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1.
In this paper, polyamide‐6 and polyamide‐6 nanocomposites were prepared by direct melt intercalation technique. The thermal degradation behavior of both polyamide‐6 and polyamide‐6 clay nanocomposites has been studied. The apparent activation energy of the nanocomposites is almost the same with that of pure polymer under nitrogen, but the apparent activation energy of the nanocomposites is greatly enhanced in air atmosphere. This increasing trend coincides with the thermal analysis and the cone calorimeter results, which may suggest that the polymer/clay nanocomposites have a higher thermal stability and lower flammability. The kinetic analysis also indicates that the pyrolytic degradation and the thermal oxidative degradation of PA6 and PA6/OMT nanocomposites are two kinds of different reaction models. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2297–2303, 2007 相似文献
2.
摘要：采用癸二胺、对苯二甲酸、己二胺和己二酸合成了耐高温聚酰胺(PA)10T/66。通过热重(TG)分析法研究了PA10T/66的热降解动力学。结果显示,随着升温速率的增大,热降解外推起始温度,最大失重速率温度和热降解外推结束温度均逐渐升高。不同升温速率下的TG曲线结果显示PA10T/66的降解过程都为一步降解。用Kissinger-Akahira-Sunose (KAS),Flynn-Wall-Ozawa (FWO)和Tang等方法确定了PA10T/66的热降解动力学参数和热降解活化能,并通过Coats-Redfern积分法确定了其热降解机理函数类型为[相边界反应(球形)](R3型)。 相似文献
3.
Piperazine pyrophosphate (PAPP) was mixed in polyamide 6 (PA6) to investigate its flame retardant properties. The PAPP was characterised by Fourier transform infrared (FT-IR), elemental analysis, proton nuclear magnetic resonance (1H-NMR) spectroscopy and thermogravimetric analysis (TGA). The elemental analysis and TGA results of PAPP indicated it had a high P element content and good thermal stability. The flame retardancy of PA6/PAPP was also characterised by TGA, limiting oxygen index (LOI), UL-94 vertical test and microscale combustion calorimetry (MCC). The TGA results showed that the PAPP increased the stability of the PA6/PAPP and resulted in a significant increase of char residue. PA6/PAPP passed the UL94 V-0 rating with a LOI value of 42 vol %. The MCC test indicated that the PAPP can greatly decrease the peak heat release rate (PHRR) and total heat release (THR). The results of scanning electron microscope (SEM) illustrated that PAPP can promote the formation of compact char layer. 相似文献
4.
Polyamide 6 (PA6) nanocomposites based on epoxy resin‐modified montmorillonite (EP‐MMT) were prepared by melt processing using a typical twin‐screw extruder. X‐ray diffraction combined with transmission electron microscopy was applied to elucidate the structure and morphology of PA6/EP‐MMT nanocomposites, suggesting a nearly exfoliated structure in the nanocomposite with 2 wt % EP‐MMT (PA6/2EP‐MMT) and a partial exfoliated‐partial intercalated structure in PA6/4 wt %EP‐MMT nanocomposite (PA6/4EP‐MMT). The thermogravimetric analysis under air atmosphere was conducted to characterize the thermal–oxidative degradation behavior of the material, and the result indicated that the presence of EP‐MMT could inhibit the thermal‐oxidative degradation of PA6 effectively. Accelerated heat aging in an air circulating oven at 150°C was applied to assess the thermal–oxidative stability of PA6 nanocomposites through investigation of reduced viscosity, tensile properties, and chemical structure at various time intervals. The results indicated that the incorporation of EP‐MMT effectively enhanced the thermal–oxidative stability of PA6, resulting in the high retention of reduced viscosity and tensile strength, and the low ratio of terminal carboxyl group to amino group. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40825. 相似文献
5.
