Graft Interpenetrating Polymer Networks Research Articles

Mechanical, damping, and thermal properties of calcium sulfate whisker-filled castor oil-based polyurethane/epoxy IPN composites

A series of calcium sulfate whiskers (CSW)-filled, castor oil-based polyurethane/epoxy resin graft interpenetrating polymer network (IPN) composites were prepared. The tensile and impact strengths, fractured surfaces, damping properties, and thermal stability of the IPN composites were studied systematically in terms of composition. Results revealed that the addition of CSW can significantly improve the tensile strength though the impact strength was impaired. The damping properties were the best when the CSW content was 3%. The thermal decomposition temperature was also improved by the incorporation of CSW. It is expected that the CSW-filled IPN composites may be used as structural damping materials.

Damping, thermal, and mechanical properties of polyurethane based on poly(tetramethylene glycol)/epoxy interpenetrating polymer networks: effects of composition and isocyanate index

A series of polyurethane (PU) samples based on poly(tetramethylene glycol)/epoxy resin (EP) graft interpenetrating polymer networks (IPNs) were prepared and their damping, thermal, and mechanical properties were systematically studied in terms of composition and the value of the PU isocyanate index (R). The damping properties and thermal stability measurements revealed that the formation of PU/EP IPN could improve not only the damping capacity but also the thermal stability. Meanwhile, mechanical tests showed that the tensile strengths of the IPNs decreased while their impact strengths increased with increasing PU content. The value of R also had significant impacts on the properties of the IPNs when the PU and EP ratio was fixed, which could be an effective means for manipulating the fabrication of PU/EP IPNs. The morphologies of the PU/EP IPNs were observed by SEM and AFM characterization and the relationship between the morphologies and properties is discussed. With the results in hand, the PU/EP IPNs hold promise for use in structural damping materials.

Physical properties of a high molecular weight hydroxyl-terminated polydimethylsiloxane modified castor oil based polyurethane/epoxy interpenetrating polymer network composites

A series of polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites modified by a high molecular weight hydroxyl-terminated polydimethylsiloxane (HTPDMS) were prepared. The effects of HTPDMS content on the phase structure, damping properties and the glass transition temperature (Tg) of the HTPDMS-modified PU/EP IPN composites were studied by scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). Thermogravimetric analysis (TGA) showed that the thermal decomposition temperature of the composites increased with the increase of HTPDMS content. The tensile strength and impact strength of the IPN composites were also significantly improved, especially when the HTPDMS content was 10%. The modified IPN composites were expected to be used as structural damping materials in the future.

Dynamic mechanical properties of castor oil‐based polyurethane/epoxy graft interpenetrating polymer network composites

AbstractA series of graft interpenetrating polymer networks (IPNs) were prepared from epoxy (EP) and castor oil‐based polyurethane (PU). The dynamic mechanical properties, as well as the tensile and impact strength, of the IPNs were studied systematically. Results revealed that PU/EP IPNs showed improved damping properties compared with that of EP matrix. In addition, the PU content and testing frequencies had much influence on the damping properties of the IPNs. The IPN composites showed better damping properties with higher PU content or under higher testing frequencies. Mechanical analysis showed that the tensile strength of IPN composites was higher than that of pure EP. However, higher PU content (beyond 5 wt %) impaired the impact strength of the IPNs. It is expected that PU/EP IPNs may be potentially used as structural damping materials. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Damping analysis of polyurethane/epoxy graft interpenetrating polymer network composites filled with short carbon fiber and micro hollow glass bead

A series of short carbon fiber (CF) and micro hollow glass bead (HGB) filled polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites were prepared. The damping properties, thermal stability properties as well as tensile and impact strength of IPN composites were studied systematically. Results revealed that the addition of short carbon fiber and micro HGB can significantly improve the damping properties of pure PU/EP IPN and can improve the thermal decomposition temperature. Mechanical tests showed that the tensile strength of the IPN composites could be improved after the incorporation of short carbon fiber and micro HGB, while the impact resistance of the composites was impaired after the addition of micro HGB. It is expected that the carbon fiber and micro HGB filled IPN composites may be used as structural damping materials.

