Fundamental foaming mechanisms governing the volume expansion of extruded polypropylene foams

This article describes the fundamental foaming mechanisms that governed the volume expansion behavior of extruded polypropylene (PP) foams. A careful analysis of extended experimental results indicated that the final volume expansion ratio of the extruded PP foams blown with butane was governed by either the loss of the blowing agent or the crystallization of the polymer matrix. A charge coupling device (CCD) camera was installed at the die exit to carefully monitor the shape of the extruded PP foams. The CCD images were analyzed to illustrate both mechanisms, gas loss and crystallization, during foaming at various temperatures, and the maximum expansion ratio was achieved when the governing mechanism was changed from one to the other. In general, the gas loss mode was dominant at high temperatures and the crystallization mode was dominant at low temperatures. When the gas loss mode was dominant, the volume expansion ratio increased with decreasing temperature because of the reduced amount of gas lost. By contrast, when the crystallization mode was dominant, the expansion ratio increased with increasing temperature because of the delayed solidification of the polymer. The processing window variation with the butane concentration, the change in the temperature ranges for the two governing modes, and the sensitivity of melt temperature variations to the volume expansion ratio are discussed in detail on the basis of the obtained experimental results for both branched and linear PP materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2661–2668, 2004     

Changes in liquid hold-up in foam and size of foam by perforated plates and contribution to mechanical foam-breaking

Changes in the liquid hold-up, ?, and the diameter of d, of a foam that are induced by perforated plates (PPs) and the contribution of PPs to foam-breaking were studied. A foaming system containing a dilute detergent solution in a column with mechanical agitation fitted with a rotating-disk foam-breaker (MFRD) was used. After the foam passed through the PPs, ? and d decreased and increased, respectively. The use of PPs to achieve a maximum reduction in ? and a maximum increase in d is confirmed. It is also demonstrated that use of PPs contributes not only to improving the foam-breaking performance of the MFRD, but also to power savings.     

高效低泡净洗剂的研制与应用

对不同配方的发泡力、泡沫稳定性以及净洗效果的测试结果表明皂剂、烷基苯磺酸盐和平平加O按适当比例进行复配可以得到泡沫少、泡沫破灭快，净洗效果好的高效低泡净洗剂。     

Short beam three point bend tests in syntactic foams. Part I: Microscopic characterization of the failure zones

Scanning Electron Microscopic (SEM) studies were carried out on the failure surface of syntactic foam material tested in a short beam three point bend test (SBT) by employing 21 × 15 × 3 mm³ dimension bearing specimens. The syntactic foams were fabricated using glass microballoons in epoxy binder. The failure of the tensile, compression, and shear dominated regions were studied by SEM at different magnifications. The tensile region had characteristic features, such as partial debonding of the microballoons from the matrix and cracking of glass microballoons, apart from matrix cracking and some river pattern features. The compression side was characterized by crushing and collapsing of microballoons, resulting in accumulation of debris with no apparent river pattern for matrix‐rich regions. The midway positions of the SBT failed surface comprised of deformation bands in the matrix and occasional debonding of microballoons. The morphology recorded in the tensile and compression regions corroborated well with the results obtained on these foam samples in those specimens that were subjected to pure uniaxial tension and compression, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 673–679, 2005     

全水发泡硬质聚氨酯泡沫塑料技术研究进展

对CFC 11发泡替代技术中全水发泡技术路线进行了分析 ,指出水作为发泡剂存在的优点与不足。着重阐述了全水发泡中几种主要因素如水的用量、聚醚多元醇性质和结构以及异氰酸酯指数对泡沫性能的影响 ,并对国外近些年来全水发泡用聚醚多元醇研究现状进行了详细论述     

露天矿潜孔钻机泡沫发生器的性能实验

为解决露天矿潜孔钻机作业粉尘污染严重的问题,从传统除尘技术应用效果差、耗风量大、取水困难等事实出发,根据泡沫除尘机理及两相泡沫发泡原理,设计了一种适用于露天矿潜孔钻机的泡沫发生器,并对其发泡性能进行研究.通过开展泡沫发生器的泡沫流量、发泡倍数及半衰期等性能实验,确定出影响泡沫发生器发泡性能的主要因素,得出泡沫发生器的最佳工况点.实验结果表明:气体流量、液体流量(气液比)、发泡网及发泡剂质量分数是影响泡沫发生器发泡性能的4个主要因素,在工况为发泡网1、质量分数1.5%的配方2、气体压力0.7 MPa、液体流量18 L/min及气体流量30 m~3/h条件下,泡沫发生器发泡性能达到最佳,其流量为515 L/min,发泡倍数为22,半衰期为65 min.经现场试验,泡沫除尘后采场平均降尘率高达90%以上,应用效果良好.     

