Surface Of Blends Research Articles

Photostabilization of Poly(vinyl chloride) Films Blended with Organotin Complexes of Mefenamic Acid for Outdoor Applications

This study develops a process for enhancing the photostabilization of PVC films blended with a low concentration of mefenamate–tin complex. One tri-substituted and three di-substituted organotin complexes containing mefenamate unit are synthesized, and their chemical structures are established. The reactions of mefenamic acid and a number of substituted tin chlorides gave the corresponding tin complexes in 70–77% yields. Tin complexes were blended with PVC and thin films. The effect of the addition of additives against long-term irradiation (290–400 nm, 300 h) is also tested. Changes in the infrared spectra, weight, and surface of the PVC blends due to irradiation are examined and analyzed. Any damage to the PVC surface and its chemical degradation level are noticeably low in the presence of additives. Minimal photodegradation levels and surface changes of the irradiated PVC films are observed when the triphenyltin complex is used. Such a complex is highly aromatic and can act as an ultraviolet irradiation absorber and a scavenger for hydrogen chloride and radicals produced due to the photooxidation and photoirradiation of PVC films.

Osteoblast/bone-tissue responses to porous surface of polyetheretherketone-nanoporous lithium-doped magnesium silicate blends' integration with polyetheretherketone.

The porous surface of a polyetheretherketone (PK)–nanoporous lithium-doped magnesium silicate (NLS) blend (PKNLS) was fabricated on a PK surface by layer-by-layer pressuring, sintering, and salt-leaching. As controls, porous surfaces of a PK/lithium-doped magnesium silicate blend (PKLS) and PK were fabricated using the same method. The results revealed that porosity, water absorption, and protein absorption of the porous surface of PKNLS containing macropores and nanopores were obviously enhanced compared to PKLS and PK containing macropores without nanopores. In addition, PKNLS, with both macroporostiy and nanoporosity, displayed the highest ability of apatite mineralization in simulated body liquid, indicating excellent bioactivity. In vitro responses (including adhesion, proliferation, and differentiation) of MC3T3E1 cells to PKNLS were significantly enhanced compared to PKLS and PK. In vivo implantation results showed that new bone grew into the macroporous surface of PKNLS, and the amount of new bone for PKNLS was the highest. In short, PKNLS integration with PK significantly promoted cells/bone-tissue responses and exhibited excellent osteogenesis in vivo, which might have great potential for bone repair.

Surface and swelling properties of mucoadhesive blends and their ability to release fluconazole in a mucin environment.

The aim of this study is to characterize the matrices for the controlled release of fluconazole and to expand the knowledge of their physicochemical properties that influence the process of mucoadhesion. Polymeric carriers of fluconazole were prepared using the following mucoadhesive polymers: Carbopol 974 P NF, Noveon AA-1, HPMC, HEC, chitosan and film-forming polymer Kollidon VA 64. The potential mucoadhesive properties of the polymers and their blends were evaluated by measuring the wettability and then calculating the surface free energy defined by OWRK and vOCG models, determining the polar and dispersion forces, spreading coefficients and work of adhesion of polymers and their blends with fluconazole in the form of tablets. Prepared tablets were characterized by swelling capacity and in vitro drug release to estimate the amount of fluconazole release from selected polymer blends. The study of drug release from selected blends both in simulated saliva fluid (pH = 6.8) and in simulated vaginal fluid (pH = 4.2) containing mucin confirmed the ability of polymeric carriers to continuously deliver drug over a period of about 8 h.

A novel combination of sandwich and co‐continuous structure based on polypropylene and styrene‐butadiene‐styrene block copolymer formed with wide range of polypropylene content

ABSTRACTThe styrene–butadiene–styrene block copolymer (SBS)/polypropylene (PP) blends with a unique sandwich layered co‐continuous structure were prepared by melt compounding. Differing from single conventional co‐continuous and sandwich structure, this structure was formed, where pure PP and co‐continuous SBS/PP phase acting as the face sheets and core. Even though the volume content was 20 or 10 vol %, PP always amazingly formed a continuous phase in SBS/PP blends, whereas the morphology of SBS phase relatively changed from dispersed particles to continuous network as its content increased to 50 vol %. For immiscible SBS/PP blends, due to the huge difference of complex viscosity and surface tension between SBS and PP, a pure PP layer existed on the surface of blends which can be ascribed to the PP enrichment. Herein, the structure of blends with more than 50 vol % SBS was presented as sandwich layered co‐continuous structure by combining the pure PP layer and co‐continuous structure. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46580.