The curing reactions, kinetics, morphology, and thermal stability of the reactive blends of diglycidyl ether of bisphenol‐A (DGEBA) and polycaprolactam were studied by differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis. DSC studies showed that the heat of reaction (ΔH) increased when the DGEBA content was increased from 50 to 80 wt % and increased drastically above 70 wt % DGEBA content because of an increase in the extent of crosslinking. The activation energy and pre‐exponential factor of cure reactions increased drastically with an increase in the DGEBA content above 70 wt % because of a drastic increase in crosslink density. The extent of curing reaction of polycaprolactam with DGEBA is dependent on the blend composition. The nucleophilic attack on oxirane ring by amide nitrogen of polycaprolactam is a dominant curing reaction in low DGEBA compositions, and another type of curing reaction with relatively large activation energy and pre‐exponential factor also occurred, which becomes dominant when the DGEBA content reaches above 70 wt %. FTIR studies also revealed that two types of reactions do exist during the curing of polycaprolactam with DGEBA. It was observed during SEM studies that the reactive blends show multiphase system and on increasing the DGEBA content from 50 to 80 wt %, the mixing of the two phases increased. The reactive blend Ep80Ca20 with 80 wt % DGEBA content exhibits a single‐phase system because of better mixing of the two phases. The results of thermogravimetric analysis also indicate that the initial degradation temperature (Ti), activation energy (E), and pre‐exponential factor (Z) increased with increasing DGEBA content from 50 to 80 wt % in the reactive blends and increased drastically above 70 wt % DGEBA content due to the higher crosslink density. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 687–697, 2004 相似文献
6.
The influence of stress, temperature, and relative humidity on plasticity-controlled failure of molded and laser-sintered polyamide 12 (PA12) has been investigated. Ree–Eyring's flow theory is employed and modified to take into account the effect of relative humidity on the deformation kinetics. By introducing the concept of critical strain, time to failure in plasticity-controlled regime is predicted starting from the yield kinetics. Creep test is performed to estimate the critical strain and to validate model predictions. The model predictions are in good agreement with the experimental results, showing that the model is a suitable and reliable tool to evaluate mechanical response as function of temperature and relative humidity. We demonstrate that, while, at high applied strain rates, a significant difference is found, the mechanical response under constant strain rate as well as the failure kinetics in plasticity-controlled regime of the sintered PA12 are comparable with those of the molded material. © 2019 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48525. 相似文献
7.
The application of near infrared (NIR) spectroscopy for the prediction of the thermal decomposition behavior of lignocellulosic biomass (three types of woody biomass and three types of herbaceous biomass) was successfully performed along with statistical analysis. The thermal degradation behaviors of the woody and herbaceous biomass were different because of their different chemical compositions. Herbaceous biomass was degraded at lower temperature than woody biomass. The weight‐loss profiles as a function of temperature were obtained by thermogravimetric analysis (TGA) at a heating rate of 25°C/min under nitrogen gas. The weight‐loss percentage at 10 temperatures in the range 150–600°C was predicted by a wavelet partial least squares (PLS) model, which showed significantly better predictive performance than the ordinary PLS model. The results show that the data predicted by the wavelet PLS model was well fitted to the original data by TGA, in which the root‐mean‐square error in prediction values less than 5.5 suggested that NIR spectroscopy was applicable for rapid analysis to characterize the thermal decomposition behavior of lignocellulosic biomass for energy production. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
8.
Yashas Gowda T. G. Vinod A. Madhu P. Vinod Kushvaha Sanjay M. R. Suchart Siengchin 《Polymer Composites》2021,42(4):1891-1900
The present research investigation focuses on the development of flax-basalt-carbon fiber reinforced epoxy/bioepoxy hybrid composites under different stacking sequence technique. The composites were fabricated using manual hand lay-up method and compression molding technique. The specimens were prepared using standard ASTM methods and subjected to various mechanical experimentations such as tensile, flexural, interlaminar shear strength, and impact tests. Water absorption study under distilled water condition, contact angle measurement, thermogravimetric analysis, and surface morphology study using scanning electron microscopy analysis was also performed. From the results obtained, the composites manufactured in the present work can be prospectively utilized in various engineering medium load structural applications. 相似文献
9.
耐高温聚酰胺的性能及应用 总被引：2，自引：0，他引：2
袁绍彦;刘奇祥;叶南飚;黄锐 《中国塑料》2009,23(10):6-9
列举了几种主要耐高温聚酰胺(PA)的结构,介绍了耐高温PA的主要性能,如耐热性、加工性、吸水性、结晶性、回流焊性及化学性能。详细叙述了主要耐高温PA如PA46、PA6T、PA9T、PA10T的各种性能优势及主要应用。最后,指出耐高温PA在汽车工业、电子电气工业领域具有很好的应用前景。 相似文献
10.
