Natural rubber-poly(methyl methacrylate) interpenetrating polymer networks—morphology and mechanical properties
TL;DR: In this paper, two types of IPNs, viz. full and semi, were prepared and characterized by measurements of tensile strength, elongation at break, tensile modulus, tear strength and toughness and by scanning electron microscopy.
Abstract: Interpenetrating polymer networks (IPNs) were prepared by the sequential mode of synthesis using natural rubber and poly(methyl methacrylate) as the elastomer and plastomer components respectively. Two types of IPNs, viz. full and semi, were prepared and characterized by measurements of tensile strength, elongation at break, tensile modulus, tear strength and toughness and by scanning electron microscopy. Dicumyl peroxide and divinyl benzene were used as the crosslinker of natural rubber and comonomer/crosslinker for methyl methacrylate monomer, with benzoyl peroxide as the polymerization initiator. Effects of changes of blend ratio and extent of crosslinking of both plastomer and elastomer on the properties were examined. Full IPNs were characterized by higher tensile strength, modulus, tear strength and finer phase distribution than the corresponding semi-IPNs, but the latter exhibited higher elongation at break and toughness than full IPNs.
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TL;DR: In this article, semi-interpenetrating networks (semi-IPNs) were prepared from natural rubber (NR) and polystyrene (PS) by the sequential method.
Abstract: Semi-interpenetrating networks (semi-IPNs) were prepared from natural rubber (NR) and polystyrene (PS) by the sequential method. In these semi-IPNs the NR phase was crosslinked while the PS phase was uncrosslinked. Different initiating systems such as dicumyl peroxide (DCP), benzoyl peroxide (BPO), and the azobisisobutyronitrile (AIBN) system were used for polymerizing the PS phase. The blend ratio was varied by controlling the swelling of NR in the styrene monomer. The mechanical properties of the semi-IPNs, namely, density, tensile strength, tear strength, elongation at break, tension set, tensile set, impact strength, and hardness, were determined. The morphology of different IPNs was studied using scanning electron microscopy. A compact morphology with a homogeneous phase distribution was observed in the semi-IPNs. The properties of the semi-IPN do not change much with the initiating system. However, in most cases, the DCP initiating system showed slightly superior performance. The tensile and tear-strength values of the IPNs were found to increase with increasing plastomer content. The crosslink density of the semi-IPNs also increased with increase in the polystyrene content. The experimental values were compared with theoretical models such as series, parallel, Halpin Tsai, Coran, Takayanaki, Kerner, and Kunori. The tensile and tear-fracture surfaces were examined using a scanning electron microscope. The fracture patterns were correlated with the strength and nature of the failure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2327–2344, 2000
22 citations
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TL;DR: The solid state structure of soluble conducting diblock copolymers of polyacetylene-polyisoprene (PA-PI), before and after I 2 -doping, was investigated in this paper using scanning electron microscope (SEM) and small angle X-ray scattering (SAXS).
Abstract: The solid state structure of soluble conducting diblock copolymers of polyacetylene-polyisoprene (PA-PI), before and after I 2 -doping, was investigated in this study using scanning electron microscope (SEM) and small angle X-ray scattering (SAXS). The SAXS study demonstrated that I 2 -doping of the PA-PI diblock copolymer in the solid state resulted in the formation of a rod-like structure of polyacetylene chains, at the nanometre scale, caused by the strong self-association of the doped polyacetylene segments. On the other hand, the SEM micrographs revealed a doping-induced morphology transformation from a homogeneous state to a phase-separated fibrous network at the micrometre scale reflecting the formation of a pseudo interpenetrating polymer network (PIPN) due to the thermodynamic immiscibility between the I 2 -doped polyacetylene ‘rods’ and polyisoprene chains. These results indicate that multiphase materials with ordered structures ranging from the nanometre to micrometre scale can be obtained by I 2 -doping of the PA-PI diblock copolymers in the solid state. The PIPN network thus formed plays an important role in regulating the electrical properties of the I 2 -doped copolymer films.
15 citations
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TL;DR: In this article, the effects of the PMMA content and the crosslinker level in poly(methylmethacrylate) component on the dynamic and physico-mechanical properties of semi-2 interpenetrating polymer networks based on natural rubber and poly (methylmethylamine) were determined.
Abstract: The effects of the PMMA content and the cross-linker level in the poly(methylmethacrylate) component on the dynamic and physico-mechanical properties of semi-2 interpenetrating polymer networks based on natural rubber and poly(methylmethacrylate) were determined. The miscibility of the components in these semi-2 interpenetrating polymer networks was determined using the loss tangent data, obtained from dynamic mechanical thermal analysis and the interphase contents were calculated from modulated scanning calorimetric data. Some component mixing in these semi-2 interpenetrating polymer networks was evident from these modulated differential scanning calorimetric and dynamic mechanical thermal analysis data. The degree of component mixing increased with cross-linker level in the PMMA phase. The PMMA content in the semi-2 IPNs has a significant effect on the tensile and hysteresis behavior of these semi-2 interpenetrating polymer networks. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
11 citations
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TL;DR: In this article, the miscibility of the components in natu- ral rubber-poly(methylmethacrylate) blends for potential use as reinforced rubbers was evaluated using the glass transition temperatures, peak widths of the loss tangent peak at the transition and the complex heat capacity data obtained from dynamic mechanical thermal analysis (DMTA), and modulated differential scanning calorimetry (MDSC).
