Presence Of PMMA Research Articles

Mechanical Properties of PMMA and PLA Modified Epoxy Resins

Last years research in polymers registered an increase of interest regarding polymer mixtures aiming to obtain materials with properties of the mixed polymers. In this respect many studies are pointing the mixtures between a thermoset polymer and a thermoplastic polymer. It is known the fact that thermoplastic polymers are much more malleable than the thermoset ones and the goal is to obtain a mixture with the general properties of the thermoset polymer and with a machining ability proper to the thermoset polymer. The vitrimers are this type of polymers and, some of them, can be obtained by mixing polymers form the two categories. This study is about using solutions of two thermoset polymers to modify the basic properties of three epoxy resins. The results show that the presence of PMMA, respectively, PLA inside the epoxy resin matrix determines changes of the mechanical properties of the formed materials. Without analysing the adhesive properties of new materials is hard to decide about their value from the composites applications point of view.

Evident improvement in burning anti-dripping performance, ductility and electrical conductivity of PLA/PVDF/PMMA ternary blend-based nanocomposites with additions of carbon nanotubes and organoclay

In this study, carbon nanotubes (CNTs) and organoclay (30B) were introduced into poly(lactic acid) (PLA)/poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) (70/30/30) ternary blend, with PMMA acting as a compatibilizer for the PLA and PVDF phases. Morphological results indicated that PMMA tended to entangle more with PVDF than with PLA, and thus formed a pseudo co-continuous PLA(rich)-PVDF(rich) phase morphology in the blend. The added CNTs and 30B clay were mainly distributed in the PVDF(rich) phase and PLA(rich) phase, respectively, to achieve nanocomposites. The co-continuous bi-phasic morphology was more evident in the composites than in the parent blend. Thermal property results revealed the nucleation effect of CNTs and 30B on the crystallization of PLA and PVDF; the presence of PMMA obviously retarded the crystal growth of PVDF due to their miscibility. Adding CNTs or hybrid CNT/30B evidently improved the anti-dripping performance of the ternary blend in burning tests. The ductility (elongation at break) of PLA/PVDF blend drastically improved with PMMA inclusion, and the composites also showed excellent ductility. The ductility of PLA and PLA/PVDF blend increased by up to 18.9 and 14.4 times, respectively, after forming the 3-phr hybrid CNT/30B-loaded composite. Rigidity of the ternary blend increased after forming the composites; flexural modulus increased by 16% with 3 phr CNT inclusion. Rheological properties revealed the (pseudo)network structure development in the composites. The electrical resistivity of the ternary blend reduced by 11 orders at 2 phr CNT loading (double percolation achieved), and the percolation threshold was at 0.5 phr CNT loading.

Enhanced Photovoltaic Properties of Perovskite Solar Cells by Employing Bathocuproine/Hydrophobic Polymer Films as Hole-Blocking/Electron-Transporting Interfacial Layers.

In this study, we improved the photovoltaic (PV) properties and storage stabilities of inverted perovskite solar cells (PVSCs) based on methylammonium lead iodide (MAPbI3) by employing bathocuproine (BCP)/poly(methyl methacrylate) (PMMA) and BCP/polyvinylpyrrolidone (PVP) as hole-blocking and electron-transporting interfacial layers. The architecture of the PVSCs was indium tin oxide/poly(3,4-ethylenedioxythiophene):polystyrenesulfonate/MAPbI3/[6,6]-phenyl-C61-butyric acid methyl ester/BCP based interfacial layer/Ag. The presence of PMMA and PVP affected the morphological stability of the BCP and MAPbI3 layers. The storage-stability of the BCP/PMMA-based PVSCs was enhanced significantly relative to that of the corresponding unmodified BCP-based PVSC. Moreover, the PV performance of the BCP/PVP-based PVSCs was enhanced when compared with that of the unmodified BCP-based PVSC. Thus, incorporating hydrophobic polymers into BCP-based hole-blocking/electron-transporting interfacial layers can improve the PV performance and storage stability of PVSCs.

