The effects of acrylate monomers and polystyrene addition on the morphology of DOP‐plasticized styrene–acrylate polymer particles prepared by SPG emulsification and suspension polymerization

Fairly uniform copolymer particles of methyl acrylate (MA), butyl acrylate (BA), or butyl methacrylate (BMA) were synthesized via Shirasu porous glass (SPG) membrane and followed by suspension polymerization. After a single‐step SPG emulsification, the emulsion composed mainly of the monomers. Hydrophobic additives of dioctyl phthalate (DOP), polystyrene molecules, and an oil‐soluble initiator, suspended in an aqueous phase containing poly(vinyl alcohol) (PVA) stabilizer and sodium nitrite inhibitor (NaNO₂), were subsequently subjected to suspension polymerization. Two‐phase copolymers with a soft phase and a hard phase were obtained. The composite particles of poly(St‐co‐MA)/PSt were prepared by varying the St/PSt ratios or the DOP amount. The addition of PSt induced a high viscosity at the dispersion phase. The molecular weight slightly increased with increasing St/PSt concentration. The multiple‐phase separation of the St‐rich phase and PMA domains, observed by transmission electron microscopy, was caused by composition drift because the MA reactivity ratio is greater than that of St. The addition of DOP revealed the greater compatibility between the hard‐St and soft‐MA moieties than that without DOP. The phase morphologies of poly(St‐co‐MA), poly(St‐co‐BMA), and their composites with PSt were revealed under the influence of DOP. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1195–1206, 2006     

Synthesis and properties of soy hull‐reinforced biocomposites from conjugated soybean oil

The tensile and flexural properties of new thermosetting composites made by the free radical polymerization of a conjugated soybean oil (CSO)‐based resin reinforced with soy hulls have been determined for various resin compositions. The effects of reinforcement particle size and filler/resin ratio have been assessed. The thermal stability of the new materials has been determined by thermogravimetric analysis and the wt % of oil incorporation has been calculated after Soxhlet extraction (the extracts have been identified by ¹H‐NMR spectroscopy). The resin consists initially of 50 wt % CSO and varying amounts of divinylbenzene (DVB; 5–15 wt %), dicyclopentadiene (DCPD; 0–10 wt %), and n‐butyl methacrylate (BMA; 25–35 wt %). Two soy hull particle sizes have been tested (<177 and <425 μm) and two different filler/resin ratios have been compared (50 : 50 and 60 : 40). An appropriate cure sequence has been established by differential scanning calorimetry (DSC) analysis. The results show a decrease in the properties whenever DVB or BMA is substituted by DCPD. Also, larger particle sizes and higher filler/resin ratios are found to have a negative effect on the tensile properties of the new materials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Rice hull biocomposites,part 2: Effect of the resin composition on the properties of the composite

A free radical thermoset resin consisting of a copolymer of conjugated linseed oil (CLO) or conjugated soybean oil (CSO), n‐butyl methacrylate (BMA), divinylbenzene (DVB), and maleic anhydride (MA) has been reinforced with rice hulls. Composites containing 70 wt % of the filler were compression molded, the conjugated oil content in the resin was kept constant at 50 wt %, and the relative amounts of BMA, DVB, and MA were varied to afford composites with different resin compositions. Tensile tests, DMA, thermogravimetric analysis, and Soxhlet extraction of the different composites prepared have been used to establish the relationship between resin composition and the properties of the composites. Overall, the mechanical properties tend to improve when MA is introduced into the resin. Scanning electron microscopy of selected samples showed a better filler–resin interaction for MA‐containing composites and samples prepared from CLO exhibit better properties than those prepared from CSO. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

共聚原甲基丙烯酸酯系吸附功能树脂合成及其性能研究

采用悬浮聚合法合成了LMA(甲基丙烯酸十二酯)均聚树脂、BMA(甲基丙烯酸正丁酯)/LMA共聚树脂、BMA/HEMA(甲基丙烯酸( 羟乙酯)共聚树脂、BMA/DVB(二乙烯基苯)共聚树脂以及BMA/HEMA/LMA共聚树脂.研究了单体种类、交联剂种类以及用量与树脂吸附性能、交联密度间的关系,利用FT-IR对树脂试样的化学结构进行了表征.结果表明,与LMA均聚物相比,BMA被引入大分子主链后,BMA/LMA共聚树脂对煤油的吸附量大大降低,对甲苯和三氯乙烯的吸附量增大,而BMA/LMA/HEMA共聚树脂对煤油、甲苯和三氯乙烯的吸附量均有所下降;化学交联型树脂的吸附量随时间变化较小,物理交联型树脂其吸附量随时间变化较为明显;物理交联剂HEMA的质量分数影响树脂的三维网状结构,进而影响树脂的吸附性能;树脂大分子间存在氢键作用,有利于物理交联结构的形成,长侧链LMA结构单元的引入,促使侧链间发生缠结甚至结晶,进一步增强了物理交联结构.     