消泡剂在发酵工业中的应用

泡沫问题是发酵工业中一个棘手的问题,几乎所用的液体深层发酵都会用到天然或者化学消泡剂。在过去的发酵过程中,泡沫控制一般是依靠经验,关于消泡剂的系统知识较少。本文综述了发酵工业中消泡剂的种类和作用机制,以及消泡剂的应用进展。     

PIBSI对油基钻井液性能影响研究

常温条件下分别采用5号和3号两种白油配制基浆和油基钻井液体系,并在基浆和钻井液体系中加入不同质量分数的聚异丁烯丁二酰亚胺(PIBSI),考察不同温度下PIBSI的质量分数对基浆和钻井液体系流变、沉降和滤失性能的影响。结果表明,对于基浆而言,低温条件下(4℃)PIBSI能够提高基浆的沉降稳定性能,基浆的黏度随PIBSI质量分数的增加先降低后增加。对于油基钻井液体系而言,在适当质量分数下(5号白油体系PIBSI质量分数为2%,3号白油体系PIBSI质量分数为0.2%),PIBSI能够有效降低体系低温条件下(4℃)的黏度,而对室温(25℃)和高温(65℃)条件下体系的黏度、动切力等参数影响程度较小。PIBSI质量分数越高,两种油基钻井液体系的高温高压降滤失量越低。     

海上油田多元热流体吞吐气窜调剖实验研究及应用北大核心CSCD

目的多元热流体吞吐技术是海上稠油开发的一种经济、有效的技术,但随着吞吐轮次的增加,暴露出易发生“气窜”的问题,即N_(2)、CO_(2)等非凝析气体容易突破到周边生产井,导致其电泵气锁关井影响生产。方法以渤海NB稠油油田为研究对象,采用可视化实验方法,研究防止气窜的治理策略。结果筛选出适合油田的磺酸基泡沫调堵体系,命名为QGQ-4,优化研究出最佳注入参数为质量分数0.4%、泡沫干度在60%以上、地面预制泡沫注入方式。与单纯多元热流体驱相比,泡沫辅助多元热流体驱可提高油藏波及,有效封堵气窜通道,提高平面波及系数37%。结论研究成果现场应用后,受益井初期高峰日产油增加到措施前的1.5倍,日产油由措施前的50.5 m^(3)增至措施后的高峰日产油75.7 m^(3),取得了较好的增产效果。     

Effect of DAPBO segment on the structure and performance enhancement of powder foamed BTDA-ODA polyimide

Achieving excellent thermal stability, good mechanical strength, and low-density in one product, is a big challenge in the design and synthesis of polyimide (PI) foams. We selected a rigid diamine monomer, 2-(4-aminophenyl)-5-aminobenzoxazole (DAPBO) to partially replace 4,4′-oxydianiline (ODA) in BTDA-ODA system, and studied the effect on properties of foamed PI products. With various molar ratio between DABPO and ODA (0:5, 1:4, 2:3, 3:2, 4:1, 5:0), the diamine(s) polymerized with 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and produced six PI precursors (PAE-0 ~ PAE-5). After foaming and thermal imidization, corresponding PI foams (PI-0 ~ PI-5) prepared. Among them, PI-3 has a glass transition temperature of 386°C, which is 95°C higher than PI-0, and its compressive strength reaches 1.32 MPa. Moreover, PI-3 has a uniform cell structure with an average pore size of ~200 μm. The analysis results show that PI-3 is in a transition state from amorphous to partial crystalline, maintaining a balance between flexibility and rigidity. The addition of DABPO not only increases the rigidity of polymer molecular segments, but also introduces N and O atoms that can form intermolecular hydrogen bonds between molecules, which increases the packing density and arrangement regularity of polymer molecules.