聚合物原位成纤方法及其在PP共混体系中的应用

介绍了聚合物共混体系原位成纤原理、影响因素、制备方法及聚丙烯(PP)与其他聚合物原位成纤共混体系研究进展,包括PP/聚酰胺(PA)、PP/聚对苯二甲酸乙二醇酯(PET)原位成纤共混体系等.重点阐述了不同共混比、相容性、黏度比和加工参数(如拉伸速率、螺杆转速、加工温度等)等对PA或PET在PP中的成纤形态和PP力学性能、...     

原位成纤复合法改善聚丙烯的力学性能

采用原位成纤复合法制备了均聚聚丙烯(PP-H)/聚对苯二甲酸乙二酯(PET)原位成纤复合材料,研究了PET原位微纤化对PP-H力学性能的影响.实验采用的设计工艺可实现PET在PP-H基体中原位微纤化;原位生成的PET纤维对PP-H力学性能的影响呈各向异性,表现为拉伸及弯曲强度提高,冲击强度下降,改善效果受PET微观形态...     

PP/a-PA66原位成纤复合材料弯曲力学行为的有限元模拟

利用"后期增容"技术制备了聚丙烯/活性尼龙66(PP/a-PA66)原位成纤复合材料,建立了复合材料的有限元模型,求解发现,该模型可以较好地模拟实际材料的弯曲性能。弯曲载荷作用下,与不添加增容剂的PP/PA66,直接将PP、PA66、反应性增容剂(SCRC)熔融共混-热拉伸制备的PP/PA66/SCRC相比,PP/a-PA66的弯曲性能最优。这是由于PP/a-PA66原位成纤复合材料中具有强界面结合的形态结构,PA66异形微纤能够起到增强基体PP的作用。     

具有原位导电微纤网络的CB／PET／PE复合材料的力学性能

在前期热塑性塑料原位成纤研究的基础上，尝试利用原位成纤方法制备炭黑(CB)／聚对苯二甲酸乙二醇酯(PET)／高密度聚乙烯(HDPE)原位导电微纤网络复合材料(CEMN)，以期增强复合体系的力学强度。通过对CEMN体系与CB／PE体系的力学性能测试发现，CEMN体系的拉伸强度低于普通CB／PE复合物。为增强复合体系的力学性能，应改变加工过程及降低体系中CB的用量。     

PA 6原位成纤复合改善PP的力学性能

采用挤出-热拉伸-淬冷法制备均聚聚丙烯(PP-H)/聚酰胺(PA)6原位成纤复合材料,研究PA 6的原位微纤化对PP-H力学性能的影响。结果表明:实验设计工艺可实现PA 6在PP-H基体中的原位微纤化,纤维直径约为0.5～2.0μm,但PA 6微纤与PP-H基体的界面结合性差,对PP-H的力学性能改善不佳;添加少量增容剂马来酸酐接枝聚丙烯,可显著改善PP-H的力学性能,当w(PA 6)为15%时,添加少量增容剂后,复合材料的拉伸强度、弯曲强度、简支梁缺口冲击强度分别为未添加增容剂时的1.27,1.39,1.49倍;注塑温度对复合材料中PA 6分散相的形态及材料力学性能有明显影响,高温注塑试样的力学性能普遍低于低温注塑试样。     

分散相含量对PP/PA66原位微纤复合材料微观形态和性能的影响

为解决玻璃纤维、碳纤维及芳纶纤维等增强聚丙烯(PP)出现的生产成本高、工艺复杂、能耗较高及难以回收等问题,采用一次挤出熔融、二次挤出拉伸的方法制备了PP/尼龙66 (PA66)原位微纤复合材料(MFCs),并通过与普通PP/PA66共混物对比,分析了分散相含量对形成微纤形貌的影响及原因。探究了分散相含量对复合材料的结晶性能、流变行为以及力学性能的影响。结果表明,PA66微纤可以对基体PP异相成核起到促进作用;随着PA66含量的增加,复合材料的储能模量、损耗模量和复数黏度也随之增大;当PA66质量分数为15%时,MFCs的拉伸强度和弯曲强度均达到一个最优值,分别为36.96 MPa和52.4 MPa,比普通共混材料增加了53.3%和40%,当PA66质量分数为25%时,MFCs的冲击强度最大增加了94%。     

PBT(聚对苯二甲酸丁二酯)共混纤维的结构与性能——(Ⅰ)微观结构及力学性能的研究

本文应用SEM、S—S曲线、DSC、WAXS以及密度梯度等测试技术,对PBT(聚对苯二甲酸丁二酯)、分别与PET(聚对苯二甲酸乙二酯)、PP(聚丙烯)和PA6(聚己内酰胺)共混熔纺成纤后的微观形态和力学性能进行了测试和分析。SEM研究表明,PBT/PET=50/50和PBT/PA6=10/90时,其各自的PET相和PBT相就已分别在PBT基体和PA6基体中形成了原纤结构。PBT/PET共混物在整个共混组分比例范围内具有好的相容性;PBT/PA6属部分相容体系;PBT/PP属不相容体系。对于获得综合物性指标均有所改善的PBT/PA6共混纤维,PBT/PA6=10/90是一比较合适的量。     

PA66异形微纤对PP基复合材料拉伸性能影响的数值模拟

研究了"后期增容"技术制备的PP/a-PA66原位成纤复合材料在拉伸载荷下的力学特性,并建立了有限元模型,对其拉伸行为进行了数值模拟。与不添加增容剂的PP/PA66、直接将PP、PA66、SCRC熔融共混-热拉伸制备的PP/PA66/SCRC相比,PP/a-PA66的拉伸屈服应力最优,且与纯PP最为接近,这是因为其具有PA66异形微纤、强结合适度柔性界面的结构特征。拉伸力学行为的数值模拟曲线与试验曲线相似度较高,表明考虑材料属性的有限元模型可以较好地模拟原位成纤复合材料的拉伸力学特性。     

微孔发泡PP/PET/CNTs复合材料的制备及其电磁屏蔽效能研究

采用聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、碳纳米管(CNTs)制备了具有纤维结构的微孔发泡复合材料,借助层叠器内部流道的变化,实现了造粒阶段PET的连续化原位成纤.通过差示扫描量热仪(DSC)、扫描电子显微镜(SEM)、矢量网络分析仪和万能试验机对复合材料的结晶性能、表观形态、电磁屏蔽效能(EMI SE)和拉...     

热塑性聚合物原位成纤研究进展

综述了近年来柔性链聚合物原位成纤技术的研究成果，简要介绍了原位复合材料的力学性能、增强增韧机理，着重总结了微纤形成条件和影响因素。     

In situ microfibrillar blends and composites of polypropylene and poly (ethylene terephthalate): Morphology and thermal properties

Microfibrillar blends were prepared from polypropylene and poly (ethylene terephthalate) by extrusion followed by cold drawing. The draw ratio employed had a prominent effect on the aspect ratio of the microfibrils produced, as revealed by scanning electron microscopy. The subsequent isotropization step between the T_m of the polymers created microfibrillar composites with randomly oriented short microfibrils of poly (ethylene terephthalate). The X ray diffraction patterns of the microfibrillar blends were different from those of corresponding composites although the polypropylene phase in both exhibited predominantly the presence of α crystallites. The crystallization of the polypropylene phase was affected by the orientation and diameter of the poly (ethylene terephthalate) microfibrils. The short microfibrils in the microfibrillar composites were not effectual in hastening the crystallization of polypropylene. The thermal decomposition studies revealed the capability of microfibrillar blends to delay the degradation better than the microfibrillar composites.     

双转子连续混炼机中PP/PET原位复合共混的研究

利用双转子连续混炼机进行了聚丙烯/聚对苯二甲酸乙二醇酷(PP/PET)原位共混实验。通过分析共混物的微观形貌,探讨了流变行为对PET原位复合材料形成微纤的影响,以及共混温度、组分含量、剪切速率等对微纤形成的作用,并研究了组分相容性与成纤的关系,最后,探讨了PET组分含量对材料拉伸强度的影响及其作用机制。研究结果表明,在双转子连续混炼机中通过控制各加工参数,PET分散相在PP基体中可以获得显著成纤,并有利于提高复合材料的拉伸性能。     

