Properties and morphology of supertoughened polyamide 6 hybrid composites

In this study, supertoughened polyamide (PA) nanocomposites were prepared by the incorporation of epoxidized polyhedral oligomeric silsesquioxane (POSS) into the polyamide 6 (PA6)/methyl methacrylate–butadiene–styrene copolymer (MBS) blend via a melt‐blending method. The effect of POSS on the rheological properties, mechanical properties, water uptake, and morphology of the hybrid PA6 nanocomposites was studied. The results show that under impact loading, the hybrid PA6 composites exhibited significant improvements in both the crack initiation energy and the crack propagation energy. This hybrid composite showed supertough behavior. Meanwhile, the tensile strength and the water absorption resistance was also improved with the addition of epoxidized POSS. The capillary and torque rheological results indicated that the epoxidized POSS, which acted as nanoscale ball bearings, significantly decreased the melt viscosity of the matrices and facilitated the melting process. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed to study the microstructure–property relationships of the hybrid PA6 composites. The TEM results showed that the MBS particles were dispersed homogeneously in the PA6 matrix. The mean diameter of the MBS particles decreased, and the size distribution of the MBS particles narrowed down with the introduction of the epoxidized POSS and compatiblizer. The SEM micrographs indicated that the impact fracture surfaces of the PA composites showed morphological characteristics of supertough polymers because of the synergistic effect of the functionalized POSS and compatibilized MBS particles. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermal and electrical properties of aluminum nitride/boron nitride filled polyamide 6 hybrid polymer composites

The effects of boron nitride (BN) and aluminum nitride fillers on polyamide 6 (PA6) hybrid polymer composites were investigated. In particular, the thermal and electrical conductivity, thermal transition, thermal degradation, mechanical and morphological properties and chemical bonds characteristic of the materials with crystal structure of BN and aluminum nitride (AlN) filled PA6 prepared at different concentrations were characterized. Thermal conductivity of hybrid systems revealed a 1.6-fold gain compared to neat PA6. The highest thermal conductivity value was obtained for the composite containing 50 vol% additives (1.040 W/m K). A slight improvement in electrical conductive properties of composites appears and the highest value was obtained for the 50 vol% filled composite with only an increase by 3%. The microstructure of these composites revealed a homogeneous dispersion of AlN and BN additives in PA6 matrix. For all composites, one visible melting peak around 220°C related to the α-form crystals of PA6 was detected in correlation with the X-ray diffraction results. An improved thermal stability was obtained for 10 vol% AlN/BN filled PA6 composite (from 405.41°C to 409.68°C). The tensile strength results of all composites were found to be approximately 22% lower than pure PA6.     

Studies on novel composites of polyoxymethylene/ polyamide 6

A series of new composite of polyoxymethylene/polyamide 6 (POM/PA 6) were synthesized by using ε‐caprolactam as a reactive solvent with POM soluble in it. Incorporating a small content of POM (1–4 wt %) into PA 6 led to a great improvement of impact resistance POM/PA 6. The effects of POM content on the mechanical, morphological, and thermal properties of the composites were investigated. Incorporating minor POM (1 wt %), disposed in finely dispersed level (about 1 μm), into PA 6 matrix can greatly reduce the crystallization rate and crystallinity of PA 6. Scanning electron microscopy measurements indicated that much microfibers with aspect ratio about 10 appeared with the addition of 3 wt % POM because of the change of phase separation mechanisms. As a result, with a small content of PA 66 (1–4 wt %) incorporated, the impact strength and elongation of POM/PA 6 were improved markedly, with retention of good tensile strength. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 335–339, 2006     

Properties of polyamide 6/multiwalled carbon nanotubes composites: The influence of processing methods

