Suspension polymerization of poly(methyl methacrylate)/clay nanocomposites

Polymer/clay nanocomposites (PCNs) of poly(methyl methacrylate) and an organically modified clay, Cloisite 15a, were synthesized in situ with a suspension polymerization technique. The amount of clay present in the PCNs was varied to provide a better understanding of the effect of the clay on the properties of the polymer matrix. However, unexpectedly, we found that the concentration of clay had a dramatic impact on the molecular weight of the polymer matrix, and a relationship between the clay concentration and polymer molecular weight was determined. The PCNs were characterized with size exclusion chromatography (SEC), X‐ray diffraction, transmission electron microscopy, and oscillatory shear rheology. From oscillatory shear rheology, the full master curves for the PCNs were obtained by application of the time–temperature superposition principle. To enable the effect of the clay on the rheology to be quantified, the experimental data was compared to the time‐dependent diffusion model of des Cloizeaux for polydisperse polymer melts, which enabled the polydispersity to be incorporated through the use of the molecular weight distribution obtained via SEC. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Temperature-dependent interaction parameters of poly(methyl methacrylate)/poly(2-vinyl pyridine) and poly(methyl methacrylate)/poly(4-vinyl pyridine) pairs

Temperature-dependent interaction parameters (α) of poly(methyl methacrylate)/poly(2-vinyl pyridine) (PMMA/P2VP) pair and PMMA/poly(4-vinyl pyridine) (PMMA/P4VP) pair were obtained from the SAXS profiles at various temperatures, and curve fitting to the random phase approximation theory. For this purpose, symmetric P2VP-block-PMMA and P4VP-block-PMMA copolymers were synthesized anionically. The molecular weights of both block copolymers were controlled to exhibit the disordered state over the entire experimental temperatures. We found that the value of α for PMMA/P4VP was larger than PMMA/P2VP, similar to polystyrene (PS)/poly(vinyl pyridine) pairs. However, the difference between in α between PMMA/P2VP and PMMA/P4VP was much smaller than that between PS/P2VP and PS/P4VP. This might be attributed to the hydrophilic PMMA block compared with hydrophobic PS block. Finally, the order-to-disorder transition temperature for symmetric P2VP-block-PMMA copolymers was determined by small angle X-ray scattering and birefringence methods.     

Preparation and properties of poly(methyl methacrylate)/iron carbonate(p) nanocomposites

The mass transport of methanol mixed with ferric chloride hexahydrate (FeCl₃ · 6H₂O) in poly(methyl methacrylate) and poly(methyl methacrylate)/iron carbonate particulate_(p) nanocomposites is prepared by chemical vapor crystallization and the resulting materials, which are subjected to characterization to evaluate thermal and optical properties, have been investigated. Mass transport is an anomalous and endothermic process and satisfies the van't Hoff plot. We have prepared successfully poly(methyl methacrylate)(PMMA)/iron carbonate particulates nanocomposites using CO₂ gas slowly diffused into saturated solvent mixture‐treated poly(methyl methacrylate) for 48 h. After SEM observation, approximately 80 nm iron carbonate particulates were precipitated and evenly distributed in the poly(methyl methacrylate) matrix. In comparison with solvent mixture‐treated PMMA, the cut‐off wavelength of transmittance in nanocomposites shifts to the shorter wavelength side (red shift). The presence of nanoscale iron carbonate particulates increased the glass transition temperature of the nanocomposites as determined by differential scanning calorimeter, and the glass transition temperature increased with increasing content of nanoscale iron carbonate particulates. The FTIR spectra of solvent mixture‐treated poly(methyl methacrylate) and nanocomposites are also studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2329–2338, 2005     

Preparation and characterization of poly(methyl methacrylate)/reactive montmorillonite nanocomposites

