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     

Thermomechanical properties and morphology of interpenetrating polymer networks of polyurethane–poly(methyl methacrylate)

Interpenetrating networks (IPNs) of polybutadiene‐based polyurethane (PU) and poly(methyl methacrylate) (PMMA) were synthesized. The effect of the incorporation of 2% glycidyl methacrylate (GMA) and 2‐hydroxyethyl methacrylate (2‐HEMA) on the thermal, mechanical, and morphological properties of IPNs was investigated. Both 2‐HEMA and GMA led to improvements in these properties. However, 2‐HEMA‐containing IPNs showed somewhat better tensile strength, elongation, and damping characteristics. The morphology of IPNs containing 2‐HEMA showed better mixing of the components. The improvement in the properties was observed for up to 40% PMMA in the IPNs. Differential scanning calorimetry thermograms showed the presence of three glass transitions. The third glass‐transition temperature was explained by possible grafting of methyl methacrylate onto PU. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1576–1585, 2002     

Polyurethane-poly(methyl methacrylate) interpenetrating polymer networks: Some mechanical properties

The mechanical behavior of polyurethane-poly(methyl methacrylate) interpenetrating polymer networks (PUR/PAc IPN's) was investigated. Stress-strain and impact resistance measurements were made on IPN's with a variable PUR content. The effect of the degree of crosslinking of each network on the mechanical properties was also studied. It appears that only the ultimate elongation varies largely upon changing the crosslink degree. The results are interpreted in terms of the contribution of each network to the mechanical behavior, but also by the interpenetration of both components and by the phase continuity of the PAc network.     

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     

Rheological,mechanical, and morphological studies of epoxy/poly(methyl methacrylate) semi‐interpenetrating polymer networks

Semi‐interpenetrating polymer networks (semi‐IPNs) of epoxy resin and poly(methyl methacrylate) (PMMA) were synthesized. Methyl methacrylate (MMA) was polymerized by free radical mechanism with azo‐bis‐isobutyronitrile in the presence of oligomeric epoxy resin (DGEBA), and hexahydrophthalic anhydride as crosslinking agent. The gelation and vitrification transitions during cure/polymerization processes have been examined using parallel‐plates rheological technique. From differential scanning calorimetry and rheological techniques, it was suggested that both curing and polymerization processes occur simultaneously. However, the gelation time was longer for the semi‐IPN than those observed for the cure of pure DGEBA or polymerization of MMA. The gelation time increased significantly when 5% of MMA was employed, suggesting a diluent effect of the monomer. Higher amount of MMA resulted in a decrease of gel time, probably because of the simultaneous polymerization of MMA during the curing process. Structural examination of the semi‐IPNs, using scanning electron microscopy, revealed phase separation in nanoscale size for semi‐IPNs containing PMMA at concentrations up to 15%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Epoxy–poly(butyl methacrylate) interpenetrating polymer networks: Morphology and various physical,mechanical, and thermal properties

Semi- and full interpenetrating polymer networks (IPNs) of epoxy resin and poly(butyl methacrylate) (PBMA) were prepared by the sequential mode of synthesis. These were characterized with respect to their mechanical properties, such as ultimate tensile strength, percent elongation at break, and modulus. The densities of these samples were evaluated and compared. Differential scanning calorimetry (DSC) and thermogravimetric analysis were undertaken for thermal characterization of the IPNs. Phase morphology was studied by polarized light microscopy of the undeformed specimens and by scanning electron microscopy of the fractured surfaces of samples undergoing tensile failure. The effects of variations of the blend ratios on the above-mentioned properties were examined. A gradual decrease in modulus and tensile strength was observed for both the semi- and full IPNs with consequent increases in elongation at break and toughness as the proportion of PBMA increased. The densities also followed the same pattern. Semi-IPNs, however, were characterized by higher densities, tensile strengths, and moduli than the corresponding full IPNs. The DSC tracings displayed broadening of transitions, indicating some phase blending. The percent weight retentions in the thermal decomposition of the IPNs and pseudo-IPNs were higher than that observed during the thermal degradation of the epoxy resin homopolymer network. Phase-separated PBMA domains of various sizes were presumed to be responsible for the increased toughness of PBMA-modified epoxy. © 1996 John Wiley & Sons, Inc.     

