聚酰亚胺泡沫的制备与性能

以2,4,6-三氨基嘧啶为三胺单体,经由聚酯铵盐前体粉末发泡合成了具有交联结构的聚酰亚胺泡沫。结果表明,三胺单体的加入对聚酰亚胺前体及其泡沫的化学结构和聚集态结构没有明显的影响。含2,4,6-三氨基嘧啶的聚酰亚胺泡沫材料的5%热失重温度均在520℃以上,且具有良好的耐燃烧性。随着三胺单体含量的增加,聚酰亚胺泡沫材料的力学性能和玻璃化转变温度得到提高。     

粉末法制备聚酰亚胺泡沫塑料

以芳香二酐和二胺为单体,甲醇/四氢呋喃为溶剂,通过酯化法合成聚酯铵盐前驱体粉末、粉末法制备泡孔均匀的聚酰亚胺泡沫塑料.采用扫描电子显微镜照片、傅里叶变换红外光谱和热重分析表征泡沫材料结构及耐热性能,研究了初始加热温度、粉末粒径对泡沫密度的影响.结果表明:初始加热温度越高,泡沫密度越小.粉末粒径对泡沫密度影响较小.     

一步法制备热塑性聚酰亚胺泡沫关键因素探讨

通过在热塑性聚酰亚胺(PI)粉末中添加高温发泡剂一步发泡制得PI泡沫材料,探讨了一步法制备PI泡沫过程中的模具密闭性、发泡温度、发泡剂用量等几个关键因素对材料结构及力学性能的影响。结果表明,一步发泡法制备PI泡沫材料过程中模具密闭性、发泡剂用量对泡沫性能有很大影响。经优化的制备条件为:树脂粉在烘箱中60℃预处理2 h,发泡剂质量分数为2%,成型温度为280℃,成型压力为10 MPa,发泡时间为30 min。在优化的实验条件下制备的热塑性PI泡沫材料样品的密度为0.463 g/cm3时,压缩强度为10.86 MPa,冲击强度为6.2 kJ/m2,弯曲强度为12.8 MPa。     

泡沫密度对乙烯-乙酸乙烯酯橡胶发泡材料压缩性能及动态力学性能的影响

以乙烯-乙酸乙烯酯橡胶(EVM)为基体,过氧化二异丙苯(DCP)为硫化剂、偶氮二甲酰胺(AC)为发泡剂,制备了不同泡沫密度的EVM发泡材料,研究了EVM混炼胶的硫化及发泡特性,采用体视显微镜表征了发泡材料的微观形貌,并考察了泡沫密度对发泡材料的压缩性能及动态力学性能的影响。结果表明,当DCP选用6份、AC选用3.5份时有利于EVM进行发泡;随着泡沫密度的增加,EVM发泡材料的泡壁逐渐变厚;低密度EVM发泡材料的线性弹性阶段范围较大,随着泡沫密度的增加,EVM发泡材料的应力增大,压缩过程中的线性弹性区逐渐变窄;泡沫密度对EVM发泡材料的玻璃化转变温度、阻尼因子(tanδ)峰值几乎没有影响;随着泡沫密度的增加,在玻璃态下EVM发泡材料的储能模量(G')和tanδ不断增大,而在高弹态下G'增大,但tanδ减小。     

复合无机填料耐温增效聚酰亚胺泡沫的制备和性能

针对市场不同行业领域特别是锂电池行业,对泡沫材料提出的更高的高温隔热性能,为了使得聚酰亚胺泡沫能够实现高温下的隔热性能,利用复合无机填料增效聚酰亚胺泡沫的耐温性能,研究了空心玻璃微球与可膨胀蛭石的不同比例、无机填料不同添加量以及不同密度聚酰亚胺泡沫对其高温隔热性能的影响,通过600℃的加热台测试泡沫背面的冷面温度,研究发现,聚酰亚胺泡沫的发泡倍率在5～10倍,添加的空心玻璃微球和可膨胀蛭石的质量是泡沫质量的50%,其中空心玻璃微球占无机物质量的20%,得到的聚酰亚胺泡沫在常温下具有较低的导热系数,并且在高温下的隔热性能优异。     