Hollow three-dimensional graphene reinforced with poly (methyl methacrylate) for selective absorption of oil

Removal of oil from water through absorbent materials such as graphene proves to be an excellent technique due to its simplicity and recoverability. However, there are several issues encountered such as poor structural integrity and complexity of the fabrication process. In this study, the hollow three-dimensional graphene (H3DG) grown using chemical vapor deposition technique is strengthened by infusing poly(methyl methacrylate) (PMMA) for structural robustness and better recovery process. The overall porous nature of the H3TG and the gaps created within the graphene layers after the nickel etching provides an excellent absorption capacity of up to 48.132 g g−1. Besides, the polymeric reinforcement gives additional flexibility and improved mechanical properties such as reduced elastic modulus and ultimate tensile strength at 452.41 MPa and 19.05 kPa, respectively, as compared to the standalone H3TG. The presence of PMMA is also advantageous as the absorbed oil is recoverable by compression and reused with only 3.616% reduction in oil absorption performance after 10 cycles.

Inducing β phase crystallinity of PVDF homopolymer, blends and block copolymers by anti-solvent crystallization

In this contribution the anti-solvent crystallization of poly(vinylidene fluoride) (PVDF) as well as its blends and block copolymers with poly(methyl methacrylate) (PMMA) is considered. The impact of precipitation conditions such as solvent, precipitant, and its additives on the type of the PVDF crystalline phase is shown. Special attention is paid to the fraction of β crystalline phase in the material. Generally, increased ion concentrations result in higher β phase contents. With sufficient amounts of CaCl2, LiCl, and HCl in methanol almost only the β crystalline phase of PVDF is obtained. The presence of PMMA is not necessarily required for β phase formation.

Highly efficient indoor light quasi-solid-state dye sensitized solar cells using cobalt polyethylene oxide-based printable electrolytes

High-performance printable electrolytes (PEs) containing Co+2/Co+3 or I−/I3− redox-couple are prepared to fabricate quasi-solid-state (QS) dye-sensitized solar cells (QS-DSSCs) for room light environment applications. Polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA) are utilized to prepare PEs. Various parameters are regulated to obtain the optimal power conversion efficiencies (PCEs). For the I−/I3− system, the QS-DSSCs using PEO and PEO/PMMA PEs achieve nearly identical PCEs (16.32% and 16.40%, respectively) under the optimal conditions. However, the PCEs obtained for the Co+2/Co+3 system are markedly higher and the cell using PEO PE has a higher PCE (21.06%) than that using PEO/PMMA (18.14%). This difference is ascribed to the different composition of Li+ and Co+3 around the photoelectrode. The presence of Li+ around the interface will repel Co+3 away from the interface, decreasing the recombination of excited electrons to Co+3. According to the molecular structure, PMMA has more lone pair electrons to coordinate with Li+ ions, which will decrease the concentration of free Li+ more significantly than does by PEO. Therefore, the presence of PMMA will decrease and increase, respectively, the Li+ and Co+3 concentrations at the photoelectrode/electrolyte interface, resulting in more significant recombination of electrons to the Co+3. Consequently, the PCE of the PEO/PMMA cell is lower than that of the PEO cell. This effect doesn’t occur in I−/I3− system because the concentration variation of negatively charged ions did not affect significantly the electrons recombination at the interfacial. By using this cobalt PE, a bifacial QS-DSSC can achieve PCEs of 17.22% and 14.25%, respectively, under front-side and back-side illumination by 200 lx T5 light. A sub-module QS-DSSC using the cobalt PE can attain a PCE of 12.56%.

Phase structure and electrical and mechanical properties of PLLA/ionic conductive polyether blends prepared by melt mixing

Poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) is known as an ionic conductive polymer and exhibits ionic conductivity when it forms a complex with a metal salt. In this study, poly(L-lactic acid) (PLLA)/POEGMA/poly(methyl methacrylate) (PMMA) blends were manufactured to develop high-performance polymer materials that exhibit high mechanical moduli (>1 GPa) and ionic conductivities in the semiconductive region (1.0 × 10 −9–1.0 × 10−7 cm−1) at room temperature. In addition, crystallized blends were prepared by annealing the amorphous blends and were subsequently evaluated. By mixing PLLA and the compound consisting of POEGMA and PMMA using a two-roll mill, a blend with a maximum ionic conductivity of ~1.1 × 10–7 S cm−1 was obtained. The scanning electron microscopy results indicated that the ionic conductive phases were finely dispersed within the blends. By comparing the storage modulus values of the crystallized blends to those of amorphous blends, we found that the crystallized blends were harder at approximately the glass transition temperature of PLLA. We prepared ionic conductive compound (ICC) by solution casting and the in situ polymerization of poly(ethylene glycol) methyl ether methacrylate (OEGMA) in the presence of PMMA and a cross-linking agent. Then, ionic conductive polymer blends was obtained by melt-mixing ICC and poly(L-lactic acid) (PLLA). We studied the relationship between phase structure and physical properties such as electrical and mechanical properties of the blends.

Poly(methyl methacrylate) embedded perovskite films for improving solar cell performance

Semi-transparent photovoltaics are promising technologies to be applied for building-integrated elements and alternative windows. Notably, organometallic halide perovskite solar cells that have shown unprecedented power conversion efficiencies (PCEs) are highly attractive for integration as solar windows in buildings because of its low-cost manufacturing and tunable transparency in the visible regime. Here, we demonstrate an approach to fabricate void-passivated transparent perovskite films by utilizing a poly(methyl methacrylate) (PMMA) as a framework for crystal growth. The semitransparent perovskite film (average visible transmittance, AVT of ˜ 35.2%) is prepared from PbICl layer assisting sequential inter-diffusion process in which PMMA (PMMA dissolved in chlorobenzene) is added into CH3NH3I (MAI) solution. The presence of PMMA in perovskite films have a negligible effect on transparency, and the coverage and crystallinity of perovskite films are improved. Intensity-modulated photocurrent spectroscopy (IMPS) and time-correlated single photon counting (TCSPC) characterization further demonstrate that the PMMA embedded perovskite films have better carrier transport and enhanced carrier extraction rate. The semitransparent perovskite film based photovoltaic device with PMMA presents 15.46% efficiency with less hysteresis, which is mainly attributed to increased Jsc.

Effect of dielectric and conductive targets on plasma jet behaviour and thin film properties

A double layer DBD plasma jet driven by a pulsed generator is used for SiOx thin film deposition. The effects of dielectric and conductive targets on discharge behavior and film properties are analyzed. Different fraction of N2 is added to the working gas (argon) to modulate film growth rate. The electrical property and optical emission of the plasma jet at different positions are characterized. Film surface morphology, composition and thickness are measured for different targets. The excitation temperature (Texc), vibrational temperature (Tvib) and rotational temperature (Trot) are calculated. The relationship between the discharge behavior and the film properties is studied. Results show that the relative optical emission intensities of Si, O, Ar and N2, as well as Texc, Tvib and Trot are higher for the PMMA target between the high voltage electrode and the grounded electrode (referred to as the H–G region). However, Tvib and Trot appear to be higher on the surface of the copper (conductive) target. The morphology of SiOx film is different: nanoparticles are formed on the PMMA (dielectric) target while dense amorphous film is formed on the copper target. With the same depositing parameters, the thickness of the SiOx film is higher on the copper target. The presence of PMMA at the downstream of the plasma can be considered as a small capacitor with a large resistance, which inhibits the current into the primary circuit passing through the H–G region. Although the presence of a dielectric target enhances the discharge in the H–G region, the charge accumulation on the PMMA surface limits the film growth. These results may contribute to the development of next-generation plasma surface modification technologies for diverse applications in electronics, material synthesis and other related areas.

