Damping characteristics and mechanical properties of silica filled PUR/PEMA simultaneous interpenetrating polymer networks

Simultaneous polyurethane/poly(ethyl methacrylate) interpenetrating polymer network was synthesised by the one-shot route at the 70PUR/30PEMA composition ratio. This semi-miscible IPN exhibited its potential as a material for damping application by a broad loss factor (tan δ) ? 0.3 spanning a temperature range of 132 °C. The TEM micrographs revealed a multiphase morphology where the mixing between the two polymers was extensive. Incorporation of silica was made in order to study the effects of filler on the IPN properties in terms of glass transition temperature, dynamic mechanical properties, and mechanical and thermal properties. Dynamic mechanical thermal analysis indicated that the filler enhanced the damping ability of the IPN at certain temperature range. Furthermore, the addition of filler resulted in improved material strength.     

Interpenetrating networks of conjugated ionic polyacetylenes

An interpenetrating polymer network (IPN) based on poly(N-butyl 2-ethynylpyridinum bromide) (PB2EPB) and polycarbonate-urethane (PCU) has been prepared and characterized. The simultaneous full IPNs of PCU and PB2EPB have two glass transition temperatures corresponding to those of the linear chain blends measured by DSC. This suggests immiscibility of the two networks in the IPNs. The IPNs display a multiphase morphology which is confirmed by SEM observation. The full IPNs exhibit excellent solvent resistance, good thermal stability and good mechanical properties. High UV absorption of these materials extending to the visible range and beyond indicates that the polyacetylene network is extensively conjugated. The electrical conductivity of the IPNs increases linearly with increasing polyacetylene content reaching 10^-4 S/cm. © 1996 John Wiley & Sons, Inc.     

Two-component interpenetrating polymer networks (IPNs) from polyurethanes and epoxies. I. Studies on full IPN,pseudo-IPN,and graft polymer alloys of polyurethanes and epoxies

In this article we review the synthesis and morphology and the physical and mechanical properties of two-component interpenetrating polymer networks (IPNs) from polyurethane and epoxy polymers; the corresponding pseudo-IPNs and grafted IPNs are also discussed. A comparison was made of full IPNs, pseudo-IPNs, grafted IPNs, and related homopolymers by examining their mechanical properties, mechanical spectra, and electron microscopy on an investigation of the effects of interpenetration or permanent entanglement in the IPN and related systems. This interpenetration has resulted in improved compatibility between the two polymer systems and has caused a decrease in the degree of phase separation. An observed shift in the dynamic glass transition temperatures (T_gs) of the two components which yielded a single IPN T_g further substantiates our results.     

Interpenetrating Polymer Networks

Besides mechanical blending and copolymerization there is a third possible way in which two polymers can be combined. Each polymer forms its own network, while both networks interpenetrate each other. There are no covalent bonds between the polymers. Such interpenetrating networks have been synthesized sequentially (from polymer A and monomer B) and simultaneously (from monomer A and monomer B). It is preferable that the polymers be of different chemical type; usually, an elastomer and a glass are combined, e.g. a polyurethane and a polyacrylate. Depending upon the ratio of component polymers either a strengthened elastomer or a glass having impact strength is formed. So far, there are no direct methods for establishing the degree of interpenetration.     

聚苯乙烯/聚丙烯酸丁酯乳胶互穿聚合物网络的动态力学性能研究

<正> 互穿聚合物网络(IPN)是一种新型聚合物共混物.自Sperling在1969年合成聚丙烯酸乙酯/聚苯乙烯异步IPN(Sequential IPN)后,该领域进展很快.乳胶IPN(latex IPN)是用改进的乳液聚合法合成的一种微观互穿IPN.在前文中,我们报道了聚苯乙烯/聚丙烯酸丁酯(PS/PBA)乳胶IPN的合成,本文研究一些因素对PS/PBA乳胶IPN动态力学性能的影响.     