Polyurethane methacrylate/silicone interpenetrating polymer networks synthesis,thermal and mechanical properties

The synthesis of an interpenetrating polymer network (IPN) combining a polyurethane methacrylate network (PUMA) and a silicone network is reported. The PUMA network is synthesized by UV-light cure. The silicone network is formed through a condensation between α, ω dihydroxy polydimethyl siloxane and γ-methacryloxypropyl trimethoxy silane (γ-MPS) as a cross-linking agent. The IPN is prepared by different mechanism: radical and condensation types. According to thermogravimetric analysis of the hybrid material, the thermal stability stayed unchanged but the kinetic of degradation changed. Tg decreased with increasing silica content. The thermal cure process under humid atmosphere influence properties just for PUMA/4.2%Si^UV+T. Condensation between γ-MPS decreases the penetration depth from 158 to 82 μm and increases the mechanical glass transition temperature from 106 to 141 °C.     

聚氨酯/聚甲基丙烯酸甲酯互穿网络的阻尼性能及相态

引言聚合物互穿网络体系由于在其形成过程中产生特殊的物理拓扑结构,使得该体系是一种永久缠结在一起的聚合物"合金"[1]。同时,由于构成该体系的聚合物组分往往不相容或部分相容,在其形成     

SBS/P(St-MMA)热塑性互穿聚合物网络结构与力学性能

采用原子转移自由基聚合(ATRP)法合成了苯乙烯一甲基丙烯酸甲酯共聚物[P(St-MMA)]。采用分步法制备了SBS／P(St-MMA)热塑性互穿聚合物网络(TIPN)。研究了P(St-MMA)质量分数、MMA／St(摩尔比,下同)和不同聚合方式对TIPN结构和力学性能的影响。结果表明：生成了具有较窄相对分子质量分布的P(St-MMA);P(St-MMA)质量分数在30％,左右时,采用ATRP法制备的SBS／P(St-MMA)TIPN拉伸强度和扯断伸长率达到最大;随MMA／St增加,TIPN拉伸强度增大,扯断伸长率不变。常规自由基聚合法制备的TIPN与ATRP法相比,前者相对分子质量高,相对分子质量分布宽,拉伸强度高,扯断伸长率随P(St-MMA)质量分数增加而下降。     

Physical,mechanical, and morphological behavior of sequential polybutadiene–poly(methyl methacrylate) interpenetrating polymer networks

Both full and semi-interpenetrating polymer networks (IPNs) of polybutadiene and poly(methyl methacrylate) were synthesized by sequential polymerization. The effect of compositional variation and the cross-linking agent of both elastomer and plastomer on the physical, mechanical, and morphological properties were investigated. Full-IPNs exhibited improved tensile strength, modulus, tear strength, gel content, and density, whereas the corresponding semi-IPNs exhibited better toughness and elongation at break. Phase morphology of full-IPNs were characterized by compact, tight network structures compared to those of semi-IPNs. © 1994 John Wiley & Sons, Inc.     

Preparation of SBS/poly(styrene–methyl methacrylate) thermoplastic interpenetrating polymer network

SBS as polymer I, poly(styrene–methyl methacrylate) polymerized by atom transfer radical polymerization as polymer II, and a thermoplastic interpenetrating polymer network of SBS/poly(styrene–methyl methacrylate) were prepared by the sequential method. The effects of the polymerization temperature, the composition of the catalyst, the ratio of the monomers studied, and the kinetics at 90°C were also investigated. It was shown that when polymerization was initiated by a BPO/CuCl/bpy (BPO:CuCl:bpy = 1:1:3) system at 90°C, the mass averaged molecular weight of the poly(styrene–methyl methacrylate) increased with monomer conversion, and the polydispersities were kept very low. Fourier transform infrared spectroscopy and gel permeation chromatogram showed that poly(styrene–methyl methacrylate) with low polydispersities had been synthesized. Thus, a thermoplastic interpenetrating polymer network comprised of both narrow molecular‐weight‐distribution components was successfully prepared. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2007–2011, 2003     

Latex interpenetrating polymer networks based on polyacrylates and poly(methyl methacrylate)

