Mechanical Compatibility Research Articles

A Universal Method to Enhance Flexibility and Stability of Organic Solar Cells by Constructing Insulating Matrices in Active Layers

AbstractWith the rapid development of power conversion efficiency (PCE), flexibility–stability of organic solar cells (OSCs) are becoming one of the primary barriers for commercialization. This work shows that insulating poly(aryl ether) (PAE) resins have highly twisted‐stiff backbones without any side chains, which possess excellent mechanical stability, thermal stability, and good compatibility with organic photovoltaic materials. After introducing 5 wt% PAE resin as supporting matrices into the bulk heterojunction (BHJ) layer, the device yields a high PCE of 16.13%. Importantly, the devices show impressive flexibility and improved stability with passivated morphology, such as PM6/Y6‐based devices with 30 wt% PAE retains the PCE of 15.17% and exhibits enhanced 4.4‐fold elongation at break (25.07%). This is the recorded stretchability of the BHJ layer for OSCs with PCE > 8%, and morphological changes during tensile deformation are first investigated by in situ wide‐angle X‐ray scattering measurements. The PAE matrices strategy exhibits good universality in the other four photovoltaic systems. These results demonstrate that heat‐resistant PAE resins serve as supporting matrices with a tunneling effect into OSCs without sacrificing photovoltaic performance and simultaneously improve the flexibility and stability of devices, which can play an important role in promoting the development of stable and wearable electronics.

A novel sensitivity analysis on friction spot joining process performed on aluminum\\polycarbonate sheets by simulation

The manufacturing research has been focusing on the improvement of product performance and lightweight design. The synergic effects between material properties and manufacturing solutions have been considered, extensively. Specifically, joining techniques have been developing with the aim to propose new suitable solutions considering dissimilarities in the properties of the materials that have to be combined. Setting of new manufacturing routes is, therefore, a demanding task. In this direction, there are several methods available in the scientific literature that are focused on sensitivity analysis or optimization/minimization techniques to reduce the necessary attempts or to find a solution/correlation among big data. In this work, the goal of obtaining high joint efficiency between Aluminum and Polycarbonate sheets by the Friction Spot Joining process is considered as a case study. This process must face two main issues, i.e., the mechanical, physical and chemical compatibilities between the parts and the integrity protection of the polymeric sheet near the joining area. The process parameters influences were analysed using numerical simulations performed by a commercial FE code. The number of executed analyses was reduced with a planned DoE. From these results, the Code2Vect algorithm was employed with the aim to visualize, efficiently, high-dimensional data and to evaluate the influences of some identified parameters on the process answer. Finally, a transfer function involving the input and output quantities of interest was derived in a compact representation by a Newton Raphson minimization technique.

Low Water Absorption, High-Strength Polyamide 6 Composites Blended with Sustainable Bamboo-Based Biochar.

To promote the application of polyamide 6 (PA6) in wood–plastic composites, the negative effects associated with the thermal degradation of plant fibers must be overcome. In this study, waste bamboo fibers were subjected to pyrolysis and ball milling to afford nano bamboo-based biochar (BC), which was subsequently used as reinforcement to prepare PA6/BC nano composites by injection molding. In addition, the processing fluidity, water absorption, mechanical properties, and interface compatibility of PA6/BC composites were discussed. Results revealed that a BC content of less than 30 wt% is beneficial to improve the processing fluidity of the composites. With the increase in the BC content, the density of the PA6/BC composites gradually increased, while the water absorption of the PA6/BC composites gradually decreased, and the maximum decrease was 46%. Compared to that of pure PA6, the mechanical strength of PA6/BC composites was improved by the addition of BC, and the maximum tensile/flexural strength and modulus of PA6/BC composites increased by 41%/72% and 195%/244%, respectively. However, the impact strength decreased by 27%. After immersion treatment, the dimensional stability and mechanical strength of the composites decreased, while toughness improved. At a BC content of less than 40 wt%, BC particles exhibited good dispersibility and wettability in the PA6 matrix, and the rough surface and rich pore structure of BC rendered strong mechanical interlocking effects and good interface compatibility, thereby enhancing the mechanical properties of the composites.