High performance poly (lactic acid)/bio-polyamide11 through controlled chain mobility

This study shows that controlled PLA chain mobility in poly (lactic acid)/polyamide11 (PLA/PA11) blends can lead to high performance materials. The addition of an appropriate amount of polyethylene oxide (PEO) or polyethylene glycol (PEG) to a PLA/PA11 blend reduces the interfacial tension and increases the interfacial interactions due to an increase in the PLA chain mobility. The mechanical properties of (PLA-PEO)/PA11 50/50 systems are highly dependent on the PEO composition and at an optimal PEO concentration show a remarkable improvement in the Izod impact strength with specimens demonstrating 17.5 times the impact strength of the neat PLA and 3 times that of neat PA11. Also, these same blends show exceptional ductility with an elongation at break of 275% as compared to 5% for the neat PLA and 6% for PLA/PA11 without added PEO. Analysis of the fracture surface of the tough blends after impact indicates controlled interfacial debonding/cavitation at the continuous PLA/PA11 interface which leads to extensive shear yielding in the surrounding matrices. An excellent correlation is found between the optimal PEO composition for high performance properties and PEO limited miscibility in the PLA phase. When PEO phase separates in the PLA it tends towards the PLA/PA11 interface and provides a locus of failure for interfacial debonding. PEG is not as effective as PEO and it has virtually no effect on the mechanical properties of the PLA/PA11 blend since it phase separates at lower concentrations, thus limiting its effect on PLA mobility and ultimately providing insufficient plastic deformation to the PLA matrix. These results indicate that controlled PLA chain mobility through the use of an optimal concentration of an appropriate plasticizer is a highly effective approach towards the development of high performance PLA/PA11 blends.

Evidence and Limits of Universal Topological Surface Segregation of Cyclic Polymers.

If you mix lines and circles, what happens at the edge of the mixture? The problem is simply stated, but the answer is not obvious. Twenty years ago it was proposed that a universal topological driving force would drive cyclic chains to enrich the surface of blends of linear and cyclic chains. Here such behavior is demonstrated experimentally for sufficiently long chains and the limit in molecular weight where packing effects dominate over the topological driving force is identified.

Mechanical properties and phase morphology of super-tough PLA/PBAT/EMA-GMA multicomponent blends

Poly(lactide) (PLA)/poly(butylene-adipate-co-terephtalate) (PBAT) blends containing varying amounts of ethylene-methyl acrylate-glycidyl methacrylate copolymer (EMA-GMA) are prepared through reactive melt-blending to improve toughness. A super-tough PLA/PBAT/EMA-GMA multicomponent blend (75wt%:10wt%:15wt%) exhibits a significantly improved notched impact strength of 61.9±2.7kJ/m2, nearly 13 times higher than those of PLA/10wt%PBAT binary blend, respectively. A special core-shell like dispersed phase microstructure involving PBAT particles and EMA-GMA phase at the cryofractured surface of the PLA blends is observed by Scanning Electron Microscopy (SEM). The strong interfacial adhesion and enormous shear-yielding deformation of the PLA matrix with the dispersed phases are responsible for the super-toughened effect exhibited by the PLA/PBAT/EMA-GMA blends.

Surface and degradation properties of thermoplastic blends from albumin and zein‐based plastics

ABSTRACTThe use of traditional petroleum‐based thermoplastics in food packaging applications pose an environmental hazard, as their lack of biodegradability creates waste that environmental systems are unable to cope with. To address this issue, the investigation of surface, biodegradation, and water solubility properties of the albumin and zein thermoplastic blends plasticized with glycerol and mixed with varying amounts of low‐density polyethylene (LDPE) is conducted. When subjected to soil burial, albumin as a bioplastic completely biodegrades within two months, while a zein‐based bioplastic is more resilient to attacks from microbes within the soil (4.34% of intial mass remains). If albumin and zein proteins are used in the production of thermoplastics in tandem with LDPE, it could be possible to produce a plastic that will naturally biodegrade over time, decreasing the environmental impact of the use of thermoplastics in medical and food packaging applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44646.

Surface Characterization of Polymer Blends by XPS and ToF-SIMS.

The surface properties of polymer blends are important for many industrial applications. The physical and chemical properties at the surface of polymer blends can be drastically different from those in the bulk due to the surface segregation of the low surface energy component. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary mass spectrometry (ToF-SIMS) have been widely used to characterize surface and bulk properties. This review provides a brief introduction to the principles of XPS and ToF-SIMS and their application to the study of the surface physical and chemical properties of polymer blends.