Chemical and physical effects of processing environment on simultaneous single crystallization of biodegradable poly(ε-caprolactone) and poly(l-lactide) brushes and poly(ethylene glycol) substrate

Through growth of poly(ethylene glycol) (PEG)-b-poly(ε-caprolactone) (PCL) and PEG-b-poly(l-lactide) (PLLA) single crystals from dilute solution, the crystallization of crystallizable PCL and PLLA brushes in homo and mixed-brush nanostructures was investigated. Using various graftings, the physical and chemical environmental effects were studied on the brush crystallization. The brush interactions were investigated as chemical environmental effects. The physical environmental effect was also determined by the amorphism/crystallinity and rigidity/flexibility of neighboring brushes. For this purpose, different single crystals were designed with mixed-brushes of amorphous-crystalline (polystyrene (PS), poly(methyl methacrylate) (PMMA), PCL and PLLA), double crystalline (PCL/PLLA), and rod-crystalline polyaniline (PANI)/PCL or PLLA. The type of surrounding brushes and their miscibility with crystallizable brushes, inherent amorphism or crystallinity, and flexibility or rigidity were effective on the behavior of crystallizable brushes and induced crystallization procedure. The neighboring brushes could also prevent the PLLA grafts from crystallization in the presence of PMMA.

Properties and phase structure of melt-processed PLA/PMMA blends

This study examines the rheological, mechanical and thermal behavior of Poly(lactic acid)/Poly(methyl methacrylate) (PLA/PMMA) blends and takes a look at the phase structure evolution during their melt processing. Semi-crystalline or amorphous PLA grades were combined with PMMA of different molecular weight to prepare the blends. The rheological properties and phase structure was first assessed using small-amplitude oscillatory shear experiments. The blends were injection molded into bars and characterized in terms of their tensile properties and of their dynamic mechanical behavior. Differential scanning calorimetry was also used to study the miscibility and crystallization behavior of prepared blends. Tensile properties of the blends nearly followed a linear mixing rule with no detrimental effect that could have been associated with an uncompatibilized interface. However, dynamic mechanical analysis and calorimetric experiments showed that some phase separation was present in the molded parts. Nevertheless, a single Tg was found if sufficient time was given in quiescent conditions to achieve miscibility. The Gordon-Taylor equation was used to assess the polymer interactions, suggesting that miscibility is the thermodynamically stable state. The ability of PLA to crystallize was strongly restricted by the presence of PMMA and little or no crystallinity development was possible in the blends with more than 30% of PMMA. Results showed an interesting potential of these blends from an application point of view, whether they are phase separated or not.

Hydrolytic stability of polylactide and poly(methyl methacrylate) blends

ABSTRACTThe hydrolytic stability of polylactide/poly(methyl methacrylate) (PLA/PMMA) blends prepared using a twin‐screw extrusion process was investigated. The effects of hydrolysis were monitored in neutral and alkaline media at 80 °C by tracking the changes in molecular weight distribution, weight loss, water uptake, and crystallization behavior. The crystallinity of PLA in blends prior to hydrolysis was shown to be largely hindered by the presence of PMMA. However, PLA recrystallized rapidly during hydrolysis. The PMMA in the blends was shown to provide increased hydrolytic and structural stability to the blends. In the neutral medium, the presence of PMMA delayed and reduced the weight loss but did not significantly affect PLA degradation kinetics. On the other hand, in the alkaline medium, the weight loss rate was strongly decreased in presence of PMMA and the kinetics of degradation was shown to be depend on PMMA content. The microstructure of these blends throughout the hydrolysis process was also examined by scanning electron microscopy. A porous structure, with interconnected pores in the 20–50 nm range, was developed due to the selective removal of PLA. Based on these morphological observations, erosion mechanism of PLA/PMMA blends was discussed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45991.

Bioactive nanocomposites for dental application obtained by reactive suspension method

Hydroxyapatite (HA) filled poly(methyl methacrylate)/poly(hydroxyethyl methacrylate) (PMMA/PHEMA) blends were prepared by reactive suspension method: HA was synthesized by co-precipitation process directly within a HEMA solution and the so-obtained suspension was polymerized in the presence of PMMA. HA particles were obtained in form of nanorods with a length of 50–200 nm and a diameter of 10–30 nm. A significant increase in glass transition temperature was observed in the nanocomposites with respect to the unfilled polymer blends. Dynamic-mechanical thermal analysis showed a significant increase in the storage modulus in the nanocomposites measured in the rubbery region. This increase was unpredicted by Mooney’s predictive equation and was attributed to the presence of cross-linking points due to the in situ generated HA particles. An increase in the elastic modulus was also observed at room temperature in compression and three-point bending tests. The presence of HA in the polymer blends resulted in an important decrease in the water sorption values. The bioactivity of the nanocomposites was verified by the precipitation of HA layer on the surface after soaking in simulated body fluid.

