Influence of constituents on thermal properties of polymethacrylate derivatives–clay materials

In this study, the solution‐mixing method was used to prepare polymethacrylate derivatives' (PaMAs) nanocomposites with kaolinite. It was observed that the resultant materials could include exfoliated, intercalated, and undispersed kaolinite depending on their XRD patterns. TEM micrographs also revealed that platy and tube structures of kaolinite and their stacked form would disperse in the PaMAs. Therefore, they were called PaMAs–kaolinite materials with mixed morphology. The effects caused by different types of PaMA, solvent, and clay (sepiolite and kaolinite) on the thermal properties of these materials were examined. When the thermal stability of the materials was compared on the basis of the functional groups in the PaMAs, it was seen that the materials of the linear PaMAs with kaolinite usually had better thermal stability than that of the ring PaMAs and also seen that the thermal stability of Kao‐PaMAs increased from PMMA to poly(ethyl methacrylate) (PEMA) and poly(butyl methacrylate) for linear PaMAs. The solvent type affected the thermal stability and the glass transition temperature of the PaMAs. It was found that THF is the most suitable solvent for increasing thermal stability of the PaMAs in the presence of kaolinite; however, it is difficult to say the same about their T_g temperatures. In addition, the thermal stabilities of PEMA and poly(2‐hydroxylethyl methacrylate) were higher in the presence of kaolinite in comparison with sepiolite. The results obtained in this study were explained by the utilization of the relationships among their solubility parameters and of the interactions among the PaMAs, clays, the modifier (octadecylamine) and solvents. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Synthesis and dielectric properties of poly(methyl methacrylate)–clay nanocomposite materials

Poly(methyl methacrylate) (PMMA)–clay nanocomposite (PCN) materials were synthesized through in situ intercalative polymerization. A cationic surfactant, [2(dimethylamino)ethyl]triphenylphosphonium bromide, was used as an intercalating agent with pristine Na⁺‐montmorillonite (MMT). The synthesized PCN materials were subsequently investigated by a series of characterization techniques, including wide‐angle powder X‐ray diffraction, Fourier transform IR spectroscopy, transmission electron microscopy, thermogravimetric analysis, and differential scanning calorimetry. Compared to pure PMMA, the PCN materials exhibit higher thermal degradation temperatures and glass‐transition temperatures. The dielectric properties of PCN blending with a commercial PMMA material in film form with clay loading from 0.5 to 5.0 wt % were measured under frequencies of 100 Hz–1 MHz at 35–100°C. Significantly depressed dielectric constants and losses were observed for these PCN‐blending materials. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2175–2181, 2005     

Poly(methyl methacrylate)/POSS hybrid networks by type II photoinitiated free radical polymerization

A new strategy for organic–inorganic hybrid networks is presented through in‐situ Type II photoinitiated polymerization of methyl methacrylate with diethanolamino‐functionalized polyhedral oligomeric silsesquioxanes (POSS‐DEA). The diethanolamino groups are simply incorporated onto POSS nanoparticles by nucleophilic ring‐opening reaction of commercially available epoxycyclohexyl POSS and diethanol amine. The photoinitiated polymerization of methyl methacrylate in the presence of benzophenone as photosensitizer and POSS‐DEA as hydrogen donor leads to poly(methyl methacrylate) (PMMA)/POSS hybrid networks under UV light irradiation. The morphology and thermal properties of hybrid networks are investigated by using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and transmission electron microscopy. The morphology results confirm that POSS cages are homogeneously distributed in PMMA matrix at the molecular levels, whereas the thermal analyses shows that the obtained hybrid networks have higher glass transition temperatures and better thermal stabilities compared to parent PMMA homopolymer. POLYM. COMPOS., 35:1614–1620, 2014. © 2013 Society of Plastics Engineers     

High‐performance polyimide–clay nanocomposite materials based on a dual intercalating agent system

BACKGROUND: Polymer–clay nanocomposites (PCNs) have attracted considerable interest in recent years owing to their unique physical and chemical properties that lead to a wide range of applications. A series of PCN materials consisting of polyimide and layered montmorillonite (MMT) clay were successfully prepared by in situ polymerization. RESULTS: Silicate layers are better dispersed in polymer matrices when dual intercalating agents (hexadecyltrimethylammonium bromide–4,4′‐oxydianiline) are applied for MMT modification according to wide‐angle X‐ray diffraction and transmission electron microscopy studies. Effects of single and dual intercalating agents on thermal stability, mechanical strength and the molecular barrier of PCN materials consisting of organo‐modified MMT were studied by means of thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analyses, gas permeability analysis and vapor permeability analysis. CONCLUSION: Improved thermal and mechanical stabilities, as well as barrier properties were observed for the PCN materials containing dual intercalating agent‐modified MMT. Copyright © 2008 Society of Chemical Industry     

