PROPERTIES OF BIODEGRADABLE THERMOPLASTIC STARCH

Thermoplastic starch is a kind of modified starch produced by mixing starch with additives and processing the mixture in an extruder. The mechanical properties, including tensile strength and elongation at break, biodegradability and rheological properties were studied. Glycerol and urea, to some extent, can both decrease the tensile strength and increase percentage elongation at break, because the former acts as a plasticizer and the latter can break down interactions among starch macromolecules. Thermoplastic starch shows thermoplasticity and its melt behaves as a pseudoplastic liquid at a low shear rate. Its biodegrading extent is slightly higher than that of native starch. The molecular weight of starch displays a decreasing tendency after thermoplastic modification.

Thermoplastic Starch Prepared with Different Plasticizers: Relation between Degree of Plasticization and Properties

Ethylene glycol, glycerol, sorbitol, formamide, and urea were used as plasticizers for the preparation of thermoplastic starch（TPS） from corn starch. The properties of TPS were tested by analysis method. The results showed that TPSs were more highly plasticized with amines than alcohols. For the same type of plasticizer, the degree of plasticization decreased as the molecular weight of plasticizer increased. The relationship between plasticization degree and TPS properties was characterized and described by mechanical properties and water absorption. The experimental results showed that when the degree of plasticization increased, the tensile strength decreased and the elongation at breakage and water absorption increased.

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.

A Novel Plasticizer for the Preparation of Thermoplastic Starch

in this paper, ethylenebisformamide was synthesized and used as a novel plasticizer for cornstarch to prepare thermoplastic starch （TPS）. FT-IR expressed that ethylenebisformamide formed stronger and stable hydrogen bond with starch molecules compared to the native cornstarch. X-ray diffraction （XRD） showed that the typical A-style crystallinity in the native starch has been destructed. By scanning electron microscope （SEM） native cornstarch granules were proved to transfer to a homogeneous system. After being stored for one week at RH=33%, the mechanical properties of EPTPS was also studied. The elongation reached to 264% utmost. As a novel plasticizer, ethylenebisformamide would be practical to extend TPS application scopes.

Severe plastic deformation (SPD) of biodegradable magnesium alloys and composites: A review of developments and prospects

The use of magnesium in orthopedic and cardiovascular applications has been widely attracted by diminishing the risk of abnormal interaction of the implant with the body tissue and eliminating the second surgery to remove it from the body.Nevertheless,the fast degradation rate and generally inhomogeneous corrosion subsequently caused a decline in the mechanical strength of Mg during the healing period.Numerous researches have been conducted on the influences of various severe plastic deformation(SPD)processes on magnesium bioalloys and biocomposites.This paper strives to summarize the various SPD techniques used to achieve magnesium with an ultrafine-grained(UFG)structure.Moreover,the effects of various severe plastic deformation methods on magnesium microstructure,mechanical properties,and corrosion behavior have been discussed.Overall,this review intends to clarify the different potentials of applying SPD processes to the magnesium alloys and composites to augment their usage in biomedical applications.

Fabrication of Manila Hemp Fiber Reinforced Cross Ply Biodegradable Composites and Their Tensile Properties

Natural plant fibers, including flax, kenaf, jute, bamboo, ramie and much more are renewable and sustainable resources and are considered good candidates for cost-effective alternatives to glass and carbon fibers. In this research, cross ply biodegradable composites were fabricated by press-forming method. The biodegradable composites consist of Manila hemp textile as a reinforcement and starch-based biodegradable plastics as a matrix was fabricated and investigated about mechanical properties. The tensile strength increased with the fiber content until fiber content of about 50% and leveled off thereafter. This dependence on the fiber content is due to the decrease in fiber strength of loading direction caused by fiber damages introduced during hot-pressing. In order to decrease the damage of fibers aligned in loading direction, Manila hemp textile was produced by using Manila hemp fibers for warp and biodegradable resin thread for weft. As a result, the tensile strength of cross ply composites increased from 153 MPa to 202 MPa.

