Terms Of Fourier Research Articles

Spherical and cylindrical shocks in a non-ideal dusty gas with magnetic field under the action of heat conduction and radiation heat flux

In this article, the propagation of spherical or cylindrical shock waves in a mixture of small solid particles of microsize and a non-ideal gas with conductive as well as radiative heat fluxes are studied under the influence of an azimuthal or axial magnetic field. The solid particles are uniformly distributed in the mixture, and the shock wave is assumed to be driven by a piston. It is assumed that the equilibrium flow conditions are maintained and the moving piston continuously supplies the variable energy input. The density of the undisturbed medium is assumed to be constant in order to obtain the self-similar solutions. Heat conduction is expressed in terms of Fourier’s law, and the radiation is considered to be of diffusion type for an optically thick gray gas model. The thermal conductivity and the absorption coefficient are assumed to vary with temperature and density. Numerical calculations have been performed to obtain the flow profiles of variables. The effects of different values of the non-idealness parameter, the strength of the magnetic field, the mass concentration, the ratio of the density of solid particles to the initial density of the gas, the piston velocity index, and the adiabatic index are shown in detail. It is interesting to note that in the presence of an azimuthal magnetic field, the pressure and density vanish at the piston, and hence, a vacuum is formed at the center of symmetry, which is in excellent agreement with the laboratory condition to produce the shock wave. The author of the article agrees to the retraction of the article effective AUGUST 20, 2021.

Error Analysis of Some Operations Involved in the Cooley-Tukey Fast Fourier Transform

We are interested in obtaining error bounds for the classical Cooley-Tukey fast Fourier transform algorithm in floating-point arithmetic, for the 2-norm as well as for the infinity norm. For that purpose, we also give some results on the relative error of the complex multiplication by a root of unity, and on the largest value that can take the real or imaginary part of one term of the fast Fourier transform of a vector x , assuming that all terms of x have real and imaginary parts less than some value b .

Coupled-channels analysis of the α decay in strong electromagnetic fields

We investigate the influence of a monochromatic strong laser electromagnetic field on $\ensuremath{\alpha}$ clustering and emission, by analyzing the Fourier components of the time-dependent $\ensuremath{\alpha}$-core realistic potential in the Henneberger representation. It turns out that the resulting potential becomes deformed and the static component is by far dominant beyond the nuclear surface where the $\ensuremath{\alpha}$ cluster is formed, while higher Fourier terms are important in the internal region, where the $\ensuremath{\alpha}$-particle probability is hindered by the Pauli principle. This fact, combined with the observation that an $\ensuremath{\alpha}$ cluster lives much longer before its emission than the laser period, allows us the use of the stationary coupled channels approach in the system of coordinates given by the laser beam direction. We predict that the angular distribution of emitted $\ensuremath{\alpha}$ particles becomes anisotropic due to the deformation of the $\ensuremath{\alpha}$-core potential induced by the laser field, even for the spherical emitter $^{212}\mathrm{Po}$.

Impact of the COVID-19 Pandemic on Infant and Pediatric Asthma: A Multi-Center Survey Using an Administrative Database in Japan

Background: Limited data are available on the relationship between infant and pediatric asthma and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).Political limitations such as social distancing (mask wearing and staying at home) and school closure may affect the treatment behavior of pediatric asthma. To investigate the trends of treatment behavior in the field of pediatrics during the COVID-19 pandemic.Methods: This is a retrospective observational study using Diagnosis Procedure Combination (DPC) data from the Quality Indicator/Improvement Project (QIP) database. We identified children with asthma aged 15 years or younger who were patients from July 1, 2018, to June 30, 2020. The main outcome was a comparison between asthma patients' treatment behavior before the COVID-19 pandemic and during the COVID-19 pandemic.We statistically tested the admission volume changes based on the discharge date after adjusting for seasonality through a Fourier term using an interrupted time-series analysis.Findings: We identified 10,481 inpatients cases in 67 hospitals and 258,911 out-patients cases in 180 hospitals who were diagnosed with asthma. We performed an interrupted time-series (ITS) analysis for inpatients. The reduction in the number of patients during this period was estimated to be 232 (P=0.0012). In addition, ITS analysis was performed for patients aged Interpretation: We found that the number of pediatric asthma patients dramatically decreased during the COVID-19 pandemic. Social distancing and school closure also decreased the number of asthma attacks for infant patients. We need to continue research into the trends of pediatric asthma patients after the COVID-19 pandemic in Japan.Funding: This study was supported by JSPS KAKENHI Grant Number JP19H01075 from the Japan Society for the Promotion of Science and by the GAP Fund Program of Kyoto University to Yuichi Imanaka.Declaration of Interests: The authors declare no competing interests.Ethics Approval Statement: The study was conducted after obtaining approval from the Kyoto University Hospital Ethics committee of the Kyoto University Graduate School and Faculty of Medicine, according to the guidelines on medical and epidemiological research (No. R0135).

