Increasing PMMA Content Research Articles

Development of poly(methyl methacrylate)/poly(lactic acid) blend as sustainable biomaterial for dental applications

Poly(lactic acid) (PLA) is gaining popularity in manufacturing due to environmental concerns. When comparing to poly(methyl methacrylate) (PMMA), PLA exhibits low melting and glass transition temperature (Tg). To enhance the properties of these polymers, a PMMA/PLA blend has been introduced. This study aimed to investigate the optimal ratio of PMMA/PLA blends for potential dental applications based on their mechanical properties, physical properties, and biocompatibility. The PMMA/PLA blends were manufactured by melting and mixing using twin screw extruder and prepared into thermoplastic polymer beads. The specimens of neat PMMA (M100), three different ratios of PMMA/PLA blends (M75, M50, and M25), and neat PLA (M0) were fabricated with injection molding technique. The neat polymers and polymer blends were investigated in terms of flexural properties, Tg, miscibility, residual monomer, water sorption, water solubility, degradation, and biocompatibility. The data was statistically analyzed. The results indicated that Tg of PMMA/PLA blends was increased with increasing PMMA content. PMMA/PLA blends were miscible in all composition ratios. The flexural properties of polymer blends were superior to those of neat PMMA and neat PLA. The biocompatibility was not different among different composition ratios. Additionally, the other parameters of PMMA/PLA blends were improved as the PMMA ratio decreased. Thus, the optimum ratio of PMMA/PLA blends have the potential to serve as novel sustainable biomaterial for extensive dental applications.

Electrochemical investigation of gel polymer electrolytes based on poly(methyl methacrylate) and dimethylacetamide for application in Li-ion batteries

In the present work, gel polymer electrolytes (GPEs) were prepared using poly(methyl methacrylate) (PMMA), lithium perchlorate (LiClO4) and dimethylacetamide as a plasticizer. Solution-casting technique was used to fabricate GPEs containing different weight percentage of PMMA. The degree of crystallinity of GPE samples was studied by X-ray diffraction (XRD) analysis. Fourier transform infrared (FT-IR) spectroscopy was applied to study the level of interactions between lithium salt and PMMA in the prepared GPEs. Electrochemical properties were studied by electrochemical impedance spectroscopy, linear sweep voltammetry and DC polarization techniques. Lithium ion conductivity of GPEs was determined by calculating the bulk resistance of polymer electrolytes from Nyquist plot. Increasing PMMA content of GPEs resulted in an improvement in the electrochemical potential window from 4.2 to 4.5 V. The highest lithium transference number (0.42) and also the best electrochemical properties were obtained for GPE containing 0.75 M LiClO4 and 10 wt% PMMA. Scanning electron microscopy images of the optimized GPE showed a porous and heterogeneous surface structure which is desirable for application in Li-ion batteries.

Pyroelectric performance of porous Ba0.85Sr0.15TiO3 ceramics

AbstractPorous Ba0.85Sr0.15TiO3 (BST) ferroelectric ceramics were synthesized by sintering compacts consisting of BST and Poly(methyl methacrylate) (PMMA) (2%, 4%, 6%, 8%, and 10% by wt.) as pore‐forming agent. Systematic investigation of role of porosity on microstructural, dielectric, and pyroelectric performance is carried out. It is observed that as PMMA increased from 0% to 10%, the porosity increased from 7.5% to 29.5%. Dielectric constant decreases and dielectric loss increases with increasing PMMA content at fixed frequency. When porosity reached 29.5%, the relative dielectric constant of the BST composition decreased by more than 78% (from 3500 to 750) at 10 kHz and 300 K. Porosity leads to a significant reduction in dielectric constant and volume‐specific heat capacity, which are of great interest for improving pyroelectric figure of merits (FOMs). Further, the pyroelectric figure of merits for current responsivity (Fi), voltage responsivity (Fv), detectivity (Fd), and energy harvesting (Fe and Fe*) are calculated for all investigated compositions. Compared with dense ceramic, porous BST (10% PMMA) showed an improvement of Fd by 19%, Fe by 61%, and Fe* by 98%. Fv increased by 210% at 300 K/10 kHz. All of these advancements are favorable for the development of pyroelectric devices.

