Free volume and the physico‐mechanical behaviour of polyurethane/polyacrylonitrile interpenetrating polymer networks: positron annihilation results

A series of semi‐interpenetrating polymer networks (SIPNs) of polyurethane (PU) and polyacrylonitrile (PAN) in the weight ratios 90/10, 70/30, 60/40 and 50/50 PU/PAN were prepared using polyethylene glycol, 4,4′‐diphenylmethane diisocyanate and acrylonitrile by sequential polymerization. Differential scanning calorimetry and scanning electron microscopy techniques were used to find the glass transition temperature and surface morphology of SIPNs. The tough and transparent SIPN films were characterized for physico‐mechanical properties such as density, surface hardness and tensile properties. Positron annihilation lifetime spectroscopy (PALS) was used to measure the free volume behaviour of the IPNs. The sorption behaviour of IPNs with benzene penetrant was also measured. An attempt was made to correlate the PALS results with the mechanical and sorption properties of the SIPNs. Copyright © 2005 Society of Chemical Industry     

Kinetics of heterogeneous polymerization of vinylidene chloride. I. Mechanism and modeling

The similarities and differences between the heterogeneous polymerization of vinylidene chloride (VDC) and vinyl chloride (VC) were compared and analyzed. The effect of the poly(vinylidene chloride)(PVDC) crystal morphology on the kinetics of VDC polymerization was discussed. Based on the assumption that polymerization occurs in the monomer phase and on the edges of the PVDC lamellar crystals, a mechanism of VDC polymerization is proposed and then a kinetic model for VDC bulk/suspension polymerization is developed according to the elementary reactions. The model can be used to predict polymerization rate and conversion. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2576‐2581, 2004     

Studies on castor oil–based polyurethane/polyacrylonitrile interpenetrating polymer network for toughening of unsaturated polyester resin

Tricomponent interpenetrating polymer network (IPN) systems involving castor oil, toluenediisocyanate (TDI), acrylonitrile (AN), ethylene glycol diacrylate (EGDA), and general‐purpose unsaturated polyester resin (GPR) were prepared with various compositions. The structures of the IPNs at various stages were confirmed using FTIR. The thermal stability of the IPNs was studied using TGA, which indicated that the polyurethane/polyacrylonitrile/GPR (PU/PAN/GPR) IPN underwent single‐stage decomposition, showing perfect compatibility at the IPN composition of 10 : 90 (PU/PAN : GPR). The mechanical properties such as tensile, flexural, impact, and hardness for the IPNs with various compositions were determined. It was found that the tensile strength of the GPR matrix was decreased and flexural and impact strengths were increased upon incorporating PU/PAN networks. The swelling properties in water and toluene were also studied. The morphology of the IPNs was studied using SEM. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 817–829, 2004     

Interpenetrating polymer networks based on polyol modified castor oil polyurethane and poly(2‐ethoxyethyl methacrylate): Synthesis,chemical, mechanical,thermal properties,and morphology

Interpenetrating polymer networks (IPNs) of glycerol modified castor oil polyurethane (GC‐PU) and poly(2‐ethoxyethyl methacrylate) poly(2‐EOEMA) were synthesized using benzoyl peroxide as initiator and ethylene glycol dimethacrylate (EGDM) as crosslinker. GC‐PU/poly (2‐EOEMA) interpenetrating polymer networks were obtained by transfer molding. The novel GC‐PU/poly (2‐EOEMA) IPNs are found to be tough films. These IPNs are characterized in terms of their resistance to chemical reagents thermal behavior (DSC, TGA) and mechanical behavior, including tensile strength, Young's modulus, shore A hardness, and elongation. The morphological behavior was studied by scanning electron microscopy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1029–1034, 2004     

Damping properties of interpenetrating polymer networks of polyurethane‐modified epoxy and polyurethanes

