Compressive Creep Behavior of TiC/AZ91D Magnesium-matrix Composites with Interpenetrating Networks

The 42.1 vol. pct TiC/AZ91D magnesium-matrix composites with interpenetrating networks were fabricated by in-situ reactive infiltration process. The compressive creep behavior of as-synthesized composites was investigated at temperature ranging from 673 to 723 K under loads of 95-108 MPa. For a comparative purpose,the creep behavior of the monolithic matrix alloy AZ91D was also conducted under loads of 15-55 MPa at 548-598 K. The creep mechanisms were theoretically analyzed based on the power-law relation. The results showed that the creep rates of both TiC/AZ91D composites and AZ91D alloy increase with increasing the temperature and load. The TiC/AZ91D composites possess superior creep resistance as compared with the AZ91D alloy. At deformation temperature below 573 K, the stress exponent n of AZ91D alloy approaches theoretical value of 5, which suggests that the creep process is controlled by dislocation climb. At 598 K, the stress exponentof AZ91D is close to 3, in which viscous non-basal slip deformation plays a key role in the process of creep deformation. However, the case differs from that of AZ91D alloy when the stress exponent n of TiC/AZ91D composites exceeds 9, which shows that there exists threshold stress in the creep process of the composites, similar to other types of composites. The average activation energies for the creep of the AZ91D alloy and TiC/AZ91D composites were calculated to be 144 and 152 k J/mol, respectively. The existence of threshold stress in the creep process of the composites leads to an increase in activation energy for creep.

Preparation and Swelling Behavior of L-Lactide Interpenetrating Networks

Novel triblock copolymers of poly (L-lactide)-poly (ethylene glycol)-sebacate-poly (ethylene glycol)-poly (L-lactide) were synthesized by Ring-Opening Polymerization of different ratios of L-lactide with other three pre-prepared poly (ethylene glycol)-sebacate-poly (ethylene glycol) polymers, coded A, B and C which had different poly (ethyleneglycol) chain lengths. The copolymers were characterized by FTIR and 1H NMR spectroscopy, which indicated that the reaction of ROP took place and led to producing nine triblock copolymers having new different lactide chain lengths (n = 10, 25 and 50), AL10, AL25, AL50,BL10, BL25, BL50, CL10, CL25, and CL50. Nine polymer networks were also prepared from copolymers with sodium alginate S1 - S9 and finally mixed with a solution of hydroxyl ethyl cellulose to form SH1 - SH9.

Studies on the Morphology of Natural Rubber/Polyacrylate Interpenetrating Polymer Networks

The interpenetrating polymer network(IPN) systems have attracted a lot of attention because of their unique two-phase structure and properties. There have been many publications concerning the IPNs in which poly (isoprene) (PIP) or polyacrylates (PAC) is formed as one of the networks.In the present study, Four serles of natural rubber(NR)/PAC IPNs were prepared and their morphologies were investigated with dynamic mechanics analysis(DMA) and transmission electron microscopy (TEM).

Tailored Carrier Transport Path by Interpenetrating Networks in Cathode Composite for High Performance All‑Solid‑State Li‑SeS_(2) Batteries

All-solid-state Li-SeS_(2) batteries(ASSLSs)are more attractive than traditional liquid Li-ion batteries due to superior thermal stability and higher energy density.However,various factors limit the practical application of all-solid-state Li-SeS_(2) batteries,such as the low ionic conductivity of the solid-state electrolyte and the poor kinetic property of the cathode composite,resulting in unsatisfactory rate capability.Here,we employed a traditional ball milling method to design a Li_(7)P_(2.9)W_(0.05)S_(10.85) glass–ceramic electrolyte with high conductivity of 2.0 mS cm^(−1) at room temperature.In order to improve the kinetic property,an interpenetrating network strategy is proposed for rational cathode composite design.Signifcantly,the disordered cathode composite with an interpenetrating network could promote electronic and ionic conduction and intimate contacts between the electrolyte–electrode particles.Moreover,the tortuosity factor of the carrier transport channel is considerably reduced in electrode architectures,leading to superior kinetic performance.Thus,assembled ASSLS exhibited higher capacity and better rate capability than its counterpart.This work demonstrates that an interpenetrating network is essential for improving carrier transport in cathode composite for high rate all-solid-state Li-SeS_(2) batteries.