Performance Investigation of Peak Shrinking and Interpolating the PAPR Reduction Technique for LTE-Advance and 5G Signals

Orthogonal frequency division multiplexing (OFDM) has become an indispensable part of waveform generation in wideband digital communication since its first appearance in digital audio broadcasting (DAB) in Europe in 1980s, and it is indeed in use. As has been seen, the OFDM based waveforms work well with time division duplex operation in new radio (NR) systems in 5G systems, supporting delay-sensitive applications, high spectral efficiency, massive multiple input multiple output (MIMO) compatibility, and ever-larger bandwidth signals, which has demonstrated successful commercial implementation for 5G downlinks and uplinks up to 256-QAM modulation schemes. However, the OFDM waveforms suffer from high peak to average power ratio (PAPR), which is not desired by system designers as they want RF power amplifiers (PAs) to operate with high efficiency. Although NR offers some options for maintaining the efficiency and spectral demand, such as cyclic prefix based (CP-OFDM), and discrete Fourier transform spread based (DFT-S-OFDM) schemes, which have limiting effects on PAPR, the PAPR is still as high as 13 dB. This value increases when the bandwidth is increased. Moreover, in LTE-Advance and 5G systems, in order to increase the bandwidth, and data-rate, carrier aggregation technology is used which increases the PAPR the same way that bandwidth increment does; therefore, it is essential to employ PAPR reduction in signal processing stage before passing the signal to PA. In this paper, we investigate the performance of an innovative peak shrinking and interpolation (PSI) technique for reducing peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) based signals at waveform generation stage. The main idea behind the PSI technique is to extract high peaks, scale them down, and interpolate them back into the signal. It is shown that PSI technique is a possible candidate for reducing PAPR without compromising on computational complexity, compatible for existing and future telecommunication systems such as 4G, 5G, and beyond. In this paper, the PSI technique is tested with variety of signals in terms of inverse fast Fourier transform (IFFT) length, type of the signal modulation, and applications. Additional work has been carried out to compare the proposed technique with other promising PAPR reduction techniques. This paper further validates the PSI technique through experimental measurement with a power amplifier (PA) test bench and achieves an adjacent channel power ratio (ACPR) of less than –55 dBc. Results showed improvement in output power of PA versus given input power, and furthermore, the error vector magnitude (EVM) of less than 1 % was achieved when comparing of the signal after and before modification by the PSI technique.

Impact of a community respiratory service on emergency hospital admissions

Abstract Background A community respiratory service was implemented in the North West of Glasgow in January 2013, comprising a team of physiotherapists, occupational therapists and support workers, to provide education, self-management advice, and, where appropriate, treatment at home, for COPD patients, to reduce the risk of hospital admission. This study measures the impact of the service on emergency admission to hospital. Methods COPD EAs were defined as emergency admissions to hospital with a primary diagnosis of COPD. Rate of COPD EAs per 1000 population aged 65 years+ in Glasgow City was compared before and after onset of the service, using segmented linear regression with 21-month pre- and 17-month post-intervention periods. COPD EAs for residents of South and North East Glasgow (S+NE) - areas with no such service in place - were used as a comparison group. The model adjusted for the rate of all-cause emergency admissions. Autoregressive terms were included in the model, as well as a fourier term to adjust for seasonality. Models were similarly run for outcome emergency admissions with COPD in any of the other five fields of diagnosis. Results Adjusting for all cause EAs and changes in S+NE, thus factoring out the impact of other initiatives that may have affected emergency admission to hospital, the impact of the service was found to be a level change of -0.33 (-0.51, -0.16) and a trend change of -0.03 (-0.05, -0.02) COPD EAs per 1000 per month. This is equivalent to a predicted reduction due to the service of -0.88 COPD EAs per 1000 popn per month, in March 2015, and a relative reduction of 35.8%. Rate of COPD EAs per month reduced over time after the introduction of the service (from the point of full staffing). Rate of EAs with COPD in a field of diagnosis other than primary saw no significant change in level or trend associated with the service. Conclusions The community respiratory service was associated with a significant reduction in the rate of COPD EAs. Key messages The Community Respiratory service was associated with reductions in emergency hospital admissions with COPD as a primary diagnosis. There was no significant change in emergency admissions with COPD as a secondary diagnosis, suggesting hospital attendance for patients with COPD overall reduced following the intervention.

