聚氨酯/环氧树脂互穿网络聚合物硬质泡沫机械性能研究

采用同步法合成了聚氨酯/环氧树脂互穿网络聚合物(PU/EP IPN)硬质泡沫,对机械性能进行了研究。结果表明,与纯聚氨酯硬质泡沫相比,PU/EP IPN硬质泡沫的压缩强度和弯曲强度明显提高,在PU/EP IPN硬质泡沫中,随环氧树脂含量增加,PU/EP IPN硬质泡沫压缩强度和弯曲强度随之增大,当E-39D质量分数增加到24.2%时,PU/EP IPN硬质泡沫压缩强度和弯曲强度出现最大值;PU/EP IPN硬质泡沫机械强度随材料密度的增大而增加;随着环氧树脂中环氧值的增加,PU/EP IPN硬质泡沫的压缩强度、弯曲强度和拉伸强度均呈逐渐升高的趋势。     

环氧树脂/空心玻璃微珠泡沫材料性能研究

以高强度环氧树脂为基体,表面改性处理的空心玻璃微珠(HGB)为填料,经高温固化制备了环氧树脂/HGB泡沫材料,并研究了HGB类型、HGB含量和固化剂用量对泡沫材料压缩性能的影响。研究发现,随着HGB填充量的增大,泡沫材料的密度和压缩强度均下降。当固化剂与环氧树脂物质的量比为0.85时,泡沫材料的抗压性能最好,压缩强度为40.19 MPa。偶联剂改性HGB可以有效改善HGB和基体树脂的粘合效果。当改性HGB质量分数为80%时,与未改性环氧树脂相比,环氧树脂/改性HGB泡沫材料压缩强度提高了5.0%,吸水率下降40.6%。     

APP对硬质聚氨酯-酰亚胺泡沫泡孔结构及力学性能的影响

采用聚酰亚胺(PI)预聚法,合成由聚磷酸铵(APP)阻燃的硬质聚氨酯-酰亚胺泡沫塑料。分析了APP添加量对泡孔结构、泡沫结构参数、力学性能的影响以及三者之间的关系,并通过幂次法则建立起压缩性能、冲击性能与泡沫密度之间的关系。结果表明:随着APP添加量的增加,硬质聚氨酯-酰亚胺泡沫塑料的泡孔孔径和冲击强度减小,而泡沫密度、压缩强度和压缩模量均增大;冲击强度、压缩强度、压缩模量与泡沫密度之间的密度指数分别为-1.688、1.062和0.934;冲击性能和压缩性能与泡孔结构和孔隙率有密切关系。     

含溴环氧树脂对聚氨酯硬泡性能的影响

采用聚醚多元醇、多亚甲基多苯基多异氰酸酯(PAPI)、泡沫稳定剂、催化剂、高效阻燃剂、发泡剂、含溴环氧树脂等原料通过一步法制备了聚氨酯硬质泡沫材料,研究了不同含溴环氧树脂添加比例的聚氨酯硬质泡沫材料的压缩强度和阻燃指数。结果表明,随着含溴环氧树脂添加量的增加,压缩强度出现先增加后减少的趋势。在含溴环氧树脂添加量占白料总质量10%时,压缩性能最佳;随着含溴环氧树脂添加量的增加,聚氨酯硬泡的极限氧指数呈上升趋势;高效阻燃剂用量可以使改性聚氨酯硬泡极限氧指数得到显著增加,达到30%以上。     

不同填充材料的引入对环氧树脂泡沫力学性能的影响

环氧树脂泡沫是一种多胞体结构的材料,具有比模量高、比强度高、密度低的特性,被广泛用作轻质结构材料。本研究通过在环氧树脂泡沫发泡过程中引入不同的填充料(碳纳米管,铝粉和SiO_2),考察了其对环氧树脂泡沫各项性能的影响。结果表明以上三种材料都可以在不改变环氧树脂泡沫固化过程的前提下显著改善环氧树脂泡沫的性能。铝粉和SiO_2可以有效增加环氧树脂泡沫的热分解温度从而改善其热性能,而CNTs的加入在不改变环氧树脂泡沫其他固有性质的前提下可以有效地提高环氧树脂泡沫的抗压强度。     

空心玻璃微珠填充环氧树脂复合材料压缩性能研究

制备了空心玻璃微珠 (HGM )填充环氧树脂复合材料 ,对材料进行了单轴静态压缩实验。研究了HGM的粒径和体积分数 (Vf)对材料压缩性能的影响 ,研究发现 ,Vf增大 ,材料中HGM外部空气泡的含量增大 ;材料的压缩强度和压缩模量可在 5 0～ 10 0MPa和 1.5 0～ 1.80GPa之间调节 ;材料断裂应变较小 ,用扫描电镜观察了其结构形态和破坏形式 ,断裂面与应力方向约成 45°角 ,破坏主要由HGM的破裂引起 ;HGM粒径减小 ,材料压缩强度增大 ;Vf 增大 ,压缩强度减小 ,压缩模量先增大后减小 ,断裂应变减小。用改进Turcsanyi方程对压缩强度进行了模拟计算 ,材料的密度与计算值基本一致     