Enhanced pyroelectric figure of merits of porous BaSn0.05Ti0.95O3 ceramics

Porous BaSn0.05Ti0.95O3 (BTS) ceramics were prepared by sintering compacts consisting of BTS and Poly (methyl methacrylate)(PMMA)as pore former. Porous BTS ceramics were systematically characterized for microstructural, ferroelectric, dielectric and pyroelectric properties. Porosity increased from 4% to 22.5% with increasing PMMA content. Dielectric constant decreases and loss increases with porosity. At 22.5% porosity, relative dielectric constant of BTS decreased by 47% (from 2525 to 1335) at 1MHz/303K. Porosity leads to significant reduction in dielectric constant and volume specific heat capacity, which are of great interest for improving pyroelectric figure of merits (FOMs). Further, FOMs for current responsivity (Fi), voltage responsivity (Fv), detectivity (Fd) and energy harvesting (Fe and Fe*) are calculated. Compared with dense ceramic, 2% PMMA specimen showed an improvement of Fe by 166% and Fe*by 177%. Fv increased by 77%, Fd by 73% and Fi by 56% at 303K. All of these advancements are favorable for pyroelectric device applications.

Critical Insights into the Effect of Shear, Shear History, and the Concentration of a Diluent on the Polymorphism in Poly(vinylidene fluoride)

The effect of shear, shear history, and addition of poly(methyl methacrylate) (PMMA) in inducing the β-polymorph in poly(vinylidene fluoride) (PVDF) was investigated systematically for melt-mixed PVDF/PMMA blends. Various techniques such as polarized optical microscopy (POM) coupled to a hot stage and a shear cell, Fourier transform infrared spectroscopy (FTIR), differential thermal analysis, melt-rheology, and dielectric relaxation spectroscopy were used to gain a mechanistic insight for the observed polymorphism in PVDF. Different PVDF rich blends were prepared by melt-mixing and were subjected to different shear histories on a rheometer, and the induction time was monitored with respect to PMMA content and the applied shear flow in the blends. The rheological measurements revealed that the induction time was significantly lower for blends with a higher PVDF content (≥80 wt %), which was ascribed to the diluent effect of PMMA that restricts the chain mobility of PVDF and a longer time is required to start the crystallization process. The crystalline morphology observed from POM demonstrates that the growth rate of spherulites was greatly reduced with increasing PMMA content in the blends. FTIR results were used to determine the amount of β phase in the blends before and after the shear history. The blends that were sheared at high temperature (220 °C) showed more β phase than the blends that were sheared around the crystallization temperature. This study clearly demonstrates the fact that shear, shear history, and the content of PMMA significantly influence the conformational change that results in phase transformation in PVDF. Further, this study will help guide researchers working on various aspects of polymer processing where the effect of blending and shear on polymorphism is very important.

Nanostructure and morphology of poly(vinylidene fluoride)/polymethyl (methacrylate)/clay nanocomposites: correlation to micromechanical properties

Nanocomposites based on poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) with untreated clay were prepared in one step by reactive melt extrusion. Chemical reactions took place between the polymer matrices, the inorganic clay particles, and three reactive agents, leading to the PVDF/PMMA/clay nanocomposites. The microstructure characterizations were carried out by differential scanning calorimetry and wide-angle X-ray scattering (WAXS). The mechanical behavior was investigated by tensile experiments, impact tests, and microhardness measurements. The morphological characterization was carried out by optical and atomic force microscopy (AFM). The decrease of the melting and crystallization temperatures of the PVDF with the increasing PMMA content is attributed to the interactions between the oxygen of the PMMA carbonyl group and the PVDF’s hydrogen atom. WAXS analysis shows that there is neither an intercalation step nor total exfoliation in any composition. As the PMMA content increases, WAXS diagrams show either the PVDF α-crystallographic form, both, α- and β-forms, or only the β-form. For PMMA contents higher than 40 wt%, the materials became amorphous. The microhardness of the samples decrease for a PMMA content up to 20 wt%. The study by optical microscopy and AFM illustrates the significant effect in the presence of clay on the film’s surface morphology.

