丙烯酸酯橡胶/聚乳酸发泡材料的结构与性能

以偶氮二甲酰胺(AC)为发泡剂制备了丙烯酸酯橡胶(ACM)/聚乳酸(PLA)发泡材料,考察了ACM/PLA(质量比)和AC用量对发泡材料结构与性能的影响。结果表明,随着PLA并用比的增加,发泡材料的泡孔密度减小,泡孔逐渐变大,泡孔壁变薄,邵尔C硬度增大,撕裂强度和拉伸强度均降低,耐老化性能得到改善;随着AC用量的增加,发泡材料的泡孔壁变薄,大泡孔数增加,泡孔大小均匀度降低,密度、邵尔C硬度、拉伸强度和撕裂强度均逐渐降低,并且下降幅度逐渐变小,耐老化性能没有明显变化;发泡材料的压缩应力-应变变化包括较宽的线弹性区域、较窄的泡孔塌陷平台和泡孔壁相互接触后的密实化区域3个阶段。     

硫化体系对再生胶发泡性能的影响

采用跳模法对再生胶进行发泡,考察了硫黄、促进剂CZ、TMTD对再生胶发泡特性及发泡体物理机械性能的影响,并用体视显微镜表征了泡孔结构。结果表明,随着硫黄用量的增加,再生胶发泡体的密度增大,发泡率、收缩率、泡孔体积分数及泡孔直径均减小,邵尔C硬度和压缩强度增大;随着CZ用量的增加,再生胶发泡体的密度和泡孔直径减小,发泡率和泡孔体积分数先减小后增大,收缩率先增大后减小,压缩强度和邵尔C硬度均先减小后增大;随着TMTD用量的增加,再生胶发泡体的密度增大,发泡率和泡孔体积分数均减小,收缩率和泡孔直径先增大后减小,压缩强度增大后略有下降。     

PP/PS/nano-clay超临界CO_2连续挤出发泡成型研究

以聚丙烯(PP)/聚苯乙烯(PS)/纳米黏土(nano-clay)为研究对象,采用单螺杆连续发泡挤出机系统进行发泡,并用扫描电镜观察了发泡样品的泡孔结构。通过比较泡孔形态、发泡膨胀率、泡孔密度、泡孔直径等分析了PP/PS/nano-clay共混物组分配比对泡孔结构的影响。结果表明,将PP与PS共混,可以改善PP的发泡性能;同时,nano-clay的加入进一步改善了共混体系的发泡性能。随着nano-clay用量的增加,泡孔平均直径减小,泡孔密度增加,当nano-clay用量为5%(质量分数)时,制得了泡孔密度达到2.16×108个/cm3的微孔泡孔塑料。     

化学发泡法制备发泡三元乙丙橡胶/聚丙烯热塑性硫化胶Ⅰ.挤出工艺参数

以偶氮二甲酰胺(AC)为发泡剂,采用单螺杆挤出机制备了发泡三元乙丙橡胶(EPDM)/聚丙烯(PP)热塑性硫化胶(TPV),探讨了挤出温度、机头温度及螺杆转速对发泡TPV性能及形态结构的影响。结果表明,在保证EPDM/PPTPV充分塑化熔融及顺利挤出的前提下,较低的挤出温度和机头温度有利于制备密度低、泡孔尺寸小且分布均匀、表面光洁度高的发泡TPV,最佳的挤出温度和机头温度分别为185,170℃;随着螺杆转速的提高,发泡TPV的密度和拉伸性能均先降低后增高;泡孔平均直径基本不变,泡孔面密度先增大后减小,泡孔尺寸分布先变窄后变宽,最佳的螺杆转速为65r/min。     

POE/EVA复合发泡材料性能

采用化学发泡法制备以聚乙烯-醋酸乙烯酯(EVA)为基体,不同含量乙烯-辛烯共聚物(POE)及马来酸酐(MAH)接枝的乙烯-辛烯共聚物的复合发泡材料,并研究POE对EVA发泡材料发泡行为及力学性能的影响。结果表明:随着POE含量的增加,一方面增加了发泡材料的弹性,压缩永久变形降低,但拉伸及撕裂强度降低,另一方面减小了泡孔直径,增加泡孔密度,POE在质量分数30%的时候性能最好,泡孔直径是79.2μm。而随着POE-g-MAH含量的增加,一方面显著提高了发泡材料的拉伸、撕裂强度及耐磨强度,另一方面进一步降低了泡孔直径,增大了泡孔密度。接枝马来酸酐的POE质量分数在30%～40%发泡材料的性能最好,泡孔直径为68.1μm。     