Synthesis and characterization of semi-interpenetrating polymer networks using biocompatible polyurethane and acrylamide monomer

Semi-interpenetrating polymer networks (semi-IPNs) of acrylamide based polyurethanes were synthesized from different NCO-terminated polyurethane prepolymers derived from polytetramethylene ether glycol (PTMEG). The resulting semi-IPNs were characterized using FTIR, DSC, and TGA measurements. Variation in the NCO/OH ratio and the molecular weight of the diol gave semi-IPNs with different types of mechanical characteristics varying from elastomer to brittle plastic properties. Differential scanning calorimetry (DSC) data revealed a difference in the glass transition temperature (T_g) of the semi-IPNs relative to the normal polyacrylamide (PAAM) network. Incorporation of polyurethane into polyacrylamide network in the form of an interpenetrating polymer networks enhanced the mechanical and thermal properties of the semi-IPNs due to higher crosslink density imparted by the hard segment content. The swelling behavior of both the semi-IPNs and the individual polyacrylamide (PAAM) network in different pH conditions were investigated to check their biocompatibility and possible usage in biomedical field. The hydrolytic stability of the semi-IPNs and the polyacrylamide (PAMM) network was studied using phosphate buffer solution. The hydrolytic stability of the semi-IPNs was found to be more compared to PAMM network. The morphology of both the semi-IPNs and the individual polyacrylamide (PAAM) network was investigated using SEM.     

Structural changes in glassy polymers studied by thermal analysis and dynamic mechanical tests

Structural changes which take place in many amorphous polymers, when they are annealed at temperatures near the glass transition temperature, have important theoretical, physical, and mechanical consequences. In this paper the possible existence of some local ordering in highlycrosslinked epoxy resins is studied. Three kinds of tests—TMA, DSC, and dynamic experiments—are used for a type of epoxy resin, cured with six different amounts of curing agent. In order to study the effect of the thermal history on the behavior of the polymer at its transition region, as well as the morphology of the materials tested, three different thermal treatments have been followed. Interesting results were derived concerning the influence of these parameters to these parameters to the mechanical characterization of the polymer.     

聚氨酯/聚苯乙烯互穿聚合物网络的研究

互穿聚合物网络形态和力学性能的研究已有报道^[1～3],但有关合成过程中分子量变化形态和性能的影响研究甚少。本文在动力学研究的基础上^[4],用GPC、DSC和Instron万能机研究了聚氨酯/聚苯乙烯互穿聚合物网络(PU/PSt-IPN)的分子量,玻璃化转变温度和力能,考察了分子量与相分离点之间的关系。     

Interpenetrating polymer networks of poly(carbonate-urethane) and polystyrene

Simultaneous two-component interpenetrating polymer networks (IPN's), pseudo IPN's, and linear blends of urethane-containing aliphatic polycarbonate (PCU) and polystyrene (PS) have been synthesized and characterized. The simultaneous full IPN's of PCU and PS had one T_g only at compositions above 50 wt % PCU, as determined by DSC and DMA. The single phase morphology in the one T_g region was confirmed by transmission electron microscopy (TEM). However, the pseudo IPN's and linear blends of PCU and PS exhibited multiple (melting and glass) transitions by DSC measurements and phase separation was observed by TEM over the whole composition range. The full IPN's exhibited a maximum in ultimate mechanical properties at an intermediate composition. Superior solvent resistance as well as better thermal stability was shown by the IPN's as compared to the pseudo IPN's linear blends, and pure crosslinked components.     

Viscoelastic behavior and phase domain formation in Millar interpenetrating polymer networks of polystyrene

Millar-type interpenetrating polymer networks (IPNs) are composed of two identical networks. In the present case Millar IPNs of polystyrene/polystyrene were prepared where the crosslinker levels of the two networks differed by a factor of 10. Polymer network I contained 0.4% divinylbenzene (DVB) and polymer network II contained 4% DVB, the polymers having the following weight proportions: 75/25, 50/50, and 25/75. A single polystyrene network containing 2.2% DVB was synthesized for comparison with the 50/50 Millar IPN, both containing the same average amount of crosslinker. The creep behavior of the Millar IPNs was found to be dominated by polymer network I, as were the rubbery moduli and swelling behavior in toluene. These results suggested that polymer I domains are more continuous in space and polymer II domains are less continuous. The Donatelli equation predicted polymer II domain sizes of 60 Å to 100 Å for the Millar IPNs. Electron micrographs of specimens containing 1% isoprene in polymer II offered visual evidence for the segregation of polymer II domains from polymer I, and showed that the polymer II domains were, in fact, less continuous. Polymer II domains varied from about 50 to 100 Å in size, as predicted. These results have implications for gelation processes in general.     