Graphene-based Test Platform in Potential Application for FET with Guanine as Gate Dielectric

Guanine and poly(methyl methacrylate) (PMMA) layers 60 nm thick were fabricated by physical vapor deposition and spin-coating, respectively, for potential application as bio-based field-effect transistors. A few layers of graphene on a variety of non-flexible and flexible supports were used as substrates for the guanine and PMMA layers. The interactions between these layers and graphene were studied and their effects on the electrical properties of the graphene were monitored over an extended period of time. Guanine had no noticeable effects on the transport properties of graphene. The presence of PMMA reduced the charge-carrier mobility of graphene by up to 42%. This combination has potential for use as a device in biosensors, environmental science, computer-processing, and graphene-based electronics.

Thermal and dynamic mechanical properties of grafted kenaf filled poly (vinyl chloride)/ethylene vinyl acetate composites

The effects of kenaf and poly (methyl methacrylate grafted kenaf on the thermal and dynamic mechanical properties of poly (vinyl chloride), PVC and ethylene vinyl acetate, EVA blends were investigated. The PVC/EVA/kenaf composites were prepared by mixing the grafted and ungrafted kenaf fiber and PVC/EVA blend using HAAKE Rheomixer at a temperature of 150°C and the rotor speed at 50rpm for 20min. The composites were subjected to Differential Scanning Calorimetric (DSC), Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), Fourier transform infrared (FTIR) and Scanning Electron Microscopy (SEM) studies. The DSC data revealed that the crystallinity of the EVA decreased with the addition of 30% grafted and ungrafted kenaf fibers. TGA and derivative thermogravimetric (DTG) curves displayed an increase in the thermal stability of the composites upon grafting of the fiber. Studies on DMA indicate that the Tg of the PVC and EVA in the PVC/EVA/kenaf composites has been shifted to higher temperature with the addition of the kenaf fiber. The presence of PMMA on the surface of grafted kenaf fiber was further confirmed by the analytical results from FTIR. The morphology of fractured surfaces of the composites, which was examined by a scanning electron microscope, showed the adhesion between the kenaf fiber and the PVC/EVA matrix was improved upon grafting of the kenaf fiber.

Effects of various polymer brushes on the crystallization of poly(ethylene glycol) in poly(ethylene glycol)-b-polystyrene and poly(ethylene glycol)-b-poly(methyl methacrylate) single crystals

The effects of PS and PMMA brushes on the crystallization of PEG in poly(ethylene glycol)-block-polystyrene (PEG-b-PS) and poly(ethylene glycol)-block-poly(methyl methacrylate) (PEG-b-PMMA) single crystals that have the same crystalline block molecular weight but different amorphous block molecular weights were investigated. The quality of the solvent (amyl acetate) employed and the interaction of the single-crystal substrate with the brush were found to influence the conformations of the PS and PMMA brushes, leading to more extended and packed pancake conformations, respectively. For PS and PMMA brushes with similar features, the conformation of the PMMA brushes led to a higher osmotic pressure on the substrate, so the substrate thickness was found to be significantly less than that seen when PS brushes were used. Even when the molecular weight of PMMA (M n = 8,700 g/mol) is considerably lower than that of PS (M n = 14,800 g/mol), the substrate in the presence of PMMA is thinner than that in the presence of PS (3.65 vs. 4.14 nm). Moreover, because there is less entropic repulsion between PS brushes than between PMMA brushes, the thickening of the substrate chains beneath them was more conspicuous when the crystallization temperature was increased.

In-Situ Incorporation of Poly(methyl methacrylate) in Suspension Styrene Polymerizations

Blends of poly(styrene)/poly(methyl methacrylate) (PS/PMMA) are produced in situ during suspension polymerizations of styrene performed in the presence of PMMA. The effects caused by the in situ incorporation of PMMA on the kinetic behavior of the reaction and on the molar mass distributions (MMD) and particle size distributions (PSD) of the obtained PS/PMMA polymer particles are evaluated. It is shown that the PMMA content can lead to significant changes of the initial viscosity of the reaction medium, also leading to significant changes of styrene conversions during the reaction course. Besides, addition of PMMA can cause an increase of the average molar masses and average particles sizes of the obtained polymer beads, also leading to broadening of the MMD and PSD of the final resin.