Walker Camacho Ana Valls‐Lluch Amparo Ribes‐Greus Sigbritt Karlsson 《应用聚合物科学杂志》2003,87(13):2165-2170
The effects of moisture on the morphology and mechanical properties of polyamides have been extensively studied by a number of researchers. However, the assessment of water content in the resins has been carried out by thermal or thermogravimetric methods, which are destructive. In the present work partial least‐squares (PLS) calibration models based on near‐infrared (NIR) spectroscopy were produced in order to predict the moisture content of nylon 6,6. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and the loss‐on‐drying (LOD) method were used as reference methods. TGA, LOD, DSC, and NIR analysis were performed in parallel, and the obtained data were used for multivariate calibration purposes. Data pretreatment techniques such as derivation and multiplicative scattering correction (MSC) successfully eliminated the baseline offset present in the raw spectra and compensated for differences in thickness and light scattering of the analyzed samples. Calibration models were validated by full cross validation with the help of a test set. A comparison of the prediction ability of PLS models based on pretreated data was also done. NIR spectroscopy is a rapid and nondestructive method for the determination of moisture in recycled nylon. The moisture content can be predicted with a RMSEP = 0.05 wt %. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2165–2170, 2003 相似文献
11.
分别采用聚丙烯接枝马来酸酐(PP-g-MAH)和硬脂酸(ST)作为相容剂,通过熔融共混法制备了PA6/PP(聚酰胺6/聚丙烯)合金,研究相容剂用量对该合金性能的影响。结果表明,随着相容剂的增加,PA6/PP合金的吸水性和熔体流动速率下降,拉伸强度和缺口冲击强度先增大后减小。当PP-g-MAH和ST用量分别为PA6/PP合金的4.0%(质量分数,下同)和2.0%时,复合材料的综合性能更佳。 相似文献
12.
摘要：通过双螺杆挤出机熔融共混制备低吸水率聚酰胺(PA)6材料,研究增韧剂、低吸水助剂及其复配对PA6材料的吸水率、力学性能的影响。结果表明,增韧剂聚烯烃弹性体接枝马来酸酐(POE-g-MAH)能在一定程度上降低PA6材料的吸水率,缺点是添加量大、降低PA6材料的刚性。添加质量分数10%的增韧剂,PA6材料的吸水率下降16%;低吸水助剂能明显降低PA6材料的吸水率,添加量越高,吸水率越低,但导致PA6材料的力学性能下降;当添加3%低吸水助剂,PA6材料的吸水率下降了22%,拉伸强度下降了11.2%,缺口冲击强度下降了35.4%;增韧剂与低吸水助剂的复配使用降低PA6材料的吸水率,同时具有添加量少和对力学性能影响小等优点;添加2%增韧剂和2%低吸水助剂制备的低吸水率PA6材料的吸水率下降了31%左右,拉伸强度略有下降,缺口冲击强度略有增大。 相似文献
13.
The water absorption and hygrothermal aging behavior of organomontmorillonite (OMMT) reinforced polyamide 6/polypropylene (PA6/PP ratio = 70/30), with and without maleated PP (MAH‐g‐PP), was studied at three different temperatures (30, 60, and 90°C). The water absorption and hygrothermal aging response of the composites was studied and analyzed by tensile tests and morphology assessment (scanning electron microscopy and transmission electron microscopy), indicating the effect of the immersion temperature, OMMT, and MAH‐g‐PP compatibilizer. The mathematical treatment used in analyzing the data was the single free phase model of diffusion, which assumed Fickian diffusion and utilized Fick's second law of diffusion. The kinetics of water absorption of the PA6/PP nanocomposites conformed to Fickian law behavior, whereby the initial moisture absorption follows a linear relationship between the percentage gain at any time t and t1/2 (the square root of time), followed by saturation. It was found that the equilibrium moisture content and the diffusion coefficient are dependent on the OMMT loading, MAH‐g‐PP concentration, and immersion temperatures. Both the tensile modulus and strength of the PA6/PP nanocomposites deteriorated after being exposed to hygrothermal aging. MAH‐g‐PP acted as a good compatibilizer for PA6/PP/OMMT nanocomposites, which was attributed to its higher retention ability in modulus and strength (in the wet and redried states), lower equilibrium moisture content, and reduced water diffusivity of the nanocomposites. Morphological sketches for both uncompatibilized and MAH‐g‐PP compatibilized PA6/PP/OMMT nanocomposites, toward water uptake are proposed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 780–790, 2005 相似文献
14.
