EVA增容改性玉米淀粉／LDPE共混体系的研究

以LDPE和玉米淀粉为主要原料,与EVA熔融共混制备了玉米淀粉／LDPE／EVA共混材料,并对其热学性能和抗张性质进行了研究。DSC分析显示EVA可以明显改善LDPE和淀粉之间的相容性,机械性能也有所改善,在EVA含量为10％时,抗张强度为9．2MPa,断后伸长率为117．4％。     

CaCO3/淀粉/LDPE复合材料流变性能研究

以活化的CaCO3和淀粉两种典型无机和有机粉体与LDPE树脂共混,通过熔融共混法制备了CaCO3/淀粉/LDPE共混物,用毛细管流变仪研究了其流变性能.结果表明CaCO3/淀粉/LDPE共混物属假塑性流体,其表观黏度随剪切速率和温度的增加而减少,随淀粉在CaCO3/淀粉/LDPE共混物中含量的增加而增加.     

HDPE/LDPE复合交联物的热降解研究

采用热重分析仪（TG）考察了高密度聚乙烯（HDPE）／低密度聚乙烯（LDPE）复合交联物的热稳定性。结果显示，HDPE／LDPE复合交联物的热稳定性低于HDPE／LDPE共混物。FTIR分析证实，交联反应使聚乙烯（PE）的支化程度提高，取代基的位阻效应在一定程度上影响了PE的热降解过程。在N2气氛下，HDPE／LDPE共混物及交联物的热降解过程均为一步降解反应。Kissinger法求解HDPE／LDPE共混物及其复合交联物的热降解活化能发现，LDPE质量分数在20％～30％之间变化时，HDPE／LDPE交联物的热降解过程对温度的敏感性发生了突变。     

淀粉细化改性及其与聚乙烯增容性的研究

本文采用将淀粉进行微细化后再对其进行亲油改性，然后再与树脂共混制备可降解性塑料的工艺，可以明显地提高淀粉在树脂中的分散性，提高制品的力学性能，本文对改性工艺条件，改性淀粉及其共混体系的性质进行了研究。     

淀粉/LDPE复合材料制备及性能研究

以低密度聚乙烯为基体树脂,淀粉为可降解改性填料,经双辊精密开炼机熔融共混制备了淀粉/低密度聚乙烯复合材料。研究了淀粉改性前后对LDPE的吸水性和力学性能的影响,以及改性淀粉量对LDPE力学性能的影响。研究结果表明:添加未改性淀粉,LDPE易吸水,力学性能损失大;添加疏水改性淀粉,LDPE与淀粉相容性好,耐水性没有明显变化;相比而言,铝酸酯改性淀粉使LDPE的力学性能损失小,三偏磷酸钠改性淀粉使LDPE的力学性能损失大。     

不同处理方法对淀粉/LDPE共混物性能的影响

通过对淀粉添加偶联剂的表面处理、添加增容剂、熔融接枝和化学交联反应的4种方法处理淀粉/LDPE共混物,采用X光衍射仪、DSC热分析仪和红外光谱分析仪对改性后的体系进行全面分析。并结合不同处理方法对共混物力学等性能的影响进行分析,认为对淀粉添加偶联剂的表面处理、添加增容剂和交联反应均未能明显改变淀粉和聚乙烯两个结晶相混合的状态,而采用丙烯酸单体进行接枝的方法可以降低两相的结晶度,并能较好地提高淀粉和LDPE的相容性,显著提高淀粉/LDPE共混物的力学性能和塑化性能。     

可降解材料对聚乙烯薄膜性能的影响

通过聚乳酸、淀粉分别与低密度聚乙烯(LDPE)共混,制备了具有一定降解性能的PE薄膜.研究了聚乳酸和淀粉对PE薄膜力学性能、熔体质量流动速率、结晶、微观结构等方面的影响.结果表明,聚乳酸和淀粉能提高LDPE复合薄膜的力学性能,降低LDPE的结晶度,对PE的加工性能影响不大.     

淀粉／硬脂酸铈配合体系的降解LDPE包装薄膜的研究

研究了淀粉／硬脂酸铈配合体系的组成，讨论了铝酸酯对淀粉的疏水处理，氧化聚乙烯对淀粉／ＬＤＰＥ共混体系的增容，硬脂酸铈对光氧降解ＬＤＰＥ羰基指数的影响，并对含２０％淀粉，０。４％硬脂酸铈的ＬＤＰＥ包装薄膜进行性能测试和应用试验。     

淀粉/PVA在自然土壤环境下的生物降解性能研究

将淀粉与聚乙烯(醇PVA进)行共混,研究了共混物在自然土埋环境中的生物降解过程。结果表明:淀粉的加入可促进PVA的微生物降解速度,使淀粉/PVA试样在120d后分解成小碎片,失重率达到67.8%;对降解不同时间的淀粉/PVA(60/40)片材进行DSC和TG测试发现,降解使材料结晶度和热稳定性提高,说明体系的降解是在无定形区开始的;淀粉/PVA试样的降解过程中,淀粉首先分解,然后是PVA的非晶部分,最后才是PVA的结晶部分。     

淀粉/PS-g-MAH共混体系相容性及降解性能的研究

研究了淀粉/马来酸酐接枝聚苯乙烯(PS-g-MAH)共混体系的相容性及降解性能。采用红外光谱对接枝产物进行了表征,并用滴定法测定了产物的接枝率,结果表明MAH与PS发生了接枝反应。SEM分析表明当PS/MAH=95/5时,淀粉/PS-g-MAH共混体系的相容性最好,接枝率达到最大,为2.27 %。最后,对淀粉/PS和淀粉/ PS-g-MAH共混体系的降解性能进行了比较,结果表明40 d后淀粉/PS-g-MAH共混物的降解率为20.09 %,小于淀粉/PS共混物的降解率。     

Environmentally Degradable Blends of Low Density Polyethylene (LDPE) and Partially Carboxymethylated Starch (PCMS)

Abstract

Sodium - salt of partially carboxymethylated starch (Na-PCMS) with degree of substitution (DS) 0.21 and 0.58 was synthesized by etherification of starch. These starch ethers and low density polyethylene (LDPE) were mixed with and without poly(vinylacetate) (PVAc) in various proportions using Brabender mixer. FTIR confirmed the etherification reaction of starch and blending. Positive changes in the mechanical properties as a function of blending, and environmental degradation have been observed. Addition of 5 wt% PVAc improves the blend quality. Samples were exposed to direct sunlight for one month and environmental degradation was measured in terms of change in tensile strength and per cent elongation.     

Effect of Morphology on the Biodegradation of Thermoplastic Starch in LDPE/TPS Blends

In this study, thermoplastic starch (TPS) was mixed with low density polyethylene with different melt flow indexes in a one-step extrusion process to produce LDPE/TPS blends varied from 32% to 62% by weight of TPS. The influence of starch content and LDPE viscosity on morphology, biodegradation and tensile properties of LDPE/TPS blends were evaluated. Starch continuity and biodegradability were studied by hydrolytic, enzymatic and bacterial degradation. The LDPE viscosity had a considerable effect on the morphology and the connectivity of the starch particles. Evaluation of hydrolytic extraction showed that blends having TPS content above 50 wt% possessed a full connectivity. Studies of biodegradation indicated that the bacterial attack on starch resulted in weight loss of TPS of 92%, 39% and 22%, for PE1/TPS having 62% and 32% TPS, and PE2/TPS (31% TPS), respectively. Comparatively, the weight loss was more significant at 100%, 66% and 31% by hydrolytic extraction. Differences between these two techniques were discussed in terms of the accessibility of starch domains to microorganisms. Tensile properties (ε_b and E) decreased with increasing exposure time to activated sludge. Changes in tensile properties were highly dependent on the biodegradation rate. PE1/TPS blends having 32% starch remained ductile after 45 days of exposure to bacterial attack.     

Natural weather,soil burial and sea water ageing of low‐density polyethylene: Effect of starch/linear low‐density polyethylene masterbatch

Degradation of the blends of low‐density polyethylene (LDPE) with a starch‐based additive namely, polystarch N was studied under various environmental conditions such as natural weather, soil and sea water in Saudi Arabia. Stress–strain properties and thermal behavior were investigated for the LDPE and LDPE/polystarch N blend having 40% (w/w) of polystarch N. Environmental ageing resulted in the reduction of percentage of elongation and crystallinity for the blend. Rheological studies and scanning electron microscope photomicrographs of the polymer samples retrieved after ageing showed that addition of polystarch N enhanced the degradation of LDPE. This is ascribed to high extent of chain scission and leaching out of starch present in polystarch N, which was corroborated by the results of morphology and Fourier transform infrared spectroscopy analyses. In the case of underground soil ageing, microbes present in the soil consume the starch in the blend, thus accelerating the degradation process. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