Interpenetrating polymer networks (IPNs) were prepared from polyurethane (PU)‐modified epoxy with different molecular weight of polyol and polyurethanes based on the mixture of polydiol and polytriol by a one‐shot method. Two types of PU‐modified epoxy: PU‐crosslinked epoxy and PU‐dangled epoxy were synthesized, and the effects of the different molecular weights of polyol in the PU‐modified epoxy/PU IPNs on the dynamic mechanical properties, morphology, and damping behavior were investigated. The results show that the damping ability is enhanced through the introduction of PU‐modified epoxy into the PU matrix to form the IPN structure. As the molecular weight of polyol in PU‐modified epoxy increases, the loss area (LA) of the two types of the IPNs increases. PU‐dangled epoxy/PU IPNs exhibit much higher damping property than that of the PU‐crosslinked epoxy/PU IPNs with 20 wt % of PU‐crosslinked epoxy. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 328–335, 1999     

Characterization of castor oil–based interpenetrating polymer networks of PU/PS

A series of interpenetrating polymer networks (IPNs) of polyurethane/polystyrene (PU/PS; 90/10, 75/25, 60/40, and 50/50) have been synthesized by condensation reaction of castor oil with methylene diisocyanate and styrene, employing benzoyl peroxide as initiator. Polystyrene is extracted from IPNs by the Soxhlet extraction method. The IPNs of PU/PS before and after PS extraction were characterized for physical, optical, and X-ray diffraction properties. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1739–1743, 1998     

偏氯乙烯及其聚合物的研究进展及应用

对偏氯乙烯的合成方法进行了综述,并对其聚合物聚偏氯乙烯的合成方法进行了介绍,指出了乳液聚合和悬浮聚合2种聚合方法各自的影响因素.同时对聚偏氯乙烯热稳定性研究进行了介绍,并提出了相应的提高聚偏氯乙烯稳定性的办法.     

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

The 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 (G_IC). 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     

Damping analysis of polyurethane/polyacrylate interpenetrating polymer network composites filled with graphite particles

The graphite‐filled polyurethane/poly(methyl methacrylate‐butyl methacrylate) (PU/P(MMA‐BMA)) semi‐interpenetrating polymer networks (IPNs) were synthesized by sequential method. The influences of graphite particle content and size on the 60/40 PU/P(MMA‐BMA) IPNs were studied. The damping properties of IPN composites were evaluated by dynamic mechanical thermal analysis (DMA) and cantilever beam resonance methods. The mechanical performances were investigated using tensile and hardness devices. DMA results revealed that the incorporation of graphite particles improved damping properties of IPNs significantly. The 5% graphite‐filled IPN composite exhibited the widest temperature range and the highest loss factor (tan δ) when the test frequency was 1 Hz. As to the damping properties covering a wide frequency range from 1 to 3,000 Hz, the addition of graphite particles broadened the damping frequency range (Δf, where tan δ is above 0.3) and increased the tan δ value of IPNs. Among them, the composite with 7.5% graphite showed the best damping capacity. And the hardness and the tensile strength of IPN composites were also improved significantly. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers     

双酚-S环氧树脂/聚氨酯互穿网络的热性能

研究了双酚-S环氧树脂/聚氨酯(BPSER/PU)互穿网络的性能。实验表明,完全固化后的双酚-S环氧树脂的玻璃化温度比双酚-A环氧树脂在相同条件下高40～50℃。通过动态力学谱仪(TBA)研究了BPSER与PU的配比和玻璃化温度之间的关系,讨论了两相间的相容性。结果表明,随着BPSER用量的增加,体系的玻璃化温度升高。m(BPSER)/m(PU)=25/75是两组分均匀混合的最佳值,形成了反应型互穿聚合物网络。另外,用热重分析仪(TGA)研究了完全固化后的互穿聚合物网络的热分解行为,结果表明,BPSER的加入可提高PU的初始热分解温度。     