The effect of methacrylic acid (MAA) concentration in the polyacrylate seed on the formation of latex interpenetrating polymer networks (LIPNs) with poly(methyl methacrylate) (PMMA) as polymer II in the ratio of 65 : 35 (w/w) has been studied. LIPNs were prepared using three different seeds having the compositions of n-butyl acrylate (BA), methyl methacrylate (MMA), and tetra(ethylene glycol)dimethacrylate (TEGDM) in the ratio of 55 : 45 : 0.7 by weight and varying amounts of MAA (0, 2.5, and 6% by wt) at two different pH values (∼ 3.3 and 8.5). LIPNs prepared from seeds having MAA > 2.5% resulted in the formation of continuous films, whereas LIPNs without MAA in the seed yielded discontinuous films (i.e., films with many cracks). Characterization using differential scanning calorimetry (DSC) showed the presence of multiphase morphology in all the LIPNs, indicating better mixing of the two polymers. Another set of LIPNs using the seed of the composition BA : MMA : TEGDM in the ratio of 63 : 37 : 6 : 0.7 by wt, possessing a glass transition temperature of 0°C and PMMA as polymer II, was prepared at two different pH values, as mentioned earlier, and with two different initiators—namely, 2,2′-azobisisobutyronitrile (AIBN) and potassium persulfate (PPS)—for the polymerization of monomer II. The tensile strength and hardness of both the LIPNs processed at high pH (8.5) did not show significant differences, whereas the LIPNs prepared at low pH using the AIBN initiator showed an inverted core-shell morphology possessing very low hardness and tensile strength with high elongation. The PPS-initiated polymer showed core–shell morphology yielding film of poor strength. © 1996 John Wiley & Sons, Inc.     

Polyurethane interpenetrating polymer networks. V. Engineering properties of polyurethane–poly(methyl methacrylate) IPN's

The engineering properties of polyurethane–poly(methyl methacrylate) simultaneous interpenetrating networks (SIN's) were evaluated. The hardness behavior reflected the observed phase inversion in the electron-microscopic studies. The maximum ultimate tensile strength was observed at 85% polyurethane–15% poly(methyl methacrylate) IPN and was due to the filler-reinforcing effect of the rigid poly(methyl methacrylate) phase. The ultimate tensile strenght of the 75/25 polyurethane–poly(methyl methacrylate) IPN was higher than that of the corresponding pseudo-IPN's (only one network crosslinked) and the linear blend. The leathery and glassy compositions did not show any reinforcement in the ultimate tensile strength. This indicated that the reinforcement in the ultimate tensile strength was not directly related to interpenetration (by increased physical entanglement crosslinks), but indirectly related by reducing the rigid phase domain sizes and increasing the adhesion between the two phases, thus enhancing the filler-reinforcing effect similar to that observed in a carbon black-filled rubber. The tear strengths of the polyurethane-rich IPN's pseudo-IPN's, and linear blends were found to be higher than that of the pure polyurethane as a combined result of increased modulus and tensile strength. The weight retentions in the thermal decomposition of the IPN's, pseudo-IPN's, and linear blends were higher than the proportional average of the component networks. The results seemed to indicate that this enhancement was related to the presence of the unzipped methyl methacrylate monomer. It was suggested that the monomers acted as radical scavengers in the polyurethane degradation, thus delaying the further reaction of the polyurethane radicals into volatile amines, isocyanates, alcohols, olefins, and carbon dioxide.     

Study on the properties,morphology, and applications of castor oil polyurethane—poly(methyl methacrylate) IPNs

A series of castor oil polyurethane—poly(methyl methacrylate) interpenetrating polymer networks (IPN COPU/PMMA) were produced from castor oil, toluene diisocyanate, and methyl methacrylate. The properties and morphology of the IPNs were estimated. The adhesives based on the IPN COPU/PMMA prepolymer were prepared and the influence of the composition on the adhesion strength was studied. The experimental results showed that the adhesives have an effective adhesive power for metals and these adhesives have good prospects in a practical project. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1393–1401, 1997     