Glass-Reinforced Epoxy Effective Alternative to Alloys in Gas Wells

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper IPTC 19696, “The Application of a Fiberglass Liner in Well Tubing as a Cost-Effective Material Option in High-Velocity Production Wells,” by Carmen Repetto, Simone Gorini, and Giacomo Andrea Nutricato, Eni, et al., prepared for the 2020 International Petroleum Technology Conference, Dhahran, Saudi Arabia, 13-15 January. The paper has not been peer reviewed. Copyright 2020 International Petroleum Technology Conference. Reproduced by permission. The complete paper describes an operator’s experience in confirming glass fiber-reinforced epoxy (GRE) as an effective alternative to high-grade corrosion-resistant alloys (CRA) to extend tubing life in high-velocity gas wells. Laboratory testing and applications in several fields, both on and offshore, and in oil-production and water-injection wells and surface-gathering lines, demonstrate that, when used within the operating limits, GRE can extend tubing life and provide life-cycle cost savings. GRE The material has been intensively tested in the past to determine characteristics and capabilities. Mechanical properties, fatigue resistance, chemical compatibilities, connection properties, and abrasion trials have been proved by specific laboratory tests and field trials, demonstrating that GRE can be applied inside production tubing strings. API RP15CLT, first issued in 2007, provides guidelines for the design, manufacture, qualification, and application of composite-lined carbon-steel downhole tubing in the handling and transport of multiphase fluids, hydrocarbon gases, hydrocarbon liquids, and water. Carbon steel guarantees the system’s mechanical resistance, and the internal GRE liner ensures corrosion resistance. GRE provides outstanding corrosion resistance, even in very aggressive environments. For oil-well applications, the system consists of a GRE resin composite liner inserted inside a low-alloy carbon steel tubing with a cement grout (Fig. 1). The grout transfers pressure directly to the steel tubing even if there is little or no bonding between liner, grout, and metal. The end of the liner is protected from mechanical damage by a GRE end cap (flare) or a T-end flange. A polymeric corrosion barrier ring usually provides the continuity of the corrosion barrier across the coupling between two adjacent flares. The lining is lightweight, adding no more than 13% of the weight of the steel pipes and eliminating the need for additional lifting equipment. The operator has been involved in the development of deepwater gas fields with high production rates and sour environments. On the basis of corrosion assessments performed on actual field conditions, CRA (high nickel content) material was selected as most suitable for the production tubing string. Following positive experiences with the installation of GRE, the company decided to evaluate its performance in potentially high-erosion conditions, aiming to find an alternative material to high-grade CRA for installation in high-velocity gas wells that would reduce cost and delivery time. The GRE liner was selected as a cost-effective alternative to high-alloy materials starting from 2005, when GRE was successful in reducing onshore workover costs and extending the life of carbon-steel tubing in oil producer wells with high carbon dioxide and water cut, to recent installations offshore Norway in water injection wells with highly corrosive injection fluids.

Alginate Hydrogels with Embedded ZnO Nanoparticles for Wound Healing Therapy.

IntroductionIn this in-vitro study, we designed a 3D printed composite of zinc oxide (ZnO) nanoparticles (NPs) with photocatalytic activities encapsulated within hydrogel (alginate) constructs, for antibacterial purposes applicable towards wound healing. We primarily sought to confirm the mechanical properties and cell compatibility of these ZnO NP infused scaffolds.MethodsThe antibacterial property of the ZnO NPs was confirmed by hydroxyl radical generation using ultraviolet (U.V.) photocatalysis. Titanium dioxide (TiO2), a well-known antibacterial compound, was used as a positive control (1% w/v) for the ZnO NP-based alginate constructs and their antibacterial efficacies compared. Among the ZnO group, 3D printed gels containing 0.5% and 1% w/v of ZnO were analyzed and compared with manually casted samples via SEM, swelling evaluation, and rheological analysis. Envisioning an in-vivo application for the 3D printed ZnO NP-based alginates, we studied their antibacterial properties by bacterial broth testing, cytocompatibility via live/dead assay, and moisture retention capabilities utilizing a humidity sensor.Results3D printed constructs revealed significantly greater pore sizes and enhanced structural stability compared to manually casted samples. For all samples, the addition of ZnO or TiO2 resulted in significantly stiffer gels in comparison with the alginate control. Bacterial resistance testing on Staphylococcus epidermidis indicated the addition of ZnO NPs to the gels decreased bacterial growth when compared to the alginate only gels. Cell viability of STO-fibroblasts was not adversely affected by the addition of ZnO NPs to the alginate gels. Furthermore, the addition of increasing doses of ZnO NPs to the alginate demonstrated increased humidity retention in gels.DiscussionThe customization of 3D printed alginates containing antibacterial ZnO NPs leads to an alternative that allows accessible mobility of molecular exchange required for improving chronic wound healing. This scaffold can provide a cost-effective and durable antibacterial treatment option.

Study of modifications on the chemical and mechanical compatibility between cement matrix and oil palm fibres

Nowadays, the substitution of the traditional reinforcements of cement-based composite materials by natural fibres is more and more common. However, some problems remain, mostly because the addition of natural fibres to cement can delay its hydration due to the high concentration of polysaccharide in the fibres’ leachates. Many studies have shown the effectiveness of alkaline treatments in order to improve the natural fibre/cement compatibility but the mechanical compatibility, i.e. the bonding strength between the cement and the fibres has never been characterized. Therefore, this study aims to fully understand the natural fibre/cement interface. Oil palm fibre is chosen as reference fibre because of its very low compatibility with cement. NaOH treatments and superplasticizer are used, in order to modify the surface of the fibre and the viscosity of the matrix. Both chemical and mechanical compatibilities are characterized, by various methods such as isothermal calorimetry, FTIR, tensile tests on single fibres and pull-out tests. Results show that alkali-treatments are very effective since it can improve both compatibilities, while a more fluid matrix allows to further enhance the properties of the interface, by limiting the amount of sugar at the fibre’s surface without hindering the cement hydration.

Mechanical Rupture-Based Antibacterial and Cell-Compatible ZnO/SiO2 Nanowire Structures Formed by Bottom-Up Approaches.

There are growing interests in mechanical rupture-based antibacterial surfaces with nanostructures that have little toxicity to cells around the surfaces; however, current surfaces are fabricated via top-down nanotechnologies, which presents difficulties to apply for bio-surfaces with hierarchal three-dimensional structures. Herein, we developed ZnO/SiO2 nanowire structures by using bottom-up approaches and demonstrated to show mechanical rupture-based antibacterial activity and compatibility with human cells. When Escherichia coli were cultured on the surface for 24 h, over 99% of the bacteria were inactivated, while more than 80% of HeLa cells that were cultured on the surface for 24 h were still alive. This is the first demonstration of mechanical rupture-based bacterial rupture via the hydrothermally synthesized nanowire structures with antibacterial activity and cell compatibility.

Assessment of the mechanical properties of peruvian Stipa Obtusa fibers for their use as reinforcement in composite materials

This paper presents the study of the mechanical properties of technical fibers extracted from the Stipa Obtusa grass considering three different alkali treatment times, 1.5, 3 and 5 h; additionally, fiber/matrix compatibility is evaluated via the single fiber fragmentation test, and the best treatment in terms of mechanical properties and compatibility is used to test the effect of gage length, strain rate and cyclic deformation. Result shows that mechanical properties increase with treatment time until a maximum (strength ~ 569 MPa, modulus ~ 28 GPa and strain 0.026), and afterwards decreases; furthermore, strength and strain decreases as the fiber length increases; while, the strain rate’s effect is negligible unless at very low speed, and a cyclic deformation leads to an increase of the modulus (~13%). It can be concluded that fibers extracted from the Stipa Obtusa show potential and can compete with commercial natural fibers as a reinforcement in polymeric matrix composites.