Preparation,Morphology and Damping Property of PU/UP Interpenetrating Polymer Networks

Interpenetrating polymer networks （IPNs） composed of acrylate-modified polyurethane （PU）/unsaturated polyester （UP） resin via simultaneous polymerization with various component ratios of PU/UP were prepared. The polymerization processes of IPNs were traced through infrared spectrum （IR） techniques, by which the phase separation in systems could be controlled effectively. Results for the morphology and miscibility among multiple phases of IPNs, obtained by transmission electron microscope （TEM） indicated that the domains between two phases were constricted in nanometer scales. The dynamic mechanical thermal analyzer （DMTA） detection results revealed that the loss factor （tanS） and loss modulus （E″） increased with the polyurethane amounts in system, and the peak value in curves of tanδ and E″ appeared toward low temperature ranges. Maximum tanδ values of all samples were above 0.3 in the nearly 50℃ ranges. Also, the mechanical properties of PU/UP IPNs were studied in detail.

SYNTHESIS AND CHARACTERIZATION OF POLYDIMETHYLSILOXANE/POLYSTYRENE SEMIINTERPENETRATING POLYMER NETWORKS

The synthesis of pseudo- and semi-interpenetrating polymer networks (IPNs) based on polydimethylsiloxane (PDMS) and polystyrene (PS) is described. IPNs were obtained by simultaneous and in situ sequential synthesis procedure. The preliminary studies on IPNs properties such as transition temperature, microphase separation and mechanical behaviors have been carried out by using differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The experimental evidence clearly showed that semi-IPNs obtained by sequential synthesis procedure have higher interpenetrating extent than pseudo-IPNs synthesized by simultaneous procedure. Over the full composition, the PDMS/PS IPNs are immiscible. The pseudo-IPNs microphase separation can be greatly subdued through the formation of grafting bonds between two networks as well as the kinetic rate-matching of the individual network crosslinking.

Microstrueture and Properties of Fluoroelastomer/Butadiene-Acrylonitrile Rubber Interpenetrating Polymer Networks

Interpenetrating polymer networks （IPNs） based on fluoroelastomer/butadiene-acrylonitrile rubber （FKM/NBR） by molten blending at a high temperature and chemical cross-linking of two components were prepared. The influence of the two networks component on the mechanical properties and thermostabilities was studied. The experimental results show that the mechanical properties of the IPNs are superior to those of the individual FKM and NBR networks due to forming the case of interpenetrating and intercross-linking between the two networks, the mechanical properties and thermal resistance exhibit higher values when 80/20 （w/w） FKM and NBR is blended and respectively cured simultaneously. The co-continuous morphology of the IPNs in the blends of 80/20 （w/w） FKM/NBR is found by transmission electron microscopy （TEM）, the differential scanning calorimetry （DSC） determination shows that the blends of 80/20 （w/w） FKM/NBR have better compatibility, and the glass transition temperature of the elastomer is -21.5 ℃.

Influence of Interpenetrating Polymer Networks (IPN) Microstructure on Underwater Acoustic Stealth Performance

According to the configuration and absorption theory of polymer macromolecule materials, a kind of IPN with wider temperature range and higher damping property was designed and synthesized. By using the spectrum of dynamic mechanical thermal analysis （DMTA） and acoustic pulse tube device, the microstructure, phase separation degree, phase size and phase continuity of IPN with different components were analyzed. The experimental results show that the nano size grade of phase, the continuous and homogeneous IPN phase can provide higher absorption coefficient. The absorption coefficient of optimized sample I09 is 0.7 in 2 kHz, and the absorption peak is 0.9 in 4 kHz. Then the underwater acoustic properties of modified IPN filled with mica, micro-balloon and nano-SiO2 were discussed respectively to indicate that the inhomogeneous property of filler-modified IPN can improve the underwater acoustic stealth performance effectively, and the micro size grade of these filler-modified IPN can work well in low frequency acoustic stealth.

High Water Resistance and Enhanced Mechanical Properties of Bio-Based Waterborne Polyurethane Enabled by in-situ Construction of Interpenetrating Polymer Network

In this study,acrylic acid was used as a neutralizer to prepare bio-based WPU with an interpenetrating polymer network structure by thermally induced free radical emulsion polymerization.The effects of the content of acrylic acid on the properties of the resulting waterborne polyurethane-poly(acrylic acid)(WPU-PAA)dispersion and the films were systematically investigated.The results showed that the cross-linking density of the interpenetrating network polymers was increased and the interlocking structure of the soft and hard phase dislocations in the molecular segments of the double networks was tailored with increasing the content of acrylic acid,leading to enhancement of the mechanical properties and water resistance of WPU-PAA films.Notably,with the increase in content of acrylic acid,the tensile strength,Young’s modulus,and toughness of the WPU-PAA-110 film increased by 3 times,and 8 times,and 2.4 times compared with WPU-PAA-80,respectively.The WPU-PAA-100 film showed the best water resistance,and the water absorption rate at 96 h was only 3.27%.This work provided a new design scheme for constructing bio-based WPU materials with excellent properties.