The preparation of carbon nanotube/poly(ethylene oxide) composites using amphiphilic block copolymers

Polymer/multiwall carbon nanotube (MWCNT) composites were prepared by using amphiphilic block copolymers as dispersant. First, MWCNTs were wrapped with amphiphilic block copolymers in aqueous solution. Poly(ethylene oxide) was selected as the hydrophilic block because of its strong affinity with water while one of the following polymers: poly(ethylene), poly(butadiene), poly(styrene), poly(propylene oxide), or poly(thiophene) was used as the hydrophobic block of the copolymers. The dispersions were characterized by optical microscopy and transmission electron microscopy along with UV–Visible adsorption and dynamic light scattering. Based on the results, we could assess the effect on CNT dispersion quality of both, the molar mass of copolymers, the nature of the hydrophobic block and the length of hydrophilic block. The crystallization behavior of composites prepared from these dispersions was investigated. Results were related to the dispersion of the nanoparticles in the polymer matrix.     

The impact performance of thermoplastic sheet composites

Sheet composites of polypropylene and poly(ethylene terephthalate) were produced by melt consolidation of alternating layers of polymer films and random glass fiber mats. The composites had a nominal glass content of 50 wt% (～30 vol%). The sheets were stamped into a complex part from which test specimens were machined, and mechanical properties determined. Flexural strengths as high as 159 MPa were recorded for polypropylene composites and 313 MPa for poly(ethylene terephthalate) composites. The flexural modulus of the polypropylene composites reached 9.1 MPa, whereas the modulus of the stiffest poly(ethylene terephthalate) composite was 15 GPa. The impact properties of the composites were equally high. Polypropylene composites absorbed up to 257 J/cm during an instrumented falling dart impact test. Poly(ethylene terephthalate) composites absorbed as much as 116 J/cm in the same test.     

Rheological,thermal and morphological properties of polyethylene terephthalate/polyamide 6/rice husk ash composites

This work deals with the rheological, morphological, and thermal properties of composites having poly(ethylene terephthalate) (PET), polyamide-6 (PA6), and their blends as matrices, and rice husk ash (RHA) as a filler. The study determines the effect of composition on the change in viscosity and rate of degradation during processing in a torque rheometer. Our data indicates that thermal stability and degradation during processing depend on matrix composition and filler concentration. SEM micrographs show both partial adhesion of the filler to the matrices and filler pullout. Optical microscopy shows particle agglomeration and that agglomerate size increased with filler content. FTIR investigates the shifting of absorption bands of PET/PA6 composite after the addition of RHA and attributes the selective dispersion of RHA to the formation of hydrogen bonds. Our data supports the idea that filler employed here is an option to develop polymer composites with improved properties.     

The properties of wet-formed thermoplastic sheet composites

Glass fiber reinforced thermoplastic matrix sheet composites of polypropylene and poly(ethylene terephalate) were produced in a two-stage pilot scale impregnation and consolidation process. The first stage consisted of preparing wet-formed mats of long, discontinuous fibers and polymer powder on an inclined wire paper-making machine. The second stage consisted of consolidating approximately 15 wet-formed mats into a solid composite laminate by the application of heat and pressure in a compression press. The resulting composites had a nominal glass content of 26 wt% (∼12 vol %). Flexural strengths as high as 108 MPa for polyproplene composites and 132 MPa for poly(ethylene terephthalate) composites were measured on specimens cut from stamped parts. The flexural modulus of the polypropylene compsites reached 5.4 Gpa, while the modulus of the stiffest poly(ethylene terephthalate) composite was 8.1 Gpa. The impact properties of the composites were equally good. Polyproplene compsites absorbed up to 62 J/cm during an instrumented falling dart impact test, while poly(ethylene terephthalate) composites absorbed as much as 32 J/cm during the same test.     