超临界二氧化碳间歇式发泡法制备PP、PP/POE微孔发泡材料

采用超临界二氧化碳间歇式发泡法，成功制备了聚丙烯(PP)、PP/POE(乙烯-辛烯共聚物)微孔发泡材料。研究了发泡温度、饱和压力、POE含量对PP复合材料发泡性能的影响，并且，通过研究发泡材料的微观形貌、泡孔直径和膨胀倍率，得到最佳POE添加量。结果表明，在156℃、20 MPa条件下，PP可形成泡孔直径均一、高体积膨胀比的闭孔结构材料。加入POE后，PP复合材料的发泡性能得到改善，对发泡区间影响显著，PP/POE(80∶20)的发泡温度区在40℃以上；PP/POE(80∶20)随着发泡温度的上升，泡孔平均直径先增加后下降，泡孔密度和体积膨胀比逐渐增大；在120℃、20 MPa条件下，添加20%POE,得到了发泡范围大且泡孔均一性较好的发泡材料，泡孔密度为1.13×10¹¹个/cm³,泡孔孔径为2.81μm。     

橡胶型氯化聚乙烯/聚乙烯-辛烯弹性体共混发泡材料的性能研究

采用模压化学发泡法制备不同共混比橡胶型氯化聚乙烯(CM)/聚乙烯-辛烯弹性体(POE)发泡材料,研究其泡孔结构和物理性能。结果表明:不同共混比CM/POE发泡材料均具有闭孔结构;随着POE用量增大,共混发泡材料的泡孔直径先减小后增大,泡孔由扁平塌陷不均匀分布变为富有立体感的均匀分布,泡孔壁增厚,邵尔C型硬度和压缩强度增大,拉断伸长率减小,100%定伸应力和拉伸强度先增大后减小,回弹值轻微波动。     

顺丁橡胶/丁苯橡胶并用发泡材料的制备及性能研究

研究硫黄和发泡剂OBSH-75用量及预硫化工艺对顺丁橡胶/丁苯橡胶并用发泡材料性能的影响。结果表明:添加2份硫黄和3份发泡剂的发泡材料的泡孔直径较小、泡孔均匀且为闭孔结构,动静刚度比较小,物理性能和减震性能较好;预硫化温度为125℃、预硫化时间为14min时,发泡材料的泡孔密度适中,动静刚度比较小,减震性能较好。     

聚丙烯/碳纳米管微孔注塑发泡行为及力学性能

研究了不同含量单壁碳纳米管(CNT)的加入对聚丙烯(PP)流变、热稳定性及微孔注塑发泡行为和力学性能的影响。结果表明,随着CNT含量从不足1.0 %(质量分数,下同)逐渐增加,PP熔体黏度显著增大,热稳定性逐渐提升,即使CNT的加入量仅为0.15 %也会产生团聚现象,但团聚体尺寸较小且与基体结合紧密;微孔发泡注塑样品中泡孔分布不均匀,泡孔尺寸范围在10~70 μm,直径随着CNT含量增加呈现先减小后增大;PP/CNT复合材料微孔发泡成型后,弹性模量、屈服应力下降不大,但断裂伸长率平均提升了近400 %,不同组分发泡样品间力学性能指标变化不大。     

EVM/PLA共混发泡材料泡孔结构和性能的研究

以乙烯-醋酸乙烯酯橡胶(EVM)和聚乳酸(PLA)共混物为基体材料,经模压发泡制备了共混发泡材料。研究了EVM/PLA不同共混比、硫化剂(DCP)、发泡剂(AC)和白炭黑用量以及不同发泡时间对EVM/PLA共混物发泡材料泡孔结构和物理机械性能的影响。结果表明,随PLA组分的减少,白炭黑和DCP用量的增加,泡孔逐渐减小,均匀度增加,孔壁增厚,材料的密度、拉伸强度和拉断伸长率呈升高趋势,发泡倍率呈降低趋势。随发泡剂AC用量的增加,泡孔壁变薄,平均泡孔尺寸变化不大,材料的密度、拉伸强度和拉断伸长率呈降低趋势,发泡倍率增加。随硫化时间的延长,泡孔尺寸变小,孔壁增厚、发泡倍率逐渐下降,拉伸强度先增大后减少,拉断伸长率先下降后上升。     

