芳香族支链聚酰胺6的制备及共混纺丝研究

通过添加均苯四甲酸二酐水解聚合工艺制备芳香族支链聚酰胺6(PA6),采用熔融共混制备芳香族支链PA6/Ti O2母粒,然后与线型PA6共混纺丝,经拉伸后得到含芳香族支链PA6的共混纤维;研究了均苯四甲酸二酐含量对芳香族支链PA6流动性及热学性能的影响,以及芳香族支链PA6对芳香族支链PA6/Ti O2共混物结晶行为、可纺性及纤维力学性能等的影响。结果表明:随着均苯四甲酸二酐含量的添加,芳香族支链PA6的相对黏度逐渐降低,熔体流动指数增大,流动性增加,而结晶熔融温度逐渐降低;含芳香族支链PA6的共混体系纺丝温度较纯PA6降低4℃,芳香族支链PA6有助于提高PA6的可纺性,且纤维力学性能较好,含质量分数8%芳香族支链PA6的共混纤维的断裂强度为2.8 c N/dtex,断裂伸长率为45.4%。     

纺丝条件对干纺氨纶性能的影响

通过改变干纺时的纺丝条件并对所得产品的断裂强力、断裂伸长率及均一性进行测试,发现氨纶的断裂强力随着热风的温度升高、风量增大及纺丝速度的提高而增大,断裂伸长率随着风温升高而增大,但随着风量及纺速的增大而减小,双导丝器的使用对于改善氨纶的均一性有利。     

Processability of polysulfone improved by adding polyamide 6 and polysulfone‐polyamide 6 block copolymer

Although polysulfone (PSU) is a potential thermoplastic engineering plastic with high heat resistance, good dimensional stability and excellent mechanical properties, its poor processability has greatly restricted its application in electrical, aerospace, and medical fields. In this work, polyamide 6 (PA6) and PSU‐PA6 block copolymer (PSU‐b‐PA6) were used to improve the processibility and formability of PSU depending on their excellent fluidity and good compatibility between two components. Furthermore, the fluidity, thermal and mechanical properties of the blends were carefully investigated. It was found that, melt flow index of PSU could be increased above 10 times, and strength and toughness could be enhanced by 4–10% with the introduction of 10 wt % PA6 and PSU‐b‐PA6 without compromising the heat resistance of PSU obviously. The processing conditions of PSU could be improved while maintaining a decent comprehensive performance. Thus, the method has great potential for extending the applications of PSU. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41139.     

PA6/蒙脱土熔融插层复合材料结构与性能分析

通过熔融共混法插层复合制备了聚酰胺(PN)6／蒙脱土纳米复合材料，测试了力学性能并对不同蒙脱土含量的PA 6／蒙脱土纳米复合材料进行了对比。实验表明，通过熔融插层可使PN 6基体插层于蒙脱土中，所得到的复合材料的性能较PN 6有很大提高。蒙脱土特殊的层状结构使得利用熔融共混在机械力的作用下插层到纳米级复合材料成为可能。     

Syntheses of intrinsically flame-retardant polyamide 6 fibers and fabrics

In this study, flame-retarded polyamide 6 (FR-PA6) was prepared via the direct co-condensation of ε-caprolactam with two different organophosphorus compounds in a typical melt-polymerization process. Polymer microstructures, especially the incorporation of the phosphorus-containing comonomers, as well as the thermal and physical properties of the resulting copolyamides have been studied in detail. The phosphorus-modified PAs have a P-content of 0.10–0.30 wt %, possess high relative viscosities of 2.2–2.4 and good thermal stability. FR-PA6 multifilaments were prepared by melt spinning and show tensile strengths up to 40 cN/tex and tenacities up to 0.5 GPa. Knitted fabrics of FR-PA6 exhibit high limiting oxygen index values around 35%. Due to the very low phosphorus content, there is no impairment of the material properties of PA6. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47829.     

