Effect of Co‐Rotation and Counter‐Rotation Extrusion Processing on the Thermal and Mechanical Properties,and Morphology of Plasticized Soy Protein Isolate and Poly(butylene succinate) Blends

Blends of plasticized soy protein isolate (PSPI) and poly(butylenes succinate) (PBS) were prepared in a 70:30 wt.‐% ratio via co‐rotation (CR) and counter‐rotation (CTR) twin‐screw extrusion. The novelty in this research suggests that CTR extrusion provides enhanced interfacial adhesion, tensile elongation and prolonged onset (T_onset) and end (T_end) thermal degradation temperatures. The average tensile strain at break showed to be ≈40% higher for PSPI‐CTR material and ≈55% higher for PBS:PSPI‐CTR (70:30) blends. Both T_onset and T_end for CTR processed PBS:PSPI(70:30) and PSPI were ≈10 °C greater than those of CR. These results suggest that the enhanced shear rate and radial motion associated with CTR allows for better destructurization and blending of PSPI within the PBS matrix, resulting in enhanced structural integrity due to the formation of possible amide and ester linkages. Scanning electron microscopy (SEM) provides further support based on evidence of reduced voids on the surface of all CTR blends

     

PBS基降解塑料的共混与就地增容扩链改性研究

采用扩链剂2,4甲苯二异氰酸酯(TDI)、2,2'-双(2-恶唑啉)(BOZ)以及新型扩链剂ADR-4370对聚丁二酸丁二醇酯(PBS)进行扩链,研究了三种扩链剂对PBS性能的影响。采用聚乳酸(PLA)与PBS共混,选择最佳配比以及合适的共混工艺。结果表明:新型扩链剂ADR-4370可以明显改善PBS的加工性能和力学性能,PBS/PLA最佳配比为70:30,在共混同时进行就地增容扩链改性可以更好地提高PBS/PLA的性能。     

微波辐照对玉米淀粉及其改性淀粉理化特性的影响

微波辐照水分含量为30%的普通玉米淀粉及其辛烯基琥珀酸改性后的淀粉。结果表明:随着辐照时间的延长,淀粉的水分含量均出现下降趋势,4min时两种淀粉的含水量已降至正常水平。通过扫描电子显微镜观察到两种淀粉微波辐照后,其颗粒表面出现破损,部分颗粒甚至完全破裂。而玉米淀粉及改性淀粉微波辐照前后的结晶性质都基本相似。改性前后的淀粉其糊化后都属于假塑性非牛顿流体,幂律模型对其剪切应力与剪切速率曲线的拟合精度高。随着辐照时间的延长,玉米淀粉的黏度有所降低,改性淀粉呈现先下降后上升的趋势,玉米淀粉的储能模量先增加后减小,耗能模量变化不大,损耗因子的变化趋势则与储能模量相反。而对于改性淀粉,除了辐照6min的样品,其余组的黏弹性变化甚微,该处理时间的储能模量与耗能模量都高于其他处理时间的样品,而损耗因子也出现显著降低。     

聚乙二醇丁二酸酯/酚醛树脂共混物的结晶行为

考察了聚乙二醇丁二酸酯(PESu)/酚醛树脂共混物的熔融和结晶行为。显示:酚醛树脂对PESu的结晶起异相成核作用,同时酚醛树脂的羟基对PESu分子链会产生干扰作用,降低其结晶能力,这两种作用的主次地位取决于共混物中酚醛树脂的含量。采用Avrami方程分析了该共混物的等温结晶动力学参数,并利用Arrhenius方程计算了共混体系的活化能变化。     

降解塑料PBS／农药缓释微胶囊的制备与表征

以可生物降解的聚丁二酸丁二醇酯（PBs）为载体，通过乳化-溶剂挥发法制备了包覆毒死蜱的农药缓释微胶囊。通过扫描电镜、透射电镜、激光粒度分析仪等研究了不同农药／PBS投料比对微胶囊形貌的影响。用紫外／可见分光光度计评价毒死蜱从微胶囊中释放的行为，并通过凝胶渗透色谱仪表征了PBS壁材相对分子质量变化。结果表明，当投料比为3：1时，所得产品平均粒径为10μm，为包覆良好的基质型结构，可以实现约1000h的长效缓释。缓释过程中，渗透扩散释放为主要模式。     

Kinetics of nucleation and crystallization in poly(butylene succinate) nanocomposites