Polyamide-6/cellulose nanocomposites: Influence of fiber treatment and screw rotation on nanofibrillation of jute during extrusion process

The present work studied the preparation of nanocomposites of polyamide-6 (PA6) containing nanofibrillated cellulose by melt blending in a twin screw extruder at different screw rotations to verify the fibrillation of cellulose fibers. Initially, the jute fibers were purified, hydrolyzed, and modified with titanium isopropoxide and aminopropyl silane, as well as with the two chemical modifications. They were incorporated into the polymeric matrix aiming that the shear in processing further aids in fiber fibrillation. The scanning electron microscopy analysis images of the composites showed the presence of fibers with nanodiameters dispersed in the PA6 matrix. The doubly modified fibers resulted in more fibrillation during extrusion. Increasing the screw speed of the extruder improved the degree of crystallinity for the composites with the modified fibers. The thermogravimetric measurements showed that the composite containing the doubly modified fibers increased the maximum degradation temperature. The storage modulus increased for the composites with the insertion of the treated fibers, and the glass transition temperature decreased in some composites. The composites showed higher pseudoplastic behavior, especially at high shear rates.     

Effect of LCP and rPET as reinforcing materials on rheology,morphology, and thermal properties of in situ microfibrillar‐reinforced elastomer composites

Microfibrillar‐reinforced elastomer composites based on two dispersed phases, liquid crystalline polymer (LCP) and recycled poly(ethylene terephthalate)(rPET), and styrene‐(ethylene butylene)‐styrene (SEBS) were prepared using extrusion process. The rheological behavior, morphology, and thermal stability of SEBS/LCP and SEBS/rPET blends containing various dispersed phase contents were investigated. All blends and LCP exhibited shear thinning behavior, whereas Newtonian fluid behavior was observed for rPET. The incorporation of both LCP and rPET into SEBS significantly improved the processability by bringing down the melt viscosity of the blend system. The fibrillation of LCP dispersed phase was clearly observed in as‐extruded strand with addition of LCP up to 20–30 wt %. Although the viscosity ratio of SEBS/rPET system is very low (0.03), rPET domains mostly appeared as droplets in as‐extruded strand. The results obtained from thermogravimetric analysis suggested that an addition of LCP and rPET into the elastomer matrix improved the thermal resistance significantly in air but not in nitrogen. The simultaneous DSC profiles revealed that the thermal degradation of all polymers examined were endothermic and exothermic in nitrogen and in air, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Conducting property of carbon black filled poly(ethylene glycol)/poly(methyl methacrylate) composites as gas‐sensing materials

To reveal the role of crystalline polymers in carbon black (CB) filled amorphous polymer composites and improve the mechanical properties of composite films, CB/poly(ethylene glycol) (PEG)/poly(methyl methacrylate) (PMMA) composites were synthesized by polymerization filling in this work. The electrical conductive property and response to organic solvent vapors of the composites were investigated. The composites, characterized by a relatively low percolation threshold (～ 2.1 wt %), had lower resistivity than CB/PMMA composites prepared with the same method because of the different dispersion status of CB particles in the matrix polymer. The concentration and molecular weight of PEG notably influenced the electrical response of the composites against organic vapors. The drastic increase in the electrical resistance of the composites in various organic vapors could be attributed mainly to the swelling of the amorphous polymer matrix in the solvent but not to that of the crystalline polymer. These findings could help us to understand the conductive mechanism and electrical response mechanism of the composites as promising gas‐sensing materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Synthesis and characterization of poly(methylene disulfide) and poly(ethylene disulfide) polymers in the presence of a phase transfer catalyst

Poly(methylene disulfide) and poly(ethylene disulfide) were synthesized from the polycondensation of methylene dichloride and ethylene dichloride monomers, respectively, in the presence of benzyltriethylammonium chloride as a phase transfer catalyst. The structures of the synthesized polysulfides were confirmed via the elemental analysis, attenuated total reflectance Fourier transform infrared spectroscopy and X-ray diffraction techniques. Moreover, the thermal behaviors of synthesized poly(methylene disulfide) and poly(ethylene disulfide) were characterized using differential scanning calorimetry and thermogravimetric analysis methods. The synthesized poly(methylene disulfide) and poly(ethylene disulfide) have molecular weights of about 2262 and 2863 g/mol, respectively. In addition, the polymers have crystalline structures absorbed in the amorphous sections. However, the d-spacing of polymers’ crystalline parts was different. Moreover, poly(methylene disulfide) and poly(ethylene disulfide) have a two- and one-step degradation behavior, respectively.