Synthesis and properties of hydroxyapatite nanorod‐reinforced polyamide 6 nanocomposites

BACKGROUND: Polyamide 6 (PA6)/hydroxyapatite (HA) nanocomposites, which combine the bioactivity and biocompatibility of HA and the excellent mechanical performance of PA6, have emerged as new biomaterials with potential applications in the clinical setting. It has been shown that these nanocomposites show good similarity to natural bone in terms of chemistry and mechanical properties. RESULTS: In this study, highly crystallized hydroxyapatite nanorods (HANR) were used to fabricate PA6/HA nanocomposites via in situ hydrolytic ring‐opening polymerization of ε‐caprolactam. The effect of the HANR on the thermal stability, crystallization behavior and hydrogen bonding of PA6 was investigated using thermogravimetric analysis, differential scanning calorimetry and Fourier transform infrared (FTIR) spectroscopy, respectively. It was found that HANR can obviously increase the crystallization temperature and decrease the degree of supercooling. In addition, the thermal degeneration temperature of PA6 is also increased by the incorporation of HANR. FTIR analysis of the hydrogen bonded N? H stretching vibration revealed that, with increasing HANR loading, the hydrogen bonded N? H stretching band shifts to higher frequency and decreases in intensity. CONCLUSION: The thermal stability and crystallization ability of PA6 are improved considerably by the incorporation of HANR. However, the hydrogen bonding strength is weakened and the degree of ordering of hydrogen bonding is reduced by the incorporation of HANR, which can be explained by the formation of hydrogen bonds at the interface between ? OH groups of HANR and the ? N? H or ? C?O groups of PA6. Copyright © 2009 Society of Chemical Industry     

Melt blending of polypropylene‐blend‐ polyamide 6‐blend‐organoclay systems

The melt blending of polypropylene‐blend‐polyamide 6‐blend‐organoclay (PP/PA6/organoclay) systems has been investigated using an internal mixer without any traditional compatibilizer. In the presence of organoclay, the melting of PA6 phase is accelerated and the dimension of the dispersed phase in the matrix is reduced. Transmission electron microscopy results reveal clay‐rich interface zones formed between the PA6 dispersed phase and the PP matrix in the PP/PA6/organoclay system. An interface blending approach has been designed to investigate the interface zones between the immiscible polymers, and the interface zones have been characterized by Fourier transform infrared and X‐ray photoelectron spectroscopy. In the presence of the organoclay, the PA6 component in interface zones is stable even after etching extraction with formic acid, suggesting a strong interaction takes place among PP, PA6 and the organoclay. Such clay‐rich interface zones act as a compatibilizer for the two immiscible polymers, resulting in a better dispersion of PA6 phase in PP matrix. Copyright © 2006 Society of Chemical Industry     

Stress photo‐oxidative aging behaviour of polyamide 6

The long‐term stress accelerating aging behaviour of polyamide 6 (PA6) was studied by exposure to UV irradiation. The aging behaviour and mechanism were investigated in terms of creep behaviour, mechanical properties, chemical structure, crystallization and orientation behaviour. It was found that the creep deformation of PA6 under stress/UV irradiation was lower than that of the sample aging only under stress, resulting from crosslinking and low mobility of molecules under UV irradiation. The tensile strength of PA6 under stress and stress/UV irradiation substantially increased at the primary aging stage due to stress‐induced molecular orientation. The oxidation of PA6 may also be inhibited by orientation, leading to a relatively low content of carboxylic groups. Under UV irradiation, stress accelerates the degradation of PA6, resulting in strengthening UV absorption due to formation of isolated carbonyl groups. The melt temperature and crystallinity both showed an increase with time, which were much higher for the sample aged under stress/UV irradiation than for that aged only under UV irradiation. Wide‐angle X‐ray diffraction analysis also showed that the orientation factor and crystallinity of PA6 increased with aging time before 16 days, indicating a clear orientation and crystallization of molecules induced by stress. The UV‐induced crosslinking reduced the mobility of PA6 chains, resulting in a lower crystallinity and orientation factor of the sample aged under stress/UV irradiation compared with that under stress aging only. Copyright © 2011 Society of Chemical Industry     

Study on the long‐term thermal‐oxidative aging behavior of polyamide 6

The long‐term thermal‐oxidative aging behavior of polyamide 6 (PA6) was studied by comparison with the stabilized sample in this work. The variation of mechanical properties of the pure and the stabilized samples of PA6 with aging time at 110°C, 130°C, and 150°C were investigated, respectively. The aging mechanism of PA6 under heat and oxygen was studied in terms of the reduced viscosity, crystallization behavior, dynamic mechanical behavior, and chemical composition through the methods of polarized light microscopy (PLM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X‐ray photoelectron energy spectrum (XPS), and so on. The results indicated that at the initial stage of aging, the molecular crosslinking reaction of PA6 dominated resulting in the increase of the mechanical strength, reduced viscosity, and the glass transition temperature of the sample. And the molecular degradation dominated in the subsequent aging process resulting in the decrease of the melting temperature, the increase of the crystallinity, and the formation of the oxides and peroxides products. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Grafting polyamide 6 onto multi‐walled carbon nanotubes using microwave irradiation