The objective of this work was to elucidate the influence of shear rates on the properties of polyamide 6/multiwalled carbon nanotube (PA6/CNT) composites which was realized by adopting different types of processing methods that feature different orders of magnitude in shear rates, such as compression molding (CM, ~0 s⁻¹), conventional injection molding (CIM, ~10² s⁻¹) and microinjection molding (μIM, ~10⁵ s⁻¹). Electrical conductivity (σ) results indicated that the prevailing high shearing conditions in injection molding was unfavorable for the formation of intact filler network, thereby resulting in a much lower σ than CM counterparts. Moreover, the σ of PA6/CNT microparts was higher than that of CIM macroparts when the filler content was less than 5 wt%, otherwise the σ of CIM macroparts prevailed over that of μIM counterparts. A better filler distribution was observed when PA6/CNT composites were processed under higher shearing conditions, as corroborated by SEM. In addition, CNTs were preferentially aligned along flow direction and a higher degree of CNT orientation was expected with increasing shear rates, as confirmed by Raman spectral analysis. The tensile strength of injection molded PA6/CNT samples increased with increasing filler concentrations, and the more preferential orientation and better distribution of CNT were considered to be the contributing factors. The comparative study of the properties of PA6/CNT composites that processed using different methods was important for their practical applications in industrial sectors.     

尼龙-6/芳纶浆粕/马来酸酐接枝聚合物复合材料的结构与性能

利用双螺杆挤出机制备了尼龙6(PA6)/芳纶浆粕(PPTA-pulp)/马来酸酐接枝聚合物复合材料,研究了两种马来酸酐接枝物(POE-g-MAH、LLDPE-g-MAH)对复合材料的力学性能、断面形态以及结晶性能的影响。其中POE-g-MAH能明显的提高复合材料PA6/PPTA-pulp的冲击强度和断裂伸长率,POE-g-MAH含量为3%时,PA6/PPTA-pulp/POE-g-MAH的拉伸强度和弯曲强度达到实验范围内的最佳值,此时其断裂伸长率和冲击强度较未加马来酸酐接枝物体系,分别提高了57.9%和28.8%。3%马来酸酐接枝物的加入有效增强了PA6和PPTA-pulp间的界面结合力,对复合材料的结晶具有诱导作用,且并不会改变PA6的晶型。     

Properties of polycarbonate/acrylonitrile‐butadiene‐styrene/talc composites

The morphology, tensile, impact properties, and thermal expansion behavior of polycarbonate (PC)/acrylonitrile‐styrene‐butadiene (ABS)/talc composites with different compositions and mixing sequences were investigated. From the studies of morphology of the PC/ABS/talc composites, it was observed that some talc particles were located in both the PC and the ABS phases of the blend but most were at the interface between the PC and ABS phases for every mixing sequence. Aspect ratios of the talc particles determined by TEM image analysis reasonably matched values computed from tensile modulus using composite theory. The thermal expansion behavior, or CTE values, was not significantly influenced by the mixing sequence. The impact strength of the PC/ABS/talc composites depended significantly on the mixing sequence; a premix with PC gave the poorest toughness. The molecular weight of the PC in PC/talc composites was found to be significantly decreased. It appears that the impact strength of the PC/ABS/talc composites is seriously compromised by the degradation of the PC caused by talc. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

有机改性蒙脱土制备聚酰胺6/蒙脱土复合材料

采用有机复合改性的方法制备了改性蒙脱土,并采用原位聚合方法制备了尼龙-6/蒙脱土复合材料,利用FTIR、TG-DTA、XRD对有机蒙脱土进行了表征。结果表明,有机插层剂已进入蒙脱土的层间,使蒙脱土的层间距由原来的1.39 nm增大到2.32 nm,从而改善了它的分散性以及与尼龙-6之间的粘结作用,二者构成的纳米复合材料具有很好的力学性能。当加入2%的有机蒙脱土时,拉伸强度提高16%,冲击强度提高5%。     

Crystallization kinetics of highly filled glass fibre/polyamide 6 composites

Summary The present paper deals with the isothermal and non-isothermal crystallization of pure polyamide 6 (PA 6) and PA 6/glass fibre composite with a high fibre content of 81 % by weight. The so-called Avrami exponent n of pure PA 6 seems to be nearly independent of crystallization temperature fluctuating around 3.0 whereas for the composite this quantity increases strongly with crystallization temperature from 1.2 to about 6.     