聚氨酯泡沫材料的性能研究

聚氨酯泡沫具有多孔性、相对密度小、比强度高等特点,根据所用原料的不同和配方的变化可制成阻尼减震性能优异的材料。为了满足铝型材内填充材料的阻尼减震的要求,通过改变原料的组成和配比,制备了一种密度低、阻尼性能优异的聚氨酯泡沫材料。研究了发泡剂、N220和环氧树脂的含量对泡沫材料性能的影响,结果表明调节发泡剂用量可以改变材料的密度和粘接性能,N220和环氧树脂的加入可以提高聚氨酯泡沫的阻尼性能,所制得的聚氨酯泡沫材料可以满足铝型材填充材料的要求。     

环氧树脂复合泡沫材料的制备及压缩性能研究

以空心玻璃微珠填充环氧树脂制备高强复合泡沫材料,在选取不同种类室温固化剂的基础上,研究了空心玻璃微珠含量对复合泡沫材料压缩性能的影响。研究表明当空心玻璃微珠质量分数为105%时,复合泡沫材料的比强度达最大值,此时压缩强度为62.91MPa,密度为0.55g/cm3。     

端羟基液体橡胶改性RPUF的结构与力学性能

制备了3种端羟基液体橡胶改性硬质聚氨酯泡沫塑料(RPUF)。研究了所制备材料的形态结构,以及泡沫材料的冲击韧性、屈服强度模量、缓冲吸能特性和阻尼性能与材料密度、液体橡胶的含量和液体橡胶的种类之间的关系。结果表明,粘度较低的端羟基聚丁二烯改性的硬质聚氨酯泡沫具有更好的冲击韧性;粘度较高、含极性氰基端羟基聚丁二烯丙烯腈改性的硬质聚氨酯泡沫塑料具有较低的屈服强度、模量和缓冲能量吸收值,具有较高的力学损耗。为高阻尼硬质聚氨酯泡沫塑料的制备奠定了基础。     

环氧树脂复合泡沫材料的制备研究

以缩水甘油酯环氧树脂(EP)、酸酐固化剂和空心玻璃微珠为主要原料,通过添加一定的活性稀释剂,高温固化制备了EP复合泡沫材料。研究了空心玻璃微珠的表面改性对复合泡沫材料性能的影响。结果表明,复合泡沫材料性能与空心玻璃微珠的表面性能密切相关,当EP/固化剂/稀释剂的质量比为100/120/15、KH-560改性的空心玻璃微珠用量为30份时,所制备的复合泡沫材料密度为0.826 g/cm3,压缩强度达115.8 MPa,比强度为140.2。     

Flexural modulus prediction of symmetric structural polymer foams with complex density profiles

In this work, a new phenomenological model is proposed to predict the flexural modulus of symmetric structural foams with complex density distribution across their thickness. The model is based on a generalized Fourier series to represent the density profile and the simple square power-law relation to relate density with modulus. The model predictions are compared with data on polyethylene (LDPE and HDPE) structural foams produced by compression and injection molding. The results show that a very high degree of agreement (less than 3% deviation) can be obtained for these complex structures.     

High internal phase emulsion foams: Copolymers and interpenetrating polymer networks

High internal phase emulsion (HIPE) copolymer and interpenetrating network foams were prepared from 2‐ethylhexyl acrylate (EHA), styrene (S) and divinylbenzene (DVB) using a unique process. The morphologies, thermal properties and dynamic and static mechanical properties of these foams were investigated. The glass transition temperatures and damping properties of the EHA/S copolymer foams vary with its composition. IPN foams with very broad tan 5 peaks were obtained. The damping properties of IPN foams were tailored through changing copolymer composition and monomer composition. The IPN foams based on a copolymer foam and styrene had a broader tan δ peak, a higher glass transition temperature and a higher modulus than tne copolymer foams of similar overall styrene contents. It is therefore possible to prepare novel damping foams based on polyHIPE foams through the synthesis of interpenetrating polymer networks.     

Water-blown rigid and flexible polyurethane foams containing epoxidized soybean oil triglycerides

Both rigid and flexible water-blown polyurethane foams were made by replacing 0–50% of Voranol® 490 for rigid foams and Voranol® 4701 for flexible foams in the B-side of foam formulation by epoxidized soybean oil. For rigid water-blown polyurethane foams, density, compressive strength, and thermal conductivity were measured. Although there were no significant changes in density, compressive strength decreased and thermal conductivity decreased first and then increased with increasing epoxidized soybean oil. For flexible water-blown polyurethane foams, density, 50% compression force deflection, 50% constant force deflection, and resilience of foams were measured. Density decreased first and then increased, no changes in 50% compression force deflection first and then increased, increasing 50% constant force deflection, and decreasing resilience with increase in epoxidized soybean oil. It appears that up to 20% of Voranol® 490 could be replaced by epoxidized soybean oil in rigid polyurethane foams. When replacing up to 20% of Voranol® 4701 by epoxidized soybean oil in flexible polyurethane foams, density and 50% compression deflection properties were similar or better than control, but resilience and 50% constant deflection compression properties were inferior. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Young’s modulus and thermal conductivity of closed-cell,open-cell and inverse ceramic foams – model-based predictions,cross-property predictions and numerical calculations