不同发泡剂及工艺条件对BR／SBR／NR发泡材料相结构及尺寸稳定性的影响

分别采用一段和两段模压法制备了以顺丁橡胶（BR）／丁苯橡胶（SBR）／天然橡胶（NR）为基体的橡胶发泡材料,研究了三种化学发泡剂N,N＇-二甲基戊次甲基四胺（H）、4,4＇-氧代双（苯磺酰肼）（OBSH）以及H／OBSH（质量比1：1）复配对发泡及硫化特性的影-向,以及3种发泡剂和2种成型工艺对收缩率及相结构的影响。结果表明,发泡剂H对硫化性能影响最大,含发泡剂H的混炼胶在分解过程中释放的热量最多;加入3种发泡剂都具有一种较大的泡孔镶嵌在较小的泡孔丛中的泡孔形态;密度和线收缩率均随着时间的增加而增加,经H／OBSH复配的发泡剂更适合该体系成型,材料线收缩率均比单独使用H和OBSH小,两段模压法可以有效地提高发泡材料的尺寸稳定性,收缩率降低至3．88％,同时发泡剂使用率最多可提高31．67％。     

交联剂用量对BR/EVA热塑性硫化胶性能的影响

采用动态硫化法制备了BR/EVA热塑性硫化胶(TPV),考查了硫化体系中硫黄用量对混炼胶的硫化行为、静态硫化胶的溶出物含量及性能的影响,并对BR/EVA型TPV的力学性能及微观结构进行了研究。结果表明,随着硫黄用量的提高,混炼胶硫化历程中的平坦期较长,但t90趋于明显降低,静态硫化胶溶出物含量及力学性能均呈下降趋势;当硫黄用量为0.5份时,静态硫化胶及BR/EVA TPV表现出良好的综合性能。显微镜照片表明,BR硫化胶的粒状物平均尺寸为5～10μm左右,较均匀地分散在EVA树脂基体中;FE-SEM的测试表明,TPV的断面平滑,TPV具有良好的形变回复性。     

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     

NR/SBR并用胶配比对其硫化特性和力学性能的影响

考察了天然橡胶与丁苯橡胶不同配比对并用胶硫化特性和力学性能的影响.无转子硫化仪的测试结果表明,随着丁苯橡胶的占比增加,最小转矩和最大转矩均变大,且两者差值也随之增大,硫化时间延长,硫化胶的拉伸强度和撕裂强度明显下降,硬度增加;120℃老化后拉伸强度有不同程度的下降,天然橡胶占比越多下降越明显.     

Microcellular foaming of silicone rubber with supercritical carbon dioxide

In spite of great concern on the industrial application of microcellular silicone rubber foams, such as in electric and medical devices, only a few works can be found about the foaming of silicone rubber. In this study, microcellular silicone rubber foams with a cell size of 12 μm were successfully prepared with curing by heat and foaming by supercritical CO₂ as a green blowing agent. The microcellular silicone rubber foams exhibited a well-defined cell structure and a uniform cell size distribution. The crosslinking and foaming of silicone rubber was carried out separately. After foaming, the silicone rubber foam was cross-linked again to stabilize the foam structure and further improve its mechanical properties. Foaming process of cross-linked silicone rubber should be designed carefully based on the viscoelastic properties because of its elastic volume recovery in the atmosphere. The basic crosslinking condition for small cell size and high cell density was obtained after investigating the rheological behavior during crosslinking.     

废旧聚氨酯硬质泡沫塑料的降解回收及再利用

采用双组分醇解剂乙二醇（EG）和丙二醇（PG）对废旧聚氨酯（PU）硬质泡沫塑料进行降解,获得了降解产物低聚物多元醇,并将其与木质素为原料制备出再生聚氨酯（r?PU）硬质泡沫塑料复合材料。利用导热系数测定仪、扫描电子显微镜、热重分析仪、傅里叶变换红外光谱仪等对废旧PU的降解效果和r?PU硬质泡沫复合材料的压缩强度、吸水率、导热系数、微观形貌及热稳定性等进行了分析和表征。结果表明,双组分醇解剂EG和PG质量比（m_EG：m_PG）为2：3时,废旧PU的降解效果最佳;当木质素添加量为6 %（质量分数,下同）时制备r?PU硬质泡沫复合材料的泡沫孔壁较厚且比较均匀,骨架几何构型完整,其压缩强度为185.3 kPa、导热系数为0.021 5 W/（m·K）,均能够达到国家标准要求。     