Synthesis of multi-arm poly(l-lactide) and its modification on linear polylactide

Multi-arm poly(l-lactide)s (PLLAs) were prepared by using alcohols with different numbers of hydroxyl groups as initiator and Sn(Oct)2 as catalyst. The structure and composition was confirmed by NMR and GPC analysis. A series of blends of PLLA/multi-arm PLLA were prepared by melt-mixing. Several techniques were applied to investigate the effects of multi-arm PLLA on the melt rheology, crystallization, thermal stability, morphology and mechanical properties of the linear PLLA. Multi-arm PLLA enhanced crystallization rate of PLLA as a nucleating agent. Rheological analysis showed that the viscosity of PLLA at low frequencies increased after addition of multi-arm PLLA. In addition, the tensile strength was increased with the increase of multi-arm PLLA and can achieve a maximum. FE-SEM measurements revealed that the surface of blends was homogenous, indicating good compatibility between PLLA and multi-arm PLLA. The results had an important guiding role in PLA modification, which provided an opportunity for generating new PLA blending systems with enhanced properties.

Physical mechanisms responsible for the water‐induced degradation of PC61BM P3HT photovoltaic thin films

ABSTRACTWe show that [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) at the surface of thin film blends of poly(3‐hexylthiophene) (P3HT):PC61BM can be patterned by water. Using a series of heating and cooling steps, water droplets condense onto the blend film surface. This is possible due to the liquid‐like, water swollen layer of poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate. Breath pattern water deformation and subsequent drying on the film surface results in isolated PC61BM structures, showing that migration of PC61BM takes place. This was confirmed by selective wavelength illumination to spatially map the photoluminescence from the P3HT and PC61BM. Within a device, redistribution of the surface PC61BM into aggregates would be catastrophic, as it would markedly alter device performance. We also postulate that repeated volume change of the poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate layer by water swelling may be, in part, responsible for the delamination failure mechanism in thin film solar cells devices. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 141–146

Synthesis of a novel phosphorus-containing plasticizer based on castor oil and its application for flame retardancy of polyvinyl chloride

A novel flame-retardant plasticizer based on castor oil (FRC) was synthesized, and its potential application for polyvinyl chloride (PVC) was evaluated through the study of torque during melt processing, thermogravimetric analysis (TGA), limiting oxygen index instrument, scanning electron microscope (SEM) and mechanical tests. The results suggested that the FRC has a plasticizing effect in blends with PVC. The addition of FRC resulted in reduction of processing torque, good compatibility, improvement in thermal stability and efficient flame retardant. Torque reduction was observed (33.6%), indicating the reduction of viscosity and the improvement of process. The increase (31.9%) of LOI value indicated that incorporation of FRC system had obviously improved the flame retardant property of PVC blends. The excellent flame retardant properties were obtained by forming an isolation layer on the surface of PVC blends in the process of FRC burning. FRC could improve the thermal ability of PVC blends by enhancing the decomposition temperature of PVC. The performance in all properties of PVC products could be obtained by controlling the formula blends. Therefore, castor oil-based flame retardant plasticizers would appear suitable for a wide range of application.

Hydrogenated nanosized polyisoprene as a thermal and ozone stabilizer for natural rubber blends

Abstract Hydrogenated polyisoprene (HPIP) nanoparticles, synthesized via organic solvent-free hydrogenation using RhCl3/TPPMS as a catalyst, are novel nanofillers for natural rubber (NR) blends. Hydrogenation of a polyisoprene (PIP) emulsion was carried out in a Parr reactor. Rhodium trichloride (RhCl3.3H2O) and monosulfonated triphenylphosphine (TPPMS) were used as the catalyst precursor. The HPIP was characterized by proton nuclear magnetic resonance spectroscopy. The PIP hydrogenation in the absence of organic solvent is a first-order reaction with respect to carbon–carbon double bond concentration, and the rate constant was dependent on catalyst concentration. The highest hydrogenation degree of 93% was achieved at a catalyst concentration of 250 μM with a reaction time of 12 h. The NR/HPIP blends (blend ratio = 80:20) after thermal aging show high % retention of their tensile strength and modulus, maintaining 94.5% and 93.7%, respectively. Moreover, a combination of HPIP in NR improved the ozone resistance at the surface of the rubber blends. Therefore, the NR/HPIP composite exhibited a good retention of tensile properties after thermal aging and good resistance toward ozone.

