨了PHA与天然高分子材料、人工合成高分子材料以及纳米粒子的共混改性研究进展,例如淀粉、丁酸纤维素、聚己内酯、聚碳酸丙烯酯、有机蒙脱土、碳纳米管等。并就共混体系的相容性、结晶性、机械性以及热稳定性进行了总结和评述,展望了PHA的改性方向。     

PVA/接枝改性淀粉热塑性生物降解材料的制备及应用

以过硫酸铵为引发剂,采用固相法合成了乙酸乙烯酯(VAC)/玉米淀粉接枝共聚物.将其与聚乙烯醇(PVA)、加工助剂在流变仪中共混,制备了PVA/接枝改性淀粉热塑性生物降解材料;分别研究了淀粉接枝共聚物对PVA/淀粉/接枝改性淀粉共混物的加工流动性、耐水性、力学性能和生物降解性能及形态结构的影响.结果表明,PVA/淀粉/接...     

淀粉改性及其与聚乙烯共混

分别采用偶联剂处理和反应共混方法对玉米淀粉进行了改性,研究了偶联剂处理淀粉的疏水性和加工性能,考察了改性淀粉的工艺条件及其与线性低密度聚乙烯(LLDPE)共混物的力学性能。结果表明,在硅烷偶联剂、钛酸酯偶联剂和铝酸酯偶联剂中,用硅烷偶联剂处理淀粉的效果较好;硅烷偶联剂处理淀粉的疏水性得到了较大的提高,其与低密度聚乙烯共混时,体系的熔体黏度变小。淀粉和丙烯酸丁酯或甲基丙烯酸甲酯在130℃高温密炼机中共混6 m in,可制得丙烯酸丁酯改性淀粉和甲基丙烯酸甲酯改性淀粉,使用少量的改性淀粉即可明显提高LLDPE/淀粉共混物的扯断伸长率,拉伸强度变化不大;该改性淀粉对LLDPE/淀粉的共混起到增容剂的作用。     

改性淀粉/聚乳酸复合材料的制备与性能表征

采用接枝共聚-共混法制备了丙烯酸接枝淀粉/聚乳酸复合材料。通过拉伸强度测试、红外光谱、X射线衍射以及扫描电镜等对共混物进行分析,研究了复合材料的力学性能、结晶性、吸水性以及降解性能。结果表明,相对于未改性的淀粉/聚乳酸材料,经过接枝丙烯酸的淀粉/聚乳酸复合材料拉伸强度提高,结晶度减小,吸水性增加。SEM分析表明,经丙烯酸接枝改性后的淀粉与聚乳酸之间的相容性有较大提高,降解速率变缓。     

改性淀粉/LLDPE共混体系生物降解材料性能的研究

将自制接枝改性淀粉与LLDPE、玉米淀粉以及另外两种相容剂进行共混。通过对共混体系的形态结构、力学性能、流变性能、热性能以及对共混物薄膜的生物降解性能等的研究说明:复合相容剂MAH-g-PE+LA-g-starch的加入改善了淀粉和LLDPE的相容性,使得共混物体系具有适宜的拉伸强度及断裂伸长率;LLDPE/淀粉/(MAH-g-PE+LA-g-starch)共混物薄膜具有很好的生物降解性能。     

PVA与丁二酸酯化淀粉共混膜的力学性能

制备了不同改性程度的丁二酸酯化淀粉,并与聚乙烯醇（PVA）以溶液共混法制备了丁二酸酯淀粉/PVA共混膜,通过X射线衍射仪表征共混膜与酯化膜的结构,通过扫描电子显微镜观测其表面结构,并测试了共混膜的力学性能。结果表明,丁二酸酯化改性程度、PVA分子结构以及酯化淀粉/PVA的共混比对共混膜的力学性能有影响;随着改性程度的增加,共混膜的断裂强度及断裂伸长率均增大;随着PVA聚合度与醇解度的增大,共混膜的断裂强度及断裂伸长率均增大;随着淀粉含量的增加,共混膜的断裂强度先减小后增大,断裂伸长率逐渐减小;当共混比为50:50时,断裂强度最小。     

