Study on the modification effects of metal salt addition on the brittle–ductile transition of poly(methyl methacrylate)

Anchorage of the femoral head prosthesis to the shaft of the femur.

The ceric ion‐initiated graft copolymerization of methyl methacrylate onto wood cellulose was found to depend on the concentrations of initiator, monomer, and cellulose. The structure of cellulose—methyl methacrylate graft copolymers was studied by hydrolyzing away the cellulose backbone to isolate the grafted poly(methyl methacrylate) branches. The molecular weights and molecular weight distributions of the grafted poly(methyl methacrylate) were determined by using gel‐permeation chromatography. The number‐average (M̄n) molecular weights ranged from 36 000 to 160 000 and the polydispersity ratios (M̄w/M̄n) varied from 4.0 to 7.0. The grafting frequency or the number of poly(methyl methacrylate) branches per cellulose chain calculated from the per cent grafting and molecular weight data varied from 0.38 to 3.2. The structure of cellulose—methyl methacrylate graft copolymers and the effect of stepwise addition of initiator on the structure are discussed.

Effect of lithium salt concentrations on blended 49% poly(methyl methacrylate) grafted natural rubber and poly(methyl methacrylate) based solid polymer electrolyte

Background: The most common materials used for fabrication of denture bases are poly methyl methacrylate (PMMA). Fracture or debonding of plastic teeth from denture base are common clinical problems which are facing both the patient and the dentist. The aim of this study is to evaluate and compare the shear bond strength of acrylic resin artificial teeth treated by different chemical surface treatments (solvents like acetone & thinner) to the experimental prepared material and to the control material before and after thermocycling. Materials and methods: Preparation of modified heat cured denture base acrylic resin was carried out by preparing of (PMMA) (80%) and poly vinyl pyrrolidone (PVP) (20%) and the liquid part composed of methyl methacrylate (MMA) monomer. Control: poly methyl methacrylate (PMMA) + methyl methacrylate ( MMA ) as control group ( 2.5 : 1 ) by weight (1). Experimental: PMMA (80% ) + PVP ( 20% ) + MMA as experimental group ( 2.5 : 1 ) by weight. Sixty artificial acrylic teeth were prepared and cured by control and experimental denture base acrylic resin, then teeth were divided into three groups and treated with different surface treatment; first group received no further treatment (control), second group treated with acetone and third group treated with thinner. The denture teeth were flasked and wax was eliminated with running hot water. Denture resin was packed and cured according to manufacturer's instructions and specimens were deflasked upon the completion of resin processing. Then half of specimens from all surface treatments were tested by using Instron machine and subjected to shear force until failure. The other half of specimens which also include the surface treatments groups were thermocycled. Teeth surfaces after treatment and fracture sites were examined and photographed visually and under reflecting light microscope. Results: The results showed that all surface treatments produced significantly high improvement in shear bond strength (SBS). Control group had shown significantly lower (SBS) than experimental group bonded to artificial acrylic teeth. On the other hand, experimental denture base resin bonded to artificial acrylic teeth were affected more significantly by thermocycling than the same teeth bonded to control denture base resin. Results indicated that thinner treatment for acrylic teeth is recommended prior to denture base processing. Conclusion: higher SBS of artificial acrylic teeth bonded to experimental denture bases rather than to control denture bases.

The effect of oxygen addition to an argon plasma on the etching selectivity of poly(methyl methacrylate) (PMMA) to polystyrene (PS) (hereafter “PMMA/PS etching selectivity”) was investigated. The PMMA/PS etching selectivity was evaluated by using inductively coupled plasmas composed of argon and oxygen. The etching selectivity in the case of argon plasma was estimated to be 3.9, which is higher than that of oxygen plasma, which is 1.7. The time dependence of etching depth shows that the etching rate of PMMA is reduced to less than one half of its initial value after the etching depth exceeds 15 nm. X-ray photoelectron spectroscopy of the PMMA surface revealed that the reduction of etching rate is caused by a depletion of oxygen concentration by argon-ion bombardment. To compensate the oxygen-concentration depletion, 1% oxygen was added to the argon plasma. As a result, the reduction of PMMA etching rate was suppressed, and constant etching rate was obtained even when etching depth exceeded 50 nm. The mixed argon-oxygen plasma was used to fabricate a PS mask pattern with a full pitch in the range of 25.5 to 77 nm.