Impact of the Govan SHIP case management project on emergency hospital admission and GP interactions

Abstract Background The Social and Health Integration Partnership (SHIP) project was implemented in Govan, a deprived area in Glasgow in 2015. This involved multidisciplinary teams, including GPs and social workers, identifying and supporting vulnerable patients at risk of attending A&E and GP surgeries. This study measures the impact of SHIP on A&E presentations and GP interactions. Methods Rate of A&E presentations per 1000 population in 3 participating GP practices in Govan was compared before and after onset of the service, using segmented linear regression with 9-month pre- and 36-month post- intervention periods. Rates of GP interactions were also compared, using 21-month pre- and 36-month post- intervention periods. Rates of A&E presentations and GP interactions for practice population in Drumchapel- an area with similar rates of deprivation - were used as a control. Models included autoregressive and moving average terms, and a fourier term to adjust for seasonality. Results Govan had a lower rate of A&E presentations than Drumchapel. A&E presentations did not change significantly over time prior to SHIP in either area. At April 2015, SHIP onset, a level change of -4.34 (-7.44, -1.24) A&E presentations per 1000 was observed in both areas, however , onset of SHIP was not associated with a reduction in level or trend in A&E presentations. Rate of interactions with GP was greater in Govan than Drumchapel prior to SHIP, increasing over time in both areas. After SHIP implementation there was a significant level change of 33.78 (19.57, 47.99) per 1000 across both areas. GP interactions in Govan however saw a further reduction of -1.48 (-2.87, -0.09) per 1000 per month. This is equivalent to SHIP being associated with an absolute reduction of 37 GP interactions per thousand and a relative reduction of 7.2% by March 2018. Conclusions The Govan SHIP initiative was associated with no significant change in A&E presentations and some small reduction in GP interactions. Key messages The Govan SHIP initiative was associated with no significant change in A&E presentations and a small significant reduction in GP interactions. A cost effectiveness analysis of the project is recommended, given the relatively small benefits observed.

Real Paley-Wiener theorems in spaces of ultradifferentiable functions

We develop real Paley-Wiener theorems for classes Sω of ultradifferentiable functions and related Lp-spaces in the spirit of Bang and Andersen for the Schwartz class. We introduce results of this type for the so-called Gabor transform and give a full characterization in terms of Fourier and Wigner transforms for several variables of a Paley-Wiener theorem in this general setting, which is new in the literature. We also analyze this type of results when the support of the function is not compact using polynomials. Some examples are given.

Unsteady interface boundary conditions for near-wall turbulence modeling

Numerical modeling near-wall turbulent flows is one of major challenges in the fluid dynamics. It inevitably requires significant computational resources. To overcome these difficulties, there are two principal ways based on simplification of the mathematical model and development of ad-hoc computational approaches. The near-wall non-overlapping domain decomposition approach with the use of Robin interface boundary conditions proved to be very efficient. As has been shown, to apply this approach to essentially unsteady flows, the interface boundary conditions must be nonlocal in time and should be modified to include a memory term. In the current paper, it is proven that the memory term must be caused by the unsteadiness of both the solution at the interface boundary and driving force. The properties of the derived unsteady interface boundary conditions are studied in detail in the application to oscillatory and pulsating laminar flows in a channel and pipe. In particular, we study the effect of the memory term on the reproduction of the unsteady effects. The convergence to the exact solution is theoretically proven and numerically demonstrated. A practical calculation of the memory term is based on a Fourier expansion. It is also proven that the convergence is quadratic with respect to the inverse number of Fourier terms. A key question whether the near-wall domain decomposition can damage an external instability plays an important role to identify the perspectives of the technique to be extended to RANS/ LES (or DNS) decompositions.