The poly(methyl methacrylate) (PMMA)/reactive montmorillonite nanocomposites were prepared by emulsion polymerization. The double bonds were introduced to both the surfaces and interlayers of the montmorillonites to obtain the reactive montmorillonites. The structure of the nanocomposites measured by wide angle X‐ray diffraction (WAXD) indicated that the montmorillonites were exfoliated. The average molecular weight of the nanocomposites revealed by gel permeation chromatography (GPC) was larger than that of pure PMMA. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated that the thermal properties of the nanocomposites were enhanced and could be affected by the amount of the reactive montmorillonites. In addition, the tensile properties of the nanocomposites measured by an Instron testing machine improved and the nanocomposites including 3 wt% reactive montmorillonites showed the best tensile strength. The Young's modulus increased with the addition of the reactive montmorillonites. The aging properties of the nanocomposites had an improvement compared with pure PMMA. The optical properties assessed by UV‐Visible spectroscopy revealed that the transmittance decreased as the amount of the reactive montmorillonites increased. Finally, the mechanism to prepare PMMA/reactive montmorillonite nanocomposites was proposed. POLYM. COMPOS., 37:2396–2403, 2016. © 2015 Society of Plastics Engineers     

Synthesis and characteristics of poly(methyl methacrylate)/expanded graphite nanocomposites

In this work, we synthesized poly(methyl methacrylate) (PMMA)/expanded graphite (EG) nanocomposites by a new polymerization method. The volume electrical conductivity of the nanocomposite prepared by this way is very high (when the content of EG is about 8 wt %, the conductivity could reach 60 S/cm). The structure of the nanocomposite was investigated by SEM, TEM, IR, and XRD. And we found temperature and voltage were important parameters of governing the electrical conductivity of PMMA/EG nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1427–1431, 2006     

聚甲基丙烯酸甲酯/SiO2纳米复合物的制备

基于纳米SiO2表面羟基与γ-甲基丙烯酰氧基丙基三甲氧基硅烷间的缩合反应,于SiO2表面引入双键.以甲基丙烯酸甲酯为单体,偶氮二异丁腈为引发剂,采用原位自由基聚合的方法,制备了聚甲基丙烯酸甲酯/SiO2纳米复合材料.FTIR和TGA证实聚甲基丙烯酸甲酯大分子链成功接枝在SiO2表面.聚合体系黏度是影响SiO2表面聚甲基丙烯酸甲酯接枝率的关键因素.甲基丙烯酸甲酯浓度为6 mol/L,偶氮二异丁腈浓度为0.05～0.1 mmol/L时,SiO2表面聚甲基丙烯酸甲酯接枝率可达到94％;SiO2用量对表面接枝聚合没有影响.     

Mechanical property studies of poly(methyl methacrylate)-grafted viscose fibers

Graft copolymerization of methyl methacrylate (MMA) on viscose fibers (grade 1.5 × 51 mm; Nagda; grey staple; bright bleached) was studied under a photoactive condition with visible light using conventional Mohr's salt–potassium persulphate as the redox initiator. The mechanical properties of the grafted viscose fiber, such as tenacity, breaking extension, and initial modulus were studied. The effect of monomer–solvent combination on viscoelastic nature (elasticity work recovery and stress relaxation) of the grafted fibers have also been explained. The moisture regain characteristics of the grafted fibers were also studied. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2585–2591, 1998     

Synthesis and properties of poly(methyl methacrylate)/montmorillonite (PMMA/MMT) nanocomposites

PMMA/MMT nanocomposites were successfully synthesized via in situ intercalative polymerization, and characterized by means of wide‐angle X‐ray diffractometry, transmission electron microscopy, thermal gravimetric analysis, dynamic mechanical analysis and Fourier‐transform infrared analysis. The nanocomposites possess partially exfoliated and partially intercalated structure, in which the silicate layers are exfoliated into nanometre secondary particles with thickness of less than 20 nm and uniformly dispersed in the polymer matrix. In comparison with pure PMMA, the thermal stability, glass transition temperature, and mechanical properties of the polymer are notably improved by the presence of the nanometric silicate layers. It was found that part of the PMMA chains in the nanocomposites are well immobilized inside and/or onto the layered silicates and, therefore, the unique properties of the nanocomposites result from the strong interactions between the nanometric silicate layers and the polymer chains. Copyright © 2003 Society of Chemical Industry     

Thermal stability of poly(methyl methacrylate)

Summary The average solid-state molecular structures of end-groups generated through chain termination reactions in the polymerization of methyl methacrylate have been derived from published crystallographic data. Evidence is provided for the reduced stability of the head-head chain-termination configuration and in support of the postulate that it is a preferred site of chain scission. Comparable evidence for the unsaturated end group has not been found.     