Chemical reactions under microwave irradiation can be very efficient, with a significant shortening of reaction time. Few studies have reported the use of microwaves to functionalize carbon nanotubes. In the work reported, a new method of formulating functionalized multi‐walled carbon nanotubes (MWNTs) was developed by covalent grafting of polyamide 6 (PA6) chains onto the carbon nanotubes assisted by microwave irradiation. PA6 chains were grafted onto acidified MWNTs through condensation reaction between the carboxylic groups of the MWNTs and the terminal amine groups of PA6 using microwave radiation heating. The functionalized carbon nanotubes (MWNT‐g‐PA6) were characterized systematically using infrared and Raman spectroscopy, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). TEM showed that the surface of the MWNTs was covered with a layer of PA6. TGA results indicated that the MWNT‐g‐PA6 contained about 47 wt% of polymer. A novel, convenient and efficient functionalization approach is reported, involving covalently grafting PA6 chains onto MWNTs assisted by microwave irradiation. Copyright © 2010 Society of Chemical Industry     

尼龙-6/蒙脱土纳米复合材料用POE-g-MAH改性及性能研究

制备了尼龙-6(PA6)/马来酸酐接枝乙烯-1-辛烯共聚物(POE-g-MAH)和PA6-蒙脱土纳米复合物(NCH)/POE-g-MAH两种复合材料,其脆韧转变点都是在POE-g-MAH质量分数为8%～10%。在脆韧转变点前,PA6/POE-g-MAH和NCH/POE-g-MAH的缺口冲击强度几乎相同;在脆韧转变点后,NCH/POE-g-MAH的冲击强度远高于PA6/POE-g-MAH。复合材料的拉伸强度都随POE-g-MAH的增加而线性下降,在相同POE-g-MAH含量时,NCH/POE-g-MAH的拉伸强度比PA6/POE-g-MAH的低4MPa左右。     

A processing-induced clay dispersion and its effect on the structure and properties of polyamide 6

The nanostructures and morphologies of polyamide 6 (PA6)/organoclay nanocomposites prepared by melt compounding have been studied by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). A combination of XRD and TEM indicates that an exfoliated clay morphology dominates at low clay loadings (≤5 wt%) and a mixture of intercalated and exfoliated structures exists at high clay concentrations. It is worth noting, however, that optical microscopy (OM) even shows the presence of large clay agglomerates in samples with higher clay contents. OM images further present an overview of an uneven clay distribution due to the effect of injection molding. The crystalline structure of PA6 is greatly affected by this unevenness in the processing-induced clay dispersion, as evidenced by differential scanning calorimetry (DSC). The thermal dynamic and mechanical properties of PA6 and the nanocomposites have been investigated as a function of clay concentration. The tensile tests show that the degree of dispersion of the nanoclay within the polymer matrix plays a vital role in property improvement. Copyright © 2004 Society of Chemical Industry     

高相对粘度聚酰胺6冻胶的研究

采用阴离子淤浆聚合方法制备了聚酰胺6(PA6)冻胶,用扫描电镜、差示扫描量热和广角X射线衍射等手段对冻胶结构和性能进行了分析。探讨了PA6的相对粘度(η_r)、浓度和络合剂用量及不同溶剂对PA6冻胶的溶胶-冻胶转变点(T_f)的影响。结果发现:随冻胶中PA6的浓度、三氯化镓与PA6摩尔比的增加,T_f都会随之升高,呈较好的线性关系;η_r的增加使T_f升高,η_r小于12.5时,η_r和T_f呈线性关系,当η_r大于12.5时,则会发生偏离;冻胶表面有均匀的层状结构,有利于纺丝和高倍拉伸,络合剂三氯化镓能有效地将PA6分子间的氢键屏蔽,对冻胶的形成有很大作用。     