微细化马铃薯淀粉的颗粒显微结构和粒度变化研究

通过机械球磨对马铃薯淀粉进行粉磨 ,研究了粉磨前后淀粉颗粒形貌、粒度分布及比表面积的变化 ,并从超细粉碎理论角度分析了淀粉颗粒破碎的方式和过程。结果表明机械球磨方法能有效地使马铃薯淀粉颗粒微细化     

Thermogravimetric determination of starch content in starch–polyethylene blend films

Thermogravimetric analysis as a technique for rapid determination of starch content in LDPE/starch blend films was investigated. The percent weight loss in a specified temperature range, under a constant heating rate, correlated well with the starch content of films in the range of 0–12 wt % starch, as determined by chemical analysis. The method was used to estimate the residual starch content of LDPE/starch films, containing approximately 6.0% starch, exposed under several biotic exposure conditions. Generally 87–88% of the initial starch content was present in the films after different types of environmental exposures.     

Physicochemical Studies on Interaction Behavior of Potato Starch Filled Low Density Polyethylene Grafted Maleic Anhydride and Low Density Polyethylene Biodegradable Composite Sheets

Study presents compatibility behavior of polar group potato starch and non-polar LDPE using 50%, 0.5% maleated LDPE. The aim was to improve intermolecular interaction between two different types of moieties (LDPE and Potato Starch). Samples were prepared by mixing potato starch (upto 30% by weight) with LDPE and LDPE-grafted maleic anhydride in a single step twin screw extruder having vent zone. XRD and DSC results suggested that maleic-anhydride group of LDPE helped the interaction with starch and brought two chemical moieties closer to each other. FTIR results also strongly supported new bond formation between two chemical moieties.     

Preparation and Characterization of Potato Starch Based Low Density Polyethylene/Low Density Polyethylene Grafted Maleic Anhydride Biodegradable Polymer Composite

Polysaccharide-filled plastics have attracted immense interest from research scientists as a means to develop a biodisintegrable polymer. The objective of the present study is to develop a biodisintegrable polymer composite using potato starch, which may be a step toward an alternative user friendly polymer composite. Keeping in mind the compatibility issue between potato starch and polyethylene, we used a base material with a polar group in its low density polyethylene (LDPE) backbone. Polymer composite sheets with a combination of potato starch, LDPE, and LDPE grafted maleic anhydride (LDPE-g-mA) were prepared. The LDPE and LDPE-g-mA were used in equal amounts and as a base material. The starch contents varied between 0 and 30%. The composites so prepared were tested for their thermal and mechanical properties. The results show that the thermal stability and melting temperature of these composites did not change significantly with various combinations of potato starch. The mechanical testing results show that tensile strength of material could be maintained at up to 15% mixing of potato starch in composites, and at up to 5% mixing of potato starch the percentage elongation was intact.     

Susceptibility of starch-filled and starch-based LDPE to oxygen in water and air

The susceptibility of starch-filled and starch-based polyethylenes to oxygen in water and air was analyzed and compared. LDPE containing 7.7% starch and a pro-oxidant formulation in the form of masterbatch (LDPE-MB) was compared to pure LDPE, LDPE with 7.7% starch (LDPE-starch), and a blend with 70% starch and 30% ethylene maleic anhydride (starch-EMA). Thermal ageing at 80°C in air and water was followed by monitoring the molecular weight changes, the formation of carbonyl groups, and degradation products by SEC, FTIR, and GC-MS. It was demonstrated that LDPE-MB was the most susceptible material to degradation in both environments, although the degradation was faster in air than in water. The slower degradation in water is explained by a deactivation or leaching out of the pro-oxidant during the aging. The degradation of pure LDPE and starch-EMA is faster in water than in air. LDPE-starch was the only material that did not degrade during 11 weeks in water at 80°C. The addition of starch to LDPE made this material even more stable than pure LDPE to aging in water. The molecular weight distribution of LDPE-MB narrowed during aging in air. In water, on the other hand, the MWD of LDPE-MB, LDPE, and LDPE-starch broadened. The lower oxygen concentration in water increases the probability for molecular enlargement reactions in comparison to the case in air. Mono- and dicarboxylic acids were the major products identified in both environments. Ketoacids were formed in both air and water, but ketones and hydrocarbons were only identified after aging in air. Either these products are not formed or they remain in the polymer matrix rather than migrate out into the water. Lactic acid and 2-furancarboxaldehyde were only identified in the starch-EMA material degraded in water at 80°C. LDPE, LDPE-starch, and starch-EMA did not form any degradation products during 11 weeks at 80°C in air in agreement with the neglible molecular weight changes observed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 959–967, 1997