Wide-band underwater acoustic absorption based on locally resonant unit and interpenetrating network structure

The interpenetrating network structure provides an interesting avenue to novel materials. Locally resonant phononic crystal （LRPC） exhibits excellent sound attenuation performance based on the periodical arrangement of sound wave scatters. Combining the LRPC concept and interpenetrating network glassy structure, this paper has developed a new material which can achieve a wide band underwater strong acoustic absorption. Underwater absorption coefficients of different samples were measured by the pulse tube. Measurement results show that the new material possesses excellent underwater acoustic effects in a wide frequency range.Moreover, in order to investigate impacts of locally resonant units,some defects are introduced into the sample. The experimental result and the theoretical calculation both show that locally resonant units being connected to a network structure play an important role in achieving a wide band strong acoustic absorption.

SYNTHESIS,CHARACTERIZATION AND PROPERTIES OF ORGANOCLAYMODIFIED POLYSULFONE/EPOXY INTERPENETRATING POLYMER NETWORK NANOCOMPOSITES

Organoclay-modified hydroxylterminated polysulfone (PSF)/epoxy interpenetrating network nanocomposites (oM-PSF/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polysulfone and epoxy resin (PSF/EP) using diaminodiphenylmethane (DDM) as curing agent.The mechanical properties like tensile strength,tensile modulus,flexural strength,flexural modulus and impact properties of the nanocomposites were studied as per ASTM standards.Different...

SYNTHESIS, STRUCTURE AND PROPERTIES OF INTERPENETRATING SULFONIC ACID RESINS WITH HIGH CAPACITY

Two series of interpenetrating sulfonic acid resins (ISAR), 10×n and n×10, were prepared by means of the wet method, and the physicochemical, thermodynamic and kinetic properties of the ISAR were measured. The results show: 10×n resins exhibit better properties than n×10 ones, mainly in higher apparent degree of crosslinking and larger conformational entropy effect, among which, 10×1 resin exhibits the best thermodynamic and kinetic properties. In the DTA graphs of n×10 resins, there are two T_g and two T_(ox), but in those of 10×n, only one T_g and one T_(ox). This result well supports the conclusion that 10×n resins have much better interpenetrating structural aspects.

Thermoreversible Thickening and Self-assembly Behaviors of pH/Temperature Dually Responsive Microgels with Interpenetrating Polymer Network Structure

The pH /temperature dually responsive microgels of interpenetrating polymer network( IPN) structure composed of poly( N-isopropylacrylamide)( PNIPAM) network and poly( acrylic acid)( PAA) network( PNIPAM /PAA IPN microgels) were synthesized by seed emulsion polymerization. The results obtained by dynamic laser light scattering( DLLS) show that the microgels have good pH /temperature dual sensitivities. The temperature sensitive component and the pH sensitive component inside the microgels have little interference with each other. The rheological properties of the concentrated PNIPAM /PAA IPN microgel dispersions as a function of temperature at pH 4. 0 or 7. 0 were investigated by viscometer,and the results displayed that only at pH 7. 0 the dispersions presented thermoreversible thickening behavior. Then the PNIPAM /PAA fibers were prepared by self-assembly of the PNIPAM /PAA IPN microgels in the ice-crystal templates formed by unidirectional liquid nitrogen freezing method. Field emission scanning electron microscopy( FESEM) images indicate that the PNIPAM /PAA fibers are rounded,randomly orientated and interweaved.

Preparation of Semi-interpenetrating Polymer Network of Silicon Rubber and Poly(methyl methylacrylate) Using Supercritical CO_2

The heterogeneous free-radical polymerization of methyl methylacrylate (MMA) and divinylbenzene (DVB) as cross-linker within supercritical carbon dioxide-swollen silicon rubber (SR) has been studied as an approach to preparing semi-interpenetrating polymer network (semi-IPN) of SR and poly(methyl methylacrylate) (PMMA). The SR/PMMA semi-IPNs were characterized by scanning electron microscopy (SEM) and dynamic mechanical analyzer (DMA).

