等通道转角挤压对PAl01O结晶结构和力学性能的影响

探索了各种挤压工艺条件对PAl010结晶结构和力学性能的影响。结果表明：经过挤压后PAl010的结晶度高于原始试样的结晶度，拉伸强度也高于未经挤压的PAl010的拉伸强度，最大增加幅度为21％，增大幅度与挤压工艺条件有关。等通道转角挤压对材料结晶结构和力学性能均有重要的影响。     

剪切作用下POE-g-MAH和PP-g-MAH对PA1010/PP共混物的增容作用

采用熔融共混的方法制备了聚酰胺1010/聚丙烯（PA1010/PP）共混物,通过扫描电镜、力学性能和差示扫描量热等方法研究了剪切作用下马来酸酐接枝乙烯-辛烯共聚物（POE-g-MAH）和马来酸酐接枝聚丙烯（PP-g-MAH）对PA1010/PP共混物的增容作用。结果表明,同样条件下,PP-g-MAH增容体系的相区尺寸较小,相界面更模糊,PP相的结晶温度和结晶度明显提高,共混物的拉伸强度和冲击强度均高于非增容体系。而POE-g-MAH增容体系的相区尺寸相对较大,PP相的结晶温度和结晶度明显降低,共混物只有冲击强度明显高于非增容体系,拉伸强度略低于非增容体系。     

CaCl_2含量对PA1010/CaCl_2复合材料结构与性能的影响

采用熔融挤出的方法制备了PA1010/CaCl2复合材料,研究了CaCl2含量对PA1010/CaCl2复合材料的结晶行为、力学性能及流动性能的影响。结果表明:CaCl2的加入提高了PA1010的结晶速率和结晶温度,降低了PA1010的结晶度;随着CaCl2含量的增加,拉伸强度及断裂伸长率先增大后减小,弯曲强度先减小后增大,缺口冲击强度逐渐增大,熔体质量流动速率及热变形温度逐渐减小。     

LiCl对PA1010/LiCl复合材料结构与性能的影响

采用熔融挤出的方法制备了尼龙1010/氯化锂(PA1010/Li Cl)复合材料,研究了Li Cl对PA1010结晶行为和力学性能的影响。结果表明:Li Cl的加入能降低PA1010的结晶温度,使PA1010的结晶度降低,提高复合材料的透明性,当Li Cl质量分数为6%时,PA1010已经完全不能结晶。并且Li Cl的加入能够提高复合材料的拉伸强度和冲击强度,当Li Cl质量分数为4%时,复合材料的冲击强度最大。     

热氧老化对长玻璃纤维增强聚酰胺6复合材料的影响

研究了160℃条件下不同热氧老化时间对未添加抗氧剂和添加抗氧剂的长玻璃纤维(LGF)增强聚酰胺(PA)6(PA 6/LGF)复合材料力学性能、热稳定性、结晶度及表面形貌的影响,并采用热重分析,差示扫描量热法分析和扫描电子显微镜观察对PA 6/LGF复合材料进行了表征。结果表明:PA 6基体分子链的断裂、降解以及LGF与PA 6基体的脱黏导致了PA 6/LGF复合材料宏观力学性能、熔融温度、结晶温度、结晶度以及热稳定性的下降。添加抗氧剂的PA 6/LGF复合材料拉伸强度保持率为83.9%,而未添加抗氧剂的复合材料则为76.8%。添加抗氧剂能使PA 6/LGF复合材料具有相对优异的力学性能保持率。     

聚酰胺66/改性耐热聚乳酸共混物的力学性能和结晶行为

采用熔融共混和注射成型制备了改性耐热聚酰胺66/聚乳酸（PA66/PLA）共混物,经热处理后,探讨了PLA含量对共混物的断口样貌形态、力学性能以及结晶性能的影响。结果表明,PLA与PA66具有一定的相容性,当PLA的含量不超过10 %（质量分数,下同）时,PA66/PLA共混物的拉伸强度在PA66的93 %以上,其断裂伸长率对比PLA得到了倍数级的增长,是PLA断裂伸长率的8.6倍;当PLA的含量不超过20 %时,共混物的结晶性能变好,提升结晶速率,缩短结晶时间,结晶度有所提高;但当PLA的含量超过20 %以后,共混物的拉伸强度则出现了不同程度的降低。     

双峰聚乙烯/PA6共混体系的结晶行为和力学性能

以高密度聚乙烯接枝马来酸酐(HDPE-g-MAH)作为相容剂,采用熔融挤出法制备双峰高密度聚乙烯/尼龙6(PE100/PA6)共混物。通过广角X射线衍射和偏光显微镜研究了PA6用量对PE100结晶行为的影响,同时也考查了PA6对PE100力学性能的影响。结果表明,PA6的加入,阻碍了PE100的结晶,使结晶度降低,同时又限制了球晶的生长,使晶粒细化。所以PA6的加入使PE100的拉伸强度降低,冲击强度增加。     

固相剪切碾磨制备PA6/蒙脱土纳米复合材料

采用固相剪切碾磨方法制备尼龙6/蒙脱土(PA6/MMT)纳米复合材料。表征了复合材料的结构,研究了其力学性能、热稳定性能及结晶性能。结果表明,PA6/MMT纳米复合材料的力学性能较PA6有较大提高,含4%MMT的PA6/MMT纳米复合材料的拉伸弹性模量从2697 MPa提高到3299 MPa,拉伸强度从63.6 MPa提高到77.8MPa;起始分解温度和最大失重温度均高于纯PA6;PA6/MMT纳米复合材料中PA6的结晶温度和结晶速率提高。     

1,3-双(2-噁唑啉)基苯扩链聚酰胺6的研究

采用1,3-双(2-噁唑啉)基苯(MPBO)与聚酰胺6(PA6)进行熔融扩链反应,考察了MPBO用量对PA6力学性能、流变性能和结晶性能的影响。在240 ℃条件下,当MPBO用量在2.0%时,MPBO对PA6的扩链效果最佳,PA6的数均相对分子质量从1.4×104提高到了2.5×104,其拉伸强度、断裂伸长率和特性黏度均有一定程度的提高,熔体流动速率明显降低;MPBO对PA6有显著的扩链效果,但是同时也导致PA6结晶度和结晶温度有所下降。     

交联剂对聚醚酰胺弹性纤维力学性能的影响

采用两步法工艺路线,以PA6齐聚物、聚醚和少量交联剂为原料共聚合成聚醚酰胺热塑性弹性体(TPAE)。对TPAE进行模拟纺丝,对初生纤维进行拉伸和热定型。测定了纤维的力学性能。利用WAXD分析了交联剂对TPAE结晶性能的影响,讨论了纤维弹性及回复率与纺丝条件、交联剂用量的关系。结果表明,随交联剂含量的增加,拉伸丝较初生丝的结晶度提高幅度小,交联剂的化学交联作用明显。交联剂的引入使TPAE纤维断裂强度和弹性回复率提高,断裂伸长率降低,交联剂质量分数(相对PA6)为0.7%时,TPAE纤维的弹性回复率可提高到95%以上。     

Deformation behaviour and mechanical properties of polypropylene processed by equal channel angular extrusion: Effects of back-pressure and extrusion velocity

Severe plastic deformation by equal channel angular extrusion (ECAE) is an ingenious deformation process used to modify texture and microstructure without reducing sample cross-section. The application of single ECAE pass to polypropylene (PP) was meticulously investigated at room temperature using a 90° die-angle tooling. The ECAE-induced deformation behaviour was examined in relation to the load versus ram-displacement curves. Depending on extrusion conditions, PP displayed various types of plastic flow. For ram velocities beyond 4.5 mm/min, severe shear bands consisting of successive translucent and opaque bands were observed, accompanied on the top surface by more or less pronounced periodic waves. Although the application of a back-pressure significantly reduced the wave and shear-banding phenomena, slightly inhomogeneous shear deformation was still observed. Shear bands were only suppressed by decreasing extrusion velocity. The strain-induced crystalline microstructure was investigated by X-ray scattering. Shear-banded samples exhibited a strong texturing of the (hk0) planes along the shear direction in the translucent bands whereas perfect crystalline isotropy appeared in the opaque bands. Application of back-pressure and/or reducing ram velocity resulted in uniform texturing along the extruded sample. Yet, texturing changed from single shear to twin-like shear orientation about the shear direction. Mechanical properties changes of the extruded samples due to back-pressure and extrusion velocity effects were analyzed via uniaxial tensile tests. The tensile samples displayed multiple strain localizations in shear-banded materials whereas quite homogeneous deformation appeared for non-banded ones. These effects were connected with the crystalline texturing. The results also revealed significant increase in the strain hardening after ECAE. Digital image correlation technique suitable for large deformation was used for determining the full-field strain of the tensile samples in relation to tensile strain and ECAE conditions.     

Impact fracture behavior of molecularly orientated polycarbonate sheets

The impact fracture behavior of molecularly orientated polycarbonate (PC) sheets was investigated. The molecular orientation was achieved via a newly developed equal channel angular extrusion (ECAE) process. Improvement in impact fracture propagation resistance was observed in the ECAE processed PC sheets. The improved impact resistance was found to be directly related to the changes in molecular orientation because of ECAE. The unique characteristics of the ECAE process for polymer extrusion are described. The potential benefits of ECAE in enhancing physical and mechanical properties of the extruded PC sheets are discussed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2060–2066, 2001     

Polyamide‐6 structure modification by combined solid‐phase extrusion

Methods of wide‐angle X‐ray analysis and transmission electron microscopy were performed to investigate structural and phase transformation occurring in polyamide‐6 (PA‐6) by combined solid‐phase processing including extrusion through a conical die (ED) and the following equal‐channel multiple‐angular extrusion (ECMAE). It was shown that high level of plastic and strength characteristics of extruded PA‐6 is determined by the formation of a duplex structure consisting of elongated disoriented fiber‐like entities and fragmented globular formations. Conservation of high values of plasticity of deformed PA‐6 is also controlled by the transition of the crystals of α‐form to the crystals of γ‐form with higher plasticity reserve. We have established rational technology parameters of PA‐6 processing by ED‐ECMAE processes (the deformation degree ε_ED at ED, deformation intensity ΔΓ and the value of accumulated deformation ε_ECMAE at ECMAE). POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