Synthesis and properties of oil absorption resins filled with polybutadiene

Polybutadiene (PB) is used to fill an oil absorption resin as a physical crosslinker to construct a kind of 3‐dimensional network with a high degree crosslinking and low crosslink density. A series of acrylic resin particles with various compositions are prepared by suspension polymerization, using benzoyl peroxide (BPO) as an initiator and ethylene glycol dimethacrylate (EGDMA) as a chemical crosslinker. The effects of the polymerization temperature, initiator concentration, monomer feed ratio, and chemical and physical crosslinker concentrations on the oil absorbency and gel fraction (degree of crosslinking) are studied. The recipe and operation conditions are optimized as follows: a mass ratio of 3:1 for styrene (St)/dodecyl methacrylate or St/butyl acrylate, 0.5 wt % BPO, and 80°C for 7–8 h. The effect of the physical crosslinker (PB) concentration is complex. The oil absorbency increases with increasing PB at lower EGDMA concentrations. However, under this same condition, particles cannot be formed if the PB concentration is higher than a certain value. By contrast, there is an optimum PB concentration when the EGDMA concentration is higher. The oil absorption speed is also investigated. The presence of PB can speed up absorption. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3309–3314, 2003     

Dispersion copolymerization of acrylamide and dimethyl diallyl ammonium chloride in ethanol‐water solution

Poly (acrylamide‐dimethyldiallylammonium chloride) (PAM‐DMDAAC) particles have been prepared via dispersion polymerizations using poly (vinyl pyrrolidone) (PVP) as a steric stabilizer in ethanol‐water media. The monomer reactivity ratios of acrylamide (AM, r₁) and dimethyldiallylammonium chloride (DMDAAC, r₂) were determined as 6.664 and 0.120, respectively, which means that PAM‐DMDAAC is a nonideal copolymer. The effects of various polymerization parameters (e.g., concentration of monomer and initiator, medium polarity, the ratio of AM to DMDAAC, initial temperature and ethylene diamine tetraacetic acid disodium (EDTA)) on the intrinsic viscosity and conversion of copolymer have been investigated. The copolymer was characterized by FTIR and NMR. The optimum operating conditions for preparing PAM‐DMDAAC were determined as ethanol content 50%, C_monomer (wt %) 40%, n_AM: n_DMDAAC 8 : 2, C_initiator (wt %) 0.04% and initiate temperature 40°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Superabsorbent polymeric materials VIII: Swelling behavior of crosslinked poly[sodium acrylate‐co‐trimethyl methacryloyloxyethyl ammonium iodide] in aqueous salt solutions

A series of xerogels based on sodium acrylate (SA), cationic comonomer, trimethyl methacryloyloxyethyl ammonium iodide (TMMAI), and N,N‐methylene‐bis‐acrylamide (NMBA) were prepared by inverse suspension polymerization. The water absorbency and the swelling behavior for these high absorbent polymers in deionized water and various saline solutions were investigated. Results indicated that the water absorbency for the present copolymer gel increased when a small amount of TMMAI monomer was introduced into the SA gel, then decreased with increase in TMMAI content. The water absorbency was 583 g H₂O/g for a gel sample in deionized water containing 2.5 × 10⁻³ molar fraction TMMAI. But a contrary result was observed for initial absorption rate, that is, the initial absorption rates increased with an increase of TMMAI in deionized water and 0.9 wt % NaCl solution. The absorbency in the chloride salt solution decreased with an increase in the ionic strength of the salt solution. Finally, the adsorption of copper ion by these gels was also investigated. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1665–1674, 2001     

