玉米秸秆碎粉填充聚氨酯泡沫隔热塑料的研究及应用

采用玉米秸秆碎粉填充聚氨酯(PUR)泡沫塑料,研究了玉米秸秆碎粉的含量、粒径对PUR泡沫塑料的密度和压缩强度的影响,并对其导热性能进行了研究。结果表明,玉米秸秆碎粉填充PUR泡沫板的性能与未填充PUR泡沫板的性能相当,但成本相对较低;玉米秸秆碎粉填充PUR泡沫板可用作渠道防渗保温材料。     

长纤维增强反应注射成型聚氨酯基复合材料固化动力学研究

采用长纤维增强反应注射成型工艺制备了聚氨酯(PUR)/玻璃纤维(GF)复合材料,为了优化PUR/GF复合材料的固化工艺,运用DSC仪研究了GF对PUR固化动力学特性的影响,计算了PUR/GF复合材料的固化表观活化能和反应级数,并建立了相应的固化反应动力学方程。结果表明,随着GF的加入,PUR的固化特性对升温的敏感性降低,与纯PUR的表观活化能和指前因子相比,加入GF后其值有较大幅度增加,反应级数由0.7805变为0.529 9。GF的加入,使PUR/GF复合材料的固化反应热温度区域变宽,反应热明显减少,固化起始温度变化不大,固化峰值温度和固化终止温度有所升高。     

nano-SiO_2/BCE/BMI复合材料的固化动力学的研究

采用非等温差示扫描量热法（DSC）研究了nano-SiO2填充BCE/BMI（nano-SiO2/BCE/BMI）体系的固化动力学,用Kissinger、Crane和Ozawa法确定固化动力学参数。结果表明,nano-SiO2/BCE/BMI体系的固化反应表观活化能和频率因子为293.69 kJ.mol-1和4.5×1033 s-1;反应级数为0.97;nano-SiO2/BCE/BMI体系的固化工艺参数：凝胶温度为117.28℃、固化温度为184.78℃及后处理温度为234.84℃。     

填充轮胎用聚氨酯材料的研究

对填充轮胎用聚氨酯材料的配方和性能进行了研究,开发出了原液黏度低、操作时间长并能够常温固化和熟化的填充轮胎用聚氨酯原液;与国外同类材料进行对比,其性能与国外同类材料相当。     

不同无机填料在聚氨酯弹性体中的性能对比

以聚醚N-204、甲苯二异氰酸酯为原料,用1,4-丁二醇为扩链剂,填充经超声波分散、偶联处理的不同无机填料,分别合成填充型聚氨酯(PUR)弹性体。研究了填充型PUR弹性体的耐磨性、力学性能以及填料在弹性体中的分布状况。结果表明,不同无机填料在PUR弹性体中所表现出的性质不同,碳化硅主要提高了弹性体的耐磨性,而陶瓷微珠、玻璃微珠在增强增韧方面发挥了作用。     

高压CO_2流体发泡制备微孔PVC/PUR–T泡沫材料

以聚氯乙烯(PVC)、热塑性聚氨酯弹性体(PUR–T)为原料,通过溶液共混方法,用四氢呋喃(THF)溶解混合物,浇涛在聚四氟乙烯模具中制得PVC/PUR–T共混材料,采用高压CO_2为发泡剂用间歇发泡法制备PVC/PUR–T发泡共混材料。通过对解吸附时间的测定,确定了饱和时间为24 h。通过改变饱和压力得到一系列不同体积膨胀倍率和泡孔大小的材料,随着PUR–T含量的增加,体积膨胀倍率呈下降的趋势;PUR–T含量为5%时,混合材料的泡孔密度最大,随后又会降低,同时随着饱和压力的提高,试样的泡孔密度随之变大。在对发泡样品进行力学性能测试时,发现加入5%的PUR–T对断裂伸长率影响不大,但随着PUR–T含量的增加,断裂伸长率增加;随着PUR–T含量的增加,发泡共混物的拉伸强度也增加,说明PUR–T的加入增强了体系的强度和韧性。     

偶联剂表面处理nano-SiO2填充BCE/BMI体系的固化动力学研究

采用非等温差示扫描量热法（DSC）研究了偶联剂KH560处理的nano-SiO2填充BCE/BMI体系（nano-SiO2/BCE/BMI）的固化动力学,用Kissinger、Crane和Ozawa法确定固化动力学参数。结果表明,nano-SiO2/BCE/BMI体系的固化反应表观活化能为65.05 kJ.mol-1和6.61×106 s-1;反应级数为0.89;nano-SiO2/BCE/BMI体系的固化工艺参数：凝胶温度为116.33℃、固化温度为163.34℃及后处理温度为213.27℃。     