水对硬质聚酰亚胺泡沫泡孔结构与性能的影响

采用预聚法制备了1种芳香族聚酰亚胺泡沫,研究了水含量对聚酰亚胺泡沫分子结构﹑泡孔结构﹑发泡密度、发泡程度以及热稳定性的影响规律。结果表明:在所研究的水含量范围内,水含量对聚酰亚胺泡沫的分子结构和热稳定性几乎没有影响;随着水含量增加,大泡孔增多,泡孔尺寸变大,发泡程度更大,泡沫密度更低。     

苯酚-尿素-甲醛共缩聚树脂基泡沫材料的制备和性能

以木材工业用苯酚-尿素-甲醛(PUF)共缩聚树脂为原料制备出了PUF发泡材料,采用扫描电镜和元素分析等手段对PUF泡沫材料的结构和化学特性进行分析,进而研究了制备工艺,尤其是发泡剂用量、固化剂用量以及发泡温度三个主要的工艺参数对泡沫材料表观密度的影响,制备出了密度在0.035~0.12 g/cm3范围内的PUF泡沫材料。最后探讨了材料的表观密度和抗压强度之间的关系,即PUF泡沫材料的抗压强度随着密度的增大而增大,可以作为承重用防火保温材料。     

聚乙烯醇在超临界二氧化碳中的发泡行为

采用甘油作为聚乙烯醇(PVA)的塑化改性剂,实现了PVA的热塑成型,以超临界二氧化碳(scCO_2)为物理发泡剂,采用间歇式降压法制备了一系列PVA泡沫材料。利用差式扫描量热仪和流变仪系统研究了甘油对PVA的熔融行为和流变性能;并采用扫描电镜(SEM)研究了发泡温度、饱和压力和保压时间对泡孔形态的影响。结果表明,40%甘油增塑PVA体系的熔融温度降低至177.7℃,且在发泡温度下具有合适的黏度;随发泡温度的提高,PVA泡沫材料的泡孔尺寸增大,泡孔密度下降;增大饱和压力和适当延长保压时间,可提高增塑PVA体系的发泡效果。在合适的工艺条件下,发泡温度为185℃,饱和压力为15 MPa,保压时间为60 min时,PVA泡沫材料的发泡效果良好,其泡孔尺寸50.6μm,泡孔密度为8.8×10~6个/cm~3。     

短切碳纤维增强聚酰亚胺泡沫的制备及性能

针对现有软质聚酰亚胺泡沫强度低的缺点,通过一步法制备了短切碳纤维增强聚酰亚胺泡沫,研究了短切碳纤维的添加量对聚酰亚胺泡沫的化学结构、微观形貌、压缩强度及热导率的影响。结果表明,短切碳纤维在发泡过程中起到成核剂的作用,随着其添加量的增加,泡沫的泡孔平均尺寸先减小后增加;当短切碳纤维质量分数为20%时,泡孔的最小平均尺寸为507μm;泡沫密度随着短切碳纤维用量的变化没有明显的改变;泡沫的压缩强度随着短切碳纤维的用量先增大后逐渐减小,压缩强度最大为54.52 kPa;短切碳纤维的加入对聚酰亚胺泡沫材料的化学结构和热稳定性没有明显的影响,但是材料的热导率随着短切碳纤维含量的增加有一定的增加。     

高熔体强度聚丙烯的发泡性能研究

通过反应挤出法对聚丙烯(PP)进行硅烷接枝交联改性获得高熔体强度PP(HMSPP),并对HMSPP的发泡性能及影响因素进行了研究。结果表明,HMSPP具有良好的发泡性能,可以制备出高质量泡沫材料;随着HMSPP的熔体流动速率的降低,泡沫材料的密度和泡孔平均直径降低;随着HMSPP用量减少,HMSPP/PP泡沫材料的泡孔平均直径和密度增大,泡孔尺寸及分布的不均匀程度增加;发泡条件对泡沫结构具有一定的影响,最佳的发泡温度为185~190℃,螺杆转速为40~100r/min;随着口模厚度的增加,泡孔平均直径增加,材料密度下降,而材料内外层泡孔直径不均匀性增加。     