Abstract: The miscibility of the components in natu- ral rubber-poly(methylmethacrylate) blends for potential use as reinforced rubbers was evaluated using the glass transition temperatures, peak widths of the loss tangent peak at the glass transition and the complex heat capacity data obtained from dynamic mechanical thermal analysis (DMTA), and modulated differential scanning calorimetry (MDSC). In addition, the effect of the poly(methylmetha- crylate) content on the dynamic mechanical and the physi- cal properties such as tensile behavior and hysteresis loss was studied. DMTA and MDSC data clearly indicated that the blends were phase-separated. Nevertheless, the glass transition temperature of the natural rubber component in the 30-50 wt % NR/PMMA blends has shifted to higher temperatures compared to the natural rubber treated under the same condition, indicating some limited extent of mixing of components in these blends. The physicome- chanical properties including moduli at 100, 300, and 500% and tensile strength of the NR/PMMA blends were determined. Incorporation of PMMA into NR matrix improved the strength properties of the NR/PMMA blends prepared reasonably akin to interpenetrating poly- mer networks (IPN) polymerization method. V C 2009 Wiley
10 citations
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TL;DR: In this article, the interpenetrating polymer networks (IPNs) of polyurethane (PU)/polyacrylates have been synthesized by sequential polymerization of castor oil, methylene diisocyanate (MDI), and acrylate monomers such as methyl acrylated (MA), methyl methacrylate (MMA), and ethyl acrylayer (EA), with benzoyl peroxide (BPO) and ethylene glycol dimethyl acrylation (EGDM) as an initiator and cross
Abstract: Interpenetrating polymer networks (IPNs) of polyurethane (PU)/polyacrylates have been synthesized by sequential polymerization of castor oil, methylene diisocyanate (MDI), and acrylate monomers such as methyl acrylate (MA), methyl methacrylate (MMA), and ethyl acrylate (EA); with benzoyl peroxide (BPO) and ethylene glycol dimethyl acrylate (EGDM) as an initiator and crosslinker, respectively. The physico-mechanical properties, such as density, surface hardness, tensile strength, percentage elongation at break, and tear strength; and the optical properties, like total transmittance and haze, of PU/polyacrylate IPNs have been reported. Microcrystalline parameters of IPNs have been computed by using wide angle X-ray scattering (WAXS) recordings. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 764–773, 2005
8 citations
References
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TL;DR: In this paper, the authors point out the wealth of work done on inter penetrating polymer networks (IPNs) or closely related materials and point out that many papers and patents are not so designated, this literature is significantly larger than first imagined.
Abstract: To the surprise of practically no one, research and engineering on multi polymer materials has steadily increased through the 1960s and 1970s More and more people are remarking that we are running out of new monomers to polymerize, and that the improved polymers of the future will depend heavily on synergistic combinations of existing materials In the era of the mid-1960s, three distinct multipolymer combinations were recognized: polymer blends, grafts, and blocks Although inter penetrating polymer networks, lPNs, were prepared very early in polymer history, and already named by Millar in 1960, they played a relatively low-key role in polymer research developments until the late 1960s and 1970s I would prefer to consider the IPNs as a subdivision of the graft copolymers Yet the unique topology of the IPNs imparts properties not easily obtainable without the presence of crosslinking One of the objectives of this book is to point out the wealth of work done on IPNs or closely related materials Since many papers and patents actually concerned with IPNs are not so designated, this literature is significantly larger than first imagined It may also be that many authors will meet each other for the first time on these pages and realize that they are working on a common topology The number of applications suggested in the patent literature is large and growing Included are impact-resistant plastics, ion exchange resins, noise-damping materials, a type of thermoplastic elastomer, and many more"
796 citations
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TL;DR: In this article, the engineering properties of polyurethane-poly(methyl methacrylate) simultaneous interpenetrating networks (SINs) were evaluated and the results indicated that the reinforcement in the ultimate tensile strength was not directly related to 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.
Abstract: 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.
47 citations
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TL;DR: The morphology and loss properties of polymeric composites of poly(methyl methacrylate) (PMMA) and polyurethane (PU) prepared according to an interstitial method have been studied as discussed by the authors.
Abstract: The morphology and loss properties of polymeric composites of poly(methyl methacrylate) (PMMA) and polyurethane (PU) prepared according to an interstitial method have been studied. To a first approximation the structure is shown to consist of PMMA domains embedded in a PU matrix. A second approximation shows that there is some molecular interaction between the polymeric species, probably at the domain boundaries. Variations in the domain size and molecular motions are studied as a function of composition and experimental variables. Attempts are made to correlate these results with the mechanical properties of the composites.
39 citations
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TL;DR: In this paper, the mechanical behavior of polyurethane-poly(methyl methacrylate) interpenetrating polymer networks (PUR/PAc IPN's) was investigated.
Abstract: 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.
22 citations