A Methodological Outlook on Bioplastics from Renewable Resources

Bio plastics products have a rapid growing demand and market across the globe. Polymers synthesized from renewable resources have gained immense popularity, in numerous applications ranging from films, bottles, food packaging, drug delivery, bags to agriculture mulch films. Various naturally occurring resources available for starch and PLA extraction and the associated polymer processing techniques are discussed. Alongside some basic concepts on blown film extrusion, the modifications needed for such specialized polymer processing techniques are also explored, giving a comprehensive outlook on bioplastics. Special process analysis, for its application as films are discussed. In the current scenario, as the world aspires for environmental and polymer sustainability, Bioplastic products are of high value. The review article would be beneficial to those embarked on designing bio-plastics products from renewable resources.

Evaluation of Mechanical Properties of Highly Filled Jute Fiber Reinforced Composites

This study aims for development of highly filled jute fiber reinforced composites that contains jute fiber over fiber weight fraction 60%,and jute fiber reinforced composite was fabricated by the hot-pressing method.The molding temperature was changed from 175°C to 230°C,to investigate the effect of molding temperature on the mechanical properties of jute fiber reinforced composites.The effect of surface treatment of jute fiber on the mechanical properties of jute fiber reinforced composites was also investigated.As a result,the jute fiber reinforced composites using surface treated fiber has low porosity,and the jute fiber reinforced composite having low porosity has high flexural strength and modulus.The jute fiber reinforced composite using acetone treated fiber molded at 200°C has the maximum flexural strength and modulus.

Wood Plastic Composites Prepared from Biodegradable Poly（butylene succinate） and Burma Padauk Sawdust （Pterocarpus macrocarpus）： Water Absorption Kinetics and Sunlight Exposure Investigations

Wood plastic biocomposites of biodegradable poly（butylene succinate） （PBS） and Padauk sawdust was successfully pre- pared by using a twin screw extruder and an injection molding machine. The effects of water absorption and sunlight exposure on some properties of the composites were investigated. Water absorption of PBS composites was found to follow the Fick＇s law of diffusion, while the diffusion coefficient increased with increasing wood content. Maximum water absorption of around 4.5% was observed at 30 wt.% sawdust. Optical micrograph indicated the swelling of wood particles by around 1% - 3% after 30 days of water immersion. The tensile and flexural strengths reduced slightly both under the water immersion and sunlight exposure. After 90 days of exposure, the composites clearly looked paler than the non-weathered ones. Thermal scan indicated the re- duction of crystalline region due to the plasticization effect derived from water molecules.

Degradability of biodegradable plastic films and its mulching effects on soil temperature and maize yield in northeastern China

Plastic film is an important resource in agricultural production,but it takes hundreds of years to degrade completely in natural environment.The large-scale use of plastic film will inevitably lead to serious environmental pollution.One way to solve the problem is to develop a substitutable mulching film,such as a biodegradable film that can ultimately be decomposed to water,carbon dioxide,and soil organic matter by micro-organisms.In this study,a 2-year experiment was conducted to determine the degradation properties of a biodegradable plastic film,including degradation rate,surface microstructure,tensile strength and elongation at break,and the effects of different mulching treatments on soil temperature and maize yield.The mulching experiment was conducted with three different biodegradable plastic films with different degradation rates,using a common plastic film and a non-mulched treatment as control.With the addition of the additives for degradation in the biodegradable plastic films,the degradation rates increased significantly,which were 7.2%-17.8%in 2017 and 18.1%-35.2%in 2018 after maize harvesting.However,the degradation occurred mainly on the ridge side.The decrease in tensile strength and elongation was proportional to the degradation rate of the degradable film.The SEM results indicated that the surface microstructures of the biodegradable films were loose and heterogeneous after maize harvesting.Biodegradable plastic film mulching increased the soil temperature at soil depths of 5 cm,15 cm,and 25 cm,over the maize’s entire growth period,by 3.1℃-3.2℃ in 2017 and 1.2℃-2.1℃ in 2018 compared with the non-mulched treatment.The biodegradable plastic film increased the maize yield by 10.4%-14.3%in 2017 and 11.6%-24.7%in 2018.The soil temperature and maize yield increases were statistically significant;however,with respect to maize qualities,there were no statistically significant increases among the five treatments.This study shows that biodegradable plastic film can be used as a substitute for common plastic film.However,the ingredients in biodegradable plastic films should be improved further to ensure that they can be degraded completely after crop harvest.