Preparation of epoxy/urethane graft interpenetrating polymer networks and study of mechanical, thermal and morphological properties

AbstractThis paper describes the preparation of Epoxy/Urethane (EP/PU) graft interpenetrating polymer networks (g-IPNs) and investigates the effect of EP/PU weight ratio and urethane's prepolymer molecular weight on the mechanical, morphological and thermal properties of the IPN system. Here, g-IPN was prepared by thorough mixing of an isocyanate-terminated urethane prepolymer with an epoxy resin followed by simultaneous curing of the resins. Polytetra hydrofuranate (PTHF), molecular weights (Mw) 1000, 2000 and 3000 g/gmol, was used to prepare urethane prepolymers. EP/PU weight ratios were 75/25, 50/50, 30/70 and 15/85. Disappearance of epoxide and isocyanate functional groups was followed by Fourier Transform Infrared spectroscopy (FT-IR), showing curing of the resins. Differential Scanning Calorimetry (DSC) was used to investigate the glass transition temperature (Tg) of the IPNs. Thermal Gravimetric Analysis (TGA), Dynamic Mechanical Thermal Analysis (DMTA), tensile measurements and Scanning Electron Microscopy (SEM) were used to study thermal, mechanical and morphological properties of the prepared systems. The best mechanical properties were obtained at EP/PU weight ratio 75/25 which also shows a fine and uniformly dispersed morphology. Moreover, at this ratio, with increasing PTHF Mw in the urethane prepolymer, the mechanical properties were improved whereas a decrease was observed in Tg and thermal degradation temperature of g-IPNs.

Graft interpenetrating polymer networks of polyurethane and epoxy containing rigid rods in side chain

AbstractThe rigid rod‐like 4,4′‐bis(6‐hydroxyhexyloxy)biphenyl (BHHBP) units were distributed in either the epoxy or polyurethane to become SR‐epoxy and PU (with or without BHHBP) polymer matrices. The interpenetrating polymer networks (IPNs) of PU (with or without BHHBP) and SR‐epoxy were synthesized through simultaneous polymerization, and connected each other via the grafting reaction between the NCO groups of the PU polymer network and the OH groups on the side chains of SR‐epoxy network. The thermal and mechanical characteristics, compatibilities, and morphologies of these PU (with or without BHHBP)/SR‐epoxy graft‐IPNs were investigated. The polyether‐type PU(PPG series)/SR‐ epoxy graft‐IPNs exhibited two‐phased morphologies (i.e., phase separation occurred), and higher fracture energies (GIC). Whereas the polyester‐type PU(PBA series)/SR‐ epoxy graft‐IPNs were homogeneous (no phase separation), and exhibited higher tensile and Izod impact strengths. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Effects of NCO/OH molar ratio on structure and properties of graft-interpenetrating polymer networks from polyurethane and nitrolignin

A series of graft-interpenetrating polymer networks (graft-IPNs) with different NCO/OH molar ratio was synthesized from castor oil-based polyurethane (PU) and nitrolignin (NL) by changing the content of 1,4-butanediol as chain-extender. The effects of NCO/OH molar ratio on the morphology and properties of the PU–NL films (UL) were investigated by infrared, wide-angle X-ray diffraction (WAXD), differential scanning calorimetry, dynamic mechanical analysis, and tensile test. WAXD patterns showed that all the UL films were nearly amorphous. With an increase in NCO/OH molar ratio, the glass transition temperature (Tg), the stiffness and tensile strength (σb) increased, while the breaking elongation (εb) and strain recoverability (Re) decreased. The UL films with 1.20 of NCO/OH molar ratio exhibited the maximum value of tensile strength (σb=30.2MPa;εb=152%). 2.8wt% NL plays an important role in the simultaneous enhancement of σb and εb of the UL films. Solid-state 13C nuclear magnetic resonance (13C NMR) showed that the introduction of NL into PU restricted the motion of PU molecules, indicating a relatively high cross-link network structure in the UL films. Therefore, a relatively great network structure like a star by grafting with multi-PU networks on a NL molecule as the graft-IPNs model was deduced in this work.

Graft interpenetrating polymer networks of urethane-modified bismaleimide and epoxy (I): mechanical behavior and morphology