等通道转角挤压制备自增强高密度聚乙烯的结构与性能研究

采用等通道转角挤压方法对高密度聚乙烯进行自增强挤压，研究和分析了挤压工艺条件与材料结构、性能之间的关系。利用扫描电镜、广角X-射线衍射、差示扫描量热分析等手段对材料结构进行了表征。结果表明，经过等通道转角挤压后，高密度聚乙烯的结晶度提高、晶粒细化、熔点升高，形成明显的取向结构，拉伸强度提高了23％。     

PA1010的熔融扩链反应

研究3种扩链剂（环氧树脂、二异氰酸酯和亚磷酸三苯酯）对聚酰胺（PA）的熔融扩链反应。针对具有不同熔体流动指数（MI）的PA材料，得出最佳的扩链剂加入量；并研究了扩链后的PA1010的MI，机械性能和结晶性能。结果表明：以环氧树脂为扩链剂反应活性最高，扩链效果比较明显，但有一定的交联反应发生，导致挤出物熔体破裂；二异氰酸酯在扩链时，由于其在高温下自身会发生化学反应，使扩链效率降低，利用亚磷酸三苯酯在单螺杆挤出机中进行扩链反应，扩链后PA1010的熔体粘度明显增加，MI下降，且交联轻微。     

Microstructure,mechanical properties and bio-corrosion properties of Mg-HA bionanocomposites fabricated by a novel severe plastic deformation process

This research investigates the alterations in microstructure, mechanical properties, and corrosion behavior of binary magnesium-hydroxyapatite bionanocomposites with 2, 5, and 10 wt%HA. By mixing Mg and HA powders with different percentages of HA contents, a combined method of cyclic extrusion compression (CEC), equal channel angular pressing (ECAP) and conventional extrusion were employed to consolidate the mixture of powders. All composites were examined. The results indicate that the addition of hydroxyapatite to magnesium improves the mechanical properties, but these properties are deteriorated with the hydroxyapatite content of over 5 wt%. The corrosion behavior of the composites was examined by immersion test, mass loss and polarization tests in Hank’s solution. The results indicate that Mg-5HA exhibits the best corrosion resistance and the corrosion rate increases when the HA content rises to more than 5 wt%. In addition, the specimen produced through the proposed method in this work indicates better corrosion resistance in comparison with cast and extruded pure Mg.     

Simple shear plastic deformation behavior of polycarbonate plate due to the equal channel angular extrusion process. I: Finite element methods modeling

Simple shear plastic deformation behavior of polycarbonate (PC) plates due to the novel equal channel angular extrusion (ECAE) process is modeled using a commercial finite element methods (FEM) package. The true stress and true strain contour plots as well as the strain rate variation across the PC plate during the ECAE process are analyzed. The FEM results correlate well with the experimental findings. The present study indicates that the novel ECAE process is effective in producing a high degree of simple shear plastic deformation across the extruded polycarbonate plate. The high degree of plastic deformation due to ECAE induces a high level of nearly uniform molecular orientation across the extruded PC plate. As a result, significantly improved physical and mechanical properties in PC are expected. The simple shear plastic deformation behavior of PC plate, as a function of extrusion rate and temperature, is investigated. The significance of the ECAE process for fabricating polymer parts is also discussed.     

共混工艺对PP/PA6/纳米SiO2复合材料力学性能的影响

以聚丙烯（PP）作为基体，经表面处理过的纳米二氧化硅（nano-SiO2）和刚性聚合物尼龙6（PA6）作为改性剂，添加5％的接枝POE作增容剂，采用不同的共混工艺制备PP／PA6／纳米SiO2复合材料。研究了熔融共混挤出次数和共混方法对PP／PA6／纳米SiO2复合材料力学性能的影响，借助扫描电子显微镜从断面形貌上分析了影响复合材料力学性能的因素。结果表明：采用二次挤出熔融共混比一次挤出熔融共混制得的复合材料力学性能要好；采用PP与纳米SiO2先熔融共混挤出制得粒料，再用PA6、接枝POE与粒料熔融共混挤出的共混方法制得的复合材料综合力学性能最优。     

PPS/PA1010合金的制备及其力学性能研究

选用丙烯酸接枝聚丙烯（PP-g-AA）和自制的甲基丙烯酸缩水甘油酯（GMA）嵌段共聚苯乙烯（St）接枝聚丙烯[PP—g-（GMA—CO—St）]为增容剂,采用双螺杆挤出机熔融挤出法制备了PPS／PA1010／PP—g—AA合金和PPS／PA1010／PP-g-（GMA—CO-St）合金,并分别对两种合金的力学性能进行了研究。结果表明,在保持合金其它力学性能不下降的情况下,随着PP—g—AA含量的增加,共混合金的冲击强度先提高后降低,当PP-g—AA含量为7份时,冲击强度比原合金提高了86．7％,比纯PPS提高了39．3％;而随着PP—g-（GMA—CO—St）含量的增加,冲击强度也有明显提高。