Physical and mechanical properties of poly(methyl methacrylate)‐grafted natural rubber synthesized by methyl methacrylate photopolymerization initiated by N,N‐diethyldithiocarbamate functions previously created on natural rubber chains

Well‐defined poly(methyl methacrylate) (PMMA)‐grafted natural rubbers (NRs) were prepared to study the structure–property relationships. Syntheses were achieved by the photopolymerization of methyl methacrylate initiated by N,N‐diethyldithiocarbamate groups created beforehand in side positions on the NR chains. With this procedure, good control of the graft density and PMMA content could be obtained. Thermal, morphological, and mechanical properties of NR‐g‐PMMA copolymers were studied as a function of the NR/PMMA composition and graft density. NR‐g‐PMMAs containing 15–80% grafted PMMA showed characteristics of heterogeneous materials (characterized by two glass‐transition temperatures, those of PMMA and NR, in differential scanning calorimetry). Under these conditions, they developed the morphology of thermoplastic elastomers with PMMA nodules dispersed in the rubber matrix when the PMMA content was near 20%; conversely, they developed the morphology of softened thermoplastics with rubber nodules dispersed in PMMA when the PMMA content was near 80%. Graft copolymers containing about 20% PMMA remained essentially rubbery, but they were already different from pure NR. On the other hand, the thermal stability of NR wash improved after the introduction of PMMA grafts onto NR chains. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation,characterization, and thermal properties of poly (methyl methacrylate)/boron nitride composites by bulk polymerization

Poly (methyl methacrylate)/boron nitride (PMMA/BN) composites were prepared by dispersing BN particles into methyl methacrylate monomer phase by bulk polymerization method. BN particles modified with silane coupling agent, γ‐methacryloxypropyl trimethoxy silane, were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. Effects of modified BN particle content on thermal conductivity were investigated, and the experimental values were compared with those of theoretical and empirical models. With 16 wt% of BN particles, the thermal conductivity of the composite was 0.53 W/(m·K), 1.8 times higher than that of pure PMMA. The microstructures of the PMMA/BN composites were examined by scanning electron microscopy, energy‐dispersive X‐ray analysis, and transmission electron microscopy. Dynamic mechanical analysis and thermogravimetric analysis traces also corroborated the confinement of the polymer in an inorganic layer by exhibiting an increase in glass‐transition temperatures and weight loss temperatures in the thermogram. Mechanical properties and electrical insulation property of the PMMA/BN composites were also determined. These results showed that PMMA/BN composites may offer new technology and business opportunities. POLYM. COMPOS., 36:1675–1684, 2015. © 2014 Society of Plastics Engineers     

PVDF/PMMA复合材料的微观结构及形态

采用非晶态聚甲基丙烯酸甲酯（PMMA）与结晶型聚偏氟乙烯（PVDF）熔融共混．制备了PVDF／PMMA复合材料。利用Hilderbrand的溶解参数原则、差示扫描量热法（DSC）和微分热重法（DTG）分析了PVDFfPMMA共混物的相容性和热性能,并用X射线衍射仪和扫描电子显微镜研究了共混片材的微观结构与形态。结果表明,PMMA与PVDF具有良好的相容性,PMMA的加入降低了PVDF的结晶能力和熔融温度;随着PMMA的含量增加,PVDF的分解温度降低;PVDF的结晶度降低,球晶尺寸增大。另外,PMMA的引入改变了PVDF的结晶结构,导致了β相形成。     

Synthesis and properties of poly(methyl methacrylate)/carbon nanotube composites covalently integrated through in situ radical polymerization