Exploring the relationship of dielectric relaxation behavior and discharge efficiency of P(VDF-HFP)/PMMA blends by dielectric spectroscopy

The dielectric relaxations in P(VDF-HFP)/PMMA blends were investigated by dielectric relaxation spectroscopy. Various dielectric relaxation and their molecular mechanisms of P(VDF-HFP), PMMA, and P(VDF-HFP)/PMMA composite films were analyzed. According to the fitted data of the Havriliak–Negami (HN) function, all relaxation processes belong to non-debye relaxation, the activation energy (Ea), relaxation time (τHN) and dielectric relaxation strength (Δϵ) of P(VDF-HFP)/PMMA blends significantly decreased around and below room temperature with increasing PMMA content. But, the results of αc relaxation are opposite. In addition, the conductivities (σ) of P(VDF-HFP)/PMMA composite films also sharply decreased with the addition of PMMA. Thus, the high discharge energy density and efficiency of dielectric materials closely related with the lower Ea, τHN, Δϵ and σ.

Investigation of the dielectric relaxation, conductivity and energy storage properties for biaxially oriented poly(vinylidene fluoride-hexafluoropropylene)/poly(methyl methacrylate) composite films by dielectric relaxation spectroscopy

The dielectric relaxations in biaxially oriented P(VDF-HFP)/PMMA composite films with less than 40 % PMMA were investigated using dielectric relaxation spectroscopy. Various relaxation processes and their locations of P(VDF-HFP), PMMA, and P(VDF-HFP)/PMMA composite films were analyzed. According to the fitted data of the Havriliak–Negami (HN) function, different relaxation processes belong to non-debye relaxation, the activation energy (Ea) and dielectric relaxation strength (∆e) of P(VDF-HFP)/PMMA composite films significantly decreased around and above glass transition temperature (Tg) with increasing PMMA content. In addition, the conductivities (σ) of P(VDF-HFP)/PMMA composite films also sharply decreased with the addition of PMMA. The decrease of dielectric relaxation strength (∆e) benefits the drop of Pr, lower the activation energy (Ea) makes coercive field decrease and the lower conductivity (σ) could enhances the breakdown strength. Thus, dielectric film of high energy storage density and low loss was closely related with the lower Ea, ∆e and σ.

Enhancing the electrical conductivity of carbon black-filled immiscible polymer blends by tuning the morphology

Blends of carbon black (CB)-filled polystyrene (PS) and poly(methyl methacrylate) (PMMA) with different PS/PMMA ratios have been prepared by melt blending in order to obtain conductive polymer composites with a low electrical percolation threshold according to the concept of double percolation. The dependence of the electrical conductivity on the morphology of the composite was examined before and after annealing in the molten state. The electrical conductivity of the composites was highest when the PS and PMMA phases formed a co-continuous structure and CB particles were selectively located and percolated in the PS phase. PS/PMMA (30/70) blends exhibited the lowest electrical percolation threshold of 1.26vol% CB. A simple model is suggested to explain this effect. After annealing, the CB clearly affected the stabilization of the co-continuous structure. Moreover, the electrical conductivity increased after annealing and the percolation threshold decreased to below 1vol% CB regardless of PS content. The largest increase in electrical conductivity after annealing was found with PS/PMMA (70/30) blends filled with 1vol% CB. With increasing PMMA content, this effect became less pronounced. The different behaviors in the composites can be explained by dynamic percolation and decrease in continuity of the CB-filled PS phase induced by structure coarsening.

Solid heat-expandable polylactide-poly(methyl methacrylate) foam precursors prepared by immersion in liquid carbon dioxide

Solid heat-expandable foam precursors were prepared by impregnating melt-blended poly(d,l-lactide) (PDLLA)-poly(methyl methacrylate) (PMMA) blends with liquid carbon dioxide (CO2). The phase behavior of these blends was strongly dependent on the processing steps, but impregnation with liquid CO2 led to phase separation regardless of the prior thermomechanical history, and crystallization in blends containing a low-D grade of PDLLA suppressed subsequent expansion. On the other hand, blends containing nominally amorphous high-D PDLLA were found to be unstable with respect to expansion under ambient conditions when saturated with CO2. It was therefore necessary to reduce the overall CO2 content by allowing it to desorb partially at 10 °C immediately after impregnation. Under these conditions, the amorphous PDLLA-50 wt% PMMA precursors were stable at ambient temperature and pressure, and showed peak expansion ratios at significantly higher temperatures than pure PDLLA, thanks to the increase in effective glass transition temperature with increasing PMMA content. It was hence demonstrated that blending with PMMA may provide a convenient means of tailoring the process window for heat-expandable polylactide foams, as well as improved heat stability.

Synthesis and characterization of brush-like multigraft copolymers PnBA-g-PMMA by a combination of emulsion AGET ATRP and emulsion polymerization

In this paper, poly(n-butyl acrylate)-g-poly(methyl methacrylate) multigraft copolymers were synthesized by macromonomer technique and miniemulsion copolymerization. The PMMA macromonomers were obtained by an activator generated by electron transfer atom transfer radical polymerization (AGET ATRP) in emulsion system and subsequent allylation. Then the copolymerization of different macromonomers with nBA was carried out in miniemulsion system, obtaining multigraft copolymers with high molecular weight. The latex particles and distribution of emulsion AGET ATRP and miniemulsion copolymerization were characterized using laser light scattering. The molecular weight and polydispersity indices of macromonomers and multigraft copolymers were analyzed by gel permeation chromatography, and the number-average molecular weight range is 187,600–554,800g/mol for PnBA-g-PMMA copolymers. In addition, the structural characteristics of macromonomer and brush-like copolymers were determined by infrared spectra and 1H nuclear magnetic resonance spectroscopy. The thermal performance of brush-like copolymers were characterized by differential scanning calorimetry and thermogravimetric analysis. Atomic force microscopy results showed that the degree of microphase separation was varying with increasing PMMA content in PnBA-g-PMMA. The dynamic rheometer analysis revealed that multigraft copolymer with PMMA content of 31.4% exhibited good elastomeric properties to function as a TPE. These multigraft copolymers show a promising low cost and environmental friendly thermoplastic elastomer.

Dynamic rheology and dielectric relaxation of poly(vinylidene fluoride)/poly(methyl methacrylate) blends

Abstract The molecular relaxations in melt-extruded poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blends with less than 40 wt% PMMA were investigated using dynamic rheological measurement and broadband dielectric spectroscopy. According to dynamic rheology, the total chain entanglement density of the blend melts increased with adding PMMA, and the dissimilar chains were more likely to entangle with each other than similar ones. Furthermore, PMMA facilitated the relaxation process. The dielectric temperature spectra revealed strong structural heterogeneity in the semicrystalline blends whose αa and αc relaxations were accelerated by increasing PMMA content. The αa and αc relaxations were shown to follow the Vogel–Fulcher–Tamman and Arrhenius equations, which allows assigning their molecular origins clearly to amorphous PVDF interphase and the amorphous portions within the crystalline PVDF phase, respectively. However, there exist structural heterogeneities in amorphous PVDF/PMMA mixture phase associated to intermolecular entanglement between dissimilar chains, giving rise to one or two αm relaxations in the dielectric temperature spectra depending on the PMMA content.