含改性抗菌粉的EVA/淀粉复合发泡材料的制备及其性能表征

用偶联剂对抗菌粉进行表面处理,通过模压发泡制备出具有抗菌性能的乙烯-醋酸乙烯共聚物(EVA)/淀粉复合发泡材料。考察了偶联剂的改性效果,改性抗菌粉对熔体质量流动速率、共混物以及发泡材料的形态、发泡材料力学性能和抗菌性能的影响。结果表明,钛酸酯偶联剂改性效果最好,体系相容性变好,力学性能得到提升,材料抗菌性能良好。     

Polyethylene-octene elastomer/starch blends: miscibility,morphology and mechanical properties

In this paper, polyethylene-octene elastomer (POE) and starch blends were studied. The compatibility beyween POE and starch was improved by adding polyethylene-octene/maleic anhydride graft copolymer (POE-MA) as compatibilizer. The compatibilization reaction was followed by FTIR spectra. The morphology of the blends was investigated using scanning electron microscopy (SEM). It was found that the size of the starch phase increased with an increasing content of starch for the blends. The addition of POE-MA can lower the size of the starch phase in the POE matrix, and this was due to the formation of an ester carbonyl function group by the chemical reaction between the anhydride groups and hydroxyl groups on starch. This was reflected in the mechanical properties of the blends, the addition of POE-MA compatibilizer can improve the mechanical properties of POE/starch blends. The thermogravimetric analysis of POE/starch blends was also conducted.     

Properties of blends of starch and synthetic polymers containing anhydride groups

Corn starch was blended with styrene maleic anhydride copolymer (SMA), ethylene-propylene-g-maleic anhydride copolymer (EPMA), and corresponding nonfunctional polystyrene and ethylene propylene copolymers. The concentration of starch in the blend was varied between 50 and 80% by weight. The torque generated during blending is reported increasing starch content for starch/SMA blends: the reverse was true for starch/EPMA blends. The torque was higher for the blends of the anhydride functional polymers compared to the blends of corresponding nonfunctional polymers. Water absorption of the blends increased with an increase in the starch content. Starch/SMA blends made at higher mixer speed or time were more water sensitive. Blends containing EPMA absorbed less water than SMA blends containing the same weight fraction of starch. Tensile strengths of blends containing functional groups were superior compared to the blends made from nonfunctional polymers. When the starch contents increased from 60 to 70%, the tensile strength remained unchanged for SMA blend but increased for EPMA blend. All samples supported the growth of microorganisms, which increased with increasing starch content. © 1994 John Wiley & Sons, Inc.     

Morphology,thermomechanical properties,and biodegradability of low density polyethylene/starch blends

The biodegradability of low density polyethylene (LDPE)/starch and LDPE/starch/starch acetate (STAc) blends was tested and observed to be dependent on STAc content. The binary and ternary blends containing up to a maximum concentration of 30% starch were examined for their thermal, mechanical, and morphological properties. The blends with no STAc or 2.5% STAc show almost no adherence of two phases. With 10% STAc, dispersion of starch was observed to increase with some adherence to LDPE. Tensile strength, elongation at break, and Izod impact strength of the blends decreased with increased starch content. However, incorporation of STAc along with starch improved all these properties, particularly elongation at break and toughness. The melt flow index was also improved on partial substitution of starch by STAc. Maximum biodegradability was observed for the blends containing 30% (starch + STAc). Cell growth was observed to increase with increasing concentration of (starch + STAc) in the blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2791–2802, 1999     

Preparation and properties of biodegradable poly(butylene succinate)/starch blends