The graft copolymer of polystyrene and polyamide 6 (PS-g-PA6) was investigated by anionic polymerization of ε-caprolactam (CL), using the free radical copolymer of styrene and a kind of allyl monomer containing N-carbamated caprolactam group as macroactivator (PS-CCL). CL monomers were grafted onto PS-CCL backbone via initiating N-carbamated caprolactam (CCL) pendants along its backbone to form the graft copolymer in the presence of catalyst sodium caprolactamate. The macroactivator was characterized by Fourier-transform infrared spectroscopy and nuclear magnetic resonance, and the graft copolymer by the selective solvent extraction technique using methanol and chloroform as solvents. PS-g-PA6 copolymers with different PS content were synthesized to study the effect of PS on morphology, crystallinity, dimensional stability, and thermal properties, using scanning electron microscopy, X-ray diffraction, water absorption measurement, thermogravimetric analysis, and differential scanning calorimetry. The results show the percentage crystallinity of graft copolymer decreases with increasing PS content, but the addition of PS scarcely influences the crystalline structure of PA6. The graft copolymer has improved thermal properties and dimensional stability. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
15.
芳纶Ⅱ与芳纶Ⅲ的热分解行为比较 总被引：1，自引：0，他引：1
利用热重分析研究了芳纶Ⅱ(Kevlar49)和芳纶Ⅲ(FanglunⅢ)在不同升温速率和氮气气氛下的热分解过程,用Kissinger方法、Flynn-Wall-Ozawa方法和Coats-Redfern方法研究了芳纶Ⅱ和芳纶Ⅲ的热分解动力学及热降解机理。结果表明:聚酰胺苯并咪唑嵌段使芳纶Ⅲ的热分解温度较芳纶Ⅱ稍有降低,但残炭率升高;芳纶Ⅱ和芳纶Ⅲ的起始热分解温度随升温速率加快而升高;芳纶II的热分解活化能(E)比芳纶Ⅲ稍高,用Kissinger方法、Flynn-Wall-Ozawa方法求得芳纶Ⅱ的E值分别为210.93,200.96 kJ/mol,芳纶Ⅲ的E值分别为208.35,196.98 kJ/mol,两种芳纶的固态热分解机理都为相边界反应,一维收缩,反应级数为1。 相似文献
16.
PA6 absorbs moisture, restricting its use in humid applications. The first objective of this study is to process composite parts to be used in high humid applications using PA6 blend based matrix (PA6/PP/PP-g-MA) and SCF (3-15 wt%) reinforcement. The second objective is to perform tensile and impact tests in both dry and wet conditions. The third objective is to carry out the in-depth analysis of fractography of blends and composites. For blend, more than 50% reduction in water absorption was observed in comparison to pure PA6, indicating the need to blend with PP. The tensile strength of the composite with 15 wt% SCF was 55% and 133% higher than matrix blend in dry and wet conditions respectively indicating the need to reinforce the blend with SCF. Injection molded composites with 15 wt% SCF revealed the tensile strength of 54 MPa, 46 MPa and modulus of 5 GPa, 4 GPa in dry, wet state respectively. At higher SCF content, both SCF and PP are well dispersed in PA6 matrix but fiber pull out led to fracture of dry samples. Post water absorption, tensile fractured samples showed significant fiber pull out, indicating reduction in interfacial adhesion due to water absorption. 相似文献
17.
通过表面基团反应制备了异氰酸酯改性纤维素纳米晶（IPDI?CNC),将其与聚酰胺6（PA6）共混后研究了有机纳米晶对PA6结晶行为的影响。利用差示扫描量热仪（DSC）对比分析了纤维素纳米晶（CNC）和IPDI?CNC对PA6的结晶度、结晶动力学参数及结晶速率的影响。结果表明,由于IPDI的引入,IPDI?CNC在PA6中的分散性更好,可以有效提高PA6的结晶度;采用 Jeziorny法研究非等温结晶过程,发现IPDI?CNC起到了异相成核作用,提高了PA6的结晶速度和结晶度;由于PA6的结晶能力提高了,IPDI?CNC的加入使PA6的吸水率降低了71.4 %。 相似文献
18.