State of Knowledge on Starch as an Alternative Solution to Petrochemical Resources—A Review

The use of plastics from petrochemical resources poses environmental impacts, and one of the alternative solutions is the use of starch. The objective of this present work has been to present the literature on starch, and to highlight the debate in the development of composite films. The approach adopted was to present the state of the art on starch and thermoplastic starch matrix composites. The work shows that starch is available worldwide and can be used in the manufacture of biodegradable plastics;the debate remains on the reinforcement of thermoplastic starch to improve its physical and mechanical properties poor;then researchers must diversify the reinforcements to see the impact on the properties of thermoplastic starch.

水性丙烯酸树脂对PBAT/淀粉复合材料性能影响

研究了四种水性丙烯酸树脂对聚对苯二甲酸-己二酸丁二酯(PBAT)/淀粉复合材料性能的影响,选择最佳水性丙烯酸树脂进一步研究其用量对复合材料性能的影响。通过万能拉伸测试仪、熔体流动速率仪、接触角测试仪、差式扫描量热仪、热失重分析仪对复合材料力学性能、熔体流动性能、亲水性能、热性能进行了分析;采用红外光谱仪、偏光显微镜对PBAT/淀粉复合材的分子结构与微观组织形貌进行了表征。研究结果表明:玻璃化温度较低的水性丙烯酸树脂对淀粉的改性效果更佳;当水性丙烯酸树脂7168(B7168)用量为25.2g时,复合材料拉伸强度和断裂伸长率有最佳值,较空白样提高10.8%和38.5%;随B7168的增加,复合材料熔体流动速率先减小后趋于平缓,亲水性能增加,对PBAT的结晶和熔融温度影响不明显,对球晶形貌影响不大,但使球晶平均直径略有减小,3000~3600 cm^(-1)的红外响应峰强度有增加的趋势,波峰略向低波数方向移动;热失重显示B7168的加入,使体系热分解起始温度提前,700℃残余量增加。

壬酸增塑改性明胶膜的制备及性能研究

可生物降解塑料的研发对于实现“双碳”目标具有重要的意义和价值。以明胶为原材料,通过壬酸增塑、双醛淀粉交联和热压处理相结合的方法制得明胶膜,探究壬酸增塑和热压处理对双醛淀粉交联的明胶膜结构和性能的影响。结果表明,当壬酸添加比例为20%时,改性的明胶膜表面光滑、结构致密,具有最高的抗张强度和较低的断裂伸长率、水蒸气透过率和溶胀性能。经过11 min的热压处理后,明胶膜表现出良好的耐水性和力学性能,且在土壤中被降解22 d后仍然能够维持较完整的薄膜形貌,降解34 d后其质量损失超80%。基于壬酸增塑、双醛淀粉交联和热压处理制备的明胶膜机械强度高、耐水性好且可生物降解,其为环境友好蛋白塑料的研发提供了有益策略。

玉米淀粉-糠醛共缩聚树脂塑料的制备

以来自农林的廉价植物提取物——玉米淀粉和糠醛为原料,合成一款生物基塑料淀粉-糠醇-甲醛共缩聚塑料(SFFP)。通过电喷雾电离质谱(ESI-MS)和X射线衍射(XRD)测试,表明淀粉、糠醛和甲醛在酸性条件下进行了共缩聚反应。该生物基SFFP塑料的抗压强度与酚醛(PF)塑料相近。在300℃、氮气处理条件下的重量损失为18%,与PF塑料相比,SFFP具有较好的热降解性。此外,与PF塑料相比,SFFP具有更好的疏水性,且其可再生原材料含量高达87%,具有一定的应用价值。