Effect of methyl methacrylate grafted kenaf on mechanical properties of polyvinyl chloride/ethylene vinyl acetate composites

In this work, the effect of grafted and ungrafted kenaf fiber on tensile, flexural, impact and hardness properties of polyvinyl chloride/ethylene vinyl acetate composites were studied. Grafted fibers were obtained from graft copolymerization reaction where methyl methacrylate was used as a monomer. The fiber loadings were varied from 0% to 30%. The addition of kenaf fiber had caused a decline in the impact and tensile strength of the PVC/EVA composite. Results revealed that the presence of PMMA on the surface of kenaf fiber has further enhanced the efficiency of stress transfer from the matrix to the fiber grafting thus improved the interfacial adhesion between the fiber and PVC/EVA matrix.

Preparation and characterization of a poly(methyl methacrylate) based composite bone cement containing poly(acrylate‐co‐silane) modified hydroxyapatite nanoparticles

ABSTRACTThe purpose of this study was to study the mechanical properties of poly(methyl methacrylate) (PMMA)‐based bone cement incorporated with hydroxyapatite (HA) nanoparticles after surface modification by poly(methyl methacrylate‐co‐γ‐methacryloxypropyl timethoxysilane) [P(MMA‐co‐MPS)]. PMMA and P(MMA‐co‐MPS) were synthesized via free‐radical polymerization. P(MMA‐co‐MPS)‐modified hydroxyapatite (m‐HA) was prepared via a dehydration process between silane and HA; the bone cement was then prepared via the in situ free‐radical polymerization of methyl methacrylate in the presence of PMMA and P(MMA‐co‐MPS)–m‐HA. Fourier transform infrared (FTIR) spectroscopy, 1H‐NMR, and gel permeation chromatography were used to characterize the P(MMA‐co‐MPS). Thermogravimetric analysis and FTIR were used as quantitative analysis methods to measure the content of P(MMA‐co‐MPS) on the surface of HA. The effect of the proportion of m‐HA in the PMMA‐based bone cement on the mechanical properties was studied with a universal material testing machine. A 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay was also carried out to determine the cytotoxicity of the composite bone cement. The results showed that the surface modification of HA greatly improved the interaction between the inorganic and organic interfaces; this enhanced the mechanical properties of bone cement for potential clinical applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40587.

Binary and ternary nanocomposites based on PVDF, PMMA, and PVDF/PMMA blends: polymorphism, thermal, and rheological properties

Binary and ternary nanocomposites based on poly(vinylidene fluoride) (PVDF), poly(methyl methacrylate) (PMMA), and PVDF/PMMA blends were successfully prepared through a melt-mixing process, using a commercial organoclay (15A) as the nanofiller. The 15A was more finely dispersed (intercalated/partially exfoliated) within the PVDF matrix compared with the PMMA matrix. A higher PVDF content in the ternary composite essentially led to a superior degree of 15A dispersion. The 15A addition induced the polar β-form PVDF crystals, whereas the presence of PMMA in ternary composites reduced the efficiency in promoting β-form formation by 15A. Adding 15A also enhanced the nucleation of PVDF, but the enhancement was inferior while PMMA was present. Conversely, the crystal growth of PVDF was retarded with the existence of 15A, and the PVDF/15A binary composite exhibited the greatest retardation. The equilibrium melting temperature (Tm°) of PVDF in the neat state and in the blends increased after 15A addition. The PVDF/15A binary composite possessed an evidently higher β-form Tm° than the α-form Tm° of neat PVDF (~20.1 °C rise). Similar effects on the individual components, 15A declined the thermal stability of PVDF but increased that of PMMA in the ternary composites. Rheological property measurements revealed that the ternary composites performed in-between that of individual PVDF/15A and PMMA/15A binary composites. A percolation of 15A (pseudo)network structure was developed in the composites, and a more elastic behavior was observed with increasing PVDF content in the composites.