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     

Uralkyd and poly (butyl methacrylate) interpenetrating polymer networks

ABSTRACT:: Hydroxyl terminated alkyds synthesized from castor oil, glycerol, and different dibasic acids were used to develop uralkyds and their interpenetrating polymer networks (IPNs) with polybutyl methacrylate (PBMA). Glass transition temperature measurements gave the evidence of interpenetration. The IPNs were characterized for their physicomechanical properties and their phase morphology was studied by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). As the concentration of the uralkyd in IPNs increases, a gradual increase in elongation, density, and swelling with a consequent decrease in the hardness were observed for all IPNs. Swelling is relatively more prominent in methyl ethyl ketone (MEK) and toluene than in water. From SEM it was observed that IPNs of PBMA‐uralkyd containing phthalic anhydride (UA‐P) as an acid part showed greater compatibility than those containing dimethyl terephthalate (UA‐D). From thermogravimetric analysis (TGA) no significant change was observed in the degradation behavior of the IPNs. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 825–832, 2000     

Preparation and characterizations of interpenetrating polymer network hydrogels of poly(ethylene oxide) and poly(methyl methacrylate)

Interpenetrating polymer network (IPN) hydrogels based on poly(ethylene oxide) and poly(methyl methacrylate) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone and ethylene glycol dimethacrylate as initiators and crosslinkers, respectively. The IPN hydrogels were analyzed for sorption behavior at 25°C and at a relative humidity of 95% using dynamic vapor sorption. The IPN hydrogels exhibited a relatively high equilibrium water content in the range of 13–68%. The state of water in the swollen IPN hydrogels was investigated using differential scanning calorimetry. The free water in the hydrogels increased as the hydrophilic content increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 258–262, 2003     

Sequential interpenetrating polymer network of poly(ethyl methacrylate) and carboxylated nitrile rubber: Dynamic mechanical analysis and morphology

An interpenetrating polymer network (IPN) based on poly(ethyl methacrylate) (PEMA) and carboxylated nitrile rubber was synthesized. Peroxide crosslinked XNBR was swollen in ethyl methacrylate containing benzoyl peroxide as initiator and tetraethylene glycol dimethacrylate as crosslinking agent. A full and sequential IPN is formed by the two independently crosslinked phases of XNBR and PEMA. Dynamic mechanical analysis of the 50/50 XNBR/PEMA IPN shows a single, broad peak whereas a 50/50 blend shows two distinct peaks, indicating the pinning down of a microheterogeneous structure during the IPN formation rather that macrophase separation as in blends. SEM analysis confirms the development of a cocontinuous intimate structure of the IPN. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1487–1491, 2005     

Studies on semi‐interpenetrating polymer network based on nitrile rubber and poly(methyl methacrylate)

Sequential interpenetrating polymer networks (IPNs) based on nitrile rubber and poly(methyl methacrylate) (PMMA) were synthesized. IPN compositions were varied by varying the swelling time. Two methods were adopted for making IPNs. The first method is “single‐step IPN” (SIPN) and the second method is “multistep IPN” (MIPN). The compositions were fixed around 90, 80, 70, 60 and 50% of NBR. In SIPN mode, swelling in monomer and subsequent curing was done once. In MIPN mode, swelling in monomer and curing was repeatedly done. Tensile strength of IPNs was found to increase with PMMA content, MIPN showing higher strength compared to SIPN. Dynamic modulus showed a similar trend. The tan δ value was found to decrease with PMMA content. At 62/38 nitrile rubber (NBR)/PMMA, MIPN composition isolated tan δ peaks appeared near glass transition temperatures of NBR and PMMA, respectively. Scanning electron micrograph showed phase‐separated morphology at the same MIPN composition. Solvent resistance increased with IPN formation maintaining higher resistance for MIPN compared to SIPN. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 354–360, 2004     

Viscoelastic properties,morphology, and thermal stability of rigid and plasticized poly(vinyl chloride)/poly(methyl methacrylate) blends

Viscoelastic properties, morphology, and thermal stability of rigid and plasticized poly(vinyl chloride)/poly (methyl methacrylate) (PVC/PMMA) blends were studied. For that purpose, blends of variable composition from 0 to 100 wt% were prepared in the presence (15, 30, and 50 wt%) and in the absence of di(2‐ethylhexyl) phthalate as plasticizer. Their miscibility was investigated by using dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). The DMTA and SEM results showed that the two polymers are miscible. Thermogravimetric studies on these blends were carried out in a flowing atmosphere of air from ambient temperature to 550°C. The results showed that the thermal degradation of rigid and plasticized PVC/PMMA in this broad range of temperature is a three‐step process and that PMMA exerted a stabilizing effect on the thermal degradation of PVC during the first step by reducing the rate of dehydrochlorination. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers