Polyamide Content Research Articles

From Waste Vegetable Oil to a Green Compatibilizer for HDPE/PA6 Blends.

When properly compatibilized, the blending of polyethylene (PE) and polyamide (PA) leads to materials that combine low prices, suitable processability, impact resistance, and attractive mechanical properties. Moreover, the possibility of using these polymers without prior separation may be a suitable opportunity for their recycling. In this work, the use of an epoxidized waste vegetable oil (EWVO) was investigated as a green compatibilizer precursor (CP) for the reactive blending of a high-density PE (HDPE) with a polyamide-6 (PA6). EWVO was synthesized from waste vegetable cooking oil (WVO) using ion-exchange resin (Amberlite) as a heterogeneous catalyst. HDPE/PA6 blends were produced with different weight ratios (25/75, 75/25, 85/15) and amounts of EWVO (1, 2, 5 phr). Samples with WVO or a commercial fossil-based CP were also prepared for comparison. All the blends were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), rheology, and mechanical tests. In the case of HDPE/PA6 75/25 and 85/15 blends, the addition of EWVO at 2 phr showed a satisfactory compatibilizing effect, thus yielding a material with improved mechanical properties with respect to the blend without compatibilizer. On the contrary, the HDPE/PA6 25/75 ratio yielded a material with a high degree of crosslinking that could not be further processed or characterized. In conclusion, the results showed that EWVO had a suitable compatibilizing effect in HDPE/PA6 blends with high HDPE content, while it resulted in unsuitable for blends with high content of PA6.

Crystallization and Performance of Polyamide Blends Comprising Polyamide 4, Polyamide 6, and Their Copolymers.

Polyamide 4 (PA4) is a biobased and biodegradable polyamide. The high hydrogen bond density of PA4 bestows it with a high melting point that is close to its thermal decomposition temperature, thereby limiting the melt processing of PA4. In this study, PA4 was blended with polyamide 6 (PA6) and further modified with copolyamide 4/6 (R46). The effects of composition on the crystallization behavior of the blends were studied. The results demonstrated that the binary PA4/PA6 (B46) and ternary PA4/PA6/R46 (B46/R46) blends formed two crystalline phases (PA4- and PA6-rich phases) through crystallization-induced phase separation. With increasing PA6 content, the thermal stability and crystallinity of the B46 blend increased and decreased, respectively, and the contribution of PA6 toward the crystallization of the PA4-rich phase diminished. Molecular dynamics simulations showed the molecular chain orientation of the B46 blends well. The melting points, crystallinities, and grain sizes of the B46/R46 blends were lower than those of the B46 blends. The crystallization of the PA4-rich phase was restrained by the dilution effect of molten-state PA6, and the nucleation and crystallization of the PA6-rich phase were promoted by the presence of crystallized PA4. The B46 blends with 30-40 wt% PA6 had the best mechanical properties.

Crystal structures of polyamide 6 at the interphase and around carbon fiber and mechanical properties of their composites

This study reports the effect of the polyamide 6 (PA6) crystal structure at the interphase and around the carbon fiber (CF) on the mechanical properties of CF-reinforced PA6 composites. The transverse tensile properties of the unidirectional composites and the four-point bending properties of the quasi-isotropic composites were investigated using three types of CFs. Raman spectra of PA6 were measured to characterize the crystal structures of PA6 at the interphase and around the CFs. The results showed that higher α-crystal (the most thermodynamically stable crystal) content of PA6 at the interphase compared to β-crystal (mesophase) and γ-crystal (thermodynamically metastable) contributed to greater transverse tensile strength of unidirectional composites. Furthermore, it was demonstrated that the flexural strength of the quasi-isotropic composites increased in the case of small variations in the distribution of each crystal structure (α-, β-, and γ-crystal structures) around the CFs. This study provides a framework for the PA6 crystals around CFs to reflect the superior properties of CFs in PA6/CF composites.