Differential fast scanning calorimetry (DFSC) was employed on poly(butylene succinate) nanocomposites containing silver nanoparticles and multi-walled carbon nanotubes (MWCNT), in order to identify the temperature range of heterogeneous nucleation caused by both nanofillers. The fast scanning rates also allow investigating self-nucleation by recrystallization experiments approaching the crystallization temperature from low temperatures. The recrystallization behavior of PBSu and its nanocomposites is distinct from all other polymers studied so far as only the previously crystallized part of the material is able to recrystallize, independently on the available large number of nuclei. Since full melting of small crystals at low temperatures is observed this highlights the importance of ordered structures remaining in the polymer melt. On cooling from the melt the neat polymer did not crystallize at rates higher than 70 K/s, while the nanocomposites needed rates of 500 K/s and 300 K/s for silver and MWCNT, respectively. Below 280 K the crystallization kinetics of the matrix was almost the same with the nanocomposite samples. The nucleation mechanism changes at 280 K from heterogeneous to homogeneous. The study further confirms that below the glass transition nucleation and crystallization appears only after approaching the enthalpy value of the extrapolated supercooled liquid by enthalpy relaxation.     

Effect of coumarin and xanthotoxin on mitochondrial structure,oxygen uptake,and succinate dehydrogenase activity in onion root cells

At concentrations in which they occur on the plant surface and retard mitosis, coumarin and xanthotoxin lowered uptake of oxygen (by 60 and 30%, respectively) by meristematic cells ofAllium cepa root tips. They caused changes in the structure of the mitochondrial matrix to become dense, and protrusions of mitochondrial membranes were visible parallelling their hypertrophy, indicating alteration in the structure and physiology of these organelles. Coumarin and, to a lesser extent, xanthotoxin increased succinate dehydrogenase production in mitochondria and also in the cytoplasm, indicating changes in membrane permeability. Changes in oxygen uptake and mitochondrial structure, in addition to the retardation of mitosis, may be the reason these compounds act as allelochemicals after they have been removed from the plant surface and reach the root meristem.     

纤维素-聚丁二酸丁二醇酯复合薄膜的制备

目的利用添加剂改善离子液体溶剂再生纤维素的性能。方法以离子液体为纤维素溶剂,利用柔性聚丁二酸丁二醇酯(PBS)增韧纤维素薄膜,并对复合薄膜的结构进行研究。利用拉伸实验仪和扫描电子显微镜,研究复合薄膜的力学性能及拉伸机理。结果 PBS质量分数为1%时,复合薄膜的拉伸强度和断裂伸长率由纯纤维素的45.6 MPa和7.21%提高到58 MPa和15.6%,分别提高了30.7%和48.2%。结论 PBS是以共混的形式存在于纤维素基体中,它们之间没有化学键作用,PBS的含量显著影响其颗粒的大小和分散状态。低含量下PBS微颗粒均匀分散在纤维素基体内,降低了纤维素分子间氢键的密度,有利于纤维素分子链滑移,增强复合薄膜韧性。     

四针状ZnO晶须改性对ZnO/聚丁二酸丁二醇酯复合材料性能的影响

以四针状ZnO晶须（T-ZnO_W）为填料,经过表面处理与聚丁二酸丁二醇酯（PBS）复合,采用熔融共混法制备了T-ZnOw/PBS复合材料。利用FTIR表征表面改性T-ZnO_W的结构,利用SEM观察改性T-ZnO_W和T-ZnO_W/PBS复合材料的形貌,利用XRD分析改性T-ZnO_W和复合材料的结晶性能,利用TG和DSC分析复合材料的热稳定性,利用拉伸试验研究复合材料的力学性能。研究结果表明：聚乙二醇2000（PEG2000）（P）、硬脂酸（S）和硅烷偶联剂（KH560）（K）三种不同改性剂中,硬脂酸对T-ZnO_W的改性效果最佳。经硬脂酸改性T-ZnO_W（ST-ZnO_W）,表面负载有机活性基团,表面粗糙度增加且与纯PBS之间界面结合力增强,使ST-ZnO_W/PBS复合材料的热稳定性和力学性能明显得到改善。热分解过程中质量损失10%的温度（T_d-10%）和最大热分解温度（T_d-max）较纯PBS分别提高了37.7℃和35.3℃;拉伸强度、断裂伸长率和弹性模量分别提高了17.7%、140.5%和95.4%。     

聚丁二酸丁二醇酯/水滑石纳米复合材料的制备及性能研究

采用双螺杆挤出机制备了聚丁二酸丁二醇酯/水滑石(PBS/HT)纳米复合材料,并详细研究了复合材料的形貌及分散、结晶和熔融行为,晶体结构和球晶形态以及力学性能。采用SEM、TEM、DSC、XRD、POM和DMA进行了表征测试,结果表明层状水滑石纳米粒子较好地分散在PBS基体中,加入HT具有明显的异相成核能力,显著地提高了PBS的结晶温度。偏光显微镜结果显示,随着HT加入量的增加PBS球晶密度增加,球晶尺寸细化。HT添加量为1%(质量分数)时复合材料的拉伸强度增大,随着HT加入量增加断裂伸长率下降而弹性模量增加。动态机械测试表明复合材料的储能模量显著提高。