蒸馏水含量对三明治结构硬质聚氨酯泡沫性能的影响

采用异氰酸酯、聚酯多元醇、发泡剂（水）等原料通过一体发泡成型技术制备出一种新型的三明治泡沫夹心复合材料。利用热重分析、扫描电子显微镜等对不同水含量（质量分数分别为0、0.5 %和1.0 %）的硬质聚氨酯泡沫材料的泡孔直径、密度、热导率、压缩性能、三点弯曲和热力学性能等做了研究,进而确定提高硬质聚氨酯性能的最佳工艺。结果表明,随着水含量的增加,硬质聚氨酯泡沫材料泡孔直径增大,密度变小,热导率降低,保温性能提高,而压缩性能和三点弯曲却呈下降趋势;综合考虑硬质聚氨酯泡沫材料泡孔结构和良好的保温隔热及弯曲等力学性能,其最佳含水量为0.5 %。     

低导热系数低密度硬质聚氨酯泡沫塑料用泡沫稳定剂

通过对硬质聚氨酯泡沫塑料绝热性能和无氟发泡体系特点及对聚氨酯硬泡对物料流动性和密度分布要求的分析,开发卅了低导热系数泡沫稳定剂AK8830、AK8882。分析了它们的实验室和工业生产性能,并与进口泡沫稳定剂进行了比较。结果表明,这2种稳定剂具有优异的流动性和密度分布及成核能力,其制得的泡沫制品泡孔细密且密度分布均匀,具有较低导热系数。AK8830和AK8882的综合使用性能达到了国外产品的先进水平,可以满足低导热系数低密度硬质聚氨酯泡沫塑料的生产。     

新型疏水聚氨酯硬质泡沫的绿色制备及其性能研究

采用半预聚法作为发泡工艺,以全氟聚醚作为一种新型泡沫稳定剂,选用水作为绿色化学发泡剂,制备了疏水型聚氨酯硬质泡沫.结果表明,随着全氟聚醚含量的增加,材料的接触角增大,最高可达139.7°;添加全氟聚醚后,其泡沫具有较高的闭孔率,而且随着全氟聚醚含量的增加,泡孔更加均匀,泡孔尺寸逐渐减小,泡孔的密度增大,导热系数显著降低...     

聚氨酯硬泡发泡压力的影响因素研究

研究了硬质聚氨酯泡沫成型过程的主要工艺参数对发泡压力的影响。研究表明：填充系数是影响聚氨酯硬泡发泡压力的最重要因素，且与最大发泡压力成正比；升高模具或树脂温度均可提升发泡压力的增长速率和最大发泡压力；相比使用物理发泡剂，使用水作化学发泡剂时的发泡压力增长速率和最大发泡压力更大。此外，异氰酸酯指数以及相同填充系数下产品密度对聚氨酯泡沫发泡压力影响较小。     

MF/FEA-1100混合发泡剂对聚氨酯泡沫泡孔结构和性能的影响

以甲酸甲酯(MF)和1,1,1,4,4,4-六氟丁烯(FEA-1100)为混合发泡剂,制备了密度为30~35kg/m~3的硬质聚氨酯泡沫塑料,研究了发泡剂配比对泡孔结构和泡沫性能的影响。结果表明,随着FEA-1100比例的增加,泡沫的拉丝时间和脱粘时间延迟、泡沫流动性能提高;泡沫的压缩强度提高、导热系数降低。扫描电子显微镜(SEM)分析表明,采用MF和FEA-1100混合发泡剂,可使泡沫的泡孔结构更加均匀细腻;泡沫导热系数和压缩强度的各向异性与泡沫泡孔结构的各向异性相关。     

低CFC发泡工艺

介绍了减少75％CFC－11的聚氨酯硬质泡沫塑料的发泡工艺，对影响工艺参数和泡沫性能的一些因素进行了讨论。该泡沫的密度与导热系数较全CFC－11发泡泡沫均增大15％～20％。     

短切碳纤维增强硬质聚氨酯泡沫复合材料压缩强度与形貌研究

本文研究了短切碳纤维增强硬质聚氨酯泡沫复合材料的压缩强度和形貌.探讨了不同短切碳纤维含量对硬质聚氨酯泡沫力学性能的影响,利用光学显微镜和扫描电镜观察了不同短切碳纤维含量情况下,硬质聚氨酯泡沫复合材料泡孔形成情况及试样破坏的微观相貌.研究结果表明,当短切碳纤维含量为30％时,硬质聚氨酯泡沫复合材料的压缩强度最大,泡体泡孔均匀致密;当短切碳纤维含量超过30％后,开始出现了大量闭孔和塌泡,碳纤维与聚氨酯泡孔剥离,力学强度下降.     