多元共聚高吸油树脂的合成研究

以甲基丙烯酸十八酯(SMA)、丙烯酸丁酯(BA)和苯乙烯(St)为单体,二乙烯苯(DVB)为交联剂,过氧化苯甲酰(BPO)作引发剂,采用悬浮聚合法合成了高吸油性树脂,研究了体系中单体组成及配比、交联剂、分散剂及致孔剂用量等因素对吸油树脂性能的影响。结果表明:m(SMA):m(BA):m(St)=33:67:12,w(DVB)=1%,w(PVA)=1.2%,w(CHCl3)=35%时,所合成的树脂吸油性能最佳,其对柴油、甲苯、四氯化碳的饱和吸油倍率分别可达11.2g/g、18.9g/g、27.4g/g。     

Synthesis and properties of the copolymer of acrylamide with 2‐acrylamido‐2‐methylpropanesulfonic acid

A cross‐linked copolymer of acrylamide (AM) with 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS) was prepared by solution polymerization. In this reaction, potassium persulfate (PPS) and N,N′‐methylenebisacrylamide (NMBA) were used as initiator and cross‐linker, respectively. This copolymer, poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonic acid) (PAMA), can absorb up to 1749 g/g of dry polymer in distilled water and 87 g/g of dry polymer in 0.9 wt % NaCl aqueous solution at room temperature. The PAMA also has excellent performance in absorbing pure alcohols. Its absorbencies in methanol and glycol are about 310 g/g and 660 g/g, respectively. The effects of various salt solutions on the swelling properties were studied systematically, and the relationship between the absorbency and the concentrations of the different salt solutions can be expressed as Q = kcⁿ. Experimental results indicate that the absorbencies were stable at different water temperatures. The swelling rates of the copolymer in distilled water and a water/ethanol mixture (V_water:V_alcohol = 1:1) were also investigated, and the results showed that PAMA could absorb 992 g of distilled water per gram of dry polymer and 739 g of water/ethanol mixture per gram of dry polymer in five minutes. The PAMA has such good water retention at higher temperatures that the swollen gel can retain 71.6 and 49.5% of the maximum absorbency after being heated for 9 hours at 60 and 80 °C, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3481–3487, 2003     

Synthesis and characterization of poly(methyl methacrylate-butyl acrylate) by using glow-discharge electrolysis plasma

A highly absorptive resin was prepared by glow-discharge electrolysis plasma initiated suspension copolymerization, in which methyl methacrylate and butyl acrylate were used as monomers, N,N′-methylenebis(acrylamide) as crosslinking agent, polyvinyl alcohol as dispersant, and Na₂SO₄ solution as supporting electrolyte. To optimize the synthesis conditions, the discharge voltage, discharge time, polymerization temperature, the ratio of monomers, the amounts of crosslinking agent and supporting electrolyte, as well as the ratio of water to oil, were examined in detail. The structure and properties of the obtained resin were characterized by means of attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM), respectively. The oil absorbency, absorption rate, absorption selectivity, and network parameters of the resin were also examined. Results showed that under the optimal conditions, the oil absorbency was about 28.5 g/g for benzene, 25.4 g/g for toluene, 28.0 g/g for xylene, 38.1 g/g for chloroform, and 37.0 g/g for carbon tetrachloride.     

Preparation of poly(styrene‐co‐isobornyl methacrylate) beads having controlled glass transition temperature by suspension polymerization

The styrene (St) and isobornyl methacrylate (IBMA) random copolymer beads with controlled glass transition temperature (T_g), in the range of 105–158°C, were successfully prepared by suspension polymerization. The influence of the ratios of IBMA in monomer feeds on the copolymerization yields, the molecular weights and molecular weight distributions of the produced copolymers, the copolymer compositions and the T_gs of these copolymers was investigated systematically. The monomer reactivity ratios were r₁ (St) = 0.57 and r₂ (IBMA) = 0.20 with benzyl peroxide as initiator at 90°C, respectively. As the mass fraction of IBMA in monomer feeds was about 40 wt %, it was observed that the monomer conversion could be up to 90 wt %. The fractions of IBMA unit in copolymers were in the range of 35–40 wt % and T_gs of the corresponding copolymers were in the range of 119.6–128°C while the monomer conversion increased from 0 to greater than 90 wt %. In addition, the effects of other factors, such as the dispersants, polymerization time and the initiator concentration on the copolymerization were also discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The effect of nonionic monomer HAM on properties of cationic surfactant‐free acrylic/alkyd hybrid emulsion

