聚醚聚氨酯／聚甲基丙烯酸甲酯互穿聚合物网络相容性的研究

用同步法合成了聚醚聚氨酯/聚甲基丙烯酸甲酯(PU/PMMA)互穿聚合物网络(IPN)。讨论了不同交联缠结程度对IPN形态及性能的影响,分析了影响IPN两网络相容性的热力学及动力学因素。增加网络的交联密度可有效地改善IPN网络间的相容性,同时,调节两网络生成速度基本同步,控制在热力学相分离发生前使两网络最大程度地互穿缠结,也能减小相分离的程度,改善IPN网络间的相容性。     

氢化丁腈橡胶的结构与阻尼性能的关系

通过应力-应变曲线和动态力学性能分析(DMTA),探讨了氢化丁腈橡胶(HNBR)的结构、阻尼性能及其之间的关系.结果表明,HNBR的结合丙烯腈量越高,胶料的弹性越差,阻尼性能越好;双键含量升高,玻璃化转变温度降低,弹性增加.与应力-应变曲线相比,DMTA能更全面地反映材料的阻尼性能.     

PP/PnBA(semi一Ⅱ)互穿聚合物网络共混体系的动态力学松驰转变

应用动态粘弹谱仪分析了以原位共聚法制备的聚丙烯/聚丙烯酸正丁酯(PP/PnBA)互穿聚合物网络(IPN)复合膜材料的动态力学性能.研究表明这种结晶/非晶共混体系为两相结构,两组分的玻璃化主转变峰(β松驰)和低温次级γ松驰峰的强度和温域随交联网络的化学结构和交联密度的变化依赖关系的机制有所不同;网络的缠结作用强烈影响聚丙烯的内耗峰强tanδ值,其阻尼性能有所改善.     

互穿聚合物网络阻尼材料研究进展

综述了互穿聚合物网络(IPN)阻尼材料的阻尼理论,阻尼性能的评价方法;对IPN阻尼材料的制备和应用进行了评述,并展望了高性能IPN阻尼材料发展趋势和应用前景。     

受阻酚改性聚酯/聚醚胺型PU/P(MMA-St)IPN阻尼性能的研究

用一步法制备了受阻酚AO-80改性的聚酯/聚醚胺型聚氨酯/聚(甲基丙烯酸甲酯-苯乙烯)互穿聚合物网络(PU/P(MMA-St)IPN)。通过热失重分析仪、动态力学分析以及扫描电子显微镜对IPN材料的热稳定性、阻尼性能和微观结构形态进行了表征。研究结果表明:AO-80可以提高PU与P(MMA-St)的相容性,从而有效拓宽阻尼温域;当聚氨酯中聚酯/聚醚胺=80/20,w(AO-80)=20phr,PU/P(MMA-St)=70/30时,所得IPN材料的阻尼性能最佳。     

聚碳酸酯型聚氨酯/环氧树脂互穿网络聚合物交联密度及力学性能

用同步法合成了聚碳酸酯型聚氨酯/环氧树脂互穿网络聚合物(PCPU/EPIPN)。红外光谱分析表明两组分间存在一定程度的化学结合。动态力学性能分析表明:由于两网络间的互穿、缠结以及接枝反应的发生,使体系中 PCPU 和 EP 的相容性得到改善。用溶胀法测定了 IPN 体系的交联密度,结果发现形成 IPN 后体系的交联密度相应比纯组分有所提高。力学性能测试表明:在 m(PCPU)/m(EP)=25/75处 IPN 体系的力学性能最佳。     

受阻酚改性PU/PBMA IPN材料阻尼性能的研究

以聚碳酸酯二醇(PC-2000)、二苯甲烷二异氰酸酯(MDI)为原料合成聚氨酯(PU)预聚体,再以PU预聚体、扩链剂、甲基丙烯酸丁酯(BMA)及引发剂在一定条件下反应制备了聚氨酯/聚甲基丙烯酸正丁酯(PU/PBMA)互穿网络聚合物(IPN)材料,并加入受阻酚AO-80进行功能化改性,分别采用热固化法和室温固化法制备了受阻酚AO-80改性的PU/PBMA IPN材料。讨论了固化方法、PU与PBMA的配比、受阻酚AO-80用量等对IPN材料阻尼性能的影响,通过动态机械热分析、热失重分析以及扫描电子显微镜对IPN材料的阻尼性能、热稳定性和微观形态结构进行表征。结果表明,热固法比室温固化法更有利于制备高性能阻尼材料;受阻酚AO-80的加入可以明显提高IPN材料的阻尼性能,并能够有效地拓宽阻尼温域;当PU与PBMA质量比为60/40、AO-80质量分数为28%时,所制备的IPN材料的阻尼性能最佳。     