Numerical calculations of relative Young’s modulus and thermal conductivity have been performed on computer-generated microstructures of wall-based (closed-cell) and strut-based (open-cell) cellular materials (foams) and inverse foams. The results are compared to rigorous upper bounds (Wiener-Paul, Hashin-Shtrikman), model-based predictions (power-law, exponential) and cross-property predictions (CPRs). It is shown that closed-cell foams exhibit higher property values than open-cell and inverse foams, Kelvin foams higher than random foams, and the difference between closed-cell and open-cell foams is larger than that between Kelvin and random foams. While the properties of closed-cell foams are higher than the power-law prediction, those of inverse and open-cell random foams are between the exponential and power-law predictions, and open-cell Kelvin foams follow the Gibson-Ashby power-law prediction for open-cell foams. The Pabst-Gregorová CPR is shown to predict Young’s modulus with accuracy better than ±0.02 relative property units (better than any model-based relation and any other CPR).     

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。     

Reinforcement of polyurethane/epoxy interpenetrating network nanocomposites with an organically modified palygorskite

An organophilic palygorskite (o‐PGS) prepared by the treatment of natural palygorskite with hexadecyl trimethyl ammonium bromide was incorporated into interpenetrating polymer networks (IPNs) of polyurethane (PU) and epoxy resin (EP), and a series of PU/EP/clay nanocomposites were obtained by a sequential polymeric technique and compression‐molding method. X‐ray diffraction and scanning electron microscopy analysis showed that adding nanosize o‐PGS could promote the compatibility and phase structure of PU/EP IPN matrices. Tensile testing and thermal analysis proved that the mechanical and thermal properties of the PU/EP IPN nanocomposites were superior to those of the pure PU/EP IPN. This was attributed to the special fibrillar structure of palygorskite and the synergistic effect between o‐PGS and the IPN matrices. In addition, the swelling behavior studies indicated that the crosslink density of PU/EP IPN gradually increased with increasing o‐PGS content. The reason may be that o‐PGS made the chains more rigid and dense. As for the flame retardancy, the PU/EP nanocomposites had a higher limiting oxygen index than the pure PU. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Acoustical,damping and thermal properties of polyurethane/poly(methyl methacrylate)-based semi-interpenetrating polymer network foams

In the present study, the interpenetrated polymer networks (IPN) foams of polyurethane (PU) and poly(methyl methacrylate) (PMMA) with different ratio of PU/PMMA (i.e. 85/15, 75/25 and 65/35) were prepared using the polymerisation process. The acoustical, damping and thermal properties of synthesised IPN foams with regard to different compositions were studied. As indicators of effective damping capability, viscoelastic parameters including loss factor (tan δ), glass transition temperature (T_g) and effective damping interval (tan δ?>?0.3) were also determined. The results show that the T_g shifted to higher temperature ranges, and the damping temperature range (tan δ?>?0.3) increased when the IPN was formed. The sound absorption coefficient results show that because of the formation of IPN, the sound-absorbing capacity of prepared samples increased at a certain frequency, and the resonance frequency shifted to lower frequencies by increasing the PMMA content in IPN foams.     

Study on the cell structure and compressive behavior of biodegradable poly(ε‐caprolactone) foam

Biodegradable poly(ε‐caprolactone) (PCL) foams with a series of controlled structures were prepared by using chemical foaming method. The cell morphology was detected by scanning electron microscope (SEM). The compressive behavior of the foams was investigated by uniaxial compression test. The effect of density and structural parameters on the foam compressive behavior was analyzed. It was found that the relative compressive modulus has a power law relationship with relative density. Increasing of both the cell wall thickness and the cell density lead to higher compressive modulus of the foam; however, the cell size has no distinct effect on compressive behavior. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Effect of foaming temperature and rubber grades on properties of natural rubber foams

Foaming temperature and grade of dry natural rubber were varied to evaluate their effects on the morphology and mechanical properties of natural rubber (NR) foams. Three different grades of NR were used; namely ENR‐25, SMR‐L, and SMR‐10. NR foams from these grades were produced at three different foaming temperatures, i.e. 140, 150, and 160°C. The study was carried out using formulated compositions containing sodium bicarbonate as the chemical blowing agent and were expanded using conventional compression molding technique via a heat transfer foaming process. The NR foams were characterized with respect to their relative foam density, density of crosslinking, cell size, compression stress, and compression set. Increase in foaming temperature resulted in lower relative density and larger cell size. It was also discovered that the crosslink density slightly decrease with increasing foaming temperature. For mechanical properties, the highest foam density resulted in the highest compression stress. Compression stress at 50% strain increased with increasing foaming temperature and ENR‐25 foam has the highest compression stress among the produced foams. The results showed that the morphology, physical, and mechanical properties of the rubber foams can be controlled closely by the foaming temperature and rubber grades. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008