Development of CNT Film Alignment and Geometries for Neuronal Attachment and Efficient Signal Transfer between Neurons and Electrodes

Carbon nanotubes (CNTs) are widely used in neuroscience research for its excellent properties such as high conductivity, electrochemical stability, biocompatibility, mechanical compatibility with tissues, tunable mechanical and chemical properties. CNTs are investigating for its performance as neuronal scaffolds to support neural tissues, neuron growth and differentiation as well as neural stimulating and recording electrodes to control and monitor neural activity in both vitro and in vivo environments. Surprisingly neurons show a better interaction with CNTs when neurons are grown on CNT substrates. Previous research has shown neuronal differentiation on pristine CNT and CNT composites and the alignment of neurites on CNT substrates. Current research focus on interaction of neurons at the interface of pristine CNT films with aligned and cross hatch patterned CNT layers prepared from multi-walled CNT arrays. CNTs have nano scale surface roughness and contribution of alignment of CNTs can retain and adhere neurons without any adhesive proteins. As an initial step to study the interaction of neurons with CNT films, the effect of different CNT alignment on neuron adhesion and neurite development was chosen. PC12 cell line was used to study neuron adhesion and neurite alignment on CNT substrates. It is a commonly used neuronal cell model due to its ability to attain sympathetic neurons characteristics in the presence of nerve growth factor (NGF) in low serum medium. For the study, CNT films were prepared as aligned and in cross hatch pattern on PET sheets. After sterilization with UV irradiation, PC12 cells were seeded and cultured at a density of 20 000 cells/mL on CNT films and allowed to differentiate in NGF medium. For comparison poly l lysine (PLL) coated CNT films were used. Fig 1(Left) shows SEM image of a differentiating PC12 cell on PLL coated film of aligned CNTs and Fig 1(Right) shows SEM image of a differentiating PC12 cell on a crosshatch patterned CNT film with no adhesive coating. While neurites of PC12 cells align with the CNTs on aligned CNT film as states in the literature, pristine CNTs in crosshatch pattern were also able to hold the cells without any surface adhesive coating and allow differentiation of cells. Also PC12 cells tend to show random alignment on crosshatch patterned CNTs and adhere well due to higher degree of porosity and surface roughness. As pristine CNT films were able to hold PC12 cells, the interface properties will be further evaluated by impedance spectroscopy. Figure 1

Study on Retrofitted Masonry Elements under Shear Using Digital Image Correlation.

Architectural heritage is usually built with masonry structures, which present problems under lateral in-plane loading conditions, such as wind pressure or earthquakes. In order to improve the shear behavior of masonry, the use of a fabric-reinforced cementitious matrix (FRCM) has become an interesting solution because of its synergy of mechanical properties and compatibility with masonry substrates. For a proper structural evaluation, the mechanical behavior of reinforced masonry and the FRCM itself needs to be characterized. Hence, a numerical model to evaluate the FRCM reinforcement requires some mechanical parameters that may be difficult to obtain. In this sense, the shear behavior of masonry can be evaluated by means of diagonal tension tests on small specimens (71 × 71 cm). In this work, a digital image correlation (DIC) monitoring system was used to control displacements and cracking patterns of masonry specimens under shear stress (induced by diagonal tension with FRCM layers) applied to one or two sides. In addition, the mechanical behavior of FRCM coupons under uniaxial tensile tests was also registered with DIC. The displacement measurements obtained by DIC were validated with the measurements registered with LVDT. Unlike LVDT-based techniques, DIC monitoring allowed us to measure deformations in masonry during the full test, detecting crack initiation even before it was visible to the eye.