Synthesis,characterization and properties of organoclay‐modified polyurethane/epoxy interpenetrating polymer network nanocomposites

organoclay‐modified polyurethane/epoxy interpenetrating network nanocomposites (oM‐PU/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polyurethane and epoxy resin (PU/EP) which had been prepared by a sequential polymerization technique. Wide‐angle X‐ray diffraction (WAXD) and transmission electronic microscopy (TEM) analysis showed that the interpenetrating process of PU and EP improved the exfoliation and dispersion degree of oMMT. The effects of the NCO/OH ratio (isocyanate index), the weight ratio of PU/EP and oMMT content on the phase structure and the mechanical properties of the oM‐PU/EP nanocomposites were studied by tensile testing and scanning electronic microscopy (SEM). Water absorption tests showed that the PU/EP interpenetrating networks and oMMT had synergistic effects on improvement in the water resistance of the oM‐PU/EP nanocomposites. Differential scanning calorimetry (DSC) analysis showed that PU was compatible with EP and that the glass transition temperature (T_g) of the oM‐PU/EP nanocomposites increased with the oMMT content up to 3 wt%, and then decreased with further increasing oMMT content. The thermal stability of these nanocomposites with various oMMT contents was studied by thermogravimetric analysis (TGA), and the mechanism of thermal stability improvement was discussed according to the experimental results. Copyright © 2005 Society of Chemical Industry     

Semi‐interpenetrating polymer networks based on polyurethane and polyvinylpyrrolidone. II. Dielectric relaxation and thermal behaviour

Semi‐interpenetrating polymer networks (semi‐IPNs) based on crosslinked polyurethane (PU) and linear polyvinylpyrrolidone (PVP) were synthezised, and their thermal and dynamic mechanical properties and dielectric relaxation behavior were studied to provide insight into their structure, especially according to their composition. The differential scanning calorimetry results showed the glass transitions of the pure components: one glass‐transition temperature (T_g) for PU and two transitions for PVP. Such glass transitions were also present in the semi‐IPNs, whatever their composition. The viscoelastic properties of the semi‐IPNs reflected their thermal behavior; it was shown that the semi‐IPNs presented three distinct dynamic mechanical relaxations related to these three T_g values. Although the temperature position of the PU maximum tan δ of the α‐relaxation was invariable, on the contrary the situation for the two maxima observed for PVP was more complex. Only the maximum of the highest temperature relaxation was shifted to lower temperatures with decreasing PVP content in the semi‐IPNs. In this study, we investigated the molecular mobility of the IPNs by means of dielectric relaxation spectroscopy; six relaxation processes were observed and indexed according the increase in the temperature range: the secondary β‐relaxations related to PU and PVP chains, an α‐relaxation due to the glass–rubber transition of the PU component, two α‐relaxations associated to the glass–rubber transitions of the PVP material, and an ionic conductivity relaxation due to the space charge polarization of PU. The temperature position of the α‐relaxation of PU was invariable in semi‐IPNs, as observed dynamic mechanical analysis measurements. However, the upper α‐relaxation process of PVP shifted to higher temperatures with increasing PVP content in the semi‐IPNs. We concluded that the investigated semi‐IPNs were two‐phase systems with incomplete phase separation and that the content of PVP in the IPNs governed the structure and corresponding properties of such systems through physical interactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1191–1201, 2003     

Interpenetrating polymer networks of bismaleimide and polyether polyurethane–crosslinked epoxy

In this work, we prepared the interpenetrating polymer networks of bismaleimide and polyether-type polyurethane(polyoxypropylene)–crosslinked epoxy (BMI/PU(PPG)–EP IPNs) by employing the simultaneous bulk polymerization technique. The polyurethane (PU)–crosslinked epoxy was identified via infrared (IR) spectra analysis. Also investigated herein were the mechanical properties, including tensile strength, Izod impact strength, and fracture energy (G_IC) of the IPNs with various BMI contents in PU–crosslinked epoxy matrix. In addition, differential scanning calorimetry (DSC) analysis and the thermogravimetric analysis (TGA) were performed to examine the thermal properties of the BMI/PU(PPG)–EP IPNs. In addition, morphology and dynamic mechanical analysis (DMA) of the BMI/PU(PPG)–EP IPNs were also studied. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2635–2645, 1998     

