Two-component Interpenetrating Polymer Networks Research Articles

SAXS measurements of the interface in polyacrylate and epoxy interpenetrating networks with fractal geometry

The interface thickness in two-component interpenetrating polymer networks (IPN) system based on polyacrylate and epoxy were determined using small-angle X-ray scattering (SAXS) in terms of the theory proposed by Ruland. The thickness was found to be nonexistent for the samples at various compositions and synthesized at variable conditions—temperature and initiator concentration. By viewing the system as a two-phase system with a sharp boundary, the roughness of the interface was described by fractal dimension, D, which slightly varies with composition and synthesis condition. Length scales in which surface fractals are proved to be correct exist for each sample and range from 0.02 to 0.4 Å−1. The interface in the present IPN system was treated as fractal, which reasonably explained the differences between Porod's law and experimental data, and gained an insight into the interaction between different segments on the interface. © 1997 Elsevier Science Ltd.

Interpenetrating polymer networks from polyurethanes and poly(methyl acrylate)

AbstractSimultaneous two‐component interpenetrating polymer networks (IPNs) of polyurethane (PU)–poly(methyl acrylate) (PMA) were prepared, as well as the corresponding pseudo‐IPNs. A comparison was made between the full IPNs, pseudo‐IPNs, and the respective homopolymers. Their ultimate mechanical properties were obtained and the dynamic glass transition temperatures (Tg's) were found using a thermomechanical analyzer. At all compositions, a single Tg(except 50–50 wt %) was found.

Interpenetrating polymer networks from castor oil-based polyurethane and poly(ethyl methacrylate) XVII

Two-component interpenetrating polymer networks (IPNs) of castor oil-based polyurethane (PU) and poly(ethyl methacrylate) (PEMA) were prepared by sequential polymerization. The liquid polyurethanes were formed by reacting the hydroxyl group of castor oil with isophorone diisocyanate at different NCO/OH ratios. These polyurethanes were swollen in ethyl methacrylate monomer, which was subsequently polymerized by radical polymerization initiated with benzoyl peroxide in the presence of crosslinkers, ethylene glycol dimethacrylate and 1,3-propanediamine. A series of PU/PEMA interpenetrating polymer networks (IPNs) were obtained as tough films. These IPNs were characterized in terms of: resistance to chemical reagents, thermal behaviour and dynamic mechanical thermal analysis. The morphology was determined by scanning electron microscopy, and dielectric properties at different temperatures were studied.

Two-Component Interpenetrating Polymer Networks (Ipn's) From Polyurethane and Epoxies

Modified Liquid MOCA (MLM) has been shown to have potential industrial applications in interpenetrating polymer networks (IPN's). This is due to its lower toxicity, low viscosity, appropriate crosslinking kinetics and ease of handling in comparison with unmodified MOCA. Two-component IPN systems prepared from polyurethanes and epoxies, utilizing MLM as a urethane curative, have exhibited good physical and mechanical properties. One of the most significant advantages of IPN's is their ability to achieve high modulus polymer alloys without the use of fillers that increase viscosities, making processing difficult. Further advances in these systems by the use of MLM as a urethane curative have also lessened many of the processing diffi culties for these materials.

Dynamic mechanical properties of interpenetrating polymer networks formed by UV curing processes

Abstract Two-component interpenetrating polymer networks (IPN) were made by stepwise synthesis by UV-irradiated polymerization and heat curing. The mechanical properties of normal IPN, inverse IPN and SIN (simultaneous interpenetrating networks) prepared with acrylate and epoxy were studied. Unique mechanical properties were found in each case. All of these iPN systems were composed of the individual preswollen networks. A homogeneous system is produced in the inverse IPN and SIN, while a heterogeneous system is brought about in the normal IPN. Glass transition temperatures for the inverse IPN and the SIN are lower than the normal IPN, and are attributed to molecular packing effects.

Stress–strain properties of polyurethane–polyacrylate interpenetrating polymer networks

Two-component interpenetrating polymer networks (IPN) of the SIN type (simultaneous interpenetrating networks) were prepared from two different polyurethanes (a polyester type and a polyether type) and a polyacrylate of two different crosslink densities. The linear polymers and prepolymers were combined in solution, together with crosslinking agents and catalysts, films cast, and subsequently chain extended and crosslinked in situ. In all cases, maxima in tensile strengths significantly higher than the tensile strengths of component networks occurred. This was explained by an increase in crosslink density due to interpenetration.

Stress–strain properties and thermal resistance of polyurethane–polyepoxide interpenetrating polymer networks

Two-component interpenetrating polymer networks (IPN) of the SIN type (simultaneous interpenetrating networks) were prepared from three different polyurethanes and two epoxies. The linear prepolymers were combined in solution, together with crosslinking agents and catalysts, films cast, and subsequently chain extended and crosslinked in situ. Two of the IPN's showed significant improvement in thermal resistance, as measured by thermogravimetric analysis (TGA). All of the IPN's showed maxima in tensile strength significantly higher than the tensile strengths of the component networks at 25% polyurethane and minima at 75% polyurethane. The minima were explained by an initial dilution of the strong polyurethane hydrogen bonds by the epoxies, and the maxima, by an increase in crosslink density due to interpenetration.