Poly(methyl methacrylate) (PMMA)/single‐walled carbon nanotube (SWNT) composites were synthesized by the grafting of PMMA onto the sidewalls of SWNTs via in situ radical polymerization. The free‐radical initiators were covalently attached to the SWNTs by a well‐known esterification method and confirmed by means of thermogravimetric analysis and Fourier transform infrared spectroscopy. Scanning electron microscopy and transmission electron microscopy were used to image the PMMA–SWNT composites; these images showed the presence of polymer layers on the surfaces of debundled, individual nanotubes. The PMMA–SWNT composites exhibited better solubility in chloroform than the solution‐blended composite materials. On the other hand, compared to the neat PMMA, the PMMA–SWNT nanocomposites displayed a glass‐transition temperature up to 6.0°C higher and a maximum thermal decomposition temperature up to 56.6°C higher. The unique properties of the nanocomposites resulted from the strong interactions between the SWNTs and the PMMA chains. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Double‐miniemulsion preparation of Fe3O4/poly(methyl methacrylate) magnetic latex

Magnetic poly(methyl methacrylate) (PMMA) microspheres were prepared by double‐miniemulsion polymerization. First, oleic acid coated magnetite particles synthesized by means of coprecipitation were dispersed into octane to obtain a ferrofluid. The ferrofluid and MMA were emulsified to form O/W emulsion, respectively. Subsequently two miniemulsions were mixed together for polymerization. The obtained magnetic polymer particles were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, X‐ray powder diffraction, and thermogravimetry. The results showed that oleic acid coated magnetite particles were well encapsulated in PMMA. The effects of initiator dosage and monomer concentration on the conversion of MMA were also investigated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Melt compounding of PMMA/clay nanocomposites with styrene‐maleic anhydride copolymers: Effect of copolymer type on thermal,mechanical and dielectric properties

Poly(methyl methacrylate) (PMMA)‐clay nanocomposites (PCN) were prepared through melt blending. Styrene‐maleic anhydride copolymers (SMA) of different molecular weights and MA contents were used as compatibilizers with organically modified clay. The melt‐blended PCN materials were subsequently investigated by a series of characterization techniques, including wide‐angle X‐ray diffraction, transmission electron microscopy, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical thermal analysis, and thermal mechanical analysis. Compared with unmodified PMMA, with only 5 wt% clay loading, the modified PCN materials exhibit higher glass‐transition temperatures, higher dynamic storage moduli, and lower thermal expansion coefficients. The dielectric properties of PCNs in plate form were measured with dielectric spectroscopy. Significant increase in dielectric permitivities and losses were observed for these PCNs. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Synthesis and characterization of poly(glycidyl methacrylate)/Na‐montmorillonite nanocomposites

Poly(glycidyl methacrylate)/Na–montmorillonite nanocomposites were synthesized by free‐radical polymerization of glycidyl methacrylate containing dispersed montmorillonite. By changing the concentration of glycidyl methacrylate several polymer–clay nanocomposites were prepared and the resulting nanocomposites were characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The results indicated that the properties of the composite were significantly improved. The thermogravimetric analysis results revealed that the degradation temperatures of nanocomposites were higher than that of pure polymer and the thermal degradation rates decreased. Examination of these materials by scanning electron microscopy showed that the clay layers are dispersed homogenously in the polymer matrix and the formation of intercalation nanostructure. Furthermore, adsorptive, moisture regain, and water uptake properties of nanocomposites were also investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1532–1538, 2004     

Effects of SBA-15 and its content on MMA solution polymerization and PMMA composites

An ordered mesoporous material, such as SBA-15 was considered as a promising reinforcement agent for polymeric materials due to its large surface area and uniform pore structure. In this paper, poly(methyl methacrylate) (PMMA)/SBA-15 composites were prepared by in situ free-radical solution polymerization of MMA in the presence of SBA-15. The effects of SBA-15 content on solution polymerization and the properties of the final polymer composite were investigated. The PMMA molecular weight and its distribution in PMMA/SBA-15 composites were determined by gel permeation chromatography. Fourier-transform infrared spectra, X-ray diffraction, thermal gravimetric analysis (TGA), differential scanning calorimeter and dynamic mechanical analysis were used to characterize the structure and properties of the composites. The morphology of the composites was observed by scanning electric microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the monomer conversion dropped off, but the polymer average molecular weight increased upon the introduction of SBA-15 into solution polymerization process. When compared with pure PMMA, the storage modulus of the composites was improved and the highest improvement was acquired at 1 wt% of SBA-15, based on the monomer feed content. The glass transition temperatures of the composites were increased slightly. TGA results confirmed that the thermal stability of the composite was not influenced much and a higher degree of terminal vinyl groups was formed in the product of polymerization. SEM and TEM images indicated that SBA-15 particles were incorporated into the polymer matrix.     