Synthesis and characterization of hydroxypropyl terminated polydimethylsiloxane‐polyurethane copolymers

Polyurethane (PU) block copolymers were synthesized using prepared hydroxypropyl terminated polydimethylsiloxane (HTPDMS MW 990) and polyether diols (N‐210) as soft segment with 4,4′‐diphenylmethane diisocyanate (MDI) and 1,4‐butanediol. This low molecular weight polydimethylsiloxanes (PDMS) containing hydroxypropyl end‐groups displayed better compatibility with PU than common PDMS. In this article, we illustrate its synthesis routes and confirmed the proposed molecular structures using NMR and infrared radiation (IR). We varied the contents of HTPDMS and N‐210 in soft segments (HTPDMS—N‐210: 0 : 100, 20 : 80, 40 : 60, 60 : 40, 80 : 20, and 100 : 0) to synthesize a series of PDMS‐PU copolymer. IR spectroscopy showed the assignment characteristic groups of each peak in copolymers and confirmed that the desired HTPDMS‐PU copolymers have been prepared. The different thermal, dynamic mechanical and surface properties of the copolymers were compared by thermogravimetry, DMA, contact angle and solvent resistance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A study of the morphology of polyurethane–polystyrene interpenetrating polymer networks by means of small angle X‐ray scattering,modulated‐temperature differential scanning calorimetry,and dynamic mechanical thermal analysis techniques

The morphology of polyurethane–polystyrene (PU‐PS) (60 : 40 by weight) interpenetrating polymer networks (IPNs), in which internetwork grafting via 2‐hydroxyethyl methacrylate resides (HEMA) (1, 2.5, and 10 wt %, respectively) in the polystyrene networks has been studied by means of small angle X‐ray scattering (SAXS), modulated‐temperature scanning calorimetry (M‐TDSC), and dynamical mechanical thermal analysis (DMTA) techniques. With increasing internetwork grafting, the average size of domains became smaller (SAXS data) and the degree of component mixing increased (M‐TDSC and DMTA results). For the PU‐PS (60 : 40 by weight) IPN with 10% HEMA, the DMTA tan δ‐temperature plot showed a single peak. This DMTA result implied that the morphology of this PU‐PS IPN is homogeneous. However, the M‐TDSC data showed that three PU‐PS (60 : 40) IPNs samples (with 1, 2.5, and 10 wt % HEMA, respectively) were phase separated. For the three IPN samples, the correlation length of the segregated phases, obtained from SAXS data based on the Debye–Bueche method, did not show distinct differences. With increasing internetwork grafting, the scattered intensity decreased. This study concluded that for these IPNs, SAXS is sensitive to the size of domains and component mixing, but no quantitative analysis was given for the component mixing. M‐TDSC is suitable to be used to quantify the degree of component mixing or the weight fraction of interphases, and DMTA is sensitive to damping behavior and to phase continuity. However, DMTA cannot provide quantitative information about the degree of component mixing or the weight (or volume) fraction of the interphases. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1958–1964, 2001     

PMMA/PHEA Interpenetrating Network Embedded With Iron Oxide Nanoparticles for Drug Delivery Applications

Semi-interpenetrating polymer networks (IPNs) are prepared from poly methyl methacrylate and 2-hydroxy ethyl acrylate networks with the presence of super-paramagnetic ferric oxide nanoparticles (<30 nm) through free radical polymerization. PMMA/PHEA semi-IPNs having blend ratio 60:40, 50:50, 40:60 (wt/wt) are characterized with respect to swelling, crosslink density, FTIR, DSC, TGA, SEM, and drug loading and drug release properties. Bactericidal effect on IPNs is checked by cell growth study of E. coli.     