聚氨酯/乙烯基酯树脂互穿聚合物网络泡沫性能研究

研究了两种不同固化体系对乙烯基酯树脂(VER)的固化和对聚氨酯(PU)网络的匹配,以及单体结构和配比对PU/VERIPN硬质泡沫塑料力学性能和阻尼性能的影响规律。确定了过氧化二苯甲酰和N,N-二甲基苯胺合用的固化剂体系。实验表明,增加IPN中PU网络的高羟值聚醚(N303)的添加量,PU/VERIPN泡沫材料的压缩强度和压缩模量增大,冲击强度下降。S组的泡沫塑料的VER和PU具有较好的相容性,其Tanδ曲线出现一个很宽的阻尼平台,表现出较好的低温阻尼性能。     

填充剂对氢化丁腈橡胶阻尼性能的影响

通过胶料的应力-应变性能和动态力学(DMTA)性能研究了不同填充剂对氢化丁腈橡胶(HNBR)阻尼性能的影响,并从填充剂微观结构及阻尼机理方面进行了分析讨论。实验结果表明,在所考察的填充剂范围内,填充石墨的HNBR阻尼性能最好,云母次之。石墨和云母在微观形态上均属于典型的片状结构,其良好的阻尼性能与这种片状结构有一定关系。石墨填充量增大后,胶料的弹性模量和损耗模量在整个温度范围内均有一定程度的上升,阻尼系数tanδ和阻尼峰宽Δ0.3减小,玻璃化转变温度Tg变化不大。     

卫穿聚合物网络阻尼材料研究进展

综述了互穿聚合物网络（IPN）阻尼材料的阻尼理论,阻尼性能的评价方法,对IPN阻尼材料的制备和应用进行了评述,并展望了高性能IPN阻尼材料发展和应用前景。     

Poly(ether urethane)/poly(ethyl methacrylate) IPNs with high damping characteristics: The influence of the crosslink density in both networks

Interpenetrating polymer networks (IPNs) with a controlled degree of microphase separation were synthesized from a poly(ether urethane) (PUR) and poly(ethyl methacrylate) (PEMA). The influence of the crosslink density of both networks was investigated in the 70:30 PUR/PEMA IPN. The extent of damping was evaluated by dynamic mechanical thermal analysis. Mechanical properties were studied using tensile testing and hardness measure-ments. Control of crosslinking was successful in tailoring the damping profile. Higher crosslinking in the first-formed network (polyurethane) seemed to increase slightly the area under the linear loss modulus curve, LA, whereas no influence was obvious when changing the crosslink density in the second network. TGA studies revealed improved thermal properties for the IPNs with a higher crosslink density in the PUR network. TEM micrographs confirmed a finer morphology for the materials with a higher crosslink density in the PUR, whereas increasing the crosslink density in the PEMA network resulted in a decrease of phase mixing. © 1996 John Wiley & Sons, Inc.     

交联密度对氢化丁腈橡胶热性能的影响

用核磁共振法(NMR)测定了氢化丁腈橡胶(HNBR)的横向弛豫时间(T21),用以反映硫化胶的交联密度,并研究了交联密度对硫化胶热性能和力学性能的影响。结果表明:随着硫化剂DCP用量的增多,胶料交联密度增大,玻璃化转变温度升高,耐热性提高,拉伸强度先增大后减小,拉断伸长率、永久变形和撕裂强度明显减小。     

Investigation on the mechanical properties and oil resistance of sulfur cured nitrile rubber/hydrogenated nitrile butadiene rubber blends

Nitrile rubber (NBR)/hydrogenated nitrile butadiene rubber (HNBR) blends with various ratios were compounded with internal mixer and two-roll open mill. Mechanical properties and low-temperature performance (TR10) of the NBR/HNBR blends after aging under different conditions were investigated. Furthermore, equilibrium swelling test and moving die rheometer (MDR) test were used to systematically investigate the effects of HNBR dosage on the crosslink densities and curing behaviors. Vulcanization torque and crosslink densities decreased with an increase in HNBR content. The crosslink density of pure HNBR is higher than that of pure NBR, which is related to the macromolecular structures of the rubber. Compression sets of the NBR/HNBR vulcanizates were correlated with HNBR dosage indicating a linear relationship. Low-temperature performance of the NBR/HNBR blends was improved after being aged in the synthetic hydrocarbon hydraulic oils (SH-1 and SH-2). This work shows that the low-temperature performance and oil resistance could be better balanced by blending NBR with HNBR, while the mechanical properties maintain relatively high level.     

Effect of morphology,crosslink density,and miscibility on interpenetrating polymer network damping effectiveness