The Local Alternative Ti-6Al-4V Alloy Coating of Surgery Steel Instruments for Laser Deposition Forming

Aiming at the medical practice problems of the surgical steel medical instruments, such as the crevice corrosion, the poor mechanical compatibility and the Ni, Cr plasma exudation, the laser deposition of Ti-6Al-4V alloy cladding layer at the local functional area as alternative coating was proposed and realized as a new process method. The accurate element content and good formability Ti-6Al-4V cladding powder was chosen, the low power and high duty cycle optimized laser process was adopt, the alternative coating of good fusion and low dilution was prepared. Through the elemental line scanning, the interface microstructure analysis and the experiments of basic mechanical properties, the basic properties of the cladding were characterized and verified. The experiments results showed that, the Ti, Al and V contents of the top coating were respectively about 88%, 4.9% and 3.9%, no sensitizing ions such as Cr and Ni were detected. Initial equiaxed α phase, flake β phase dist were distributed in the coating and interface, the α' martensite was precipitated at the boundary of the flake β phase, some refined granular β phase dispersion pinned to the grain boundary of basket structure. The microhardness of cladding layer was 352.08~312.76 HV0.1. The friction coefficient of the cladding layer was about 0.22~0.65. A new technology and method reference for improving and upgrading the performance of surgical medical devices is provided by this research.

Durability of Fabric-Reinforced Cementitious Matrix (FRCM) Composites: A Review

Strengthening and rehabilitation of masonry and concrete structures by means of externally bonded fabric-reinforced cementitious matrix (FRCM) (also referred to as textile reinforced mortar (TRM)) composites was proposed as an alternative to the use of fiber-reinforced polymer (FRP) composites due to their good mechanical properties and compatibility with the substrate. However, quite limited studies are available in the literature regarding the long-term behavior of FRCM composites with respect to different environmental conditions. This paper presents a thorough review of the available researches on the long-term behavior of FRCM composites. Namely, (i) test set-ups employed to study the FRCM durability, (ii) conditioning environments adopted, and (iii) long-term performance of FRCM and its component materials (mortar and fiber textile) subjected to direct tensile and bond tests, are presented and discussed. Based on the available results, some open issues that need to be covered in future studies are pointed out.

Synthesis and application of a novel thermostable epoxy plasticizer based on levulinic acid for poly(vinyl chloride)

AbstractEpoxy bisphenol acid isooctyl ester (EBAIE) was synthesized and characterized by FTIR and H‐NMR. EBAIE was used as poly(vinyl chloride) (PVC) plasticizer for the first time, and its addition amount was 30 wt% of PVC. The mechanical properties, thermal stability, compatibility, and decomposition activation energy of PVC blends were systematically studied. Compared to the commercial plasticizer‐dioctyl phthalate (DOP), the tensile strength had been significantly increased from 30.64 to 45.07 MPa, while the elongation at break had little difference. The thermal stability analysis showed that the static stability time at 180°C had been extended from 40 to 300 min. The decomposition activation energy indicated that the EBAIE plasticized PVC was with a higher thermal stability. The extraction and volatility resistance of the novel plasticizer were superior to those of DOP.

