Bulk Copolymerization Of Methyl Methacrylate Research Articles

Methyl methacrylate-styrene copolymers prepared by utilizing the Trommsdorff effect in an inverted two-stage extruder

In this work, the influence of initial viscosity on the Trommsdorff effect was firstly investigated, and it was confirmed that 1000 ± 100 Pa · s of viscosity could be a criterion of the Trommsdorff effect. On this basis, a new inverted two-stage extruder was established, the designed ‘blocking unit’ was introduced to the screw configuration, and then the continuous bulk copolymerization of methyl methacrylate (MMA) and styrene (St) was carried out. The results showed that the blocking unit could effectively enhance the residence time of copolymerization, and make the molecular weight distribution of copolymer more uniform. The position of the Trommsdorff effect in the extruder was then determined by the thermal effect of copolymerization, and the mixed monomers were continuously added to effectively utilize the Trommsdorff effect. As a result, the MMA-St copolymers with high molecular weight and narrow distribution were prepared via reactive extrusion, which possessed higher melt flow rate and better thermal stability than pure-PMMA. The present work provides important reference and guidance for the industrialization of bulk free radical copolymerization via reactive extrusion.

Investigation of mercaptan/ε-caprolactam initiated bulk copolymerization of methyl methacrylate with vinyl monomers

The bulk copolymerization of methyl methacrylate (MMA) with vinyl monomers initiated by e-caprolactam (CL) and n-dodecyl mercaptan (RSH) was investigated. Acrylonitrile (AN) and vinyl acetate (VAc) were used to copolymerize with MMA at 90 °C in the presence of CL and RSH, respectively. As evidenced by first-order kinetics of polymerization, linear increase of molecular weights with monomer conversions, and relatively low PDI values within a range of 1.3 to 1.6, both the copolymerization reactions exhibited living characteristics. Dependences of the copolymerization on the monomer feed ratio was also studied. An increase in the feed ratio of MMA induced an increased rate of copolymerization. In contrast, an increase in the initial loading of vinyl monomer leaded to the decrease in rate of copolymerization. The reactivity ratios of each pair of comonomers were also assessed using Fineman-Ross (FR) method. The results showed that the CL has an important influence on the kinetics of copolymerization, which caused the copolymerization parameters different from the most previously reported values.

Preparation of methyl methacrylate-maleic anhydride copolymers via reactive extrusion by regulating the trommsdorff effect

In this study, the influence of shear rate on the Trommsdorff effect was investigated using rotational rheometer and torque rheometer firstly, then the bulk copolymerization of methyl methacrylate (MMA) and maleic anhydride (MAH) were carried out via two connected twin-screw extruders. Based on the assumption of utilizing the Trommsdorff effect, new monomers were continually added during the copolymerization process. The results indicated that the polymerization rate was greatly accelerated and copolymers with high molecular weight and narrow distribution were obtained. Under the high temperature and high pressure in extruder, the copolymerization of MMA and MAH approached to the ideal copolymerization, which was different from the solution copolymerization. Compared with the homo-polymethyl methacrylate, the Tg and Td50 of the copolymer was respectively increased by 12 °C and 24 °C while maleic anhydride units were uniformly distributed in the MMA-MAH copolymer. The flexural strength and modulus increased by 8.2% and 20%, respectively. The high efficiency and environment friendly of reactive extrusion technology provide a way for the large-scale industrialization of MMA-MAH copolymer.

Monte Carlo Simulations of Free Radical Polymerizations with Divinyl Cross-Linker: Pre- and Postgel Simulations of Reaction Kinetics and Molecular Structure

A computationally efficient Monte Carlo method was used to simulate the reaction kinetics and molecular structure development during free-radical copolymerizations with divinyl monomers. A single parameter was used to describe the reduced reactivity of the pendent vinyl groups incorporated within the polymer backbone. The simulation results were compared with published experimental data for the bulk copolymerization of methyl methacrylate with different levels of ethylene glycol dimethacrylate. The model was able to effectively predict the reaction kinetics, the gel point, and sol–gel fractions in both the pre- and postgel regimes, including the swelling index of the gel. In the postgel regime the cross-linked molecule becomes the primary locus of reactions, and all chains eventually become part of this massive cross-linked polymer network. The Monte Carlo method allows the determination of the complete molecular structure as it evolves with time, including properties like cross-linking density, number of...

Enhanced Thermal Stability and Flame Retardancy of a Novel Transparent Poly(Methyl Methacrylate)-Based Copolymer

A novel poly (methyl methacrylate) (PMMA) based copolymer was synthesized by bulk copolymerization of methyl methacrylate (MMA) and a phosphorus-containing monomer, acryloxyethyl phenoxy phosphorodiethyl amidate (AEPPA). The chemical structure of AEPPA was confirmed by FTIR,1H NMR and31P NMR. The structure of copolymers was characterized using FTIR. TGA results indicate that the thermal stability of copolymers was remarkably enhanced with the addition of APEEA. LOI and MCC results suggest that the flame retardancy of copolymers was also improved. Detailed flame-retardant mechanism is proposed. The char formation during degradation caused by APEEA plays a key role in the property improvements.

A Novel Transparent Cross-Linked Poly(methyl methacrylate)-Based Copolymer with Enhanced Mechanical, Thermal, and Flame-Retardant Properties

A novel cross-linked poly(methyl methacrylate) (PMMA)-based copolymer was first synthesized by bulk copolymerization of methyl methacrylate (MMA) and 1-oxo-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane-4-acrylate (PEPAA) at low temperature (80 °C), which is a facile and green method. The structure of PEPAA was confirmed by FTIR, 1H NMR, and 31P NMR. The morphology and structure of copolymers were characterized using FTIR and SEM. Due to the chain transfer during copolymerization, a cross-linked network is successfully introduced into the copolymers and the gel fraction increases as the PEPAA content increases, as evinced by the results from Soxhlet extraction and DMA. The copolymers exhibit relatively high transparency and significant improvements to the mechanical properties, thermal properties, and fire retardancy when compared to PMMA. From the mechanism analysis, the cross-linked network plays a key role in the improvements to the mechanical properties and thermal properties. For enhanced fire retardancy...

Studies on binary copolymerization and glass transition temperatures of methyl methacrylate with ethyl methacrylate and n‐butyl methacrylate

AbstractIn this article, bulk copolymerization of methyl methacrylate (MMA) with ethyl methacrylate (EMA) and n‐butyl methacrylate (n‐BMA) was carried out at 60°C. The monomer reactivity ratios obtained by nonlinear fitting with Mayo‐Lewis equation were as follows: rMMA = 0.93 ± 0.03, rEMA = 0.96 ± 0.03 for the MMA/EMA, and rMMA = 0.99 ± 0.05, rn‐BMA = 1.11 ± 0.06 for the MMA/n‐BMA series. A new equation proposed in view of bond rotation flexibility (Liu et al., J Phys Chem B 2008, 112, 93), which contains mole fractions of triads and Tg's of corresponding periodic copolymers, was applied to describe the relation of Tg's of MMA‐EMA, MMA‐n‐BMA copolymers with their compositions and sequence distribution. Excellent fitting results were obtained and Tg values of the assumed periodic copolymers were predicted by fitting the random copolymers. The influence of the substituent volume as well as substituent density on the Tg of poly(methyl methacrylate) (PMMA) was also tentatively predicted. © 2009 Wiley Periodicals, Inc. J Appl Polym, 2009

Effect of polymethylmethacrylate–montmorillonite nanocomposite on the release of some biologically active 1,2,4‐triazine derivatives

AbstractMethylmethacrylate chloromethylstyrene copolymer–montmorillonite (PMMA–MMT) intercalated nanocomposite was prepared by bulk copolymerization of methylmethacrylate (MMA) and chloromethylstyrene (2 wt%) followed by phosphonium salt formation. The intercalation of polymeric phosphonium salt into montmorillonite was achieved through an ion exchange process between sodium cations in MMT and phosphonium groups attached to the copolymer. Thermogravimetric analysis (TGA) showed improved thermal stability for the intercalated nanocomposite in comparison with the pure PMMA. Biologically active compounds including 4‐amino‐6‐methyl‐3‐thioxo‐3,4‐dihydro‐2H‐[1,2,4]triazin‐ 5‐one (I), 4‐amino‐6‐methyl‐3,4‐dihydro‐2H‐[1,2,4]triazin‐3,5‐dithione (II), 4‐amino‐6‐(4‐methoxystyryl)‐3‐thioxo‐3,4‐dihydro‐2H‐[1,2,4]triazin‐5‐one (III), and 4‐amino‐6‐styryl‐3‐thioxo‐3,4‐dihydro‐2H‐[1,2,4]triazin‐5‐one (IV) have been prepared and reacted with PMMA–MMT intercalates and ion exchanged with sodium montmorillonite (MMT) in the presence of HCl. Infrared spectra (IR) show bands characteristic to amide linkage between triazine derivatives and PMMA. These nanocomposites have been characterized by X‐ray diffraction (XRD) and transmission electron microscope (TEM). The release of biologically active compounds intercalated layered silicates is controllable and these materials have a great potential as a delivery host in the pharmaceutical field. The effect of temperature and presence of saline solution on the release was studied. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers

Improving properties of modified acrylic sheet via addition of graft natural rubber

The mechanical properties of a modified acrylic sheet prepared by bulk copolymerization of methyl methacrylate (MMA) and styrene (ST) were improved by the addition of a small amount of graft natural rubber (GNR). The graft copolymerization of MMA and ST onto natural rubber latex was carried out by emulsion polymerization using potassium persulfate as an initiator. The properties of the modified acrylic sheet containing GNR with 22.5 wt.% graft copolymer were investigated as a function of GNR content. The results indicated that the impact resistance, tensile strength and elongation at break of the modified acrylic sheet increased with the increase in the amount of GNR in the range of 0.5–4 parts. From the stress–strain behavior, the characteristic of the modified acrylic sheet shifted from brittle to ductile when the amount of GNR was increased. The scanning electron micrographs of the modified acrylic sheets show the relatively smooth fracture surface with relatively few small cracks. This implies that the GNR can be used as an impact modifier for acrylic plastics.

High-Temperature Bulk Copolymerization of Methyl Methacrylate and Acrylonitrile: III. Thermal Polymerization

The thermally initiated copolymerization of methyl methacrylate and acrylonitrile has been studied in the bulk phase. Experiments for estimating reactivity ratios were conducted at 120°C and 140°C. Feed composition constraint approaches were used to design the reactivity ratio experiments. The error in variables model (EVM) method was employed to evaluate the reactivity ratios and analyze the error. The results showed that the reactivity ratios did not vary significantly with temperature up to 140°C for both thermally initiated and experiments with initiator. Full conversion range experiments were also conducted at 140°C. The rate of reaction, copolymer composition, M¯ n , M¯ w , and glass transition temperatures of samples were measured.

High temperature bulk copolymerization of methyl methacrylate and acrylonitrile. I. Reactivity ratio estimation

The copolymerization of methyl methacrylate and acrylonitrile has been studied in the bulk phase. Experiments for estimating reactivity ratios were conducted at 60, 100, 120, and 140°C. Tidwell–Mortimer and the feed composition constraint approaches were used to design the experiments. The error in variables model (EVM) method was employed to evaluate the reactivity ratios and analyze the error involved. The results show that the reactivity ratios do not vary significantly with temperature up to 140°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 843–851, 2006

High Temperature Bulk Copolymerization of Methyl Methacrylate and Acrylonitrile: II. Full Conversion Range Experiments

Full conversion range copolymerization of methyl methacrylate and acrylonitrile has been studied in the bulk phase. Experiments were conducted at 60, 100, and 140°C. The rates of reaction, copolymer composition, , , PDI, and Tg of samples were measured. Also, the WATPOLY model and Meyer‐Lowry equation were employed to model the copolymerization and to calculate some copolymerization variables. The results show that higher levels of acrylonitrile in the feed composition significantly decrease the gel effect, number, and weight average molecular weights. Also, the gel effect at higher temperatures decreases. In addition, the reactivity ratios estimated for this copolymer system over the entire temperature range were confirmed from trends in cumulative copolymer composition.

Branching and gelation in atom transfer radical polymerization of methyl methacrylate and ethylene glycol dimethacrylate

Bulk copolymerization of methyl methacrylate (MMA) and ethylene glycol dimethacrylate (EGDMA) was initiated by methyl α-bromophenylacetate (MBPA) and mediated by copper bromide (CuBr) ligated with 1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA). The atom transfer radical polymerization (ATRP) of pure MMA yielded polymers with well controlled molecular weights and the homopolymerization was taken as a reference for the copolymerization analysis. The copolymerization experienced autoacceleration in rate due to a diffusion-controlled radical deactivation. The onset of autoacceleration came earlier with an increase in the EGDMA fraction. At low EGDMA fractions, the molecular weight versus conversion data deviated from linearity due to branching. The ratio of the copolymer molecular weight over homo-poly(methyl methacrylate) gave an estimate for the branching density, which increased initially and leveled off at high conversion. At high EGDMA fractions, the ATRP system experienced gelation. The pregel branching density increased with conversion, and at the gel point, it agreed with Flory's gelation theory assuming cross-linking free of cyclization. The branching densities at the high gel fractions were very close to the maximum values possibly achieved with the added EGDMA fractions. These results suggested that the ATRP system was very effective in preparing homogeneous polymer networks with a high cross-linking efficiency. POLYM. ENG. SCI., 45:720–727, 2005. © 2005 Society of Plastics Engineers

Free radical copolymerization of methyl methacrylate and allyl acetate Part 2 structure and properties

AbstractThe structure of the product from the free radical bulk copolymerization of methyl methacrylate (MMA) and allyl acetate (AAc) was investigated. The mole fraction of AAc plays an important role in the copolymerization of these two monomers. Molecular weight (MW) and molecular weight distribution (MWD) are completely altered when the feed composition is dominantly AAc. NMR spectroscopy confirmed the incorporation of AAc into the polymer. However, no allyl–allyl linkages were observed at low conversions. Tg was found to be affected by the incorporation of AAc into the polymer.© 2001 Society of Chemical Industry