The vital differences between the use of untreated starch and gelatinized starch in blends with poly(butylene succinate) (Bionolle) were thoroughly examined in this study. The melting temperature decreased slightly with increasing dosages of untreated and gelatinized starch. The added starch perhaps tended to disrupt the intermolecular hydrogen bonding within the Bionolle matrix. On the other hand, a large increase in the crystallinity was seen with the addition of starch. Starch appeared to play a nucleating role in the blends. The trend of the glass‐transition temperature decreasing with the starch level was similar to the trend of the melting temperature. For the same starch content, the glass‐transition temperature showed some variations. For blends containing a certain amount of gelatinized starch, the thermal stability remained to a certain degree but continued to decrease. This was ascribed to the relatively low heat stability of starch. As for the mechanical properties, a significant increase in the tensile strength (up to 2 times) was observed when untreated starch was replaced with gelatinized starch in the blends. Similarly, the tear strength increased up to 1.5 times if gelatinized starch was employed. Apparently, the gelatinization of starch was efficiently achieved for promoting its compatibility with Bionolle. In all cases, the mechanical properties of Bionolle blended with gelatinized starch were better than those of Bionolle blended with untreated starch. A morphological investigation provided evidence in support of these findings. This relatively low‐cost gelatinization approach provides an alternative to a high‐cost compatibilizer approach for improving the performance of biodegradable blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 257–264, 2005     

Tensile properties,morphology, and biodegradability of blends of starch with various thermoplastics

In the present study, blends of starch with different thermoplastics were prepared by a melt blending technique. The tensile properties and morphology of the blends were measured. It was found that with increasing starch content in starch/ionomer blends, the tensile strength and modulus increase. But for starch/low‐density polyethylene (LDPE) and starch/aliphatic polyester (APES) blends, tensile strength and modulus decrease with increasing the starch loading. Elongation at break values of all the blend systems decrease with increasing starch loading. The scanning electron micrographs (SEM) support the findings of tensile properties. Better homogeneity is observed in starch/ionomer systems compared with that in starch/APES and starch/LDPE systems. Up to 50% starch content, the starch/ionomer blends appear as a single phase. The extent of phase interactions of starch/APES system lies in between the starch/LDPE and starch/ionomer systems. From the biodegradability studies of the blends it was found that, although the pure LDPE and ionomer are not biodegradable, the starch/LDPE and starch/ionomer blends are biodegradable with an appreciable rate. The rate of biodegradation of the starch/APES is very high as both the components are biodegradable. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2907–2915, 2002     

Biodegradable polymer blends of poly(L‐lactic acid) and gelatinized starch

Gelatinized starches were prepared with various content of glycerol and were investigated in terms of the effect of the glycerol addition on characteristics of starch and its blends. Poly (L‐lactic acid) (PLA) with various ratios of linear/star shaped PLA and starch gelatinized with various ratios of water/glycerol were melt‐blended by using twin screw mixer. The blends were characterized by DSC thermal analysis, tensile test and morphological analysis. Gelatinization of starch was found to lead to destruction or diminution of hydrogen bonding in granules and a decrease of crystallinity of starch. DSC data showed that starch played a role as a nucleating agent and glycerol as plasticizer contributed to an improvement in crystallinity in PLA blends. When the content of starch increased, the size of spherulites in PLA blends was smaller and less regular. In the case of PLA/pure starch blends, the voids appeared, which were formed by the separation of starch particles from the matrix. But for PLA/gelainized starch blends, these voids were not observed. In the case of blends with linear PLA and starch gelatinized with water/glycerol ratio of 100/40, the greatest superiority of mechanical properties was shown and the toughness was improved compared with PLA/pure starch blends.     

Properties of blends of starch and synthetic polymers containing anhydride groups. II. Effect of amylopectin to amylose ratio in starch

Corn starch with different amylopectin to amylose ratios was blended with styrene maleic anhydride copolymer (SMA) and ethylene–propylene-g-maleic anhydride copolymer (EPMA). The starch had an amylose content of approximately 0, 50, and 70%. The concentration of starch in the blend was kept constant at 60% by weight. The samples were melt blended in a corotating twin screw extruder. Scanning electron micrographs showed that the amount of starch granules remaining in the samples varied with the torque. Optical micrograph showed that starch/EPMA blends formed a cocontinuous phase in all blends irrespective of starch variety. For starch/SMA blends, the starch granules remained dispersed in the SMA phase. The torque during blending, tensile strength, water absorption, storage and loss modulus, and data on biodegradability of the blends are presented. Tensile strength and water absorption correlated well with the torque generated during blending: the higher the torque, the lower the tensile strength and the higher the water absorption. The tensile strength of blends containing SMA decreased when the humidity increased. Fractured surfaces of starch/SMA blends exhibited brittle failure; for the ductile starch/EPMA blends, shear tearing appeared to be the major failure mechanism. For blends containing EPMA, the percentage elongation increased with increased humidity. Dynamic mechanical analysis of the blends showed two sharp peaks for tan δ vs. temperature plot for starch/EPMA plots, but showed a single peak for starch/SMA blends. Starch/EPMA blends had a higher percentage of water aborption that became constant after 20 days. Using the ASTM test method D5902, the starch content in the samples was found to degrade. © 1995 John Wiley & Sons, Inc.     