Usage Durability and Comfort Properties of Socks Made from Differently Spun Modal and Micro Modal Yarns

Socks, being a necessary item of clothing, must be comfortable and maintain their quality throughout their life. Since the applicability of modal fibers and microfibers, as well as yarns produced using unconventional processes, in sock knitting has been insufficiently researched, this paper evaluated three groups of medium sized socks knitted in a plain single jersey pattern produced with the highest percentage of ring, rotor and air-jet spun modal or micro modal yarns of the same linear density in full plating with different textured polyamide 6.6 yarns compared to conventional cotton socks. The sock quality was evaluated through an investigation of the physical properties, wear resistance and dimensional stability, as well as the water vapor absorption, air permeability and thermal resistance using the thermal foot model before and after five repeated washing and drying cycles, according to the proposed methodology. The results showed that the fiber fineness, the structure of the differently spun yarns and the sock plain knits, the polyamide content and the implementation of the pretreatment of the socks had an influence on the obtained results. The socks made from modal and micro modal yarns differed in their properties. Compared to cotton socks, they have better comfort properties, a generally better pilling resistance and, after pretreatment, a comparable abrasion resistance.

Insight into the synergistic reaction mechanism of biomass pseudocomponents and polyamide by TG-MS and Py-GC/MS: Pyrolysis properties, reaction kinetics and N-containing species evolution

To unveil the nitrogen migration and conversion characteristics, catalytic copyrolysis of biomass pseudo components and polyamide (PA) with different blend ratios (1:0, 5:1, 3:1, 1:1, 1:3, 1:5, 0:1) under an ammonia atmosphere was proposed to boost the yield of N-containing compounds (NCCs) and N-rich biochar. The evolution and distribution of NCCs in liquid, gas and biochar were systematically investigated with a combination of TG-MS, Py-GC/MS and EPR. Synergistic effects and possible reaction pathways were also evaluated. Experimental results showed that PA could obviously boost biomass conversion due to increasing the chance of secondary cleavage, and the comprehensive synergistic effect of biomass-derived H* radicals, acid sites of the catalyst and cracking reactions (-C-N and C-C bonds) that reduced the reaction energy barrier and enhanced the NH3 and HCN yields. NH3 comes from the amino acids that are released from the amino acid pyrolysis and hydrolysis of HCN on the surface of char, while HCN is from the secondary cracking of primary pyrolysis products. Adding biomass increased CO2, CO, CH4, C-O and CO emissions from co-pyrolysis. Additionally, significant synergetic effects were observed when Biomass/PA= 3:1, which improved the NCCs and pyridine yields by 78.58% and 48.23%, respectively, under the HZSM-5 catalyst. A lower proportion of PA addition facilitated the Maillard reaction and amide bond cleavage to enhance the NCCs content and suppressed π-conjugated ring structure compound evolution and coke-derived O-containing compound polymerization, while a higher content of PA was favorable for amine and diaza heterocycle compound formation. Moreover, the addition of PA reduced the HHV and N content in biochar, resulting in lower pyrrole-N content and graphitization degree due to secondary cross-polymerization reaction of reaction volatiles, but it enhanced the polarity due to higher oxygen content (14.98%).

Combined Effects of Polyamide Microplastics and Hydrochemical Factors on the Transport of Bisphenol A in Groundwater

Polyamide (PA) and bisphenol A (BPA) are selected as typical microplastic and endocrine-disrupting chemicals in this study. The adsorption of BPA on the surface of PA and the effect of PA on the transport behavior of BPA in groundwater are systematically investigated using a combination of batch experiments, column experiments and numerical models. The results of scanning electron microscope (SEM) and Fourier transform infrared spectra (FTIR) show that the surface of PA particles is changed significantly after adsorption of BPA. The isothermal adsorption process of BPA can be simulated by the Langmuir model and the Freundlich model. Kinetic adsorption, on the other hand, can be fitted by a quasi-first-order adsorption model, and the adsorption results indicate that the maximum adsorption of BPA on PA reaches 13 mg·g−1. The results of the column experiments suggest that the mass recovery rate of BPA decreases with PA content, and increases with flow velocity, while initial concentration has no apparent influence on BPA transport. In addition, due to the hydrolysis of BPA, the mass recovery rate of BPA does not change with pH under conditions of pH < 10.2 and increases substantially to 94% when pH > 10.2. Moreover, Ca2+ has a significant inhibitory effect on the transport of BPA, while Na+ has no apparent influence on the transport of BPA. The transport process of BPA in porous media is simulated using a single-point kinetic model, and the fitted mathematical relationships for the variation of kinetic parameters with environmental factors are obtained by regression analysis.

Investigating the mechanical properties of epoxy resin composites modified by polyamide and nano‐Al2O3

AbstractThis work aims to evaluate the effects of polyamide (PA) and nano‐Al2O3 on the mechanical properties of epoxy resin (EP) and obtain the optimal addition content of PA and nano‐Al2O3. Epoxy matrix composite (EMC) is prepared via the solution blending method using the PA as the curing agent, toughening agent, and the nano‐Al2O3 modified with the silane coupling agent as the filler. Then it is tested for tensile, hardness, impact and wear resistance performances. The results show that when the ratio of PA to EP varies in the range of 40 wt.% to 80 wt.%, increasing the PA content can improve the impact toughness and plasticity of EMC but reduce its hardness, tensile strength and wear resistance. When the content of PA is 60 wt.% of EP, the elongation at break and impact strength of EMC are increased by 66.4% and 12.9%, respectively. The mechanical performances of EMC can be enhanced by loading nano‐Al2O3 fillers in a specific range. When the content of nano‐Al2O3 is 2 wt.% of EP, the elastic modulus, the tensile strength and the wear resistance of EMC are increased by 27.9%, 20.8% and 49%, respectively. The research can provide a valid technical reference for the industrial application of EMC materials.

Improvement of the Thermal Stability of Polymer Bioblends by Means of Reactive Extrusion

Poly(lactic acid) (PLA) and biosourced polyamide (PA) bioblends, with a variable PA weight content of 10-50%, were manufactured by melt blending in order to improve the behavior of PLA against thermal degradation. The effect of reactive extrusion on the thermal performance of PLA within bioblends was analyzed. The reactive extrusion was made by means of the addition of a styrene-acrylic multi-functional-epoxide oligomeric reactive agent (SAmfE), with the commercial name of Joncryl. Four parameters were considered in order to study the thermal behavior of bioblends against thermal decomposition: the onset decomposition temperature, the shape and temperature interval of the thermal decomposition patterns, the activation energy of the thermal decomposition, and the evidence leading to the most probable mechanism. The latter was determined by means of three evidence: standardized conversion functions, y(α) master plots, and integral mean error. It was shown that reactive extrusion of PLA as well as PA incorporation to the polymer matrix of PLA were responsible for an increase in the onset decomposition temperature of 10.4 °C. The general analytical equation (GAE) was used to evaluate the kinetic parameters of the thermal degradation of PLA within bioblends for various reaction mechanisms. It was shown that the random scission of macromolecular chains is the best mechanism for both untreated and treated PLA by means of reactive extrusion. It was shown that reactive extrusion together with higher content of PA resulted in an increased protective effect against the thermal degradation of PLA as demonstrated by an increase in activation energy of 60 kJ/mol. It was found that there is a relationship between the increase in activation energy and the increase in the onset decomposition temperature when using reactive extrusion. The improvement of the thermal stability of bioblends by means of reactive extrusion was explained by an increase in the complex viscosity from 980 to 2000 Pa·s at 0.06 rad/s and from 250 to 300 Pa·s at 630 rad/s for bioblend containing 30% of PLAREX and by a finer dispersion of PA within the PLAREX matrix. Results from DSC were not conclusive regarding the compatibility between both phases.

New insights into adsorption mechanism of pristine and weathered polyamide microplastics towards hydrophilic organic compounds

The widespread coexistence of hydrophilic organic compounds and microplastics (MPs) in the environment has greatly increased their associated environmental problems. To evaluate the potential carrier effect of oxygen-containing MPs on coexisting pollutants, adsorption behaviors of four hydrophilic organic compounds (benzoic acid, sulfamethoxazole, sulfamerazine and ciprofloxacin) on MPs (pristine and weathered polyamide (PA)) were studied in the aquatic environment. The results showed that the surface morphology, size, oxygen content, molecular structure, surface charge and crystallinity of PA were changed after weathering, and the weathering degree of PA treated with heat-activated potassium persulfate was the highest. The main adsorption mechanisms included hydrogen bonding, hydrophobic interaction, charge-assisted hydrogen bonding, and electrostatic interaction. Hydrogen bonding and hydrophobic interaction contributed to the adsorption, while electrostatic interaction weakened the adsorption under the specific pH conditions. The formation of charge-assisted hydrogen bonding (CAHB) was also verified through pH influence experiments, and this force can overcome the electrostatic repulsion. The high adsorption of KPA (PA weathered by K2S2O8) under alkaline conditions was well explained by the formation of homonuclear CAHB due to the increase of oxygen-containing functional groups compared to the other three PA. Additionally, weathering did not always enhance the adsorption of hydrophilic organic compounds on PA, which was related to the changes in surface charge, crystallinity and hydrophilicity of PA. Overall, the physical and chemical properties (e.g., specific surface area, oxygen content, molecular structure) of PA after weathering and its trend of adsorption were different from other oxygen-free MPs in this study. This work can provide basic data for environmental risk of MPs and contribute to clarify and understand the processes of oxygenated MPs in the aquatic environment.

Exercising hybrid model to design an optimized electrospun polyamide-6 nanofibrous mat for air filtration applications

There are several factors affecting the filtration efficiency and pressure drop in the nanofibrous filters including the basis weight of the mat, the thickness of the mat, and the nanofiber diameter. Besides, such parameters are dependent on manufacturing factors which should have been taken into account before manufacturing. In this study, first an experiment based on central composite design (CCD) to investigate the effect of electrospinning factors such as polyamide-6 concentration, applied voltage, nozzle-to-collector distance, and electrospinning time on main structural parameters consisting of basis weight, thickness, and nanofiber diameter is performed. Then, three models with similar inputs but different outputs to establish relationships between electrospinning factors and main parameters utilizing two procedures including response surface methodology (RSM) and artificial neural network (ANN) are developed. Next, the outputs of a procedure with best-performing models are used to compute two analytical models to estimate filtration efficiency (considering interception and diffusion effect) and pressure drop. Finally, a genetic algorithm (GA) is coupled to the analytical models to optimize electrospinning factors using a cost function constructed by filtration efficiency and normalized pressure drop. The results highlighted that ANN-based models have more average goodness value (≈2.00) than RSM ones (≈1.83). Also, the GA has the capability of resulting in an optimized sample with higher quality factor (0.015) than the optimum one (0.011).

Co-pyrolysis of beech wood and polyamide-6: Impact of plastic concentration and wood/plastic synergistic effects

Biomass residues and waste can be converted into bioliquids by pyrolysis, which can contribute to both the production of renewable fuels and the recycling of waste. In this paper, the catalytic co-pyrolysis of mixtures of beech wood (BW) and polyamide-6 (PA6) in different ratios was investigated to assess the effect of PA6 concentration on the properties of bio-oils and on the catalyst performances in upgrading the bio-oils. The catalytic treatment was applied to the pyrolysis vapors that were driven across a H-ZSM-5 catalyst bed before their condensation into liquid products. Increasing the PA6 concentration in the BW+PA6 blends led to an increase in the average molar mass of bio-oils and to an increase in their N-content. Caprolactam and 5-cyano-1-pentene were the main products derived from PA6 pyrolysis, and their ratio also changed with the PA6 concentration. The production of fully deoxygenated compounds was strongly reduced in the presence of PA6, as the result of catalyst deactivation, also evidenced by the increase in sugars and decrease in furans concentrations. The amount of coke deposited on the catalyst decreased as the PA6 concentration increased, but this coke contained more nitrogen. Synergistic effects in the BW+PA6 pyrolysis were evidenced by the positive or negative deviation of different parameters (mass of gas, liquid, solid products, mass of coke on the catalyst, C, N, O composition of bio-oils) from a simple arithmetic combination of the same parameters for pure BW or pure PA6 weighted by their concentrations, in particular the N-content in the bio-oils was much higher than expected.

Facile Method for the Synthesis of PCL-b-PA6-b-PCL Using Amino-Terminated PA6 as a Macroinitiator and Its Characterization

Polyesteramides have attracted much attention due to their intriguing properties. However, the synthesis of di- or triblock polyesteramides based on polyamide 6 (PA6) remains challenging owing to their harsh reaction conditions. In this work, we introduced a new strategy to synthesize poly(ε-caprolactone)-block-PA6-block-poly(ε-caprolactone) (PCL-b-PA6-b-PCL) in a mild way. A series of well-designed copolymers were characterized by gel permeation chromatography, 1H, DOSY, and 13C NMR, and their crystallization and melting behavior, degradation rate, and compatibilization effect on PA6/PCL blends were found to be strongly composition dependent. Interestingly, the copolymers exhibited diverse spherulite morphologies, including curving stems and banded spherulites, which also correlated with the different relative content of PA6. Besides, PA6 nanodomains could act as physical cross-linking points to improve the tensile strength and Young’s modulus of PCL. This work fills the synthesis gap of well-defined PA6-based triblock polyesteramides, providing new materials for material modification and elucidation of some basic scientific questions.

Flexible Poly(ether-block-amide)/Carbon Nanotube Composites for Electromagnetic Interference Shielding

Conductive nanofillers usually act as nucleating agents in the semicrystalline polymer matrix, and the crystals formed on the filler surface can impede electrical percolation development. In this work, flexible poly(ether-block-amide)/carbon nanotube (PEBA/CNT) nanocomposites were fabricated for electromagnetic interference (EMI) shielding applications. It was demonstrated that CNTs can nucleate the crystallization of the polyamide (PA) block of PEBA and induce the transformation of the crystals from the γ-form to the α-form. Reducing the content of the PA block in PEBA from 50 to 20 wt % decreased the crystallinity of the nanocomposite and thus resulted in a higher electrical conductivity and an increment in EMI shielding performances. However, when ionically conductive polyethylene oxide was used as the polyether block, the hindrance effect of PA crystallization on electrical percolation was effectively mitigated, allowing for both high conductivity and enhanced amide dipole moment with a high PA content (e.g., 50 wt %), which is favorable for electromagnetic wave absorption. As a result, a high EMI shielding effectiveness with increased absorption can be achieved in PEBA/CNT nanocomposites.

Kinetics of the Thermal Degradation of Poly(lactic acid) and Polyamide Bioblends.

Poly(lactic acid) (PLA) and biosourced polyamide (PA) bioblends, with a variable PA weight content of 10–50%, were prepared by melt blending in order to overcome the high brittleness of PLA. During processing, the properties of the melt were stabilized and enhanced by the addition of a styrene-acrylic multi-functional-epoxide oligomeric reactive agent (SAmfE). The general analytical equation (GAE) was used to evaluate the kinetic parameters of the thermal degradation of PLA within bioblends. Various empirical and theoretical solid-state mechanisms were tested to find the best kinetic model. In order to study the effect of PA on the PLA matrix, only the first stage of the thermal degradation was taken into consideration in the kinetic analysis (α < 0.4). On the other hand, standardized conversion functions were evaluated. Given that it is not easy to visualize the best accordance between experimental and theoretical values of standardized conversion functions, an index, based on the integral mean error, was evaluated to quantitatively support our findings relative to the best reaction mechanism. It was demonstrated that the most probable mechanism for the thermal degradation of PLA is the random scission of macromolecular chains. Moreover, y(α) master plots, which are independent of activation energy values, were used to confirm that the selected reaction mechanism was the most adequate. Activation energy values were calculated as a function of PA content. Moreover, the onset thermal stability of PLA was also determined.

Improvement on the high-temperature performance and fuel resistance of SBS modified asphalt by hybridizing with polyamide resin

Binders with good high-temperature performance and fuel resistance are urgently needed in paving construction to deal with the challenge of heavy traffic load. Hybrid binders of styrene-butadiene-styrene tri-block copolymer (SBS) modified asphalt and polyamide (PA) resin were prepared with various ratio. The influence of PA content on the performance of binders and mixtures was evaluated by rheological methods, dynamic stability, residual Marshall Stability ratio after immersing in kerosene, bending test and the indirect tensile (IDT) strength ratio after freeze–thaw cycle. The results showed that PA could improve the high-temperature performance and fuel resistance. The hybrid binder with 30% PA content has excellent high-temperature performance, fuel resistance and good workability at the same time.

Characterisation and Modelling of Moisture Gradients in Polyamide 6.

Polyamide 6 (PA6) is able to absorb water from the surrounding air and bond to it by forming hydrogen bonds between the carbonamide groups of its molecular chains. Diffusion processes cause locally different water concentrations in the (component) cross-section during the sorption process, resulting in locally different mechanical properties due to the water-induced plasticisation effect. However, the water content of PA6 is usually specified as an integral value, so no information about a local water distribution within a component is provided. This paper shows a method to characterise moisture distributions within PA6 samples using low-energy computer tomography (CT) techniques and comparing the reconstructed results with a developed finite elements (FE) modelling method based on Fick’s diffusion laws with concentration-dependent diffusion coefficients. For this purpose, the ageing of the samples at two different water bath temperatures as well as at different integral water contents are considered. The results obtained by CT reconstruction and FE modelling are in very good agreement, so that the concentration distributions by water sorption of PA6 calculated by FEM can be regarded as validated.

Effect of polyamide 6 on the mechanical behavior of thermoplastic polyurethanes/polyamide 6 blends

Ductility and tensile strength are among the basic mechanical properties of polymers. Generally, it is difficult to enhance the ductility without significantly reducing the tensile strength. In this study, thermoplastic polyurethane (TPU) is mixed with 0%, 2.5%, 5%, 7.5%, 10%, and 12.5% polyamide 6 (PA6). The results show that the sample containing 100% TPU has the largest elongation of 690.5%. When PA6 is added, the elongation decreases gradually to 635.0%, 623.1%, 529.5%, 476.0%, 391.3%, and 242.8%, corresponding to 2.5%, 5%, 7.5%, 10%, 12.5%, and 100% PA6, respectively. The tensile strengths are 36.7, 33.8, 29.4, 26.5, 23.1, and 24.9 MPa, corresponding to 0%, 2.5%, 5%, 7.5%, 10%, and 12.5% PA6 samples, respectively. The tensile strength decreases gradually when the PA6 content is increased. Notably, the tensile strength of the 12.5% PA6 sample increases compared to the 10% PA6 sample. In addition, the hardness of the TPU/PA blend increases slightly as the PA6 ratio is increased. Finally, scanning electron microscope images demonstrate that PA6 particles act as particles dispersed or dissolved in TPU/PA blends.

Sustainability of flexible multilayer packaging: Environmental impacts and recyclability of packaging for bacon in block

Multilayer plastic packaging is difficult to recycle and perceived as an environmental problem, despite its valuable protective properties. This study examines environmental impacts and recyclability of six representative packaging solutions for bacon in block. Moreover, it takes into account the environmental impacts of the packaged product. The examined flexible packaging include two thermoformed films (polyamide (PA)/polyethylene (PE) & PE/ethylene vinyl alcohol (EVOH)), two vacuum bags (both PA/PE), and two shrink bags (PE/polyvinylidene dichloride (PVdC) & PA/EVOH/PE). A cradle-to-grave Life Cycle Assessment (LCA) was conducted. We assessed the recyclability of the different packagings by using the RecyClass tool, and compared the carbon footprint of the packaging with the carbon footprint of the packaged meat. The environmental impacts depend largely on the packaging weight and on the content of PA. Climate change results range from 26.64 g CO2-equivalents for the PVdC-containing shrink bag to 109.64 g CO2-equivalents for the PA-containing thermoformed film. Even if the recyclable PE/EVOH film is recycled, its climate change result (51.75 g CO2-equivalents) is considerably higher than the result for the PVdC-containing shrink bag. Only the PE/EVOH film can be recycled, however, with considerable loss of quality. Carbon footprint of the packaged bacon is on average 54 times higher than carbon footprint of packaging. Given the relatively low environmental significance of packaging compared to the packaged meat, optimal product protection should be priority for packaging designers. Weight reduction is preferable to improved recyclability. We recommend assessing recyclability and impacts of the packaged good alongside with packaging LCA to highlight potential conflict of interests and to avoid burden shifting.

Morphologies, interfacial interaction and mechanical performance of super-tough nanostructured PK/PA6 blends

Nanostructured polyketone (PK)/polyamide 6 (PA6) blends can be readily prepared via melt blending technologies and exhibit ultra-high toughness when PA6 is present as the nanoscale phase domains. When PA6 content is 30 vol%, the impact strength of the blends increases from 21.4 kJ/m2 of pure PK to 103.2 kJ/m2. The impact strength of the PK/PA6 blends with a 5:5 composition ratio reaches as high as 113 kJ/m2. The strong intermolecular force between PK and PA6 molecular chains enables the PA6 nanophase to cavitate to dissipate a significant amount of impact energy and effectively prevents the crack propagation or even terminates the cracks. The fracture mechanism of the PK/PA6 blends was further examined by the essential work of fracture method which proves that PK/PA6 blends show improved ability to prevent crack propagation. This work may deepen the understanding of polymer blend systems with strong hydrogen bonding interaction.

Measurement possibilities of water content in polyamide

Water content of polyamide is an important parameter, because it has great effect on the elongation, toughness and impact strength. The aim of our research was to determine moisture in polyamide-6 and polyamide-6.6 granules with different pretreatment of the base material. The specimens were prepared and conditioned in distilled water or non-conditioned. Thermogravimetric analysis, moisture analysis and coulometric Karl-Fisher indirect titration were used for the determination of humidity content. We used polyamide granules and flakes, and polyamide nanocomposites filled with montmorillonite for the water content measurements. First, we compared the technics and chose the most applicable to measure the water content in the samples, and made further measurement of polyamide nanocomposites.