Discovery of n-Type Zintl Phases RbAlSb4, RbGaSb4, CsAlSb4, and CsGaSb4

Zintl phases are excellent candidates for high-efficiency thermoelectrics (TEs) due to their extremely low lattice thermal conductivity. The manufacturing of an all-Zintl module is particularly attractive for practical applications, as it alleviates concerns regarding the electronic, thermal, and mechanical compatibility of the p- and n-type legs. To date, a large majority of Zintl phases have been realized as p-type TE materials. Our recent discovery of n-type transport in Ba-doped KAlSb4 and KGaSb4 has helped demonstrate the potential of n-type Zintl thermoelectrics. In this paper, we report the experimental discovery of 4 ABX4 Zintl phases: RbAlSb4, RbGaSb4, CsAlSb4, and CsGaSb4. Transport measurements on Ba-doped RbGaSb4 and CsGaSb4 demonstrate near glassy lattice thermal conductivity (<0.5 W m–1 K–1, 350 °C) and lightly doped n-type transport. However, the doping efficiency of Ba in RbGaSb4 and CsGaSb4 is significantly impeded when compared to our prior work on KGaSb4. To investigate the underlying mechanism, we performed first-principles defect calculations and found that the effect of compensating alkali metal vacancies increases in the Rb- and Cs-based analogues. Considering the TE potential of the known ABX4 n-type materials, we have also performed a computational survey over 27 plausible compositions where A = (K, Rb, Cs), B = (Al, Ga, In), and X = (As, Sb, Bi) to investigate the effect of chemistry on potential TE performance.

Breaking the limit of Young’s modulus in low-cost Ti–Nb–Zr alloy for biomedical implant applications

Biomedical implant material simultaneously requires high yield strength and low Young’s modulus. The lower boundary for the YM of Ti–13Nb–13Zr alloys is regarded to be approximately 65 GPa, which limits further improvement in their mechanical compatibility. This study proposes a novel process of cold caliber rolling to break this limit and decrease YM to 47 GPa, which is the bare minimum value since the development of this alloying system. As a result, the developed alloy exhibits a mechanical compatibility similar to those of most advanced β-Ti alloys but with a significantly lower amount of high-cost alloying elements. This study attributed the mechanical improvement to three mechanisms based on microstructural characterizations. Manufacturing advantages of the suggested method were discussed as well.

Gamma-ray irradiation effects on tantalum thin film for improved mechanical compatibility and cytocompatibility.

In this work, tantalum thin films were prepared on titanium substrates by an ion beam sputtering method. Tantalum thin films were irradiated by gamma-ray with different total dose levels. The effect of irradiation on the phase composition, microstructure, surface morphology, and chemical resistance were analyzed. Besides, in vitro cytocompatibility of tantalum films treated with different radiation doses were evaluated via 3T3-E1 cells. Experimental results showed that higher radiation dose resulted in reductions in crystalline nature, denser morphology, lower elastic modulus, less oxygen vacancies and better corrosion resistance. Additionally, 3T3-E1 cells adhered and spread well on the surface of tantalum film with irradiation exposure to 10kGy. The dense surface morphology, less density of chemical defects and amorphous phase produced by the gamma-ray irradiation played a major role in the improvement of mechanical compatibility, electrochemical stability property along with the cytocompatibility of the tantalum films.

Preparation, structural, microstructural, mechanical and cytotoxic characterization of as-cast Ti-25Ta-Zr alloys.

Titanium alloys have been widely used as biomaterials, especially for orthopedic prostheses and dental implants, but these materials have Young's modulus almost three times greater than human cortical bones. Because of this, new alloys are being produced for the propose of decreasing Young's modulus to achieve a more balanced mechanical compatibility with the bone. In this paper, it is reported the development of Ti-25Ta alloys as a base material, in which was introduced zirconium, with concentration varying between 0 and 40 wt%, with the aim of biomedical applications. The alloys were prepared in an arc-melting furnace. The microstructural analysis was performed by x-ray diffraction as well as optical and scanning electron microscopy. Selected mechanical properties were analyzed by microhardness and Young's modulus measurements, and cytotoxicity analysis by indirect test. X-ray measurements revealed the presence of α″ phase in the alloy without zirconium; α″ + β phases for alloys with 10, 20, and 30 wt% of zirconium, and β phase only for the alloy with 40 wt% of zirconium. These results were corroborated by the microscopy results. The hardness of the alloy was higher than that of cp-Ti due to the actions of zirconium and tantalum as hardening agents. The Young's modulus decreases with high levels of zirconium due to the stabilization of the β phase. The cytotoxicity test showed that the extracts of studied alloys are not cytotoxic for osteoblast cells in short periods of culture.