Copolymerization of methyl methacrylate and allyl acetate Part I. Rate of reaction

Free radical bulk copolymerization of methyl methacrylate (MMA) and allyl acetate (AAc) has been investigated using electron spin resonance (ESR) and FT–near infrared (FTNIR) spectroscopy. Data are used to evaluate the rate constants. The mole fraction of AAc plays an important role in the copolymerization of these two monomers. AAc not only delays the Trommsdorff effect but also increases the onset of percentage total conversion at which the Trommsdorff region begins. With AAc fraction 0.5 and higher, no Trommsdorff effect was observed. Inclusion of AAc into copolymer structure mainly occurs in the Trommsdorf region or when the AAc fraction in the comonomer feed is dominant. This is associated with a drop in the concentration of propagating radicals. However, ESR spectra indicate that the MMA propagating radical is predominant during the reaction. In the comonomer mixtures where a Trommsdorff region can be observed, the addition of AAc does not produce any significant change in kp and kt in the steady state region. Major changes in kp and kt are observed after the gel point and glassy state, respectively. © 2001 Society of Chemical Industry

Determination of copolymerization parameters of methyl methacrylate with dodecyl methacrylate by means of FTIR spectroscopy

AbstractThe bulk copolymerization of methyl methacrylate (MMA) with dodecyl methacrylate (DMA) initiated by 2,2′‐azoisobutyronitrile (AIBN) at 60°C was used to prepare samples with different MMA/DMA ratios. The composition of the copolymers was determined by means of FTIR spectroscopy, using the absorption intensity ratio of CH2/CO for copolymers in CDCl3 solution and as KBr tablets. Reactivity ratios, determined by the Kelen‐Tüdős method, were found to be: rMMA = 1.58 and rDMA = 1.88 for copolymers analyzed in solution, and rMMA = 1.67 and rDMA = 1.95 for samples prepared as KBr tablets. Comparison of copolymer composition of some samples was made with elemental analysis data. It was found that the shift in the CO maximum observed for the copolymer in CDCI3 solution, compared to the corresponding homopolymer solutions, could also be used for determining copolymer composition.

Spectral studies on copolymers of methyl methacrylate and copper acrylate

Copper-coordinated copolymers were prepared by bulk copolymerization of methyl methacrylate with copper acrylate. A spectral-structural correlation was investigated for the polymers. Spectral changes on the copper content is increased from 2 to 10·7 wt% revealing a tetrahedrally distorted environment around the copper centre. Calculation of the splitting parameters, Δ 0, ϱ and δ, indicates a varying degree of distortion from octahedral geometry. For higher copper contents, changes in the values of 10 Dq and the splitting parameters suggest an increasing degree of covalency with increasing association of the carbonyl group in the cross-linked chains of the copolymer. The radial distortion parameters D s and D t have been determined. Variations in D t values indicate changes in the field strength of the CO and COO − ligands dependent upon the copper content.

Propagation and termination processes in the free-radical copolymerization of methyl methacrylate and vinyl acetate

The propagation and termination processes in free-radical copolymerization were examined on the basis of a complete set of experimental data carefully obtained for the bulk copolymerization of methyl methacrylate (MMA) and vinyl acetate (VAc) at 40°C by use of the rotating-sector technique. The composition curve conformed to the terminal model within experimental error. However, a moderate penultimate-unit effect was observed for the terminal MMA radical (s 1 =k 211 /k 111 =0.4±0.2), in conformity to the predictionof the stabilization energy model. The concentration of the terminal VAc radical was too small to elucidate the details about this radical. The termination process in this system conforms to the notion of diffusion control, but the North diffusion model was found inadequate

Infrared absorption characteristics and electrical conduction of methyl methacrylate‐lithium acrylate copolymers

AbstractSemiconducting copolymer samples were prepared by bulk copolymerization of methyl methacrylate with lithium acrylate using benzoyl peroxide as initiator. The pattern of the chemical reaction is discussed. The obtained samples were found to be random copolymers. Infrared absorption spectra were measured and analysed according to the copolymer structures. The data of electrical conductivity and the effect of gamma radiation on the electrical conductivity of the copolymer samples are discussed.

Some physical and spectroscopic studies on methyl methacrylate‐copper acrylate bulk copolymers

AbstractThe bulk copolymerization of methyl methacrylate with copper acrylate was carried out using benzoyl peroxide as initiator at 60°C. The density and hardness of the obtained transparent solid copolymer samples were investigated. The pattern of the chemical reactions is discussed. The monomer reactivity ratios were determined. The obtained samples were found to be random copolymers. The electrical conductivity of the obtained samples increases with the increase of Cu‐acrylate content, while the activation energy as well as the glass transition temperature decrease.