Polyurethanes (PU) based on poly(butylene adipate) [PU(PBA)] and poly(oxypropylene) [PU(PPG)] polyols are employed as a graft agent to prepare interpenetrating polymer networks of urethane-modified bismaleimide (UBMI) and the diglycidyl ether of bisphenol A (Ep) (UBMI/Ep graft-IPNs). The UBMI is introduced and partially grafted to the epoxy by PU graft agents, and then simultaneous bulk polymerization technique is used to prepare the graft-IPNs.All the PU graft agents were characterized by infrared (IR). The tensile strength of both the UBMI/Ep graft-IPNs with PU(PBA) and PU(PPG) graft agent systems increased to a maximum value with increasing UBMI content in the system and then decreased with further increasing the UBMI content. For both kinds of PU with various molecular weight in the UBMI/Ep graft-IPNs, the Izod impact strength increased with the UBMI contents increasing. The better compatibility of PU(PBA)-based UBMI/Ep graft-IPNs led to higher impact strength. On the contrary, the fracture energy (GIC value) of the resultant UBMI/Ep graft-IPN showed that the UBMI/Ep graft-IPN with PU(PPG) graft agent had much higher GIC value than that with PU(PBA) graft agent. The morphology of this IPN with PU(PBA) graft agent exhibited a homogeneous one-phase system, while the UBMI/Ep graft-IPN with PU(PPG) graft agent showed a two-phase morphology with the UBMI particles dispersed in the epoxy matrix.

Graft interpenetrating polymer networks composed of epoxy resin and urethane acrylate resin

For enhancing the interpenetratoin and/or compatibility of the simultaneous interpenetrating networks (SINs) composed of epoxy resin (epoxy) and urethane acrylate resin (UAR), the graft epoxy consisting of different lengths of poly(oxypropylene) (PO) side chains were synthesized and characterized. It was found that the graft epoxy composed of short PO side chains [MW 480, epoxy-g-PO(480)] showed a compatible system while if consisting of longer PO grafts [MW 950, epoxy-g-PO(950)] exhibited a partial microphase separation morphology. DSC measurements as well as the SEM or TEM observation indicated that the interpenetration between the two phases for epoxy/UAR SINs including epoxy-g-PO(480) was improved appreciably due to the excellent miscibility between the PO grafts and PO segments existing in the graft epoxy and the UAR network, respectively. In this case, for SIN(80/20) containing 10 wt % of epoxy-g-PO(480) the tensile strength increases by a factor of 2.70 compared with that of pure epoxy network. However, the improvement of interpenetration and/or compatibility between the two networks as well as the mechanical properties for SINs composed of epoxy-g-PO(950) are limited resulting in the partial microphase separation of epoxy-g-PO(950) network's own self. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3568–3574, 1999

Graft interpenetrating polymer networks composed of epoxy resin and urethane acrylate resin

Graft interpenetrating polymer networks composed of epoxy resin and urethane acrylate resin

Graft Interpenetrating Polymer Networks of Bismaleimide and Epoxy Based on Maleimide-Terminated Polyurethane-Grafted Epoxy

This work used maleimide-terminated polyurethane-grafted epoxy, or epoxy-graft-maleimide-terminated polyurethane (EGMPU) based on poly (butylene adipate) (EGMPU(PBA)) and poly(propylene oxide) (EGMPU(PPG)) as a coupling agent to synthesize graft interpenetrating polymer networks of bismaleimide (BMI) and the diglycidyl ether of bisphenol A (epoxy) (BMI/epoxy/graft(EGMPU)-IPN). Infrared (IR) analysis was performed to characterize the coupling agents EGMPU. The stress-strain properties of the BMI/epoxy/graft(EGMPU)-IPNs were studied. Dynamic mechanical analysis (DMA) showed that the EGMPU(PBA) coupling agent has better grafting effect due to higher compatibility between the BMI and epoxy networks than the EGMPU(PPG) coupling agent in BMI/epoxy/graft(EGMPU)-IPNs.

Epoxy/castor oil graft interpenetrating polymer networks

Full-interpenetrating polymer networks (IPNs) were prepared from epoxy and castor oil-based polyurethane (PU), by the sequential mode of synthesis and were characterized by different techniques: swelling test, scanning electron microscopy (SEM), thermomechanical analysis (TMA), thermogravimetric analysis (TGA), tensile test, and instrumented impact test. 2,4-Toluene diisocyanate (TDI) was used as a curing agent for castor oil, at a NO/OH ratio = 1.50. Diglycidyl ether of bisphenol A (DGEBA) was cured and crosslinked using 2,4,6-tris(dimethylaminomethyl)phenol (TDMP) at 1.5%, by weight, of epoxy resin. The homogeneous morphology of IPN samples of PU compositions up to 40%, by weight, revealed by SEM may be attributed to some extent to grafting of the PU phase onto the epoxy matrix, which results from the reaction between NCO groups in the PU phase with OH groups in the epoxy matrix. This has some synergistic effect on the thermal resistance and tensile properties of IPNs compared to those of the pure components, such as illustrated by the data from TGA and tensile tests. However, the grafting structure appears not to enhance their impact resistance, which probably requires the formation of rubbery particles of suitable size. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1649–1659, 1998