Template-assisted freeze casting of macroporous Ti6Al4V scaffolds with long-range order lamellar structure

A modified water-based freeze casting to fabricate long-range order lamellar Ti6Al4V scaffolds with macropores and high porosity has been developed by using the pre-frozen WS2 substrate as the template. Pores morphologies of the scaffolds relied on the previous ice crystal which had formed in templates and thus could be adjusted by altering the template structure. The decrease of gelatin in WS2 slurry transformed the bottom template from cell pore structure into the lamellar structure followed by improvement of lamellar orientation of the top Ti6Al4V scaffold. The pore widths of the scaffolds were in the range of 84–217 μm which were difficult to realize without the assisted template. The scaffolds also exhibited mechanical compatibility with bone tissues, indicating that the template-assisted freeze casting is a promising approach to fabricate macroporous Ti6Al4V implants.

Double-layer gradient MoSi2-borosilicate glass coating prepared by in-situ reaction method with high contact damage resistance and interface bonding strength

High emissivity coating is an important part of spacecraft thermal protection system. MoSi2-borosilicate glass coatings prepared by the in-situ reaction method showed excellent thermal endurance and oxidation resistance. However, radial cracks were prone to appear under external forces due to high cohesive of in-situ reaction dense coatings, and few studies focused on the mechanical properties of gradient coatings. In this study, a double-layer gradient MoSi2-borosilicate glass coating with a porous interface layer and a dense surface layer was prepared on mullite fibrous insulation tiles by in-situ reaction method. The double-layer gradient coating was compared with a mono-layer dense coating and a high-density gradient coating (another gradient coating with higher interface layer density) with reference to microstructure, contact damage resistance, interface bonding strength and thermal shock resistance. Compared with mono-layer dense coating and high-density gradient coating, double-layer gradient coating showed higher bearing capacity and avoided radial crack initiation and propagation in Hertzian indentation test. Besides, the double-layer gradient coating endured the most thermal shock cycles between 1500 °C and 20 °C and presented substrate fracture instead of interface fracture. In addition, double-layer gradient coating and high-density gradient coating possessed much higher interface bonding strengths than mono-layer dense coating. The total emissivities of three coatings were all greater than 0.87. The porous interface in double-layer gradient coating presented the advantages in enhanced mechanical and thermal compatibility between the in-situ reaction dense coating and substrate through reducing elastic modulus and thermal expansion coefficient differences.

Structure and improved properties of PPC/PBAT blends via controlling phase morphology based on melt viscosity

ABSTRACTPoly(propylene carbonate) (PPC)/poly(butylenes adipate‐co‐terephthalate) (PBAT) blends with various composition ratios were prepared via melt mixing using a twin‐screw extruder. The effect of melt viscosities of polymers on mechanical behavior, interfacial interaction, thermal properties, rheological responses, and phase morphology was investigated. Results showed that the phase morphology and properties of PPC/PBAT blends were affected by the composition of the blends and the melt viscosities of the two polymers. Results of tensile tests, FTIR, and dynamic rheological measurement of PBAT‐rich blends exhibited a better mechanical properties, intermolecular interactions, and compatibility when compared with PPC‐rich blends due to the differences of their melt viscosities. Incorporating of PBAT effectively improved the Tg of PPC and the thermal stability of the blends. The Tc of PPC/PBAT blends markedly increased from 37.5 to 66.8 °C with addition of only 10 wt% PPC, indicating an enhanced crystallization ability of PBAT. The improvement of Tc was helpful for blown film extrusion. SEM microphotographs showed that the size of the dispersed phase particles is much smaller and the distribution is more uniform for PBAT‐rich blends, compared with that in PPC‐rich blends. The processing stability of blown film extrusion was improved by blending PPC with PBAT. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48924.