AN EPOXY/(METHYL METHACRYLATE)INTERPENETRATING POLYMER NETWORK FOR NONLINEAR OPTICS

An interpenetrating polymer networks (IPN) consisting of an epoxy-based polymer network and a polymethyl methacrylate network were synthesized and characterized. The IPN showed only one T-g, and hence a homogeneous-phase morphology was suggested. The second-order nonlinear optical coefficient (d(33)) of the IPN was measured to be 1.72 X 10(-7) esu. The study of NLO temporal stability at room temperature and elevated temperature (100 degrees C) indicated that the IPN exhibits a high stability in the dipole orientation due to the permanent entanglements of two component networks in the IPN system. Long-term stability of second harmonic coefficients was observed at room temperature for more than 1000 h.

Gas Permeability and Free Volume Hole Properties of Interpenetrating Polymer Network Studied by Positrons

A series of polyurethane/epoxy resin interpenetrating polymer networks （PU/ER IPN） were studied by positron annihilation lifetime spectroscopy （PALS）. The effects of epoxy resin type and content on the free volume properties in IPN were investigated. We found that in PU/ER IPN, the free volume hole size and fractional free volume showed a negative deviation due to closer segmental chain packing through some chemical bonding between PU and epoxy resin. Direct relationship between the gas permeability and the free volume has been established based on the free volume theory. Experimental results revealed that the free volume plays an important role in determining the gas diffusion and permeability.

Synthesis of HTPB based PU-PS IPN Membrane for Pervaporation Recovery of Butanol

Hydroxyl terminated polybutadiene（HTPB） based polyurethane（PU）-polystyrene（PS） interpenetrating polymer network（IPN） was prepared and characterized by FTIR, TGA, WCA, swelling experiments, and SEM. The IPN was used for pervaporation（PV） recovery of butanol. Both the permeation flux and separation factor increased with feed temperature, and both water and butanol fluxes increased with feed concentration while no obvious effect of concentration on separation factor was found. Through the formation of IPN structure, the total flux of HTPB based PU increased greatly with the decrease of separation factor. At the feed temperature of 60 °C, the IPN membrane obtained a total flux of 613.3 g/m^2 h with a separation factor of 6.15.

Synthesis and Water Uptake of Sulfonated Poly (phthalazinone ether sulfone ketone)/Polyacrylic Acid Proton Exchange Membranes

Novel SPPESK/PAA composite proton exchange membranes with semi-interpenetrating polymer network （sIPN） structure have been synthesized through the in-situ polymerization of acrylic acid （AA） in the presence of sulfonated poly （phthalazinone ether sulfone ketone） （SPPESK）. The composite membranes were identified by FT-IR analysis. Water uptake of the composite membranes was as high as 89.7% at 90℃, nearly one time higher than that of the corresponding SPPESK membrane.

Synthesis of PDMS-PS IPN Pervaporation Membrane for Pervaporation Recovery of Butanol

Polydimethylsiloxane(PDMS)-polystyrene(PS) interpenetrating polymer network(IPN) was prepared and characterized by FTIR, TGA, WCA, swelling experiments, and SEM. The IPN was used for pervaporation(PV) recovery of butanol. Both the permeation flux and separation factor increased with feed temperature, and both water and butanol fluxes increased with feed concentration, while no obvious effect of concentration on separation factor was found. Through the formation of IPN structure, the total flux of PDMS-PS IPN pervaporation membrane increased greatly with the decrease of separation factor. At the feed temperature of 60 °C, the IPN membrane obtained a total flux of 920.3 g/m2h with a separation factor of 9.5.

STUDIES ON APPARENT KINETICS AND RHEOLOGICAL BEHAVIOR OF EPOXY/ACRYLATE IPNS AS VACUUM PRESSURE IMPREGNATION RESINS

The apparent kinetics and cure behavior of novel interpenetrating polymer networks(IPNs) based on cycloaliphatic epoxy resin(CER) and tri-functional acrylate have been investigated by means of differential scanning calorimetry(DSC) and Fourier transform infrared spectroscopy(FT-IR).The results of DSC measurements show that the curing reaction of the TMPTMA component is much earlier than that of the CER component,which can lead to the formation of the IPNs.In contrast to neat anhydride-CER system,the anhydri...