聚丙烯/超支化聚酰胺接枝纳米Y2O3复合材料的性能

利用一步法缩聚工艺在经过偶联剂处理的纳米Y2O3粒子表面接枝超支化聚酰胺(HBPA),得到HBPA接枝纳米Y2O3(Y2O3-g-HBPA),用傅里叶变换红外光谱与热重分析对其进行了表征。通过熔融共混制备了聚丙烯(PP)/Y2O3复合材料,研究了纳米粒子含量和增容剂甲基丙烯酸缩水甘油酯(GMA)接枝PP(PP-g-GMA)对复合材料性能的影响。结果表明:Y2O3-g-HBPA比未改性Y2O3对PP有更好的增强增韧作用,当w(Y2O3-g-HBPA)为3%时,PP/Y2O3-g-HBPA复合材料的冲击强度与拉伸强度分别比纯PP提高了43.8%,16.3%;PP-g-GMA提高了PP/Y2O3复合材料的力学性能,但降低了PP/Y2O3-g-HBPA复合材料的力学性能;纳米粒子起到异相成核的作用,使PP的结晶峰温度升高,PP-g-GMA提高了复合材料的总结晶速率。     

Mechanical properties of polyamide 6 reinforced microfibrilar composites

The mechanical behavior of microfibrilar composites (MFC), consisting of a matrix of high‐density polyethylene (HDPE) and reinforcement of polyamide 6 (PA6) fibrils, with and without compatibilization, was studied. The composites were produced by conventional processing techniques with various shape and arrangement of the PA6 reinforcing entities: long, unidirectional, or crossed bundles of fibrils (UDP and CPC, respectively), middle‐length, randomly oriented bristles (MRB), or non‐oriented micrometric PA6 spheres (NOM). The tensile, flexural, and impact properties of the MFC materials (UDP, CPC, and MRB) were determined as a function of the PA6 reinforcement shape, alignment and content, and compared with those of NOM, the non‐fibrous composite. It was concluded that the in‐situ MFC materials based on HDPE/PA6 blends display improvements in the mechanical behavior when compared with the neat HDPE matrix, e.g., up to 33% for the Young modulus, up to 119% for the ultimate tensile strength, and up to 80% for the flexural stiffness. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

PET/硅灰石复合材料性能研究

主要研究了硅灰石含量对PET力学性能、耐磨性能和结晶性能的影响。力学性能测试结果表明:随着硅灰石含量的增加,PET的冲击强度和拉伸强度均先上升而后下降,在硅灰石质量分数为6%时冲击强度最大。另外,硅灰石的加入改善了PET的耐磨性能,9%的硅灰石对PET/硅灰石复合材料的耐磨性改善最佳。此外,从DSC测试结果可知:硅灰石能够促进PET结晶提高其玻璃化转变温度和结晶速率。     

Investigation on the multiwalled carbon nanotubes reinforced polyamide 6/polypropylene composites

Multiwalled carbon nanotubes (MWNTs) reinforced polyamide 6/polypropylene (PA6/PP = 70/30) composites were prepared by melt compounding. Maleated polypropylene (MPP) was used as a compatibilizer for the composites. The morphology, mechanical properties, thermal stability, rheological properties and crystallization behavior of the composites were investigated. It was found that the addition of MWNTs to PA6/PP blend resulted in decrease in the size of the dispersed particles. Most of MWNTs were selectively dispersed in the PA6 phase and a small amount of MWNTs were located in the interphase between PA6 matrix and PP phase as characterized by scanning electric microscopy. The strength and stiffness of the PA6/PP blend were greatly improved by the addition of MWNTs. The MPP and MWNTs had a synergistic effect on the improvement ofthe thermal stability. In addition, the complex viscosity, storage modulus and loss modulus of the composites increased with the addition of MWNTs or MPP. MWNTs could induce the formation of α crystalline form of PA6. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Developing electrically conductive polypropylene/polyamide6/carbon black composites with microfibrillar morphology