Poly(methyl acrylate)/poly(hydroxyethyl acrylate) sequential interpenetrating polymer networks. Miscibility and water sorption behavior

Sequential poly(methyl acrylate)/poly(hydroxyethyl acrylate) interpenetrating polymer networks with different poly(hydroxyethyl acrylate) contents were prepared by free radical polymerization of hydroxyethyl acrylate inside the previously polymerized poly(methyl acrylate) network. Differential scanning calorimetry on dry samples shows that the interpenetrating polymer networks exhibit phase separation, and no differences are found between the glass transition temperatures of the two phases present in the interpenetrating polymer network and those of the pure components. Thermally stimulated depolarization current experiments were used to study the influence of water sorption on the mobility of the different molecular groups in the poly(hydroxyethyl acrylate) phase of the interpenetrating polymer network. Isothermal water sorption of the interpenetrating polymer networks and pure poly(methyl acrylate) and poly(hydroxyethyl acrylate) networks is analyzed with different theories to compare the behavior of the poly(hydroxyethyl acrylate) phase in the interpenetrating polymer networks with that of the pure poly(hydroxyethyl acrylate) network. Diffusion coefficients of water in the interpenetrating polymer networks are obtained by means of dynamic sorption experiments. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1587–1599, 1999     

Transitions and relaxations in aromatic polymers

Transition and relaxation phenomena in 26 structurally related polyquinoxalines and other aromatic polymers were studied over a temperature range from 70 to 770°K by means of calorimetric, dilatometric, dynamic mechanical, and dielectric techniques. Differential thermal analysis and x-ray data showed these polymers to be essentially amorphous. The lack of crystallinity is attributed to geometric isomerism, resulting in conformational as well as configurational disorder. Calorimetric measurements gave discontinuities in heat capacities ranging from 12 to 54 cal/°C per mole of repeat-unit structures and provided unambiguous assignments of glass transition temperatures of these polymers. Depending upon structure, T_g varied from 489 to 668°K. Thermal expansion curves of annealed bulk polymer samples between 70 and 770°K exhibited only one discontinuity over the entire temperature range, namely at T_g, thus indicating the absence of any motion leading to transitions in the solid state of these polymers. Viscoelastic properties were obtained by means of torsional braid analysis and a longitudinal vibrational apparatus. In a typical case, the dynamic mechanical relaxation spectrum contained three loss maxima. A peak of low amplitude occurring at 483°K was attributed to impurity effects, resulting from endgroups and species of low molecular weight. The second and only major relaxation process occurred at 579°K, in the glass transition interval. A third, weak loss peak of unknown origin was found in the liquid state at 683°K. On the other hand, the dielectric loss curves of various polymers exhibited only one broad and strong absorption maximum at temperatures 30 to 100°K higher (depending upon a particular polymer) than equivalent major mechanical loss peaks. These differences are interpreted from a mechanistic point of view. Major mechanical relaxations occurring in the glass transition interval of these polymers are proposed to result from translational motions.     

室温固化蓖麻油聚氨酯/乙烯基聚合物互穿网络材料的一些规律及其性能

研究了蓖麻油与甲苯二异氰酸酯及丙烯酸酯或苯乙烯等乙烯基单体在室温下生成的互穿网络聚合物(IPN)的一些规律及其性能.用红外光谱追踪表明,聚氨酯的生成快于甲基丙烯酸甲酯的聚合.研究IPN凝胶点指出.凝胶点时间随聚氨酯含量增加及聚苯乙烯含量减少而缩短.丙烯酸甲酯在生成IPN过程中凝胶的生成速度要比苯乙烯的场合快.丙烯酸丁酯、丙烯腈或丙烯酸甲酯与蓖麻油聚氨酯生成的IPN的抗张强度在聚氨酯占一半时呈现最大值.透射电镜观察表明,生成速率较快的聚氨酯的微区存在于聚丙烯酸甲酯中.聚丙烯酸甲酯与蓖麻油聚氨酯形成的IPN在tanδ-T,曲线上呈现一个宽的玻璃化转变温度.     