Influence of chitosan addition on the mechanical and antibacterial properties of carrot cellulose nanofibre film

Films of carrot cellulose nanofibrils (CCNFs) with the addition of low-viscosity chitosan (CHIT) were prepared by the vacuum filtration. The chitosan content in the films varied from 9 to 33% (dry wt. basis). The surface morphology of the films was investigated by scanning electron microscopy, and it was found that chitosan was dispersed in the CCNF matrix. The interaction between CCNFs and CHIT was evaluated in terms of Fourier transform infrared spectroscopy (FTIR). The obtained results suggested physical interactions rather than hydrogen bonding between CCNFs and CHIT. This finding also supports the results of the water wettability experiment. The addition of chitosan to the nanocellulose matrix causes an increase in the water contact angle, i.e., the surface of the composites becomes more hydrophobic. This increase is probably connected to an interaction between nanocellulose and chitosan forming a denser structure. Analyses of thermal properties showed that the composites are stable under high temperature, and the degradation occurred above 300 °C. It was found that the addition of CHIT to CCNF matrices caused a decrease in the Young’s modulus—the higher that the concentration of chitosan in the composite was, the lower the Young’s modulus (decreased from 14.71 GPa for CCNFs to 8.76 GPa for CCNF/CHIT_5). Additionally, the tensile strength of composites, i.e., the maximum force that causes a fracture decreased after the addition of chitosan (decreased from 145.83 MPa for CCNFs to 129.43 MPa for CCNF/CHIT_5). The results indicated the highest inhibitory effect of the investigated composites against E. coli and S. epidermidis. Whereas M. luteus was inhibited only by the higher concentration of chitosan in the tested composites, inhibition was not found against C. krissii and all tested filamentous fungi.Graphic abstract

Green Formulation of Triglyceride/Phospholipid-Based Nanocarriers as a Novel Vehicle for Oral Coenzyme Q10 Delivery.

This study was aimed to develop a novel nanocarrier for coenzyme Q10 (CoQ10) by a green process that prevented the use of surfactants and organic solvents. Triglyceride/phospholipid-based nanocarriers were developed through high-pressure homogenization (an industrial feasible process), and a 25-1 fractional factorial design was adopted to assess the influences of formulation variables on the considered responses, including vesicle size, entrapment efficiency, loading capacity, and solubility of the vehicles in simulated gastrointestinal fluids. The optimized formulation was further in-depth characterized in terms of morphology, release behavior, biocompatibility (Caco-2 cell cytotoxicity and histological examination), thermal behavior, and Fourier transform infrared analysis. Optimal nanocarriers were found to have mean particle size of 75 nm, narrow particle distribution, and CoQ10 entrapment of 95%. The optimized formulation was stable upon incubation in simulated gastrointestinal fluids without considerable leakage of cargo, which was in agreement with their sustained release behavior. Microscopic observations also confirmed nanosized nature of the vesicles and revealed their spherical shape. Moreover, toxicity evaluations at the cellular and tissue levels revealed their nontoxic nature. In conclusion, triglyceride/phospholipid-based nanocarriers proved to be a green safe vehicle for delivery of CoQ10 with industrial-scale production capability and could provide a new horizon for delivery of hydrophobic nutraceuticals. PRACTICAL APPLICATION: Green nanostructure formulation approaches have recently gained tremendous attraction for their safe profile especially when it comes to supplements, which are generally recommended for daily use. However, their sufficient association with cargoes and industrial-scale production have remained considerable challenges. This study focuses on the development of lipid-based nanocarriers for CoQ10 by an industrial feasible process that prevents the use of any surfactants or organic solvents.

An image processing algorithm to estimate the melt fraction and energy storage of a PCM enclosed in a spherical capsule

The experimental investigation of the melting behavior of a phase change material (PCM) inside a spherical container is reported. PCM considered for the study is lauric acid whose melting point is about 43°C. Unconstrained melting experiments are carried out at two different temperatures, ie, at 60°C and 80°C. The initial temperature of the PCM is taken as 30°C. To carry out a detailed analysis of the heat transfer, the transient variations in the melt fraction and amount of energy stored are derived. In order to estimate the liquid/solid volumes, a novel image processing technique is developed. In this approach, a circle-fitting algorithm is employed to obtain the amount of PCM melted inside a spherical container. The total instantaneous amount of heat transport to the PCM is measured with an uncertainty of about 6.1%. The results obtained by the introduced circle-fitting algorithm have been compared qualitatively and quantitatively with the solid modeling method. The present technique could capture the asymmetric behavior of the solid PCM. The experimental findings show that the rate of melt fraction is high at the beginning of the experiment due to a larger area of contact between the spherical container and solid PCM. Further, parametric analysis has been performed and reported in terms of Fourier, Stefan, and Grashof numbers.