We have established that the PP/PA6/CB composite with 3D microfibrillar conducting network can be prepared in situ using melt spinning process. CB particles preferably were localized at the interface between polypropylene as the matrix and PA6 microfibrils, which act as the conducting paths inside the matrix. The percolation threshold of the system reduced when aspect ratio of the conducting phase was increased by developing microfibrillar morphology. The effect of annealing process on the conductivity of PP/PA6/CB composite with co‐ continuous and microfibrillar morphologies was studied. It was observed that, annealing process forces CB particles towards the interface (2D space) of PP and PA6 co‐continuous phases, and percolation threshold and critical exponent of classical percolation theory will be decreased, while the conductivity of conducting composite with microfibrillar morphology was not affected considerably by annealing process at temperatures either higher or lower than the melting point of the PA6 microfibrils. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Melting behavior and nonisothermal crystallization kinetics of polyamide 6/polyamide 66 molecular composites via in situ polymerization

The melting behavior and nonisothermal crystallization kinetics of pure polyamide 6 (PA 6) and its molecular composites with polyamide 66 (PA 66) were investigated with differential scanning calorimetry. The PA 6/PA 66 composites had one melting peak, whereas the coextruded PA 6/PA 66 blends had two melting peaks. With the addition of PA 66 to PA 6 via in situ anionic polymerization, the melting temperature, crystallization temperature, and crystallinity of PA 6 in the composites decreased. The half‐time of nonisothermal crystallization increased for a PA 6/PA 66 molecular composite containing 12 wt % PA 66, in comparison with that of pure PA 6. The commonly used Ozawa equation was used to fit the nonisothermal crystallization of pure PA 6 and its composites. The Ozawa exponent values in the primary stage were equal to 1.28–3.03 and 1.28–2.97 for PA 6 and its composite with 12 wt % PA 66, respectively, and this revealed that the mechanism of primary crystallization of PA 6 and PA 6/PA 66 was mainly heterogeneous nucleation and growth. All the results indicated that the incorporation of PA 66 into PA 6 at the molecular level retarded the crystallization of PA 6. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2172–2177, 2005     

马来酸酐对聚酰胺6短纤维/天然橡胶复合材料的增容作用

将马来酸酐直接与天然橡胶混炼，得到的马来酸酐-天然橡胶接枝物既能与聚酰胺6短纤维也能与天然橡胶形成良好的结合，有助于提高短纤维增强橡胶复合材料的物理机械性能。     

Thermal and mechanical behavior of polyamide 6/polyamide 6I/6T blends

The thermal and mechanical properties of blends, obtained by mixing polyamide 6 (PA6) and an amorphous aromatic copolyamide G21 (ISO nomenclature PA 6I/6T), were investigated by differential scanning calorimetry, dynamic mechanical analysis, and mechanical tensile tests. Quenched blends show a single glass transition temperature; the T_g-composition trend was interpreted by means of the Gordon–Taylor equation. The half-time of crystal-lization decreases by increasing the G21 content and this indicates a depression of the overall crystallization rate. A small decrease in the equilibrium melting temperature of PA6 in the blends was observed; this finding suggests that the interaction parameter in PA6/G21 blends is probably very small. The dynamic mechanical analysis of crystallized blends suggests the presence of a homogeneous amorphous phase even if the crystallization of PA6 occurred. The tensile mechanical properties reveal that G21 acts as stiffener of PA6. The collected experimental data suggest that PA6 and G21 are miscible in the composition range investigated. © 1996 John Wiley & Sons, Inc.     

