Fully bio-based Poly (Glycerol-Itaconic acid) as supporter for PEG based form stable phase change materials.

A novel fully bio-based Poly (Glycerol-Itaconic acid) (PGI) was designed and highly efficiently synthesized by solvent-free polycondensation. The Poly (ethylene glycol) (PEG) was used as the phase change material (PCM) working substance and encapsulated by the sustainable PGI supporter. PEG chains were tightly encapsulated with the PGI supporting material mainly under hydrogen bonds due to the structural compatibility between PGI and PEG. The PCMs can achieve high form stability and high phase change enthalpies in the same kinds of PCMs. Furthermore, the phase change temperatures and enthalpies of the PCMs can be adjusted conveniently by regulating the PEG content and molecular weight. Notably, this process extremely facilitates the realization of efficient mass production due to the eco-friendly nature, high efficiency and low cost.pre-print1509 K

Polyrotaxane: New generation of sustainable, ultra-flexible, form-stable and smart phase change materials.

The development of thermal energy storage materials is the most attractive strategy to harvest the solar energy and increase the energy utilization efficiency. Phase change materials (PCMs) have received much attention in this research field for several decades. Herein, we reported a new kind of PCM micro topological structure, design direction, and the ultra-flexible, form-stable and smart PCMs, polyrotaxane. The structure of polyrotaxane was fully confirmed by 1H nuclear magnetic resonance, attenuated total reflection-fourier transform infrared and X-ray diffraction. Then the tensile properties, thermal stability in the air, phase change energy storage and shape memory properties of the films were systematically analyzed. The results showed that all the mechanical performance, thermal stability in air and shape memory properties of polyrotaxanes were enhanced significantly compared to those of polyethylene oxide (PEO). The form stability at temperatures above the melting point of PEO significantly increased with the α-CD addition. Further with the high phase transition enthalpy and excellent cycle performance, the polyrotaxane films are therefore promising sustainable and advanced form-stable phase change materials for thermal energy storage. Notably, its ultra-high flexibility, remolding ability and excellent shape memory properties provide a convenient way for the intelligent heat treatment packaging of complex and flexible electronic devices. In addition, this is a totally novel insight for polyrotaxane application and new design method for form-stable PCMs.post-print4492 K

Regularity Criterion for a Two Dimensional Carreau Fluid Flow.

Carreau fuids are a source of research from both theoretical and applied approaches. They have been considered to model diferent non-newtonian phenomena such as blood fow, plasma and viscoeslastic materials. The purpose of this study is to develop the global regularity criteria for a Carreau fuid in two dimensions fowing in a strip. Firstly, a regularity criteria is shown for the initial set ( u10, u20) ∈ H1(Ω) where Ω = [0, L]× [0, ∞). Secondly, the analysis focuses on a regularity criteria when ( u10, u20) ∈ L4(Ω) and, lastly, similar results are obtained for ( u10, u20) ∈ H2(Ω) while the fuid velocity vertical component, u2(x, y), is such that 휕u2 휕x ∈ L4(Ω) and (휕∇u2 휕y , Δu2 ) ∈ L2(Ω).post-print1225 K

Finite iterative algorithms for solving generalized coupled Sylvester systems – Part I: One-sided and generalized coupled Sylvester matrix equations over generalized reflexive solutions

AbstractThe generalized coupled Sylvester systems play a fundamental role in wide applications in several areas, such as stability theory, control theory, perturbation analysis, and some other fields of pure and applied mathematics. The iterative method is an important way to solve the generalized coupled Sylvester systems. In this two-part article, finite iterative methods are proposed for solving one-sided (or two-sided) and generalized coupled Sylvester matrix equations and the corresponding optimal approximation problem over generalized reflexive solutions (or reflexive solutions). In part I, an iterative algorithm is constructed to solve one-sided and coupled Sylvester matrix equations (AY−ZB,CY−ZD)=(E,F) over generalized reflexive matrices Y and Z. When the matrix equations are consistent, for any initial generalized reflexive matrix pair [Y1,Z1], the generalized reflexive solutions can be obtained by the iterative algorithm within finite iterative steps in the absence of round-off errors, and the least Frobenius norm generalized reflexive solution pair can be obtained by choosing a special kind of initial matrix pair. The unique optimal approximation generalized reflexive solution pair [Y^,Z^] to a given matrix pair [Y0,Z0] in Frobenius norm can be derived by finding the least-norm generalized reflexive solution pair [Y∼∗,Z∼∗] of two new corresponding generalized coupled Sylvester matrix equations (AY∼-Z∼B,CY∼-Z∼D)=(E∼,F∼), where E∼=E-AY0+Z0B,F∼=F-CY0+Z0D. Several numerical examples are given to show the effectiveness of the presented iterative algorithm

A Novel Image Segmentation Algorithm Based on Graph Cut Optimization Problem

Image segmentation, a fundamental task in computer vision, has been widely used in recent years in many fields. Dealing with the graph cut optimization problem obtains the image segmentation results. In this study, a novel algorithm with weighted graphs was constructed to solve the image segmentation problem through minimization of an energy function. A binary vector of the segmentation label was defined to describe both the foreground and the background of an image. To demonstrate the effectiveness of our proposed method, four various types of images were used to construct a series of experiments. Experimental results indicate that compared with other methods, the proposed algorithm can effectively promote the quality of image segmentation under three performance evaluation metrics, namely, misclassification error rate, rate of the number of background pixels, and the ratio of the number of wrongly classified foreground pixels