A series of cationic acrylic/alkyd resin (CPAAR) hybrid emulsions was successfully prepared through surfactant‐free emulsion polymerization, using methacryloxyethyltrimethyl ammonium chloride, methyl methacrylate, butyl acrylate and alkyd resin as reaction monomers. And nonionic N‐hydroxymethyl acrylamide (HAM) of different content was simultaneously incorporated into the CPAAR backbone. The structure of CPAAR copolymer was characterized by Fourier transform infared spectrometer, and then the effect of HAM content on properties of CPAAR emulsions was studied by particle size analyzer, transmission electron microscopy and rheometer. In addition, thermal properties, water absorption and contact angle of CPAAR latex films were also investigated. The results showed that the CPAAR emulsions prepared with 4.9 wt % HAM displayed smallest average particle size of 92.2 nm. As HAM content increased from 0 to 19.6 wt %, the initial viscosity of the emulsions increased from 22.48 to 53 mPa.s. At the same time, the emulsions transferred from Newtonian fluid to pseudoplastic fluid, and a transition from viscous liquid to elastic liquid was also detected. Meanwhile, the degradation temperature at 5% weight loss increased by 30.59°C. In addition, with increasing HAM content from 0 to 4.9 wt %, the water absorption and surface free energy of films increased by 4.42% and 5.02 mJ m^?2, respectively. However, the water absorption and surface free energy kept almost invariable with further increase in HAM content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41406.     

Batch and semicontinuous emulsion copolymerization of vinylidene chloride and butyl methacrylate. I. Kinetics in VDC–BMA emulsion polymerization and surface and colloidal properties of VDC–BMA latexes

Vinylidene chloride (VDC)—butyl methacrylate (BMA) comonomer mixtures with various composition (83 : 17, 60 : 40, 33 : 67 in mol %) were polymerized at 25°C using redox catalyst by batch and seeded semicontinuous emulsion copolymerization. The reactivity ratios determined in VDC (M₁)—BMA (M₂) emulsion copolymerization system were r₁ = 0.22 and r₂ = 2.41. Seven 35% solids (83 : 17 mol %) VDC–BMA copolymer latexes were prepared: one batch (G), one seeded batch (F), and 5 seeded semicontinuous polymerizations of 5 different monomer feed rates ranging from 0.27 (A) to 1.10 wt %/min (E). The kinetic studies of seeded semicontinuous polymerizations A-E showed that the rates of polymerizations (R_p) were controlled by the monomer addition rates (R_a). The conversion versus time curves for the polymerizations of 0 : 100–100 : 0 VDC–BMA mixtures by batch polymerization showed that the rate of polymerization (R_p) was a function of the number of particles, and that the rate of polymerization in a latex particle (R_pp) increased with increasing proportions of butyl methacrylate in the monomer mixture. All of the latexes had narrow particle size distributions. The greater particle number density in VDC polymerization and the greater water solubility of VDC suggest that the homogeneous nucleation mechanism is operative in VDC–BMA copolymerizations. The latex copolymers prepared by semicontinuous polymerization had lower number-and weight-average molecular weights than those of the corresponding batch copolymers, resulting from the monomer starvation occurring during the semicontinuous polymerization. The surface characterization study of the cleaned latexes showed that for the latexes by batch process, the surface charge density derived from strong-acid groups decreased with increasing proportion of VDC in the monomer mixture. On the other hand, for the latexes prepared by semicontinuous polymerization, the surface charge density derived from strong-acid groups did not depend on the monomer composition of the copolymers.     

Enhanced fracture toughness of epoxy resins with novel amine‐terminated poly(arylene ether sulfone)–carboxylic‐terminated butadiene‐acrylonitrile–poly(arylene ether sulfone) triblock copolymers