木粉／低密度聚乙烯复合材料的发泡研究

用模压法制备木粉／低密度聚乙烯发泡材料。通过差示量热扫描分析,考察了纯偶氮二甲酰胺(AC)及与 ZnO共混物、纯NaHCO3及与柠檬酸(L)共混物的热分解特性,探讨了发泡剂AC、NaHCO3、柠檬酸、交联剂过氧化二异丙苯等对材料力学性能的影响,并在扫描电镜下观察了材料断面的微观形态。结果表明:采用放热发泡剂和复合发泡剂都能使复合材料密度下降20％左右,发泡后材料的冲击性能为发泡前体系的1．5倍左右;复合发泡剂的发泡效果优于单放热发泡剂的效果。     

The effect of curing system on the properties of the thermoplastic elastomer foams of ethylene‐vinyl acetate copolymer and styrene‐butadiene and ethylene‐propylene‐diene monomer rubbers

Thermoplastic elastomer (TPE) foams have important application in electrical, toys, and other industries. Several foams were prepared by ethylene‐vinyl acetate copolymer (EVA) lonely, and in combination with styrene‐butadiene and ethylene‐propylene‐diene monomer rubbers (SBR and EPDM). The effects of crosslinking and foaming agents and EVA type on density and mechanical properties of the cured foams with two curing systems, peroxide and sulfur‐peroxide with potential use in automotive applications, were studied. The results showed that proposed compounds formulations were foamed properly. The viscosity of the EVA was a key factor for the density values of the formed foams. The densities of the cured foams with peroxide system with various SBR contents were higher when compared with cured foams with sulfur‐peroxide system. With increasing foaming agent, the densities of the foams were reduced for studied curing systems. The densities of the EVA–EPDM foams were lower than those of the EVA–SBR foams in the same studied conditions. Increasing rubber in foam formulation had adverse effect on tensile properties of the foams. The existence of the talc powder in foam formulation had important role on the shape and type of the formed cells and resulted in foams with mostly closed cells. The results of this study help the automotive article designer to produce suitable TPE foam. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45357.     

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     

聚酰亚胺/多壁碳纳米管泡沫材料的制备及性能研究

将不同质量分数的多壁碳纳米管（MWCNT）与PI通过原位聚合制备了聚酰亚胺（PI）/MWCNT泡沫复合材料,并利用扫描电子显微镜、热失重等仪器对材料性能进行了测试。结果表明,随着MWCNT质量分数的增加,泡孔直径增大,泡沫密度降低,当MWCNT含量超过0.4 %（质量分数,下同）易发生团聚作用,限制了泡沫结构的形成,导致泡沫的形状不规则;在添加0.2 %的MWCNT时,压缩强度、压缩模量、硬度获得了最好的增强效果,并发现增强效果随MWCNT质量分数的增加增强效果呈现先增大后降低的趋势;样品的热稳定性在添加0.05 %质量分数的MWCNT时达到最佳水平。     

Elaboration and Characterization of Advanced Biobased Polyurethane Foams Presenting Anisotropic Behavior

Biobased and open cell polyurethane (PU) foams are produced from a synthesized sorbitol‐based polyester polyol. Different formulations are developed with various blowing agent systems (chemical vs physical blowing). Synthetized foams are fully characterized and compared. The cell morphology is carefully investigated by tomography and scanning electron microscopy. The chemical nature of the primary compounds, foaming kinetics, density, thermal behavior, and conductivity are fully studied, with also the main transition materials temperatures. It is shown that blowing agents especially impact the foaming kinetics. In the case of chemically blowing foams, higher foaming rate and temperatures are obtained. The mechanical behavior is particularly analyzed using quasi‐static compression tests, according two main axes compared to the rise direction. A direct relationship is observed between the formulation, foam structure, foam morphology, and corresponding mechanical properties. Results clearly highlight unexpected properties of biobased PU foams with unveil anisotropic mechanical properties.     