Bio-based poly (glycerol-itaconic acid)/PEG/APP as form stable and flame-retardant phase change materials

With the improvement of people's living level, smart home and comfortable life put forward novel and highly scientific requirements for building materials and home environment. Environmental protection, renewability, processing convenience and use safety (non-toxic/fire safety) are all core indicators that need to be considered in an all-round way in the process of material design. In this work, we used a simple and efficient green process by blending ammonium polyphosphate (APP) and poly (glycerol-itaconic acid) loaded polyethylene glycol (PEG) to prepare fire safe phase change materials (PCMs). The flame retardancy, phase change performance and thermal response behavior (including form stability, thermal conductivity, cycle stability, and latent heat etc.) were systematically characterized. The results showed that limiting oxygen index (LOI) increased significantly with the increase of APP content. Typically, when the filling amount of APP reached 15 wt%, the LOI value increased from 21.6% to 28.7%, vertical testing reached UL-94 V0 rating and the pHRR decreased by 36.15%. The as-prepared PCMs show excellent form stability, and the enthalpy of phase change keeps higher than 70 J g−1, which is at the high level as that of same kinds of PCMs. Notably, due to its high preparation efficiency for PCM fabrication and the profiles of all bio-based supporting matrix, solvent-free pathway, mild curing temperature, and fire safety, it is expected to be effectively applied in building for the thermal regulation.pre-print1269 K

Recent Advances in Flame Retardant and Mechanical Properties of Polylactic Acid: A Review.

The large-scale application of ecofriendly polymeric materials has become a key focus of scientific research with the trend toward sustainable development. Mechanical properties and fire safety are two critical considerations of biopolymers for large-scale applications. Polylactic acid (PLA) is a flammable, melt-drop carrying, and strong but brittle polymer. Hence, it is essential to achieve both flame retardancy and mechanical enhancement to improve safety and broaden its application. This study reviews the recent research on the flame retardant functionalization and mechanical reinforcement of PLA. It classifies PLA according to the type of the flame retardant strategy employed, such as surface-modified fibers, modified nano/micro fillers, small-molecule and macromolecular flame retardants, flame retardants with fibers or polymers, and chain extension or crosslinking with other flame retardants. The functionalization strategies and main parameters of the modified PLA systems are summarized and analyzed. This study summarizes the latest advances in the fields of flame retardancy and mechanical reinforcement of PLA.pre-print3656 K

Phytic acid as a biomass flame retardant for polyrotaxane based phase change materials

Petrochemical resources are facing depletion and human long-term survival needs sustainable development. In this era, it is very important to develop new sustainable phase change materials (PCMs), because it has shown great application value in the effective utilization of industrial waste heat, solar energy harvesting, and electronic heat treatment. In this work, we reported a biomass phytic acid (PA) modified polyrotaxane (PLR) as PCMs for thermal management. The tensile performances, fire safety, phase transition performances of the PCMs were investigated. It is found that all the tensile properties, char residual, and fire-safety of PLR can be enhanced remarkably by introduce of PA. Typically, the Young's modulus, yielding strength and tensile strength of the PLR were 826.7 MPa, 14.2 MPa and 14.2 MPa, respectively, and significantly increased to 1527.4 MPa, 22.1 MPa, and 24.0 MPa respectively, with the addition of 10 wt% of PA. Elongation (>783 %) for all modified PCMs was gradually increased with the increase of PA contents. Thermal analysis shows that the fire safety of PLR is significantly improved. Specifically, for the best sample PLR-PA30, the pHRR could decrease by 54.2 %, THR decreased by 34.0 %; and the LOI increased from 20.8 % to 28.2 %. The PCMs showed the perfect form stability and leakage-proof performance, enhanced thermal conductivity and outstanding cycle properties. Notably, its biomass source, and high flexibility, enhanced fire safety and completely green pathway may provide a practical way for the highly flexible and sustainable packaging of electronic devices for heat treatment.2022-2

Investigation of magnesium hydroxide functionalized by polydopamine/transition metal ions on flame retardancy of epoxy resin.

Aiming to impart epoxy resin (EP) with flame retardancy, magnesium hydroxide (MDH) was sequentially functionalized with four transition metals and polydopamine (PDA) to prepare MDH@M-PDA (M includes Fe3+, Co2+, Cu2+, Ni2+). Compared with MDH, MDH@M-PDA presented better dispersion in EP matrix. The results illustrated that a 30 mass% of MDH@Fe-PDA imparted the EP matrix with best fire retardancy and thermal stability. Specifically, the resultant EP/MDH/MDH@Fe-PDA composites remarkably reduced flammability, which is reflected by high LOI value of 29.3% and UL-94 V-0 ratings. The peak heat release rate (PHRR) and total smoke production (TSP) were reduced by 52% and 21%, respectively. Moreover, the impact and tensile strength of EP/MDH/MDH@M-PDA composites are improved compared with EP/MDH due to the better chemical compatibility of PDA in the EP matrix. Notably, this work provided a feasible design for organo-modified MDH and enriched its practical applications of MDH as functional fillers to polymers.post-print2133 K