Fabrication and apparent kinetic study of poly(methyl methacrylate)/poly(octyl acrylate) and poly(octyl acrylate)/poly(methyl methacrylate) latex interpenetrating polymer networks

Two latex interpenetrating polymer networks (LIPNs) were synthesized with methyl methacrylate (MMA) and octyl acrylate (OA) as monomers, respectively. The apparent kinetics of polymerization for the LIPNs was studied. This demonstrates that network II does not have a nucleus formation stage. The monomers of network II were diffused into the latex particles of network I and then formed network II by in situ polymerization. It indicates that the polymerization of network I obeys the classical kinetic rules of emulsion polymerization. But the polymerization of network II only appears a constant‐rate stage and a decreasing‐rate stage. The apparent activation energies (E_a) of network I and network II of PMMA/POA were calculated according to the Arrhenius equation. The E_a values of POA as network I (62 kJ/mol) is similar to that of POA as network II PMMA/POA (60 kJ/mol). However, the E_a value of PMMA as network II POA/PMMA (105kJ/mol) is higher than that of PMMA as network I (61 kJ/mol). Results show that the E_a value of the network II polymerization is related to the properties of its seed latex. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of traces of inorganic content on thermal stability of poly(methyl methacrylate) nanocomposites

Silica/titania binary inorganic component was synthesized by a nonhydrolytic sol‐gel method. Fourier transform infrared spectroscopy (FT‐IR) and transmission electron microscopy (TEM) results indicated that titania was stabilized by silica because of the formation of a connecting structure, which would greatly restrain the high aggregation tendency of titania nanoparticles. The thermal stabilities of the PMMA/silica/titania ternary nanocomposites were measured by thermo‐gravimetric analysis (TGA). Although the solvent extraction results confirmed that there were no covalent bond interactions between polymer and inorganic phases, the trace amount of stabilized titania improved the thermal and thermo‐oxidative stabilities of PMMA because titania/silica nanoparticles may have ability to trap the free radicals generated in the degradation of PMMA. POLYM. ENG. SCI., 47:302–307, 2007. © 2007 Society of Plastics Engineers.     

Preparation and tribological properties of poly(methyl methacrylate)/styrene/MWNTs copolymer nanocomposites

Poly(methyl methacrylate)/styrene/multi‐walled carbon nanotubes (PMMA/PS/MWNTs) copolymer nanocomposites with different contents have been prepared successfully by means of in situ polymerization method. The structure and the microhardness of PMMA/PS/MWNTs copolymer nanocomposites were characterized. The tribological behaviors of the copolymer nanocomposites were investigated by a friction and wear tester under dry conditions. The relative humidity of the air was about 50% ± 10%. Comparing with pure PMMA/PS copolymer, the copolymer nanocomposites showed not only better wear resistance but also smaller friction coefficient. MWNTs could help the nanocomposites dramatically improve the wear resistance property. The mechanisms of the improvements on the tribological properties of the PMMA/PS/MWNTs copolymer nanocomposites were also discussed in detail. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Morphology of polystyrene/polystyrene-block-poly(methyl methacrylate)/poly(methyl methacrylate) composite particles

Polystyrene/polystyrene-block-poly(methyl methacrylate)/poly(methyl methacrylate) (PS/PS-b-PMMA/PMMA) composite particles were prepared by releasing toluene from PS/PS-b-PMMA/PMMA/toluene droplets dispersed in a sodium dodecyl sulfate aqueous solution. The morphology of the composite particles was affected by release rate of toluene, the molecular weight of PS-b-PMMA, droplet size, and polymer composition. ‘Onion-like’ multilayered composite particles were prepared from toluene droplets of PS-b-PMMA and of PS/PS-b-PMMA/PMMA, in which the weights of PS and PMMA were the same. The layer thicknesses of the latter multilayered composite particles increased with an increase in the amount of the homopolymers. PS-b-PMMA/PS composite particles had a sea-islands structure, in which PMMA domains were dispersed in a PS matrix. On the other hand, PS-b-PMMA/PMMA composite particles had a cylinder-like structure consisting of a PMMA matrix and PS domains.     