Interactions of montmorillonite and electron beam irradiation in enhancing the properties of alumina trihydrate–added polyethylene and ethylene vinyl acetate blends

This study aims at investigating the effects of electron beam irradiation on the montmorillonite and alumina trihydrate–added low-density polyethylene and ethylene vinyl acetate blends. The mechanical, flammability and electrical resistivity of the montmorillonite and alumina trihydrate–added low-density polyethylene and ethylene vinyl acetate blends were investigated. The addition of montmorillonite provided the reinforcing effect to the alumina trihydrate–added low-density polyethylene and ethylene vinyl acetate, whereby the tensile strength of 150 kGy and 250 kGy irradiated samples gradually increased with increasing of montmorillonite composition (i.e. 5 phr to 20 phr). Furthermore, the addition of montmorillonite into low-density polyethylene and ethylene vinyl acetate blends increased the limiting oxygen index and thermal decomposition temperatures of samples, thus improving the flame retardancy and thermal stability. The increasing of montmorillonite and irradiation dosage promoted the char formation during combustion. Besides, the increasing of montmorillonite loading levels gradually decreased the surface and volume resistivities of the polymer blends. The high irradiation dosages (i.e. 150 kGy and 250 kGy) were found to slightly decrease the electrical resistivity of the alumina trihydrate–added low-density polyethylene and ethylene vinyl acetate blends especially at high loading of montmorillonite. The irradiation effect improved the mobility of montmorillonite ions in polymer matrix, subsequently causing the reduction of the electrical resistivity of the polymer blends. The storage capacity of electrical charges of samples was slightly declined with the increasing of montmorillonite loading levels and irradiation dosages as shown by the dielectric constant results. The dielectric loss tangent of samples slightly increased at the increasing of montmorillonite loading level. However, the dielectric loss tangent was declined with increasing of irradiation dosages.

Investigation of enhancing effect of nano-montmorillonite on fire-retardant added low-density polyethylene–ethylene vinyl acetate hybrid system

In this study, nano-montmorillonite (NMMT) was incorporated in alumina trihydrate (ATH) added low-density polyethylene–ethylene vinyl acetate (LDPE-EVA) for enhancing the mechanical and electrical properties of the hybrid blends. The Young’s modulus of 50 phr ATH added LDPE-EVA (LE) blends has improved significantly, when the NMMT loading level increased from 5 to 15 phr. This is because the intercalation of NMMT particles reduces the cavities while enhancing the interfacial adhesion between the particle surface and LE matrix as observed via morphology analysis. The good interfacial adhesion could effectively transfer the stress from polymer matrix to filler’s particles during straining and improved the mechanical properties. On the other hand, the volume resistivity of 5 phr added LE blends was gradually decreased as the loading level of ATH has increased from 50 to 150 phr. The surface and volume resistivity of LE blends exhibited that high polarity of ATH and NMMT molecules could increase the mobility of charges in passages through polymer matrix and surface. Thus, the incorporation of ATH and NMMT could reduce the electrical resistance of LE blends. In addition, the increasing of ATH loading level also improved fire resistivity of LE blends as indicated by the promising limiting oxygen index. This is because the endothermic reaction of ATH during combustion process could reduce the temperature of polymer blends while releasing water vapour and the formation of alumina char. Furthermore, the increasing of NMMT loading level in ATH-added LE blends was found to slightly increase the fire retardancy. This is due to the addition of NMMT that could promote the dripping characteristics and charring effect during combustion and subsequently improve the fire retardancy of ATH added LE blends.

In situ formation of nano-scale PMMA network structures on the surface of immiscible polymer blends by solvent extraction and redeposition

Abstract A continuous open structured network, with a high surface area, low solids fraction, and nano-scale domain morphology, was observed to grow from dissolved blend components on cold fractured surfaces of immiscible polymer blends, when reacted with dimethylformamide (DMF). In this work, we showed that the network is comprised of polymethyl methacrylate (PMMA), with a strong glassy character similar to or even in excess of conventional PMMA pellets used in the preparation process, in contrast to the amorphous but not glassy PMMA produced when similar materials were synthesized away from the PMMA host. Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) analyses confirmed the chemical and physical character of the network. This general network formation phenomenon, which was initially observed in PMMA/high density poly ethylene (HDPE) blends produced by conventional extrusion, PMMA/HDPE blends compression molded from powder precursors, and subsequently on bulk PMMA, produces a unique structure that has potential applications as an interfacial modification substance or as a functional material in biomaterials and catalysis.