The areas under the linear loss modulus versus temperature curves (loss area, LA) and tan δ versus temperature curves (TA) were evaluated for a number of acrylic, methacrylic, styrenic and butadiene based copolymers and interpenetrating polymer networks, IPNs, as a function of crosslink density and comliosition, and were compared with values predicted by group contribution analysis. The LAs of the sequential IPNs, cross-poly(n-butyl methacrylate)-inter-crosspolystyrene, were found to exhibit up to 30% larger LAs than the poly(n-butyl metacrylate-stat-styrene) copolymers, which had LAs slightly less than the values predicted from the group contribution analysis. At constant chemical composition (50% n-butyl methacrylate, 50% styrene), LA equals 14.4 GPa K for the IPN, attributed to a synergistic effect resulting from the IPN's microheterogeneous morphology, as compared with 10.7 GPa K for the single phase, miscible copolymer. Increases in the LA with increased concentration of polymer, network II were also observed for cross-poly(ethyl acrylate)-inter-crosspolystyrene and cross-polybutadiene-inter-cross-polystyrene IPNs. On the other hand, cross-polybutadiene-inter-cross-poly(methyl methacrylate) IPNs had LAs much lower than were predicted by the group contribution analysis, which were attributed to lower miscibility in this system relative to the other systems evaluated. In general, decreased crosslink densities and lower concentrations of network II increased TA. These findings demonstrate how the morphology of a multiphase polymeric material can affect LA and TA, with significant increases In damping capability over the average of the component polymer values.     

Mechanical properties and network structure of phenol resin crosslinked hydrogenated acrylonitrile‐butadiene rubber

The tough and stretchable crosslinked hydrogenated acrylonitrile–butadiene rubber (HNBR) could be prepared by resol type phenol resin as a crosslinker. The mechanical properties and the network structure of the phenol resin crosslinked HNBR were investigated by comparing with those of the peroxide crosslinked HNBR having the higher crosslink density and the heterogeneous network structure. The elastic modulus and the strain at break of the phenol resin crosslinked HNBR were much higher than those of the peroxide one. The residual strain was below 20 % after stretching up to 650 % and then releasing from the cramps. Since the crosslink density is low, the high elastic modulus and the good recovery deformation are attributed to the stiffness and rigidity of the crosslink junctions obtained by phenol resin. Small‐angle X‐ray scattering measurements revealed that the network structure is spatially homogeneous and the results of the wide angle X‐ray diffraction indicate that the strain‐induced crystallization is suppressed, which enable the longer elongation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Polyurethane–polystyrene interpenetrating polymer networks synthesized at low temperature: Effect of crosslinking level

Interpenetrating polymer networks (IPNs) of polyurethane (PU)–polystyrene (PS) containing 50 wt % PU were synthesized at low temperature with varying crosslink density of each component. PU was polymerized first, followed by the photopolymerization of PS at low temperature (0 and 40°C). The theoretical molecular weight between crosslink (M?_c) of PU ranged from 8200 to 2050, and the M?_c of PS varied from linear to 2000. The degree of mixing of the components in these IPNs was investigated using dynamic mechanical analysis, electron microscopy, and density measurement. The degree of mixing increased with decreasing M?_c and/or synthesis temperature. The crosslink density variation at low synthesis temperature is more effective in enhancing the miscibility of IPN than at high synthesis temperature, because both the temperature and crosslink density can affect the polymer chain mobility during the synthesis. The variation of PU network crosslink density shows the better effect in increasing the miscibility of IPN than that of the PS network. The morphology and the density behavior agree well with the dynamic mechanical result.     

Interpenetrating polymer networks based on nitrile rubber and metal methacrylates

Interpenetrating polymer networks (IPNs) based on nitrile rubber (NBR) as first component and zinc dimethacrylate (ZnDMA), aluminum trimethacrylate (AlTMA), or zirconium tetramethacrylates (ZrTeMA) as second component were synthesized. Sequential IPNs (SeqIPN) were formed by two routes such as compression molding (CM) and swelling/curing (SC). The IPNs were found to have superior properties compared to metal oxide/hydroxide‐filled NBR. Tensile strength has increased to a large extent while maintaining appreciable elongation. Total crosslink density (covalent and ionic) was found to increase in the order NBR/metal oxide or hydroxide < SeqIPN(CM route) < SeqIPN (SC route). IPNs are found to retain high storage modulus even in the rubbery region. It is observed that change of technique for IPN formation has drastically changed the modulus of the present system. Decrease in tan δ value and inward shifting of peaks were observed because of IPN formation. Morphology of SeqIPN by SC process was found to be more uniform compared to others. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2542–2548, 2006     

纳米微晶纤维素对炭黑补强天然橡胶硫化特性和耐老化性能的影响（二）

（续上期） 2．5复合材料的老化性能 在热氧条件下,橡胶大分子链断裂致使分子链变短,材料密度增大,宏观上表现为橡胶硬度提高、物理性能下降,即橡胶材料发生了老化。NR的分子链中含有大量不饱和双键,易受到氧及臭氧的侵蚀而破坏,其热氧老化性能有待提高。     

Dynamic mechanical response of model epoxy networks in the glassy state

The dynamic mechanical properties of model epoxy-amine networks are investigated in the glassy state over a wide range of frequencies, at temperatures between 123 K and 350 K. The effects of crosslink density and network chain flexibility on the β relaxation are examined. Motions responsible for the β process begin to develop at the same temperature, whatever the crosslink density. However, an increase in crosslink density is accompanied by an increase in amplitude and a broadening towards high temperatures of both damping tan δ and loss modulus E″. This effect is responsible for the decrease of elastic modulus E′ at room temperature with increasing crosslink density.