Amine‐terminated poly(arylene ether sulfone)–carboxylic‐terminated butadiene‐acrylonitrile–poly(arylene ether sulfone) (PES‐CTBN‐PES) triblock copolymers with controlled molecular weights of 15,000 (15K) or 20,000 (20K) g/mol were synthesized from amine‐terminated PES oligomer and commercial CTBN rubber (CTBN 1300x13). The copolymers were utilized to modify a diglycidyl ether of bisphenol A epoxy resin by varying the loading from 5 to 40 wt %. The epoxy resins were cured with 4,4′‐diaminodiphenylsulfone and subjected to tests for thermal properties, plane strain fracture toughness (K_IC), flexural properties, and solvent resistance measurements. The fracture surfaces were analyzed with SEM to elucidate the toughening mechanism. The properties of copolymer‐toughened epoxy resins were compared to those of samples modified by PES/CTBN blends, PES oligomer, or CTBN. The PES‐CTBN‐PES copolymer (20K) showed a K_IC of 2.33 MPa m^0.5 at 40 wt % loading while maintaining good flexural properties and chemical resistance. However, the epoxy resin modified with a CTBN/8K PES blend (2:1) exhibited lower K_IC (1.82 MPa m^0.5), lower flexural properties, and poorer thermal properties and solvent resistance compared to the 20K PES‐CTBN‐PES copolymer‐toughened samples. The high fracture toughness with the PES‐CTBN‐PES copolymer is believed to be due to the ductile fracture of the continuous PES‐rich phases, as well as the cavitation of the rubber‐rich phases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1556–1565, 2002; DOI 10.1002/app.10390     

Studies of precipitated polymerization of acrylamide with quaternary ammonium cationic comonomer in potassium citrate solution

Copolymer particles consisting of acrylamide (AM) and cationic comonomer 2‐methyl acryloyloxyethyl trimethyl ammonium chloride (DMC) were prepared by precipitation polymerization in an solution of potassium citrate using ammonium persulfate ((NH₄)₂S₂O₈) and sodium sulfite (Na₂SO₃) as an initiator. The product poly(acrylamide‐2‐methyl acryloyloxyethyl trimethyl ammonium chloride) [Poly(DMC‐AM)] is a water‐soluble cationic polyelectrolyte. The solubility of DMC, AM and Poly(DMC‐AM) in potassium citrate solution were measured, combined with the theory of solubility parameter, and the experiment results indicate that the solubility of DMC and AM is much higher than that of Poly(DMC‐AM), and also the mechanism of copolymer precipitated in salt solution was discussed. The factors influencing the conversion of comonomers were examined, such as salt mass fraction, polymerization temperature, monomers mass fraction, initiator mass fraction, and so on. The results of experiments indicate that the best conditions are salt mass fraction = 57%, monomers mass fraction = 3%, m(DMC) : m(AM) = 3 : 1, initiator mass fraction = 0.08%, polymerization temperature = 50°C, reaction time = 2 h, and the conversion is 86.4%. And the qualitative analysis experimental method for copolymer by infrared absorption spectrum show that [Poly(DMC‐AM)] was successfully synthesized by precipitation polymerization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Modified emulsifier‐free emulsion polymerization of butyl methacrylate with ionic or/and nonionic comonomers

A modified emulsifier‐free emulsion polymerization of butyl methacrylate (BMA) with ionic or/and nonionic comonomers was successfully used to prepare nanosized poly(butyl methacrylate) (PBMA) latices with high polymer contents. After seeding particles were generated in an initial emulsion system, consisting of a portion of BMA, water, ionic comonomer [sodium styrenesulfonate (NaSS)] or nonionic comonomer [2‐hydroxyethyl methacrylate (HEMA)] and potassium persulfate, most of the BMA monomer or the mixture of BMA and HEMA was added dropwise to the polymerizing emulsion over a period of 6–12 h. Stable latices with high PBMA contents up to 27% were obtained. It was found that the latex particle sizes (2R_h) were largely reduced (34 nm) by the continuous addition of monomer(s) compared to those (107 nm) obtained by the batch polymerization method. The effect of comonomer concentration on the particle size, the number of PBMA particles/mL of latex (N_d), and the molar mass (M_w) of copolymer during the polymerization were discussed. The surface compositions of latex particles were analyzed by X‐ray photoelectron spectroscopy, indicating that the surface of latex particles was significantly enriched in NaSS or/and HEMA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3080–3087, 2004     

Synthesis of high molecular weight copolymer of styrene and butadiene bearing high 1,4‐cis butadiene unit from copolymerization with CpTiCl3/methylaluminoxane catalyst