Potassium persulfate–thiourea redox couple has been employed to graft poly(methyl methacrylate) onto wool in the presence of air under different reaction conditions. Graft copolymers were characterized by scanning electron micrographs, thermogravimetry, etc. The effect of additives on graft copolymerization has been studied, and a suitable reaction mechanism has been proposed.

ESR spectra of γ-irradiated poly(methyl methacrylate) (PMMA) at 77°K and the effect of additives have been studied. γ-Irradiation of PMMA containing a small amount of 2-methyltetrahydrofuran as an additive at 77°K gives MTHF radical. Yields of MTHF radical increase with increasing MTHF concentration and reach a plateau value, and are independent of photobleaching with visible light. Yeilds of polymer radical are reduced by the addition of MTHF. Some elementary processes for the MTHF radical formation are proposed on the basis of the experimental results.

The effect of additives on the enhancement of methyl methacrylate grafting to cellulose in the presence of UV and ionising radiation

The preparation and characterization of blended solid polymer electrolyte 49% poly(methyl methacrylate)-grafted natural rubber (MG49):poly(methyl methacrylate) (PMMA) (30:70) were carried out. The effect of lithium tetrafluoroborate (LiBF4) concentration on the chemical interaction, structure, morphology, and room temperature conductivity of the electrolyte were investigated. The electrolyte samples with various weight percentages (wt.%) of LiBF4 salt were prepared by solution casting technique and characterized by Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy. Infrared analysis demonstrated that the interaction between lithium ions and oxygen atoms occurred at symmetrical stretching of carbonyl (C=O) (1,735 cm−1) and asymmetric deformation of (O–CH3) (1,456 cm−1) via the formation of coordinate bond on MMA structure in MG49 and PMMA. The reduction of MMA peaks intensity at the diffraction angle, 2θ of 29.5° and 39.5° was due to the increase in weight percent of LiBF4. The complexation occurred between the salt and polymer host had been confirmed by the XRD analysis. The semi-crystalline phase of polymer host was found to reduce with the increase in salt content and confirmed by XRD analysis. Morphological studies by SEM showed that MG49 blended with PMMA was compatible. The addition of salt into the blend has changed the topological order of the polymer host from dark surface to brighter surface. The SEM analyses supported the enhancement of conductivity with the addition of salt. The conductivity increased drastically from 2.0 to 3.4 × 10−5 S cm−1 with the addition of 25 wt.% of salt. The increase in the conductivity was due to the increasing of the number of charge carriers in the electrolyte. The conductivity obeys Arrhenius equation in higher temperature region from 333 to 373 K with the pre-exponential factor σ o of 1.21 × 10−7 S cm−1 and the activation energy E a of 0.46 eV. The conductivity is not Arrhenian in lower temperature region from 303 to 323 K.

6 - Advances in acrylic structural adhesives

A novel route to immobilize metalloporphyrins on polymeric supports was put forward, and it is the way to synchronously synthesize and immobilize porphyrins on polymeric microspheres, followed by metal salt coordination reaction. Copolymeric microspheres (GMA/MMA) of glycidyl methacrylate (GMA) and methyl methacrylate (MMA) were prepared, and then via the ring‐opening reaction of the epoxy groups on GMA/MMA microspheres, parahydroxybenzaldehyde (HBA) was bond onto the microspheres, obtaining the modified microspheres HBA‐GMA/MMA. Subsequently, the Adler reaction between solid‐liquid phases was carried out with HBA‐GMA/MMA microspheres and pyrrole as well as benzaldehyde derivate in a solution as coreactants. As a result, it was successfully realized to synchronously synthesize and immobilize porphyrin on the surfaces of GMA/MMA microspheres, resulting in three porphyrin‐immobilized microspheres, PP‐GMA/MMA (PP: phenyl porphyrin), CPP‐GMA/MMA (CPP: 4‐chlorophenyl porphyrin) and NPP‐GMA/MMA (NPP: 4‐nitrophenyl porphyrin). Further, the coordination reaction of these immobilized porphyrins with cobalt salt was conducted, obtaining three supported cobalt porphyrin catalysts, CoPP‐GMA/MMA, CoCPP‐GMA/MMA and CoNPP‐GMA/MMA. The catalytic properties of these supported mettaloporphyrin catalysts were examined in the catalytic oxidation of ethylbenzene to acetophenone by dioxygen. The experimental results indicate: (1) the prepared three solid catalysts are effective in the catalytic oxidation of ethylbenzene to acetophenone by dioxygen; (2) for these polymer‐supported metalloporphyrin catalysts, some factors, such as the substitute species on phenyl ring in the macrocycle, the immobilization density of metalloporphyrin and the added amount of the catalyst in the reaction system, affect the catalytic activity greatly; (3) the prepared supported metalloporphyrin catalysts have fine recycle and reuse property. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