Miscibility and crystallization behaviors of stereocomplex-type poly(l- and d-lactide)/poly(methyl methacrylate) blends

Stereocomplex-poly(l- and d-lactide) (sc-PLA) and poly(methyl methacrylate) (PMMA) blends were prepared by solution blending at PMMA loadings from 20 to 80 mass%. The miscibility and crystallization behaviors of the blends have been studied in detail by differential scanning calorimeter. The single-glass transition temperatures (T g) of the blends demonstrated that the obtained system was miscible in the amorphous state. It was observed that the crystallization peak temperature of sc-PLA/PMMA blends was marginally lower than that of neat sc-PLA at various cooling rates, indicating the dilution effect of PMMA on the sc-PLA component to restrain the overall crystallization process. In the study of isothermal crystallization kinetics, the reciprocal value of crystallization peak time ( $$ t_{\text{p}}^{ - 1} $$ ) decreased with increasing PMMA content, indicating that the addition of non-crystalline PMMA inhibited the isothermal crystallization of sc-PLA at an identical crystallization temperature (T c). Moreover, the negative value of Flory–Huggins interaction parameter (χ 12 = −0.16) of the blend further indicated that sc-PLA and PMMA formed miscible blends.

Characterization and water vapor sorption property of ABA-type triblock copolymers derived from polyimide and poly(methyl methacrylate)

The characterization of ABA-type triblock copolymer films derived from polyimide (PI) macroinitiator and poly(methyl methacrylate) (PMMA) synthesized by atom transfer radical polymerization was investigated by focusing on different block lengths of PMMA. The hydrophobic property tends to increase with increasing PMMA content in the triblock copolymers, while the PMMA blocks enhance the charge transfer interaction between the PI segments. The water vapor sorption measurement of triblock copolymers was determined at 35 °C. The water vapor solubility of triblock copolymers tends to decrease with increasing PMMA content. In addition, linear correlations were observed between the solubility and polymer-free volume and polymer molecular polarity in triblock copolymers as well as in other conventional polymer families. According to Zimm−Lundberg analysis, the PMMA block segments in the triblock copolymers accelerate water vapor clustering due to the high mobility of PMMA. The mobility of PMMA block segments strongly affected not only physical properties but also the water vapor solubility of the triblock copolymers. The ABA triblock copolymerization composed of PI and PMMA is one of the effective ways to improve the hydrophobic property. © 2013 Society of Chemical Industry

Ferroelectric Phase Diagram of PVDF:PMMA

We have investigated the ferroelectric phase diagram of poly(vinylidene fluoride) (PVDF) and poly(methyl methacrylate) (PMMA). The binary nonequilibrium temperature composition diagram was determined and melting of α- and β-phase PVDF was identified. Ferroelectric β-PVDF:PMMA blend films were made by melting, ice quenching, and subsequent annealing above the glass transition temperature of PMMA, close to the melting temperature of PVDF. Addition of PMMA suppresses the crystallization of PVDF and, as a consequence, the roughness of blend films was found to decrease with increasing PMMA content. Using time-dependent 2D numerical simulations based on a phase-field model, we qualitatively reproduced the effect of PMMA on the crystallization rate and the spherulite shape of PVDF. The remnant polarization scaled with the degree of crystallinity of PVDF. The thermal stability of the polarization is directly related to the Curie temperature. We show that, at high temperature, the commodity ferroelectric PVDF:PMMA blends outperform the commonly employed specialty copolymer poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)). © 2012 American Chemical Society.

Specific interactions in partially miscible polycarbonate (PC)/poly (methyl methacrylate) (PMMA) blends

Abstract Blends of bisphenol A polycarbonate and poly(methyl methacrylate) have been prepared by solution casting technique using tetrahydrofuran as a solvent. These blends are characterized using DSC, TGA, FT-IR and powder X-ray diffraction techniques. The differential scanning calorimetric and XRD results reveal large crystallinity in the solution cast PC and PC/PMMA blends which decreases with increasing PMMA content. Coherently scattering domain size, on the other hand, increases with increasing PMMA content. Our XRD results reveal that the strongest peak of PC shifts to lower 2 θ angles in the PC/PMMA blends indicating the presence of specific interactions between the PC and PMMA phases.