Production of non‐crosslinked thermoplastic foams with a controlled density and a wide range of cellular structures

A novel foaming route, with respect to existing industrial foaming processes, called “Improved Compression Molding” (ICM), which allows producing non‐crosslinked thermoplastic foams in a wide density range, is described in this work. This process is different from others because it is possible to control independently density and cellular structure and therefore, tailored cellular polymers can be produced. To understand the process, a collection of polypropylene foams, with relative densities ranging from 0.3 to 0.6 were produced. The influence of foaming parameters, on foams microstructure and mechanical response was analyzed. Results revealed that for similar densities, foams with different open cell content and cell size can be achieved. In addition, it was proved that mechanical behavior strongly depends on the degree of interconnectivity of the cells. The analysis of the relative mechanical properties allowed determining the influence of microstructure on mechanical behavior as well as quantifying the efficiency of the foaming process to produce light‐weight stiff materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42324.     

发泡母粒对ABS发泡材料泡孔结构及力学性能的影响

采用化学注塑发泡制备了丙烯腈–丁二烯–苯乙烯(ABS)发泡材料,研究发泡剂母粒载体分别为高抗冲聚苯乙烯(PS–HI),PS–HI+苯乙烯–丁二烯–苯乙烯塑料(SBS),SBS,ABS及聚烯烃弹性体(POE)时发泡剂母粒对ABS泡孔结构及力学性能的影响。结果表明,发泡母粒载体对ABS发泡试样的泡孔结构及力学性能具有较大的影响,以POE为发泡母粒载体所制得的ABS发泡样品的泡孔结构、力学性能较好。其泡孔平均直径为18.5μm,泡孔密度为4.183×107个／cm3,冲击强度为11.7 kJ／m2,拉伸强度为30.8 MPa。     

Mechanical properties of BaTiO3 open-porosity foams

Barium titanate (BaTiO₃) foams synthesized via direct foaming method using silicon-free, rigid polyurethane systems (PU), commercially purchased and lab developed, are being engineered for piezocomposites in sonar applications. The mechanical properties of these foams were measured using confined compression testing to evaluate the suitability of these foams for the intended application. Compressive modulus and collapse strain determined from the experimental data increased with increasing density. Additionally, the foams fabricated using the lab developed PU (LPU) showed a higher mechanical strength due to a higher average density than the foams developed using commercial PU (CPU) system. The data was then fit with a phenomenological model to verify the values of the compressive properties extracted from the experimental data and also to extract additional properties such as tensile strength. Based on these findings, it is proposed that these foams can be successfully incorporated into piezocomposites by infiltrating the foams with polymer.     

Effect of different concentration of rapeseed‐oil‐based polyol and water on structure and mechanical properties of flexible polyurethane foams

Flexible polyurethane foams (FPURFs) with varied concentration of water from 3.2 to 4.2% and rapeseed oil based polyol (ROP) in the range of 13–22% in polyol premix were obtained. Effects of changes in polyurethane (PUR) formulation on the foaming process and mechanical properties of FPURFs were analyzed. It was found that the change of water content in PUR formulation influences its foaming process. Higher water content in the PUR formulation increases the growth velocity and the temperature of reaction mixture. In the case of foams modified with ROP, an opposite effect can be observed, where higher content of that component resulted in overall downturn of the foaming process and decreases of registered temperature inside the foams core. An addition of ROP beneficially influences on foams cellular structure favoring creation of finer cells. Such modification of PUR formulation with ROP increased apparent density, reduced hardness, and resilience of flexible foams. What is more the support factor of FPURFs with ROP was higher in comparison to the reference foam. Along with higher water content in the PUR formulation, apparent density and hardness has decreased and foams ability to absorb energy has been increased. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42372.