In situ synthesis of bone‐like hydroxyapatite/polyamide 6 nanocomposites

BACKGROUND: Polymer/hydroxyapatite (HA) nanocomposites have emerged in recent years as a new class of biomaterials that can be used as artificial bone. Compared to pure HA or HA‐based bioceramics, and metallic implants, they exhibit good plasticity, improved toughness and good mechanical compatibility with natural bone. Compared to their microcomposite counterparts and the pristine polymer matrix, they show increased tensile strength and modulus, and enhanced bioactivity. RESULTS: In this study, polyamide 6 (PA6)/nanoscale HA (n‐HA) nanocomposites were prepared via in situ hydrolytic ring‐opening polymerization of ε‐caprolactam in the presence of newly synthesized n‐HA aqueous slurry. The synthesized n‐HA, which is similar to bone apatite in chemical composition, microscopic morphology and phase composition, dispersed uniformly in the composites even if its loading was up to 60 wt%. The PA6/n‐HA composites show a similarity to natural bone in chemical composition to a certain extent. Mechanical tests show that the composites are reinforced considerably by the incorporation of needle‐like n‐HA, and the composites have mechanical properties near to those of natural bone. CONCLUSION: The PA6/n‐HA nanocomposite with high n‐HA content shows a similarity to natural bone in terms of chemistry and mechanical properties. This makes it a possible candidate for biomaterials suitable for bone repair or fixation. Copyright © 2008 Society of Chemical Industry     

Elevated temperature nanoindentation behaviour of polyamide 6

It has been found, in this study, that there is no close correlation between the tensile and nanoindentation moduli of polyamide 6 (PA6) at high temperatures. It is demonstrated that heat modifies the surface of PA6 specimens, but its effect on the nanomechanical properties is minor. The main spurious factor which affects the nanoindentation results is adhesion, especially at low indentation depths. The overestimation in the measured indentation moduli can be corrected by performing indentations with loads high enough so that the modulus is independent of the applied load. It is concluded that the lack of strict correlations between the tensile and indentation moduli (after corrections of adhesion) is caused by the shift in the glass transition temperature of PA6 owing to the hydrostatic stress imposed by the indenter. Further proof is given with two examples on hydrostatic pressure‐dependent polymers: polytetrafluoroethylene and polycarbonate. Copyright © 2011 Society of Chemical Industry     

Preparation of polyamide resin‐encapsulated melamine cyanurate/melamine phosphate composite flame retardants and the fire‐resistance to glass fiber‐reinforced polyamide 6

In this study, melamine cyanurate (MCA)/melamine phosphate (MP) composite flame retardants were synthesized in the solution of phosphoric acid/polyamide 6 (PA6). Phosphoric acid acted as the solvent of PA6, catalyst of melamine‐cyanurate self‐assembly reaction and reactant of melamine‐phosphoric acid reaction. With the consumption of the acid, the pH value of the system increased, and the solved PA6 precipitated on the surface of the flame retardant particles to form polymeric encapsulation. This technology realized the synthesis and surface modification of the flame retardants in one process. The catalyst and solvent, phosphoric acid, was finally converted into the product MP, and need no an additional removing process. The encapsulated MCA/MP (EMCMP) composite flame retardants were successfully applied in the fire‐resistance to glass fiber (GF)‐reinforced PA6. Because the encapsulated layer of EMCMP was also PA6, good interfacial compatibility and effective dispersion of EMCMP in PA6 resin can be obtained, and the corresponding flame retardant materials showed excellent flame retardancy and mechanical performance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1773–1779, 2006     

Melt rheological properties of polypropylene–polyamide6 blends compatibilized with maleic anhydride‐grafted polypropylene

The melt rheological properties of binary uncompatibilized polypropylene–polyamide6 (PP–PA6) blends and ternary blends compatibilized with maleic anhydride‐grafted PP (PP–PP‐g‐MAH–PA6) were studied using a capillary rheometer. The experimental shear viscosities of blends were compared with those calculated from Utracki's relation. The deviation value δ between these two series of data was obtained. In binary PP–PA6 blends, when the compatibility between PP and PA6 was poor, the deformation recovery of dispersed PA6 particles played the dominant role during the capillary flow, the experimental values were smaller than those calculated, and δ was negative. The higher the dispersed phase content, the more deformed the droplets were and the lower the apparent shear viscosity. Also, the absolute value of δ increased with the dispersed phase composition. In ternary PP–PP‐g‐MAH–PA6 systems, when the compatibility between PP and PA6 was enhanced by PP‐g‐MAH, the elongation and break‐up of the dispersed particles played the dominant role, and the experimental values were higher than calculated. It was observed that the higher the dispersion of the PA6 phase, the higher the δ values of the ternary blends and the larger the positive deviation. Unlike uncompatibilized blends, under high shear stress with higher dispersed phase content, the PP‐g‐PA6 copolymer in compatibilized blends was pulled out from the interface and formed independent micelles in the matrix, which resulted in reduced total apparent shear viscosity. The δ value decreased with increasing shear stress. Copyright © 2006 Society of Chemical Industry     