POLYSILOXANE MODIFIED EPOXY POLYMER NETWORK—II. DYNAMIC MECHANICAL BEHAVIOR OF MULTICOMPONENT GRAFT-IPNs (EPOXY/POLYSILOXANE/POLYPROPYLENE GLYCOL)

Multicomponent graft interpenetrating polymer network (IPN) elastomers composed of polyurethane, epoxy and polysiloxane were prepared by a sequential technique. Although the solubility parameters suggested phase separation, the compatibility could, nevertheless, be improved significantly by varying the polysiloxane/polyurethane ratio. Broad and high tan δ were observed from the dynamic mechanical analysis, suggesting that the multicomponent graft IPN is an effective absorbing material. © 1997 Elsevier Science Ltd. All rights reserved

Graft‐interpenetrating polymer networks of polyurethane and bismaleimide

AbstractGraft‐interpenetrating polymer networks (graft‐IPNs) of polyurethane (PU) and bismaleimide (BMI) were prepared by using a simultaneous polymerization technique. The effects of the PU molecular weight and the amounts of the PU on the mechanical properties, density, and morphology of the IPNs are discussed. The graft‐IPNs exhibited superior ultimate tensile strength and large improvement in flexural strength when the short soft segments of the PU were introduced. Better thermal stability of the IPNs was shown by increasing the BMI content. The heterogeneous and phase‐separated characteristics were found from the results of dynamic mechanical analysis. The maximum density was achieved by the graft‐IPNs structure when 33.3 wt % of PU with short soft chain length was added. The graft‐IPNs also showed heterogenous morphology in the micrographs when a large amount of PU was incorporated. © 1995 John Wiley & Sons, Inc.

Polydimethylsiloxane/poly(methyl methacrylate) interpenetrating polymer networks: 2. Synthesis and properties

The synthesis of full and graft interpenetrating polymer networks (IPNs) based on polydimethylsiloxane and poly(methyl methacrylate) is described. IPNs were obtained by an in-situ sequential synthesis. Most samples were opaque; however, in a few cases, transparency was noted. Other properties like stress-strain behaviour, hardness and glass transition temperature were examined. Owing to the particular behaviour of silicone-containing polymers, the surface properties and the permeability to oxygen of these IPNs were also studied.

Graft interpenetrating polymer networks of polyurethane and epoxy. II. Toughening mechanism

AbstractGraft interpenetrating polymer networks (graft‐IPNs) of polyurethane (PU) and the diglycidyl ether of bisphenol A (epoxy) were prepared by first grafting excess PU prepolymer to the epoxy and then simultaneously polymerizing the PU prepolymer and epoxy. The fracture properties, at high shear rate (e.g., impact) and low shear rate (e.g., pseudostatic tensile fracture energy measurement) of these graft‐IPNs exhibit opposite behavior. Although dispersed rubber particles can enhance the Izod impact strength, toughening of the matrix of graft‐IPNs was found to be the main contribution. In contrast, it was found that a heterogeneous morphology with suitably dispersed rubber domains of appropriate size as well as the toughness of the matrix are requirements for effectively increasing the fracture energy at low shear rate. A reinitiating crack in the plastic matrix is proposed as the main toughening mechanism and can be invoked to interpret the fracture behavior at high and low shear rates of the graft‐IPNs.

Graft interpenetrating polymer networks of polyurethane and epoxy. I. mechanical behavior

AbstractPolyurethanes (PU) based on poly(butylene adipate) [PU(PBA)] and poly(oxypropylene) [PU(PPG)] polyols have bean introduced into the diglycidyl ether of bisphenol A (epoxy) to form interpenetrating polymer networks (IPNs) with a PU‐grafted epoxy structure (graft‐IPNs).The tensile strength in both PU(PPG)/epoxy and PU(PBA)/epoxy systems increases with increasing PU content. Maximum values emerge at PU/epoxy ratios between 19/81 and 27/73. This is explained as a result of the presence of the graft structure, which leads to more intimate interpenetration between the PU and epoxy in the graft‐IPNs.Dynamic mechanical analysis (DMA) indicates that the PU introduced can be incorporated in either the α or β transition domain of the epoxy. The tensile strength of the resulting graft‐IPNs shows a significant improvement as the PU is incorporated in the α transition domain of the epoxy. It is also noted that suitable amounts of PU incorporated in both the α and β transition domains of epoxy can increase the tensile strength of the IPNs, while excessive amounts of PU introduced into both α or β transition domains tend to decrease the tensile strength of the graft‐IPNs.