Zr(IV)‐Crosslinked Polyacrylamide/Polyanionic Cellulose Composite Hydrogels with High Strength and Unique Acid Resistance

ABSTRACTRecently, metal coordination has been widely utilized to fabricate high‐performance hydrogels, but conventional metal‐based hydrogels face some drawbacks, such as staining or acid lability. In the present study, a novel kind of colorless Zr(IV)‐crosslinked polyacrylamide/polyanionic cellulose (PAM/PAC) composite hydrogel with unique acid resistance was constructed via acrylamide polymerization in a PAC solution, followed by posttreatment in a zirconium oxychloride (ZrOCl2) solution. The prepared gels were characterized in terms of Fourier transform infrared spectroscopy, scanning electron microscopy, and tensile and compressive mechanics, as well as acid resistance. Inside the gels, the synergistic action of hydrogen bonding and Zr(IV) coordination is responsible for their improved mechanical properties and good energy dissipation ability. One hydrogel with nearly 90 wt % of water content can sustain approximately 5 MPa of compression stress at 90% strain without damage. Both microscopic network structures and macroscopic mechanics demonstrate facile adjustability via changing the PAC dosages in polymerization and/or ZrOCl2 concentrations in posttreatment. Moreover, the gels present unexpected acid resistance due to the strong Zr(IV) coordination with PAC, demonstrating their potential application as hydrogel electrolytes in supercapacitors. The current work provides a new approach to fabricate metal coordination‐based high strength, colorless hydrogels with acid resistance. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 981–991

Modelling the relationship between financing by Islamic banking system and environmental quality: evidence from bootstrap autoregressive distributive lag with Fourier terms

The aim of the paper is to contribute to the extant empirical literature on the determinants of pollution by investigating the impact of financing by Islamic banking on a comprehensive index of emission in Malaysia. Using the stochastic environmental impact, population, affluence and technology (STIRPAT) framework, we controlled for the impact of industrial production index and demography. A residual augmented least squares (RALS) method is used to examine stationarity of the series. We have also used a recently proposed bootstrap autoregressive distributive lag (ARDL) test, which is further augmented with Fourier terms to cater for any nonlinearity in the estimation. The results show evidence for cointegration among the series. The long run estimates suggest that financing by Islamic banks has a negative impact on emission, while labour force increases it. The industrial production index does not have significant impact on emission. The policy implications and recommendations are discussed in the body of the paper.

Resonant model-A new paradigm for modeling an action potential of biological cells.

Organ level simulation of bioelectric behavior in the body benefits from flexible and efficient models of cellular membrane potential. These computational organ and cell models can be used to study the impact of pharmaceutical drugs, test hypotheses, assess risk and for closed-loop validation of medical devices. To move closer to the real-time requirements of this modeling a new flexible Fourier based general membrane potential model, called as a Resonant model, is developed that is computationally inexpensive. The new model accurately reproduces non-linear potential morphologies for a variety of cell types. Specifically, the method is used to model human and rabbit sinoatrial node, human ventricular myocyte and squid giant axon electrophysiology. The Resonant models are validated with experimental data and with other published models. Dynamic changes in biological conditions are modeled with changing model coefficients and this approach enables ionic channel alterations to be captured. The Resonant model is used to simulate entrainment between competing sinoatrial node cells. These models can be easily implemented in low-cost digital hardware and an alternative, resource-efficient implementations of sine and cosine functions are presented and it is shown that a Fourier term is produced with two additions and a binary shift.

Inequalities for nonuniform wavelet frames

Abstract Gabardo and Nashed studied nonuniform wavelets by using the theory of spectral pairs for which the translation set Λ = { 0 , r / N } + 2 ⁢ ℤ {\Lambda=\{0,r/N\}+2\mathbb{Z}} is no longer a discrete subgroup of ℝ {\mathbb{R}} but a spectrum associated with a certain one-dimensional spectral pair. In this paper, we establish three sufficient conditions for the nonuniform wavelet system { ψ j , λ ⁢ ( x ) = ( 2 ⁢ N ) j / 2 ⁢ ψ ⁢ ( ( 2 ⁢ N ) j ⁢ x - λ ) , j ∈ ℤ , λ ∈ Λ } {\{\psi_{j,\lambda}(x)=(2N)^{j/2}\psi((2N)^{j}x-\lambda),\,j\in\mathbb{Z},\,% \lambda\in\Lambda\}} to be a frame for L 2 ⁢ ( ℝ ) {L^{2}(\mathbb{R})} . The proposed inequalities are stated in terms of Fourier transforms and hold without any decay assumptions on the generator of such a system.