Graft copolymers of poly(methyl methacrylate) and polyamide-6 via in situ anionic polymerization of ε-caprolactam and their properties

Graft copolymers of poly(methyl methacrylate) and polyamide-6 (PMMA-g–PA6) were investigated via in situ anionic polymerization of e-caprolactam, using PMMA precursors with N-carbamated caprolactam pendants (PMMA–CCL) as macroactivators and sodium caprolactamate as catalyst. Three grades of PMMA–CCLs obtained by free radical copolymerization were used for synthesizing the PMMA-g–PA6 copolymers with different PMMA content. The resulting graft copolymer was characterized by Fourier-transform infrared spectroscopy and selective extraction. Scanning electron microscopy is used to clarify the phase morphology of obtained polymer by fracture surface. The thermal property, crystallinity and dimensional stability of graft copolymer were studied using differential scanning calorimetry, X-ray diffraction and water absorption measurement. The results show the Tg of graft copolymer is higher than that of neat PA6, but the onset and peak points of graft copolymer melting point are shifted to lower temperature. The percentage crystallinity and water absorption of PMMA-g–PA6 copolymer decrease with increasing PMMA content, but the crystal structure of PA6 is scarcely affected by the presence of PMMA. Graft copolymers have improved dimensional stabilities relative to neat PA6. Upon the incorporation of 19.9 wt% PMMA into PA6, the water absorption of PMMA-g–PA6 copolymer has been reduced from 4.8 for neat PA6 to 2.1%.

Interest of binary PMMA/P(VDF–TrFE) blend thin films

Thin films of binary amorphous PMMA–ferroelectric P(VDF–17 mol% TrFE) copolymer have been produced by spin-coating on Ti-covered silicon wafers. Thermal, structural, dielectric, ferroelectric and pyroelectric properties were investigated as a function of PMMA content up to 10 wt%. If functional properties slightly decrease with increasing PMMA content, both the adhesion of such binary-copolymer thin films on metal electrodes and the reliability of as-grown devices can be dramatically improved. 1–2 wt% PMMA-based binary blends appear as very promising alternative materials for pyroelectric applications.

Experimental Study on Physical Properties of PMMA Mortar Mixed with Reactive Additive

In this study, the physical properties of MMA-modified polymer mortar produced by mixing a reactive additive (RA) with multifunctional agent of PMMA were experimentally surveyed. The results of the experiments showed that increasing PMMA content reduced the flow, but the maximum flow was observed with the filler to binder ratio of 1.5. Additionally, the increase of initiator and promoter content shortened the working life of PMMA mortar. RA content did not exert a noticeable influence on setting shrinkage, while the appropriate PMMA content lessened the setting shrinkage. The compressive and flexural strength showed the maximum values when the filler to binder ratio was 1.5:1. Moreover, the compressive and flexural strength increased with increasing RA content. Adding RA expedited the hardening of the mortar to result in the manifestation of its strength 60% and 90% at two and six hour curing, respectively. The strength was hardly affected by the curing temperature as long as it was 0°C or above. Even when the curing temperature was -10°C, the strength of the mortar was about 70% of the strength of the mortar cured at normal temperature.

Effect of blend composition on the morphology development of electrospun fibres based on PAN/PMMA blends

AbstractBACKGROUND: The aim of the work presented was to determine the morphology development and relevant change in fibre diameter of a binary polymer blend system during an electrospinning process. The size of the fibre diameter is one of the important factors determining the general properties of non‐woven mats formed from electrospun fibres.RESULTS: The morphology and diameter of electrospun polyacrylonitrile (PAN)/poly(methyl methacrylate) (PMMA) blends were investigated as a function of blend ratio using scanning electron microscopy. The diameter of the electrospun PAN/PMMA fibres decreased with increasing PMMA content up to 50 wt%, and then increased again with further increase of PMMA. After thermal treatment, the fibres shrank, and an irregularly shaped morphology was observed.CONCLUSION: The electrospinning of incompatible PAN/PMMA blends leads to a microphase‐separation morphology of fibres. A phase inversion occurs at a PMMA content of between 50 and 75 wt%. Due to the phase inversion, the fibre diameter shows a minimum value at the relevant composition. Copyright © 2008 Society of Chemical Industry