助剂对全水发泡阻燃聚氨酯硬泡性能的影响

采用聚醚多元醇、多异氰酸酯、泡沫稳定剂、液态阻燃剂、催化剂和水制备了全水发泡阻燃硬质聚氨酯泡沫塑料,研究了水用量、催化剂、泡沫稳定剂及阻燃剂对聚氨酯硬泡性能的影响。结果表明,水用量影响聚氨酯硬泡的泡沫密度、压缩强度、尺寸稳定性、吸水率等性能;不同催化剂复配影响聚氨酯硬泡的泡孔结构;泡沫稳定剂影响泡孔均匀性和聚氨酯硬泡的导热性能;磷酸三乙酯(TEP)对硬泡阻燃性能的影响优于磷酸三氯丙酯(TCPP)和阻燃聚醚多元醇(F-7190)。随TEP用量的增加,聚氨酯硬泡的氧指数增大,压缩强度降低;随F-7190用量增加,聚氨酯硬泡的氧指数略有增大,压缩强度先增大后变小。     

发泡方法对硬质交联聚氯乙烯泡沫的影响

文章对硬质交联聚氯乙烯(cross-linked RPVC)进行发泡成型研究,考察了模压法、烘箱法和油浴法等发泡方法对cross-linked RPVC泡沫塑料的密度、交联度、泡孔形态和压缩强度的影响。结果表明,相同的整体密度下,油浴法得到的泡沫拥有更高的密度均匀性,交联度则是烘箱法制备的泡沫最高,模压法得到的泡沫泡孔直径较小,大小分布均匀,且压缩强度较高。     

硬质PVC泡沫板材密度与性能的关系

采用两步法成型工艺开发了硬质PVC泡沫板材,测定了其密度均匀性和泡孔孔径,考察了板材密度与性能的关系.结果 表明:①所开发的硬质PVC发泡板材密度均匀,泡孔孔径在320 ～440 μm;②随着密度的增大,硬质PVC发泡板材的力学性能呈线性增长的趋势,热变形温度略微增加.     

Multiscale investigation on molecular structure and mechanical properties of thermal-treated rigid polyurethane foam under high temperature

In order to study the relationship between the molecular structure and mechanical properties of rigid polyurethane foam (RPUF) during the mechanical and chemical failure process, the variation of the molecular structure and mechanical properties of RPUF treated in temperature range of 323–473 K were characterized by both theoretical and experimental methods. The molecular structure stability of RPUF varied with thermal treatment temperature was characterized by density functional theory method. The mechanical properties of base material of RPUF were simulated by means of molecular dynamics (MD) simulation. Then the related parameters obtained from the MD simulation were assigned into a representative volume element model of RPUF for the finite element analysis. The results indicated that the vibrational frequencies of isocyanate groups and amino acid ester groups in RPUF molecule increased while the molecular orbital energy gap of RPUF decreased with the increase of treatment temperature. It indicated that the RPUF molecule had high chemical reactivity at high temperature. The results of the multiscale simulation of mechanical properties showed that the defects and voids in RPUF generated under high temperature would grow with the increase of thermal treatment temperature, which intensified the stress concentration in RPUF and decreased the tensile properties of RPUF.     

Failure mechanism of rigid polyurethane foam under high temperature vibration condition by experimental and finite element method

The failure mechanism of rigid polyurethane foam (RPUF) under room temperature (RT) and high temperature vibration conditions was investigated by experiment and finite element stimulation. Damaged RPUF specimens were prepared at different vibration amplitudes ranging from 0 to 19.879 mm at RT and 150 °C for different vibration times. The tensile test was utilized to evaluate the vibration damage degree of RPUFs, and the results exhibited that tensile strength decreased gradually with the increase of vibration amplitude and time at both RT and 150 °C. Thermogravimetric analysis and Fourier transform infrared spectroscopy illustrated that thermal degradation of RPUF is attributed to the decomposition of carbonyl urethane groups at 150 °C. The scanning electron microscopy analysis of the tensile fracture surfaces revealed that the vibration failure of RPUF mainly resulted from the existence of microcracks in cell structure. A finite element simulation was established by ABAQUS to study stress distribution of RPUF under different vibration loads, which then demonstrated that the microcracks are most likely to exist on the junction of two microcell units, which is due to convergence of stress in the process of vibration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48343.     

Effects of expandable graphite and ammonium polyphosphate on the flame‐retardant and mechanical properties of rigid polyurethane foams

In this work, the effect of expandable graphite (EG) and ammonium polyphosphate (APP) on the flame retardancy and mechanical properties of the rigid polyurethane foam (RPUF) was studied. The results indicated that both EG and APP could effectively improve the flame retardancy of RPUF, while the retardancy of EG was better than APP. When the flame‐retardant loading was 15 wt %, the limited oxygen index (LOI) values of APP‐ and EG‐filled RPUF were 24.5 and 32 vol %, respectively. According to the LOI test, the optimal ratio of APP to EG in RPUF composites was 1 : 1 by weight, at which the LOI value of 15 wt % (APP + EG)/RPUF was 30.5 vol %. Thermal degradation test of RPUF composites by thermogravimetric analysis indicated that the addition of APP and EG to RPUF could lead to an increase in the amount of high‐temperature residue. Under the same conditions, the residue amount of EG/RPUF was less than that of APP/RPUF at the same temperature. Compression test and dynamic thermal mechanical analysis indicated that both the compressive strength and modulus decreased at a certain extent with the EG‐ or APP‐filled into RPUF, respectively, but with the mixture of EG and APP added into RPUF, the mechanical properties of these materials increased. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

新型硬质聚氨酯泡沫的热分解行为及动力学

利用热重分析法比较研究了新型硬质聚氨酯泡沫[超支化聚氨酯多元醇型(HBPU型)]和硬质聚氨酯泡沫(RPUF)在氮气中的热分解行为,探讨了HBPU型RPUF在不同升温速率下的热分解动力学,运用Kissinger最大失重率法和Flynn-Wall-Ozawa等失重百分率法计算获得了其热分解过程的活化能。研究结果表明,HBPU型RPUF的初始分解温度(T5%)为205℃,半寿温度(T50%)为361℃,略低于传统的RPUF。Kissinger法得到的HBPU型RPUF的热分解表观活化能为159.8 kJ/mol;Flynn-Wall-Ozawa法得到的热分解过程分为三个阶段:第一阶段的平均活化能为82.8 kJ/mol,第二阶段的平均活化能为140.7 kJ/mol,第三阶段的平均活化能为111.3 kJ/mol,HBPU型RPUF具有较好的热稳定性。     

以大豆油多元醇制备的硬质聚氨酯泡沫塑料的性能研究

用大豆油多元醇替代石化聚醚多元醇制备出了硬质聚氨酯泡沫塑料（RPUF）,考察了石化聚醚多元醇和大豆油多元醇的比例以及RPUF密度对RPUF性能的影响。结果表明,随着大豆油多元醇用量的增加,RPUF的冲击强度和压缩模量减小,压缩屈服点逐渐消失,玻璃化转变温度升高;但随着大豆油基RPUF密度的增加,其冲击强度、压缩模量和储能模量都得到了提高,压缩模量最高可达56.44 MPa。     

阻燃硬质聚氨酯泡沫塑料垂直火蔓延特性研究

通过一步合成法制备了阻燃硬质聚氨酯泡沫,自主搭建保温材料火蔓延实验台,采用中小尺寸实验对比研究了阻燃及非阻燃硬质聚氨酯的垂直火蔓延特性,分析了火焰结构特性、火蔓延速度、火焰温度、质量损失速率等参数的变化规律。结果表明,火蔓延过程中,材料表面均出现了炭化现象,垂直双面燃烧过程中聚氨酯纯样RPUF燃烧最剧烈,阻燃剂膨胀石墨(EG)、次磷酸铝(AHP)和二乙基次膦酸铝(ADP)的加入,抑制了材料的燃烧和蔓延,使材料燃烧的火蔓延速度、质量损失速率及温度等参数都相应降低。RPUF/AHP5垂直双面火蔓延过程中,火焰稳定性差,在20 s后出现熄灭现象,原因是阻燃剂次磷酸铝(RPUF/AHP5)受热挥发出难燃气体。AHP降解后形成的含磷化合物可促进聚氨酯分子链成炭,导致产生熄灭现象。而RPUF/ADP5火蔓延过程中,同样出现了熄灭现象,其熄灭的程度低于阻燃剂次磷酸铝(RPUF/AHP5)试样。RPUF/EG5火蔓延过程中试样表面温度存在两个峰值,由于RPUF/EG5燃烧生成的炭层不稳定所致。当温度高于400℃时炭层被迅速氧化,热量穿透炭层使内部未燃样品热解,生成温度的第二个峰值。     

PAPI官能度和异氰酸酯指数对HFC-365mfc/H_2O混合发泡体系RPUF性能的影响

采用HFC-365mfc和H2O作为混合发泡剂制备了聚氨酯硬质泡沫材料,探讨了多亚甲基多苯基多异氰酸酯(PAPI)的官能度和异氰酸酯指数(R)对泡沫材料的玻璃化转变温度(Tg)、力学性能和泡孔结构的影响。结果表明,使用相同份数的发泡剂,在PAPI的官能度介于2.6～3.1范围内,官能度越高,所得泡沫密度越大、Tg越高,力学性能越好;当R介于1.05～1.50时,随R的增大,所得泡沫密度增加,Tg和力学性能均有提高,但当R过大时,泡孔的尺寸分布变宽,均一性变差。研究还发现,所得泡沫Tg和力学性能随熟化时间延长亦有所提高。     

Physical and chemical effects of diethyl N,N′-diethanolaminomethylphosphate on flame retardancy of rigid polyurethane foam

Diethyl N,N-diethanolaminomethylphosphate could react with isocyanate because it contained hydroxy group. This was confirmed by FTIR spectrum. It did not produce any effect on the foam structure of rigid polyurethane foam (RPUF). SEM, IR spectrum, and thermal analysis were used for investigation of the physical and chemical changes during the combustion of flame-retardant RPUF. It was shown that the flame retardancy changed the thermal decomposition behavior of RPUF, widened the decomposition temperature region of RPUF, reduced the amounts of decomposition products at high temperatures, and increased the decomposition residuals arisen from charring of flame-retardant RPUF. Those changes improved the flame retardancy of RPUF. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 276–282, 2001     

Synergistic effect of expandable graphite and aluminum hypophosphite on flame‐retardant properties of rigid polyurethane foam

A series of flame retarding rigid polyurethane foam (RPUF) composites based on expandable graphite (EG) and aluminum hypophosphite (AHP) were prepared by the one‐pot method. The properties were characterized by limiting oxygen index (LOI) test, cone calorimeter test, thermogravimetric analysis (TGA), real‐time Fourier transform‐infrared spectra (RT‐FT‐IR), X‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), etc. The results indicate that both EG and AHP could enhance the flame retardency of RPUF composites. Besides, the flame retardant effect of EG was better than that of AHP. The results also show that partial substitution of EG with AHP could improve the flame retardency of RPUF, and EG and AHP presented an excellent synergistic effect on flame retardancy. What is more, compared with RPUF/20EG and RPUF/20AHP, the heat release rate (HRR) and total heat release (THR) of RPUF/15EG/5AHP were lower.TGA results indicate that partial substitution of EG with AHP could improve the char residue which provided better flame retardancy for RPUF composites. The thermal degradation process of RPUF composites and the chemical component of the char residue were investigated by RT‐FT‐IR and XPS. And the results prove that RPUF/15EG/5AHP had higher heat resistance in the later stage. Compared with the RPUF composites filled with EG, a better cell structure and mechanical properties were observed with the substitution of AHP for part of EG. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42842.     

Flame retardancy of hollow glass microsphere/rigid polyurethane foams in the presence of expandable graphite

Rigid polyurethane foams (RPUF) filled with various loadings of expandable graphite (EG) or/and hollow glass microspheres (HGM) were prepared by cast molding. The flame retardant properties of these composites were investigated by limiting oxygen index (LOI), horizontal and vertical burning tests. The composite with 10 wt % HGM and 20 wt % EG had the best flame retardant properties, and its LOI value reached 30 vol %. The addition of an appropriate loading of HGM improved the compressive strength and modulus of RPUF and EG/RPUF. When the HGM content arrived at 10 wt %, the compressive strength and modulus of the composites reached the maximum value. The dynamical mechanical analysis (DMA) showed that the addition of EG and HGM made the glass transition temperature shift to a higher temperature, and 10 wt % EG and 10 wt % HGM filled RPUF had the highest storage modulus. The scanning electronic microscope (SEM) observation indicates that the additives led to the decrease in the cell size. In addition, the flame retardant mechanism, the thermal properties, the burned surfaces and the interface surfaces were elucidated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008