改性复合生物降解地膜的制备及玉米田间应用评价

[目的]使用生物降解地膜替代传统聚烯烃地膜已成为治理农业白色污染的一项重要技术。主流材料聚对苯二甲酸-己二酸丁二醇酯(PBAT)在制备生物降解地膜时表现出优异的成膜性能,但其水蒸气阻隔性较差,导致降解时间短,限制了其在农用地膜方面的应用。因此,需要进行改性研究以解决PBAT生物降解地膜在拉伸强度、水蒸气阻隔性能和降解期等方面的不足。[方法]本研究将PA6(尼龙6)与PBAT相结合,使用高分子共混法制备PBAT/PA6改性生物降解地膜。该方法制备的生物降解地膜有效地将PBAT与PA6融合在一起,电子显微镜测试表明,混合地膜的表面和横截面均无明显缺陷。于2023年春玉米生长季,在北京顺义地区农田设置不同覆膜处理(PBAT地膜覆盖,PBAT/PA6-10地膜覆盖,PE地膜覆盖,不覆膜处理即CK)的田间对比试验,研究土壤温度、地膜田间降解情况、春玉米产量及其构成因素的变化。[结果]与纯PBAT生物降解地膜相比,本研究所开发的生物降解地膜的拉伸强度提高了约2.7倍,水蒸气阻隔性能提高了79.44%,功能期延长了30 d。玉米作物田间试验表明,改性生物降解地膜更适合农业生产,因其可提高隔热性和保湿性,使玉米产量较纯PBAT地膜提高7.03%,接近传统聚乙烯地膜产量。[结论]将PA6与PBAT材料相结合,开发出了一种新型复合生物降解地膜PBAT/PA6。PA6的加入与PBAT反应形成酰胺键使其整体结构具有稳定性,所制备复合生物降解地膜表面和截面形貌良好,内部无明显孔洞,较PBAT地膜表面更光滑,同时在力学性能和水蒸气阻隔性能上较纯PBAT地膜有显著提升,在田间试验过程中,复合生物降解地膜PBAT/PA6具有优秀的耐降解性能,延长了覆盖时间,并较纯PBAT地膜显著提高春玉米的产量。

生物可降解塑料包装薄膜的制备及应用进展

综述了几种典型市售生物可降解塑料聚乳酸(PLA)、聚对二苯甲酸/己二酸丁二醇酯(PBAT)、聚碳酸亚丙酯(PPC)及聚丁二酸丁二醇酯(PBS)的基本性能及其功能改性进展。详细介绍了热塑加工制备生物可降解塑料包装薄膜的常用成型方法,包括吹膜法、流延法、压延法及双向拉伸法;总结了生物可降解塑料薄膜作为绿色包装材料的最新应用进展。

聚(己二酸丁二醇酯-co-辛二酸丁二醇酯)的合成与性能

采用熔融缩聚法,以1,4-丁二醇、己二酸和辛二酸为原料,合成了聚己二酸丁二醇酯、聚辛二酸丁二醇酯和系列聚(己二酸丁二醇酯-co-辛二酸丁二醇酯)共聚酯,并对材料性能进行了分子结构、结晶性,热性能和降解性能等方面的研究。研究表明,不同比例己二酸、辛二酸和1,4-丁二醇共聚后,提高了聚己二酸丁二醇酯的热稳定性,改善了聚辛二酸丁二醇酯的生物降解性能。部分辛二酸单元取代己二酸后,提高了聚酯的结晶性能、热稳定性能、酶降解性能,降低聚酯的熔点。当己二酸与辛二酸比例为30:70时,与PBA相比,其热稳定性提高了27℃;与PBSub相比,完全降解时间缩短了20 h。

市售生物可降解塑料袋的降解行为研究

选择市场上使用最广泛的由纯聚对苯二甲酸己二酸丁二酯(PBAT)、淀粉(St)质量分数20%和30%的PBAT/聚乳酸(PLA)/St制备的生物可降解塑料袋为研究对象,分别考察了几种塑料袋在空气、水、酸碱溶液,以及自然土壤和有机土壤中的长期降解行为。结果表明:由纯PBAT和PBAT/PLA/St制备的生物可降解塑料袋在空气、水、酸碱溶液,以及自然土壤和有机土壤中经历54周的降解后力学性能下降较快,但仍具有较高的相对分子质量,并未呈现预期的优异生物可降解性;碱性环境相对于酸性环境更有利于生物可降解塑料袋的碎裂和降解;生物可降解塑料袋中组分St含量越高,相同降解周期下塑料袋出现的孔洞越多,相对分子质量下降越多;由纯PBAT制备的生物可降解塑料袋在酸性环境下有利于细菌的生长,但对降解作用有限。