PA6/polypropylene (PP) blends are investigated for obtaining balanced strength and toughness. The focus of this study is to understand the effect of PP content on mechanical property, water absorption, impact strength, thermal behavior, and morphology of PP in the absence and presence of PP-g-maleic anhydride compatibilizer. In comparison to pure PA6, all blends have higher impact strength with 161 and 124% increase at 5 wt % PP content in uncompatibilized and compatibilized blends (UB and CB), respectively. Morphology of impact fractured samples shows brittle fracture in the case of CB. scanning electron microscope of cryogenically fractured samples show decrease in domain size and change in shape from ellipsoid to spherical, from UB to CB. Then, 75% reduction in water absorption is observed for 50 wt % PP content UB. Postwater absorption yield strength (YS) remains constant above 10 wt % PP in both UB and CB and decrease in YS is less at higher PP content in CB. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47690. 相似文献
19.
To improve the mechanical properties of blends of polypropylene (PP) and terpolymer of ethylene–propylene–diene (EPDM), a triblock copolymer, (PP‐g‐MAH)‐co‐[PA‐6,6]‐co‐(EPDM‐g‐MAH), was synthesized by coupling reaction of maleic anhydride (MAH)‐grafted PP (PP‐g‐MAH), EPDM‐g‐MAH, and PA‐6,6. The newly prepared block copolymer brought about a physical interlocking between the blend components, and imparted a compatibilizing effect to the blends. Introducing the block copolymer to the blends up to 5 wt % lead to formation of a β‐form crystal. The wide‐angle X‐ray diffractograms measured in the region of 2θ between 10° and 50° ascertained that incorporating the block copolymer gave a new peak at 2θ = 15.8°. The new peak was assigned to the (300) plane spacings of the β‐hexagonal crystal structure. In addition, the block copolymer notably improved the low‐temperature impact property of the PP/EPDM blends. The optimum usage level of the compatibilizer proved to be 0.5 wt %. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1267–1274, 2000 相似文献
20.
This article deals with the selection of quaternary ammonium groups for synthesis of water‐soluble, photosensitive phenolic resins, containing acrylate and different quaternary ammonium salt groups (AQSPRs), via ring‐opening reactions of epoxy phenolic resin (EPR) with acrylic acid and with different tertiary amine‐protonic acid salts. Conversion of epoxy groups, solubility, photosensitive properties, and thermal decomposition of the different AQSPRs were compared. Modification of AQSPR with methanol solution of KOH to form phenolic resin containing both quaternary ammonium hydroxide groups and acrylate groups (AQHPR) was also studied. Characterization by IR spectrum, DSC, and thermal gravimetric analysis was carried out. The results showed that in the synthesis of AQSPRs containing different quaternary ammonium salt groups, the efficiency of ring‐opening reaction of epoxy phenolic resin with tertiary amine salt in terms of conversion of epoxy groups decreases in the following order: for the tertiary amine, N,N‐dimethyl benzylamine (DMBA) > triethylamine (TEA) > trimethylamine (TMA) > N,N‐dimethyl aniline (DMA) > triethanolamine (TENA) > tri(n‐butylamine) (TBA); for the protonic acid, HCl > HBr > HCOOH > HI > NaHSO3 > Cl3CCOOH > HClO4 > HBF4. All the AQSPRs except that from HClO4 can be dissolved in water, methanol, DMF, or DMSO. The gel content formed during UV exposure decreases in the following order of acids used in forming quaternary ammonium salt groups: HCl > HCOOH > NaHSO3 > Cl3CCOOH; or decreases in the following order of tertiary amines or hydrohalic acids used in forming the quaternary ammonium groups: TMA. > TEA > DBMA; HCl > HBr > HI. During thermal decomposition of EPR with about half epoxy groups of EPR ring‐opened with tertiary amine salt at 160°C for 0.5 h, water‐insoluble product was formed. The insoluble content and the % decrease of epoxy groups or halide ions increase in the following order: TMA < TEA < DMBA; HCl < HBr < HI. The % decrease of epoxy groups for the insoluble residue is nearly equal to the % decrease of halide ions. A crosslinking reaction mechanism occurred in the thermal decomposition was thus proposed. During the modification of AQSPR with KOH, conversion of quaternary ammonium chloride groups can reach above 90%. The decomposition temperature of the quaternary ammonium groups was lowered from 204 to 120°C after modification of AQSPR with KOH. The photosensitive properties of the resin after modification became lower. It is better to react DMBA · HCl with EPR so as to obtain a product with higher conversion of epoxy groups, good water solubility, moderate photosensitivity, lower decomposition temperature, and better postcuring. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2914–2922, 2004 相似文献