Tailoring the morphology and properties of poly(lactic acid)/poly(ethylene)‐co‐(vinyl acetate)/starch blends via reactive compatibilization

Poly(lactic acid)/poly(ethylene‐co‐vinyl acetate)/starch (PLA/EVA/starch) ternary blends were prepared by multi‐step melt processing (reactive extrusion) in the presence of maleic anhydride (MA), benzoyl peroxide and glycerol. The effects of MA and glycerol concentration on the morphology and properties of the PLA/EVA/starch blends were studied using scanning electron microscopy, transmission electron microscopy, atomic force microscopy, the Molau experiment, dynamic mechanical thermal analysis and differential scanning calorimetry etc. The plasticization and compatibilization provided a synergistic effect to these blends accompanied by a significant reduction in starch particle size and an increase in interfacial adhesion. Starch was finely dispersed in the ternary blends with a dimension of 0.5 ? 2 µm. Furthermore, EVA‐coated starch or a starch‐in‐EVA type of morphology was observed for the reactively compatibilized PLA/EVA/starch blends. The EVA with starch gradually changed into a co‐continuous phase with increasing MA concentration. Consequently, the toughness of the blends was improved. Since property stability of starch is an issue, the tensile properties of these blends were measured after different storage times and the blends showed good property stability. Copyright © 2012 Society of Chemical Industry     

Structural,thermal and physico-chemical properties of high density polyethylene/natural rubber/modified cassava starch blends

The utilization of cassava starch as one of the components in high density polyethylene (HDPE)/natural rubber (NR) blends were investigated. The true challenge in producing new materials based on natural resources is to design materials that could level the mechanical properties of existing conventional polymers. In this study, we have focused on characterizing the HDPE/NR blends incorporated with cassava starch in the form of granulates (native and silanized) as well as plasticized starch. Cassava starch acted as a biodegradation component in the HDPE/NR blends and the incorporation of cassava starch reduced thermal stability and the degree of crystallinity in general. Several series of cassava starch modifications were performed in order to improve the final properties of the blends. Cassava starch was treated with a silane coupling agent, and proved to be effective in improving tensile strength. The better dimensional stability and compatibility between the blend phases were obtained in the silane-treated cassava starch, as observed in the dynamic mechanical analysis results. Cassava starch was also converted into a plasticized form (TPS), and from the results, the degree of TPS adhesion at the inter-phase ofthe HDPE/NR-TPS blend was clearly improved, as indicated in the morphology study. Through the comparison of thermal degradation results, the HDPE/NR/TPS blends proved to be superior to the HDPE/NR/particulate starch counterparts.     

In situ compatibilization of starch-zein blends under shear flow

Starch-zein blends show poor adhesion between the two phases. Aldehyde starch was investigated as compatibilizer for these blends. Wheat starch was oxidized under mild conditions using sodium hypochlorite in the presence of the 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) and NaBr to prepare aldehyde starch. The oxidized starch was characterized by Nuclear Magnetic Resonance and Rapid Visco-Analyzer. Starch-zein blends plasticized with water and glycerol were prepared using simple shear flow in an in-house developed shearing device. Different zein ratios were tested to study the influence of aldehyde starch on the properties of the final material. The morphology of the blends was observed with confocal scanning laser microscopy and scanning electron microscopy. Tensile tests were used to evaluate the performance of the material. Both microscopy and tensile tests indicated that the blends had improved adhesion between the zein and starch phases, probably by reaction between the aldehyde groups in the starch molecules and zein. The aldehyde starch also influenced the properties of the starch matrix (higher viscosity, larger breakdown), which shows that physical or chemical crosslinks were formed inside the starch matrix.