Thermal history and enthalpy relaxation of an interpenetrating network polymer with exceptionally broad relaxation time distribution

Differential scanning calorimetry (DSC) of an interpenetrating network polymer of composition 25% polyurethane–75% poly(methyl methacrylate) shows a slowly increasing heat capacity, instead of the usual glass transition endotherm, whose onset temperature is not clearly discernible. On aging of the polymer at several temperatures between 193 and 333 K, an endothermic peak is observed whose onset is in the vicinity of the respective temperature of aging. The area under these peaks increases with increasing aging time at a fixed temperature. The effects are attributed to a very broad distribution of relaxation times, which may be represented by either a sum of discrete structural relaxation times of local network arrangement or by a nonexponential relaxation function which is equivalent to a distribution of relaxation times. In either view the vitrified state of the polymer can be envisaged as containing local structures whose own T_gs extend over a wide range of temperature. Aging decreases the enthalpy and produces an endothermic region which resembles an increase in C_p on heating because of relaxation of that local structure. The interpretation is supported by simulation of DSC scans in which the distribution of relaxation times is assumed to be exceptionally broad and in which aging introduced at several temperatures over a wide range produces endothermic effects (or regions of DSC scans) qualitatively similar to those observed for the interpenetrating network polymer. © 1994 John Wiley & Sons, Inc.     

丁腈羟聚氨酯/聚环氧树脂互穿网络高聚物的研究

本文用同步法合成了丁腈羟聚氨酯/聚环氧树脂(PU/PE)体系的互穿网络高聚物(IPN),研究了各种因素对其形态和玻璃化转变行为的影响,并用扭辫及扭摆(TPA)在-100℃-+150℃温度区间内,测试全部试样的动态力学谱。结果表明,PU/PE是不相容体系,在电镜片上呈现细胞状结构(400-800Å)。由于两组份网络互穿,发生“强迫互容”,使T_g内移,通过调整组份比和加不同扩链剂等能提高阻尼值,加宽T_g转变区。     

Glass transition of atactic polystyrene probed at the submolecular level by dynamic infrared linear dichroism (DIRLD) spectroscopy

Dynamic infrared linear dichroism (DIRLD) spectroscopy is a rheo-optical characterization technique developed specifically to probe the submolecular dynamics of polymer segments. The technique combines the measurement of submolecular orientation based on the directionally selective absorption of polarized IR light with a small-amplitude oscillatory tensile deformation used in dynamic mechanical analysis. A DIRLD spectroscopic study of atactic polystyrene reveals that a dramatic change in the reorientation behavior of aromatic side groups is observed around the glass transition temperature of 100 °C. The transition point for the main chain backbone, on the other hand, is observed at a much higher temperature around 125 °C. Thus, the macroscopically observable glass transition of polystyrene seems to be dominated by the dynamics of side groups rather than that of the coordinated motions of polymer segments along the backbone. This result suggests a fundamental similarity between the glass transition phenomena of polymers and those of small-molecule inorganic glasses.     

Mechanical,thermomechanical, and thermal properties of polystyrene crosslinked with a multifunctional zirconium oxo cluster

Inorganic–organic hybrid materials were prepared by free radical polymerization of styrene in the presence of varying amounts of the cluster Zr₆O₄(OH)₄ (methacrylate)₁₂. Stepwise polymerization allowed the preparation of bubble‐ and crack‐free, transparent bulk samples on a 30 g scale with dimensions required for mechanical testing. Small‐angle X‐ray scattering investigations and transmission electron micrographs revealed that the clusters formed randomly distributed aggregates of random size. Solvent uptake in swelling experiments was related to the cluster proportion. Storage moduli in the glassy state were slightly increased when compared with neat polystyrene, but pronounced plateau moduli were observed above the glass transition temperature, which correlated to the cluster proportion. Plateau moduli were used to calculate network parameters such as network density. Onset temperatures of thermal decomposition and the glass transition temperatures of the cluster‐crosslinked polymers were higher than that of neat polystyrene. Thermal expansion coefficients were unaffected in the glassy state, but were gradually reduced above the glass transition temperature with increasing cluster proportion. Both the tensile moduli at room temperature and the yield points increased when polystyrene was doped with the cluster. The strain hardening moduli, as determined in compression tests at large deformations, increased linearly with the cluster proportion. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2215–2231, 2007     

环氧树脂/聚丙烯酸酯型网间交联互穿网络聚合物的研究(Ⅰ)——形态和动态力学行为

互穿网络聚合物(IPN)中两个网络相互贯穿、缠结,增大了组分间的相容性,使玻璃化转变温度(T_g)内移,表现出相当宽的温度(频率)范围,引起人们广泛注意。但由于普通的IPN体系两个T_g间往往有一个凹谷,不是一种理想的吸震材科,Scarito及其同事采用网络间交联的方法提高了凹谷的高度。本工作以甲基丙烯酸乙二醇脂为网     

SYNTHESIS, CHARACTERIZATION AND PROPERTIES OF ORGANOCLAY-MODIFIED 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.Differ...