The surface of ultrahigh molecular weight polyethylene (UHMWPE) was modified by radiation-grafting methylmethacrylate (MMA) in the presence of sulfuric acid and metallic salt to increase bonding strength with polymethylmethacrylate. The effect of the addition of metallic salts and sulfuric acid on the radiation grafting reaction was investigated when MMA was grafted to the irradiated UHMWPE. The adhesive characteristics with the grafting yield were investigated using conventional acrylic bone cement based on poly(methyl methacrylate) [PMMA]. The results showed that the inclusion of an FeSO4 . 7H2O and sulfuric acid in MMA grafting solutions was extremely beneficial and led to a most unusual synergistic effect, while CuSO4 . 5H2O led to a detrimental effect. The tensile bonding strength between UHMWPE and PMMA sheet increased remarkably with an increased grafting yield on UHMWPE surfaces.

Vermiculite (VMT) as clay was introduced into a ternary polymer blend composed of poly(L‐lactic acid) (PLLA), poly(methyl methacrylate) (PMMA), and poly(ethylene oxide) (PEO), whose ternary miscibility was proven within low certain contents of PMMA and PEO in PLLA. VMT was incorporated to the ternary polymer blend as matrix after proper organic modification on the clay. The organically modified vermiculite (OVMT) shows good interaction and acceptable dispersion in the ternary polymer matrix without altering the crystal structures of PLLA/PEO constituents. The effect of OVMT addition was then analyzed in isothermal crystallization by using the Avrami kinetic analysis, and the addition of OVMT is evident in altering nucleation process of the polymer blend as well as the crystal perfection. The activation energy is much lowered by the addition of OVMT, as evident from the analysis; the overall crystallization kinetic rates are increased with the incorporation of OVMT. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

ABSTRACTThe study aims to produce poly(methyl methacrylate) (PMMA)‐based lower density syntactic foams with hollow glass microspheres (HGMs) and to improve their mechanical properties by the addition of polyhedral oligomeric silsesquioxanes (POSSs) while maintaining the thermal properties of the neat polymer. First to understand the effect of POSS addition, PMMA–POSS composites with octaisobutyl and octaphenyl POSS were produced through extrusion. Higher relative flexural and impact strengths were obtained with POSS addition to PMMA. Obtaining more enhanced properties with octaphenyl POSS, PMMA‐HGM‐POSS hybrid syntactic foams were prepared with this additive. In general, the specific flexural strength and modulus of the PMMA syntactic foams were improved with the POSS loading, while the lower density and thermal properties of the PMMA syntactic foams were maintained. PMMA hybrid syntactic foams with 15 wt % HGMs and 0.25 wt % POSS exhibited 37.6% improvement in the specific flexural modulus with respect to the neat PMMA. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48368.

Solid amine sorbents having adequate particle size with high CO2 adsorption capacity were successfully prepared using poly(ethylenimine) (PEI) as the amine and mesoporous poly(methyl methacrylate) (PMMA) beads as the support. The PEI-impregnated PMMA-supported sorbent exhibited CO2 adsorption capacity up to 4.26 mmol/g with PMMA-55 at 75 °C in pure CO2 gas flow. The effect of the temperature on the adsorption capacity of PMMA-55 was investigated, and the maximum adsorption capacity was obtained at 50 °C with a CO2 exposure time of 180 min, different from the tendency of most silica-supported sorbents. The effect of surfactant addition on the adsorption performance of PMMA-supported sorbents differed from those of silica-supported sorbents because of the different surface characteristics between PMMA and silica. Adsorption/desorption cycling was also performed to examine the suitability of the amine sorbent for potential application.