Mechanical and thermal properties of talc and calcium carbonate filled polypropylene hybrid composites

The main aim of this work was to study and compare the mechanical and thermal properties of hybrid polypropylene (PP) composites and single‐filler PP composites. With two main types of mineral fillers—calcium carbonate (CaCO₃) and talc—PP composites of different filler weight ratios (talc/CaCO₃) were compounded with a twin‐screw extruder and then injection‐molded into dumbbell specimens with an injection‐molding machine. Tensile, flexural, and impact tests were performed to determine and compare the mechanical properties of the hybrid and single‐filler PP composites. A synergistic hybridization effect was successfully achieved; the flexural strength and impact strength were highest among the hybrids when the PP/talc/CaCO₃ weight ratio was 70:15:15. The nucleating ability of the fillers and its effects on the mechanical properties were also studied with differential scanning calorimetry. Because of the influence of talc as the main nucleating agent, the hybrid fillers showed significant improvements in terms of the nucleating ability, and this contributed to the increase in or retention of the mechanical properties of the hybrid composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3327–3336, 2004     

PP/硅灰石复合材料在室内家具设计中的应用研究进展

综述了聚丙烯(PP)/硅灰石复合材料在室内家具设计中的应用,主要介绍了其在室内家具装饰件和承载力构件的应用.当相容剂甲基丙烯酸丁酯和苯乙烯-丙烯酸丁酯-马来酸酐共聚物接枝改性聚丙烯与改性硅灰石质量分数均为30％时,PP/硅灰石复合材料的力学性能最好,制备的家具抗冲击性能好.按材料的性能沿承载结构布置传力路径,可以最大限...     

High performance polyamide 6 composites prepared by reactive extrusion

To improve the properties of polyamide 6 (PA6) composites, a series of modified PA6 composites was prepared by reaction extrusion. An amorphous PA6 was first obtained by the complexing reaction of Li⁺ in lithium chloride with amino groups, and then epoxy resins, nano‐SiO₂ as well as POE‐g‐MAH were in turn added into the PA6/LiCl system. The effect of different additives on the crystallization behavior and mechanical properties of PA6 composites was well‐studied by X‐ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), and mechanical properties tests. The results demonstrated that PA6 was amorphous at 6 phr lithium chloride and a network structure was formed in PA6 matrix in the presence of epoxy resins, thus the mechanical properties of composites greatly were enhanced. However too many nano‐SiO₂ particles might impair the tensile strength of PA6 composites. Additionally, a PA6 composite with excellent properties was obtained in the presence of POE‐g‐MAH due to the crystal form change in PA6 matrix and the strong interaction between PA6 and POE‐g‐MAH. POLYM. COMPOS., 35:985–992, 2014. © 2013 Society of Plastics Engineers     

Microfibrillar composites based on polyamide/polyethylene blends. 1. Structure investigations in oriented and isotropic polyamide 6

The present paper discloses the structural changes caused by heating of polyamide 6 (PA6) samples with different thermal and mechanical histories in the 30-240 °C range. Wide and small-angle X-ray scattering (WAXS and SAXS) of synchrotron radiation, as well as solid-state nuclear magnetic resonance spectroscopy (NMR) measurements are performed. The NMR spectra show that in both isotropic and oriented samples there is a co-existence of α and γ-PA6 crystalline forms. Deconvolution of the WAXS patterns is performed to follow the temperature dependence of the unit cell parameters of the α and γ-forms and also of the equatorial (ECI) and total crystallinity indexes (CI), evaluating the contributions of the two crystalline phases. Estimates for the long spacing and for the average thicknesses of the crystalline (l_c) and amorphous (l_a) phases within the lamellae are calculated as a function of the heat treatment employing analysis of the linear correlation function calculated from the SAXS patterns. The X-ray results allowed the conclusion that upon heat treatment up to 160-200 °C, intensive transitions between the PA6 crystalline forms take place, whereby the content of the initial major crystalline phase decreases and that of the initial minor one increases reaching almost 1:1. Close to 200 °C a general trend toward increasing the content of the α-form is registered. The influence of annealing and quenching after melting on the PA6 crystalline structure is also studied.