Copolymerization of styrene (St) and butadiene (Bd) with CpTiCl₃/methylaluminoxane (MAO) catalyst in the presence or absence of chloranil (CA) was investigated. The CpTiCl₃/MAO catalyst showed a high activity for the copolymerization of St with Bd. The 1,4‐cis contents in the Bd units for the copolymerization of St and Bd with the CpTiCl₃/MAO catalyst was observed, and the 1,4‐cis content was optimum at a MAO/Ti mole ratio of around 225. The effect of the polymerization temperature on the copolymerization was noted, as was the effect of the 1,4‐cis microstructure in the Bd units for the copolymerization of St and Bd. The addition of CA to the CpTiCl₃/MAO catalyst was found to influence the molecular weight of the copolymer. The high weight‐average molecular weight copolymer (M_w = ca. 50 × 10⁴) consisting of mainly a 1,4‐cis microstructure of Bd units (1,4‐cis = 80.0%) was obtained from the copolymerization with the CpTiCl₃/MAO catalyst in the presence of CA (CA/Ti mole ratio = 1) at 0°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2942–2946, 2003     

Anticorrosive properties of epoxy resin coatings cured by aniline/p‐phenylenediamine copolymer

Aniline/p‐phenylenediamine copolymer [poly(ANI‐co‐p‐PDA)] was prepared by chemical oxidative polymerization. FTIR and ¹H‐NMR analysis indicate that the poly(ANI‐co‐p‐PDA) is oligomer with end‐capped amino groups, which can cure epoxy resin. The anticorrosion performance of carbon steel (CS) samples coated by epoxy resin coating cured with poly(ANI‐co‐p‐PDA) and epoxy resin coating cured with triethylenetetramine exposed to 5 wt % NaCl and 0.1 mol/L HCl aqueous solution is studied by the potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the CS coated by epoxy resin coating cured with poly (ANI‐co‐p‐PDA) has more excellent corrosion protection than that of epoxy resin coating cured with triethylenetetramine. Raman spectroscopy analysis indicates that the surface of CS coated by epoxy resin coating cured with poly(ANI‐co‐p‐PDA) forms passive layer, which is composed of α‐Fe₂O₃. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Encapsulation of titanium dioxide in styrene/n‐butyl acrylate copolymer by miniemulsion polymerization

Miniemulsion copolymerization of styrene/n‐butyl acrylate was investigated as a means of encapsulating hydrophilic titanium dioxide (TiO₂) in a film‐forming polymer. Dispersion studies of the TiO₂ were first carried out to determine the choice of stabilizer, its concentration, and the dispersion process conditions for obtaining stable TiO₂ particles with minimum particle size. Through screening studies of various functional stabilizers and shelf‐life stability studies at both room and polymerization temperatures, Solsperse 32,000 was selected to give relatively small and stable TiO₂ particles at 1 wt % stabilizer and with 20–25 min sonification. The subsequent encapsulation of the dispersed TiO₂ particles in styrene/n‐butyl acrylate copolymer (St/BA) via miniemulsion polymerization was carried out and compared with a control study using styrene monomer alone. The lattices resulting from the miniemulsion encapsulation polymerizations were characterized in terms of the encapsulation efficiencies (via density gradient column separations; DGC) and particle size (via dynamic light scattering). Encapsulation efficiencies revealed that complete encapsulation of all of the TiO₂ by all of the polymer was not achieved. The maximum encapsulation efficiencies were 79.1% TiO₂ inside 61.7% polystyrene and 63.6% TiO₂ inside 38.5% St/BA copolymer. As the density of the particles collected from the DGC increased from one layer to another, both the average particle size and the number of the TiO₂ particles contained in each latex particle increased. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3479–3486, 2006     

Soybean and linseed oil‐based composites reinforced with wood flour and wood fibers

Composites consisting of a conjugated linseed or soybean oil‐based thermoset reinforced with wood flour and wood fibers have been prepared by free radical polymerization. The thermoset resin consists of a copolymer of conjugated linseed oil (CLO) or conjugated soybean oil (CSO), n‐butyl methacrylate (BMA), divinylbenzene (DVB), and maleic anhydride (MA). The composites were cured at 180°C and 600 psi and postcured for 2 h at 200°C under atmospheric pressure. The effect of varying filler load, time of cure, filler particle size, origin of the fillers, and resin composition has been assessed by means of tensile tests, DMA, TGA, Soxhlet extraction followed by ¹H‐NMR spectroscopic analysis of the extracts, and DSC. The best processing conditions have been established for the pine wood flour composites. It has been observed that the addition of MA to the resin composition improves the filler‐resin interaction. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012