Effects of preparation methods on the property of PMMA/SBA-15 mesoporous silica composites

In the paper, poly(methyl methacrylate)(PMMA)/SBA-15 composite materials were prepared by four different methods, that is, in-situ batch emulsion polymerization in the presence of mesoporous SBA-15, PMMA emulsion mixed with SBA-15 powder or dispersion in water, PMMA powder mixed with SBA-15 powder, and the properties of the composite materials were determined and compared. The composites were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanics analysis (DMA) and scanning electron microscope (SEM). The results showed that the glass transition temperatures (Tg), the storage modulus and tensile strength of the PMMA/SBA-15 composites were all improved obviously, while the thermal decomposition temperature did not influenced apparently. The composite made by in-situ batch polymerization exhibited the most improvement in the mechanical properties and Tg while the composite prepared by mixing PMMA emulsion and SBA-15 dispersion gave rise to the least improvement in the mechanical properties and Tg. These results were contributed to introducing different amount of voids into polymer matrix which were demonstrated by dielectric constant measurement and SEM morphology observation.     

Synthesis and characterization of hyperbranched poly(ethyl methacrylate) by quasi‐living radical polymerization of photofunctional inimer

The hyperbranched poly(ethyl methacrylate)s (PEMAs) were prepared by the quasi‐living radical polymerization of 2‐(N,N‐diethylaminodithiocarbamoyl)ethyl methacrylate (DTCM). DTCM monomer plays an important role in this polymerization system as an inimer that is capable of initiating quasi‐living radical polymerization of the vinyl group. Hyperbranched PEMAs with relatively narrow polydispersity ( M _w/ M _n ≈ 1.6) were obtained. The compact nature of the hyperbranched PEMAs is demonstrated by solution properties which are different from those of the linear analogues. © 2002 Society of Chemical Industry     

Epoxy resin–poly(ethyl methacrylate) interpenetrating polymer networks: Morphology,mechanical, and thermal properties

Full (interpenetrating networks (IPNs)) and semi-IPNs of the epoxy resin and poly(ethyl methacrylate) (PEMA) were prepared by the sequential mode of synthesis. These were characterized with respect to their mechanical properties, namely, tensile strength, elongation at break, modulus, and toughness. Thermal properties were studied by differential scanning calorimetry and thermogravimetry. The morphological features were studied through scanning electron microscopy (SEM) and polarized light microscopy. The effects of variation of the blend ratios on the above-mentioned properties were examined. There was a gradual decrease of modulus and tensile strength with consequent increases in elongation at break and toughness for both types of IPNs with increases in PEMA content. The weight retentions in the thermal decomposition of both the semi-IPNs and full IPNs were higher than the epoxy homopolymer. This enhancement was presumably related to the presence of the unzipped ethyl methacrylate monomer, which acted as radical scavengers in the epoxy degradation. An inward shift and lowering (with respect to pure epoxy) of the T_g of the IPNs was observed. The polarized light microscopy exhibits bimodal distribution of particle sizes. The fractography as studied by SEM shows change in fracture mechanics from shear yielding to crazing with increasing PEMA content. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1051–1059, 1998     

Efficient preparation and characterization of paraffin-based microcapsules by emulsion polymerization

Microencapsulated phase-change materials (MEPCMs) with paraffin as the core and poly(methyl methacrylate) (PMMA) and PMMA copolymers as the shell were prepared by emulsion polymerization using redox initiators at low temperatures. Fourier transform infrared spectroscopy was used to characterize the chemical composition of MEPCMs. The thermal properties and thermal stabilities of MEPCMs were tested by differential scanning calorimetry and thermogravimetric analysis. The morphologies and sizes of the microcapsules were investigated by scanning electron microscopy and particle size distribution analysis. The results indicated that the yield of microcapsules is as high as 96.2%, and the encapsulation efficiency of paraffin is nearly 100% when the paraffin content in MEPCM is 70%. The MEPCMs have good stability: the leakage ratios of MEPCMs can be less than 1% after 50 heating–cooling cycles. Therefore, the microencapsulation of paraffin using redox initiators has good production and application prospects. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47552.     