A Study of FTIR, Thermal Properties and Natural Weathering Test on NBRVirgin/Recycled with SBR Blends

The effects of styrene butadiene rubber/virgin acrylonitrile butadiene rubber (SBR/NBRv) blends and styrene butadiene rubber/recycled acrylonitrile butadiene rubber (SBR/NBRr) blends on properties such Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) were carried out. Results indicated that, based on intensity of amine peak from FTIR at 85/15 blend ratio (R15) revealed optimum formation of crosslink between SBR and NBR either using virgin or NBRr. TG thermograms of SBR/NBRv blends of all ratios showed better onset thermal stability than SBR/NBRr blends. The change in the horizontal baseline from high to low energy level occurred in virgin NBR blends because the amount of reactive sites available in virgin NBR is higher compared to NBRr. Meanwhile NBRr blends showed Tc because the amount of crosslink occurred in these blends were slightly lower than NBRv blends. Up to 25 phr of NBRr, the tensile strength and elongation at break (Eb) retention of SBR/NBRv blends was better than SBR/NBRr blends after 6 months' weathering test except for M100. The scanning electron microscopy on the surface of both blends after 6 months exposure indicated that the severity of the crack was minimal for SBR/NBRr blends compared to SBR/NBRv particularly at 50/50 blend ratio designated the SBR/NBRr blends that contained more NBRr particles could reduce the degradation towards natural weathering.

Modification of poly(ether urethane) with fluorinated phosphorylcholine polyurethane for improvement of the blood compatibility

In order to improve the blood compatibility, poly(ether urethane) (PEU) and fluorinated phosphorylcholine polyurethane (P-HFPC) were used to prepare PU/P-HFPC blends by solution mixing. The hemocompatibility in vitro was evaluated with protein adsorption and platelet-rich plasma (PRP) contact tests. It was found that the amount of adsorbed protein on surface was decreased by 87%, and almost no platelet adhesion and activation was observed on the surface of blends when P-HFPC content was above 5 wt %. After adding P-HFPC, the blends basically kept favorable mechanical properties of PEU though the content of P-HFPC rises to 20 wt %. To better understand the relationship between structure and properties, the phase structure and surface property of the blend films were further investigated via differential scanning calorimetry, dynamic mechanical analysis, atomic force microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The results indicated that the fluorinated phosphorylcholine units could be easily enriched on the surface of blend films due to the phase separation between the PEU and P-HFPC. Therefore, ordinary poly(ether urethane)s can obtain both satisfactory blood compatibility and good mechanical properties just by blending with small amount of P-HFPC.

Effect of Co-Rotation and Counter-Rotation Extrusion Processing on the Thermal and Mechanical Properties, and Morphology of Plasticized Soy Protein Isolate and Poly(butylene succinate) Blends

Blends of plasticized soy protein isolate (PSPI) and poly(butylenes succinate) (PBS) were prepared in a 70:30 wt.-% ratio via co-rotation (CR) and counter-rotation (CTR) twin-screw extrusion. The novelty in this research suggests that CTR extrusion provides enhanced interfacial adhesion, tensile elongation and prolonged onset (Tonset) and end (Tend) thermal degradation temperatures. The average tensile strain at break showed to be ≈40% higher for PSPI-CTR material and ≈55% higher for PBS:PSPI-CTR (70:30) blends. Both Tonset and Tend for CTR processed PBS:PSPI(70:30) and PSPI were ≈10 °C greater than those of CR. These results suggest that the enhanced shear rate and radial motion associated with CTR allows for better destructurization and blending of PSPI within the PBS matrix, resulting in enhanced structural integrity due to the formation of possible amide and ester linkages. Scanning electron microscopy (SEM) provides further support based on evidence of reduced voids on the surface of all CTR blends

Preparation and Characterization of Biodegradable and Electroactive Polymer Blend Materials Based on mPEG/Tetraaniline and PLLA

A novel PGTA diblock copolymer containing electroactive TEA and mPEG is described. Biodegradable PLLA/PGTA polymer blends are shown to be electroactive. Nanopores of different sizes can be formed on the surface of the polymer blends. An MTT assay shows that the PLLA/PGTA blends exhibited reduced cytotoxicity as compared to TEA due to the introduction of the biocompatible PLLA moiety. Cell culture results show that the cells grow better when they were adhered to the surface of the PLLA/PGTA blends. The 80/20 wt.-% PLLA/PGTA blend shows the best biocompatibility and an electroactivity that accelerates the differentiation of rat C6 glioma cells.