New poly(itaconate)s with bulky pendant groups as candidates for “all-polymer” dielectrics

This work presents the synthesis and characterizaiton of three new poly(itaconate)s containing nitriles functional groups as high dipole moment entities and three different cycloalkyl pendant groups, in order to increase the rigidity of the system and therefore, their dipolar glass polymer temperature interval. The structural, thermal and dielectric characterization has been carried out in terms of Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and broadband dielectric spectroscopy (BDS), respectively. All polymers showed good thermal properties with degradation temperatures above 250 °C, presenting higher glass transition temperatures than those of recently reported poly(itaconate)s. Regarding dielectric properties, dielectric constant values between 4.0 and 4.3 (at 25 °C and 1 kHz) and relative low loss tangent values (below 0.01) were obtained. BDS measurements showed in all cases, notorious sub-glass transitions even at temperatures below −100 °C, resulting in a broad temperature interval in which these polymers could work without high dielectric losses. Therefore, these materials seem to be good candidates for dielectric applications such as energy storage, among others.

Nondestructive Evaluation of Microwave-Penetrable Pipes by Synthetic Aperture Imaging Enhanced by Full-Wave Field Propagation Model

A qualitative approach for microwave imaging multilayered cylindrical structures (e.g., dielectric pipes) is proposed in this paper. This approach relies on a modified circular synthetic aperture imaging technique that exploits closed-form Green’s function to account for the different propagation delays, internal reflections, and refractions. The image can then be computed by employing a matched filter expressed in terms of efficient Fourier Transforms. Consequently, a high-resolution and contactless approach for the inspection of this kind of structures is achieved. Moreover, the computational resources to render the images are negligible. Practical aspects of the technique such as sampling criteria, resolution, and limitations of the technique are discussed. The efficacy of the method is illustrated via several examples including imaging of objects and anomalies inside different types of dielectric pipes.

The harmonic analysis associated to the Heckman-Opdam's theory and its application to a root system of type $BC_d$

In the five first sections of this paper we define and study the hypergeometric transmutation operators $V^W_k$ and ${}^tV^W_k$ called also the trigonometric Dunkl intertwining operator and its dual corresponding to the Heckman-Opdam's theory on $\mathbb{R}^d$. By using these operators we define the hypergeometric translation operator $\mathcal{T}^W_x, x \in \mathbb{R}^d$, and its dual ${}^t\mathcal{T}^W_x, x \in \mathbb{R}^d$, we express them in terms of the hypergeometric Fourier transform $\mathcal{H}^W$, we give their properties and we deduce simple proofs of the Plancherel formula and the Plancherel theorem for the transform $\mathcal{H}^W$. We study also the hypergeometric convolution product on $W$-invariant $L^p_{\mathcal{A}_k}$-spaces, and we obtain some interesting results. In the sixth section we consider a some root system of type $BC_d$ (see [17]) of whom the corresponding hypergeometric translation operator is a positive integral operator. By using this positivity we improve the results of the previous sections and we prove others more general results.

Influence of reactive blending temperature on impact toughness and phase morphologies of PLA ternary blend system containing magnesium ionomer

ABSTRACTIn this study, effects of extrusion temperature on impact toughness and phase morphologies in the reactive poly(lactic acid) (PLA)/epoxy‐containing elastomer (ethylene/n‐butyl acrylate/glycidyl methacrylate [EBA‐GMA]) blend system with magnesium ionomer (magnesium ionomer of ethylene/methacrylic acid copolymer [EMAA‐Mg]), were investigated, and the underlying origin for the dependence of morphology development on reactive blending temperature was analyzed. The extent of reactive compatibilization between PLA/EBA‐GMA and crosslinking of EBA‐GMA initiated by EMAA‐Mg, were determined in terms of Fourier transform infrared spectra of dioxane‐extracted residues, torque rheometer, dynamic mechanical analysis, and gel contents after chloroform extraction. The phase morphologies were studied by electron microscopic observation and dynamic rheological tests. Compared to the ternary blend system containing zinc‐neutralized ionomer of EMAA copolymer (EMAA‐Zn), the ones containing EMAA‐Mg exhibited the less pronounced dependence of notched impact strength on extrusion temperature. With elevating extrusion temperature, the latter ternary blends exhibited different “salami‐like” dispersed phase structure. The morphology development with reactive blending temperature was attributed to the remarkable temperature dependence of crosslinking rate of EBA‐GMA phase initiated by the EMAA‐Mg rather than the difference in the extent of compatibilization. The morphology development mechanism with respect to reactive blending temperature was also discussed. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47682.