Injection Molded Strong Polypropylene Composite Foam Reinforced with Rubber and Talc

Lightweight plastic foams are of great significance for saving resources and reducing energy consumption. Foam injection molding (FIM) shows a promising future to provide lightweight and shape‐complex plastic components. However, it is still challenging to produce lightweight and strong polypropylene (PP) foams by FIM due to PP's poor foaming ability. Herein, rubber and talc are employed to improve PP's foaming ability, and hence to enhance PP foam's mechanical properties. Due to the significantly enhanced rheological properties, injection molded PP composite foam exhibits greatly refined and homogenized cellular structure compared with pure PP foam. Thanks to rubber toughening effect and improved cellular morphology, PP/rubber foam shows much higher ductility than pure PP foam. Moreover, talc particles lead to remarkably enhanced rigidity of PP/rubber foams. Thus, lightweight and strong PP/rubber/talc composite foam is achieved with tensile toughness increased by 82.58% and impact strength increased by 106.21%, and they show broad industrial application prospects.     

硫化体系对遇油膨胀橡胶性能的影响

以丁苯橡胶(SBR)为主要原料通过不同硫化体系制备了相应遇油膨胀橡胶(OSR)。研究了普通硫化体系、有效硫化体系、半有效硫化体系和过氧化物硫化体系对OSR性能的影响。结果表明,半有效硫化体系适合制备的多元共混OSR,硫磺用量在1.2质量份左右时,吸油膨胀率达775%左右,拉伸强度为6.8MPa,其综合性能最佳,符合制品要求。     

离子液体改性炭黑增强丁腈橡胶的研究

先采用离子液体（1-丁基-3-甲基咪唑六氟磷酸盐BMIM.PF6,IL）处理炭黑,而后进行微波处理得到改性炭黑（m-CB）,将m-CB用于增强丁腈橡胶（NBR）。研究了m-CB的结构、混炼胶的硫化特性和补强效果。结果表明,IL可吸附到炭黑表面,而且部分IL强烈吸附于炭黑表面,微波处理之后,IL会发生部分分解;m-CB使混炼胶的硫化延迟;NBR/m-CB硫化胶的断裂伸长率、拉伸和撕裂强度相对于未改性炭黑均有较大提高,而模量和硬度略有下降。通过对硫化胶的交联密度、动态力学分析（DMA）、形态学等研究,探讨了改性炭黑补强橡胶机理。     

Behaviour of open-cell cordierite foams under compression

Cordierite foams were produced using the polymer foam replication method. The effects of both the structure of the polymeric foam template and the slurry's solid loads on the compressive strength and the sintered structure of the ceramic foam were evaluated in order to achieve the optimal manufacturing conditions. The compressive strengths of cordierite foams were measured at room temperature. Polyurethane (PU) foams were used as templates. Aqueous ceramic suspensions were prepared with solids weight fraction ranging from 50 to 65%. The effects of both the PU density and the solids volume fraction on porosity and strength of the developed cordierite foams were evaluated. The cordierite foams produced are of semiclosed-cell type. Some impregnation difficulties were experienced with increasing of the PU density. The compressive strength of the cordierite foams increased (from 0.1 to 2 MPa) with increasing solids volume fraction. These data are in agreement with the predictions of the model developed by Gibson and Ashby. However, the exponent of the model was half of the measured one (≈3) over the range of relative densities investigated (80–90%). Such discrepancy might be related to several factors such as the morphological differences in the structural unit of the developed foams with respect to a cubic open-cell foam or to the mixture of both open and closed cells or to the presence of non-periodic cells. In addition, it was found that the compressive strengths depended on the cell size for foams of similar relative densities and generally decreased with increasing of the cell size, which deviates from the theoretical predictions. When the starting polymeric substrate contained a higher fraction of closed cell windows, however, the ceramic material present on the cellular structure was not only distributed on the struts but also filled the cell walls. This contributed to an increase of the relative density of the cordierite foams and consequently to higher compressive strengths.