Radiation synthesis and environmental responsiveness of semi‐interpenetrating polymer networks composed of poly(dimethyl–aminoethyl methacrylate) and poly(ethylene oxide)

Semi‐interpenetrating polymer networks (semi‐IPNs) composed of poly(dimethyl–aminoethyl methacrylate) (PDMAEMA) and poly(ethylene oxide) (PEO) were synthesized by γ‐radiation; three semi‐IPNs with 80 : 20, 90 : 10, and 95 : 5 weight ratios of DMAEMA/PEO were obtained by use of this technique. The gel–dose curves showed that the hydrogels were characterized by a structure typical of semi‐IPNs and the results of elemental analysis supported this point. The temperature‐induced phase transition of semi‐IPNs with the composition of 95 : 5 was still retained, with the lower critical solution temperature of PDMAEMA shifting from 40 to 27°C. The temperature sensitivity of the other two semi‐IPNs gradually disappeared. The pH sensitivity of three semi‐IPNs was still retained but the pH shifted slightly to lower values with increasing PEO content in the semi‐IPNs. The effect of PEO content in semi‐IPNs on their environmental responsiveness was discussed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2995–3001, 2004     

Dynamic mechanical properties of semi‐interpenetrating polymer network‐based on nitrile rubber and poly(methyl methacrylate‐co‐butyl acrylate)

In this article, semi‐interpenetrating polymer network (Semi‐IPNs) based on nitrile rubber (NBR) and poly(methyl methacrylate‐co‐butyl acrylate) (P(MMA‐BA)) were synthesized. The structure and damping properties of the prepared Semi‐IPNs blends were characterized and by fourier transform infrared spectrum (FTIR), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), thermogravimetric analysis (TGA/DTG), and tensile mechanical properties. The results showed that interpenetrating network based on P(MMA‐BA) and NBR was successfully obtained, which showed the improved thermal stability compared to NBR/P(MMA‐BA)‐based two‐roll mill blends. Furthermore, Semi‐IPNs showed significantly better the dynamic mechanical properties than that of the two‐roll mill system. With the increasing feed ratio of BA and MMA during the preparation of Semi‐IPNs, the loss peak position for P(MMA‐BA) in NBR/PMMA IPNs shifted to a lower temperature from 20°C to ?17°C, and when NBR in Semi‐IPNs was accounted for 40 wt %, the dynamic mechanical thermal analysis showed that much more advanced damping material with wider temperature range (?30°C < T < 80°C) as tan δ > 0.45 can be achieved. Therefore, it was expected as a promising way to obtain the excellent damping materials with good oil‐resisted properties according the Semi‐IPNs system. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40217.     

聚偏二氯乙烯树脂增韧改性研究

介绍了聚偏二氯乙烯(PVDC)树脂的增韧改性方法,包括化学改性和物理改性方法。化学改性主要是通过提高氯乙烯(vC)单体含量、引人缩水甘油基丙烯酸甲酯(GMA)或丙烯腈(AN)单体来改善PVDC的韧性。物理改性方法主要有弹性体增韧改性和纳米碳酸钙刚性粒子增韧,文中主要介绍了PVDC和乙烯一酷酸乙烯共聚物(EVA)、甲基丙烯酸甲酷一丁二烯一苯乙烯共聚物(MBS)弹性体、丙烯酸酷共聚弹性体(ACR)的共混增韧体系。最后,指出了PVDC增韧改性的研究前景和发展方向。     

Thermal properties of poly(vinyl alcohol)/poly(diallyldi‐methylammonium chloride) interpenetrating polymer networks

Interpenetrating polymer networks (IPNs) constructed with poly(vinyl alcohol) (PVA) and poly(diallyldimethyl ammonium chloride) (PDADMAC) using a sequential IPN method were prepared. The thermal characterization of the IPNs was investigated by differential scanning calorimetry (DSC), dielectric analysis (DEA), and thermogravimtric analysis (TGA). Decreases in the melting temperature of PVA segments in IPNs were observed with increasing PDADMAC content using DSC. DEA was employed to ascertain glass transition temperature of IPNs. The thermal decomposition of IPNs was investigated using TGA, and thermal decomposition of IPNs could be decelerated by changing PVA content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1346–1349, 2003