Interactions in poly(vinylidene fluoride)/poly(methyl methacrylate-co-ethyl methacrylate) blends

Summary The interaction parameters B for blends of poly(vinylidene fluoride) (PVDF) with poly(methyl methacrylate) (PMMA), poly(ethyl methacrylate) (PEMA) and five methyl methacrylate/ ethyl methacrylate copolymers (PMEMA) were determined by measurements of melting point depression of PVDF. The B values are negative, indicating an attractive intermolecular interaction. The intramolecular interaction parameter between MMA and EMA segments in PMEMA was found to be +3.25 cal/cm³, indicating a repulsive interaction between different monomer segments in the copolymer.     

Synthesis,structure, and thermal stability of poly(methyl methacrylate)‐co‐ poly(3‐tri(methoxysilyil)propyl methacrylate)/ montmorillonite nanocomposites

The structure and the thermodegradation behavior of both poly(methyl methacrylate)‐co‐poly(3‐tri(methoxysilyil)propyl methacrylate) polymer modified with silyl groups and of intercalated poly(methyl methacrylate)‐co‐poly(3‐tri(methoxysilyil)propyl methacrylate)/Cloisite 15A? nanocomposite have been in situ probed. The structural feature were comparatively studied by Fourier transform infrared spectroscopy (FTIR), ¹³C and ²⁹Si nuclear magnetic resonance (NMR), and small angle X‐ray scattering (SAXS) measurements. The intercalation of polymer in the interlayer galleries was evidenced by the increment of the basal distance from 31 to 45 Å. The variation of this interlayer distance as function of temperature was followed by in situ SAXS. Pristine polymer decomposition pathway depends on the atmosphere, presenting two steps under air and three under N₂. The nanocomposites are more stable than polymer, and this thermal improvement is proportional to the clay loading. The experimental results indicate that clay nanoparticles play several different roles in polymer stabilization, among them, diffusion barrier, charring, and suppression of degradation steps by chemical reactions between polymer and clay. Charring is atmosphere dependent, occurring more pronounced under air. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Photocurrent in and miscibility of poly(N-vinylcarbazole)/poly(methyl methacrylate) blends

Summary Steady-state photocurrent in poly(N-vinylcarbazole)(PVCz) (26,48 wt%)/poly(methyl methacrylate)(PMMA) blends is for the first time measured. The PVCz(26,48 wt%)/PMMA blends showed almost the same carrier-generation efficiencies at electric fields higher than 1 × 10⁵ V · cm⁻¹. The results are explained by high miscibility of the PVCz(26,48 wt%)/PMMA blends, suggesting the existence of PVCz chains in continous PMMA-rich phase in the phase-separated structure. The miscibility is also evaluated by means of excimer fluorescence of PVCz in these blends and fluorescence microscopy. Received: 26 December 2000/Revised version: 16 January 2001/Accepted: 19 January 2001     

Properties of mineral filled poly(lactic acid)/poly(methyl methacrylate) blend

This study examines the influence of three different minerals, that is, clay, calcium carbonate, and quartz on the physical, thermal, and mechanical properties of poly(lactic acid) (PLA)/poly(methyl methacrylate) blend. Rheological behavior and phase structure were initially studied by small-amplitude oscillatory shear rheology. Clay- and quartz-filled materials presented an increase in viscosity at low frequency associated with the presence of a yield stress. However, this behavior was not observed for calcium carbonate filled materials due to a matrix degradation effect. To elucidate this aspect, thermal stability and thermal properties were examined by thermogravimetric analysis and differential scanning calorimetry, showing that calcium carbonate promotes degradation of the PLA phase. No nucleating effect was observed in the presence of the minerals. Dynamical mechanical analysis and mechanical characterization revealed an increase of the overall softening temperature and, a reinforcing effect for clay- and quartz-based composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46927.     

Synthesis and characterization of poly(methyl methacrylate)/montmorillonite nanocomposites by in situ bulk polymerization

Poly(methyl methacrylate)/montmorillonite (MMT) nanocomposites were prepared by in situ bulk polymerization. The results showed that the silicone coupling agent affected the structure and properties of hybrid materials. XRD analysis showed that the dispersion of clay in nanocomposites with silicone‐modified organophilic MMT was more ordered than that in nanocomposites with unmodified organophilic MMT. The glass transition temperature (T_g) of the nanocomposites was 6–15°C higher and the thermal decomposition temperature (T_d) was 100–120°C higher than those of pure PMMA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2256–2260, 2003