Monomer cast polyamide 6 composites and their treatment with high‐energy electrons

At first, the impact of selected spherically structured nanofillers made of different polar materials (carbon, silicon carbide, surface‐modified silica, 2 wt % each) on mechanical properties of monomer cast polyamide 6 (MCPA6) was examined. Only the low‐polar carbon‐based nanofiller showed an average particle size below 100 nm in the liquid phase before polymerization was initiated. With regard to neat MCPA6, mechanical properties of the composite loaded with the carbon nanoparticles like tensile strength, Young's modulus, and heat distortion temperature could be improved by 6.4%, 13.5%, and 27.5%, respectively. The efficiency of carbon as filler material for MCPA6 was also shown for carbon short‐cut fibers. A fiber content of 15% improved tensile strength from 78 to 93 MPa (19%) and Young's modulus could be doubled from 2660 MPa to nearly 5300 MPa. Regardless of the improved mechanical properties, the composites showed reduced degrees of crystallinity. Therefore, electron beam irradiation was applied to crosslink the polymer chains as an alternative to improve material properties. Crosslinking was supported by the application of a curing agent (CA). Two strategies for crosslinking experiments were tested: (1) Irradiation of CA‐containing neat MCPA6 to find the most effective dose and subsequent treatment of the composites under this special condition; (2) Optimization of the properties by irradiation of the composites itself at graduated dose values. The second way was more convenient and showed, with regard to the composites without CA, improvements of tensile strength and Young's modulus of 6% each. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Physical properties of polyamide 6/H‐NBR blends and the effects of dynamic vulcanization on them

Polyamide 6 (PA 6) and hydrogenated nitrile rubber (H‐NBR) were blended with various blend ratios in a brabender plasticoder at 240°C/100 rpm. The processing characteristics with a mixing torque of the blends were investigated. The effect of the blend ratio on physical properties such as tensile strength, Young's modulus, elongation at break, permanent set, hardness, and swelling behavior of blends was analyzed. Most mechanical properties were found to decrease with an addition of H‐NBR. The morphology of the blends was observed, and the results show a two phase system where the component with high proportions exists as a continuous phase. A cocontinuous phase was observed in blend ratios of 50/50 and 40/60. Dynamic mechanical properties were observed to study a viscoelastic property of the blends. In addition, the effect of dynamic vulcanization with peroxide on physical properties was studied, and the influence of peroxide on PA 6 was also examined. It was found that the peroxide can have an effect on PA 6 as well as act as a crosslinker to H‐NBR. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Gel‐spinning of partially saponificated poly(vinyl alcohol)

DMSO/water (80/20 volume ratio) solutions of commercial poly(vinyl alcohol)s (a‐PVA₉₉, a‐PVA₈₈) with degrees of saponification of 99.3 and 88 mol % were gel‐spun into methanol (−20 and −70°C). The dry filaments obtained were drawn at 200°C (a‐PVA₉₉) and 150–180°C (a‐PVA₈₈). The maximum draw ratio and Young's modulus were 26 and 34 GPa for a‐PVA₉₉ and 21 and 24 GPa for a‐PVA₈₈ (drawing temperature: 160°C). So, at first, the dry filaments obtained for a‐PVA₈₈ were drawn at 150–180°C until 10 times their original length. Moreover, the predrawn a‐PVA₈₈ filaments were perfectly saponificated under fixing at the both ends and then the filaments were redrawn at 200°C. The maximum draw ratio and Young's modulus for the filaments (a‐PVA_88→99) predrawn at 150°C were 28 and 39 GPa, respectively. The a‐PVA_88→99 filaments had two melting peaks (228 and 236°C). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2872–2876, 2000