Investigation of polymer blends of polyamide-6 and poly(methyl methacrylate) synthesized by RAFT polymerization

Morphological and thermal properties of immiscible and incompatible polymer blends of commercial polyamide-6 (PA-6) and poly(methyl methacrylate) (PMMA) synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization have been studied in the presence of a compatibilizer consisting of either a random copolymer of styrene-maleic anhydride (SMA) or a diblock copolymer poly(methyl methacrylate) and polystyrene (PMMA-PS) also synthesized via RAFT polymerization. Blends of PA-6/PMMA were obtained by extrusion mixing. During melt compounding in the extruder, the functional groups of the polymer components were reacted in the presence of a compatibilizer, which changed considerably the morphology of the blend. After compatibilization, particles of PMMA in the PA-6 were smaller and better dispersed. The morphology and thermal properties of the blends were characterized using scanning electron microscopy (SEM) and differential scanning calorimetry (DCS).     

Microheterogeneous polymer systems prepared by suspension polymerization of methyl methacrylate in the presence of poly(ε‐caprolactone)

Poly(methyl methacrylate) – polycaprolactone (PMMA/PCL) microheterogeneous beads were synthesized by suspension polymerization starting from methyl methacrylate (MMA) monomer and PCL, which was synthesized by ring‐opening polymerization of ε‐caprolactone using ZnCl₂ as initiator. The resulting polymer was fully characterized by ¹H and ¹³C NMR, differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and dynamic mechanical thermal analysis (DMTA). The size distribution and morphology of the resulting beads were investigated by optical microscopy and scanning electron microscopy (SEM). Moreover, blends of PMMA beads and PCL in different proportions were prepared and the morphology of the films was examined by optical microscopy. The low compatibility between PMMA and PCL was clearly evidenced through these experiments.     

Novolac resin–poly(ethyl methacrylate) interpenetrating polymer networks: Morphology and mechanical and thermal properties

Full interpenetrating networks (IPNs) and semi‐IPNs of Novolac (phenolic) resin and poly(ethyl methacrylate) (PEMA) were prepared by the sequential mode of synthesis. These were characterized with respect to their mechanical properties, that is, ultimate tensile strength (UTS), percentage elongation at break, modulus, and toughness. Thermal properties were studied by DSC and thermogravimetric analysis (TGA). The morphological features were studied through polarizing light microscopy (PLM). The effects of variation of the blend ratios on the above‐mentioned properties were examined. There was a gradual decrease of modulus and UTS with consequent increases in elongation at break and toughness for both types of IPNs with increasing proportions of PEMA. An inward shift and lowering (with respect to pure phenolic resin) of the glass‐transition temperatures of the IPNs with increasing proportions of PEMA were observed, thus indicating a plasticizing influence of PEMA on the rigid and brittle matrix of crosslinked phenolic resin. The TGA thermograms exhibit two‐step degradation patterns. Although there was an apparent increase in thermal stability at the initial stages, particularly at lower temperatures, a substantial decrease in thermal stability was observed in the regions of higher temperatures. The surface morphology as revealed by PLM clearly indicates two‐phase structures in all the full and semi‐IPNs, irrespective of PEMA content. The matrix–PEMA domain interfaces are quite sharp at higher concentrations of PEMA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 412–420, 2003     

Preparation,structural characterization,and properties of poly(methyl methacrylate)/montmorillonite nanocomposites by bulk polymerization

Poly(methyl methacrylate) (PMMA)/montmorillonite (MMT) nanocomposites were synthesized by a simple technique of a monomer casting method, bulk polymerization. The products were purified by hot acetone extraction and characterized by Fourier transform infrared spectroscopy, X‐ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), examination of their mechanical properties, and light transmittance testing. Although XRD data did not show any apparent order of the MMT layers in the nanocomposites, TEM revealed parallel MMT layers with interlamellar spacings of an average of 9.8 nm and the presence of remnant multiplets of nonexfoliated layers. Therefore, PMMA chains were intercalated in the galleries of MMT. DSC and TGA traces also corroborated the confinement of the polymer in the inorganic layer by exhibiting the increase of glass‐transition temperatures and mass loss temperatures in the thermogram. Both the thermal stability and the mechanical properties of the products appeared to be substantially enhanced, although the light transmittances were not lost. Also, the materials had excellent mechanical properties. Measurement of the tensile properties of the PMMA/MMT nanocomposites indicated that the tensile modulus increased up to 1013 MPa with the addition of 0.6 wt % MMT, which was about 39% higher than that of the corresponding PMMA; the tensile strength and Charpy notched impact strength increased to 88 MPa and 12.9 kJ/m², respectively. As shown by the aforementioned results, PMMA/MMT nanocomposites may offer new technology and business opportunities. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 348–357, 2005