矿渣-粉煤灰地聚物固化淤泥力学性能和路用性能研究

为实现河底淤泥的资源化处置,常采用水泥等胶凝材料固化淤泥提高承载力作为路基材料。传统固化材料能耗大、碳排放量高。为开发可持续性固化材料,本研究采用矿渣-粉煤灰二元地聚物固化淤泥,研究其力学性能及路用性能。通过研究Si/Al摩尔比、Na/Al摩尔比对地聚物凝结时间和抗压强度的影响规律,确定地聚物配合比设计。依据优化配合比固化淤泥,研究地聚物掺量、养护龄期对固化淤泥力学性能的影响,并对固化淤泥进行水稳性、加州承载比、干缩和温缩试验,以评估其路用性能;采用扫描电镜和X射线衍射等试验方法对固化淤泥进行微观分析,揭示其固化机制。试验结果表明,矿渣-粉煤灰基地聚物地质聚合产物为无定形地聚物凝胶、水化硅酸钙、水化铝酸钙等,增强了土颗粒之间的胶结并且填充了孔隙,提高了固化淤泥的力学性能和路用性能。研究结果为地聚物固化淤泥土工程应用提供了实验基础。     

电子行业用湿固化聚氨酯热熔胶的制备及性能研究

以聚酯多元醇、聚醚多元醇、异氰酸酯等为主要原料制备理论湿固化聚氨酯热熔(PUR),对其结构进行了红外光谱表征;相对分子质量及分布通过GPC法测定;热性能特性进行TGA-DSC表征;分析其对不同材料的粘结性能及老化性能。结果表明,制备的PUR热熔胶各项结构性能与汉高PUR-3542类似,各项物理性能、对不同基材的粘结强度及老化性能都良好,可取代汉高3542的PUR热熔胶用于电子行业。     

电子行业用反应型聚氨酯热熔胶的研究进展

介绍了电子行业用反应型聚氨酯热熔胶(PUR)的特点和优势。从反应型聚氨酯热熔胶的原材料及制备工艺、电子行业用反应型聚氨酯热熔胶、光/湿双固化和封端改性等几方面论述了国内外的技术进展。最后对电子行业用PUR的发展进行了展望。     

Thermal stability of polyurethane elastomers before and after UV irradiation

In this work, we investigated the thermal degradation behavior of segmented polyurethane (PUR) elastomers before and after UV irradiation. The thermal degradation of PUR elastomers was studied over the temperature range of 25–600°C in an atmosphere of nitrogen using thermal gravimetric analysis (TGA). Four series of PUR elastomers derived from poly(oxytetramethylene)glycol (PTMO) of 1000 and 2000 molecular weight and poly(caprolactone glycol) (PCL) of 1250 molecular weight, 4,4′‐diphenylmethane diisocyanate (MDI), and 4,4′‐dicyclohexylmethane diisocyanate (H₁₂MDI) and 1,4‐butanediol as an chain extender were synthesized by the prepolymer method. The derivative thermogravimetric (DTG) peaks observed in the experiments indicated that PUR elastomers degraded through two steps. We attributed the first step to degradation of the hard segment. The second degradation step could be ascribed to degradation of the soft segment. We found that the PUR elastomers based on poly(ester polyol) and aromatic diisocyanate exhibit better thermal stability than that of PUR elastomers based on the poly(ether polyol) soft segment in both steps of degradation. The thermal degradation is more prevalent in PUR elastomers based on cycloaliphatic diisocyanate. The higher values of the temperature of initial decomposition (Tⁱ) indicate a higher thermal stability of UV‐exposed elastomers on the beginning of degradation. This may be due to the formation of a crosslinking structure in the presence of UV irradiation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 864–873, 2001     

基于有限元分析的扁平轮胎硫化工艺的优化

硫化是轮胎生产工艺的一个重要步骤,直接决定轮胎的力学性能,是生产中耗能最多的一个环节。传统的扁平轮胎硫化工艺没有考虑后硫化的作用,这可能造成能源的浪费。通过有限元模拟可以了解轮胎硫化的全过程,尤其后硫化在轮胎硫化中所起的作用。如果模拟结果表明后硫化的作用不容忽视,那么传统工艺就有改进的必要和空间。本文在模拟方法上也有所创新,运用子程序HETVAL给橡胶加载反应热,并做了有反应热和无反应热两组硫化模拟,开发ABAQUS后处理模块运用UVARM子程序直观地得到硫化程度场。     

Electron Beam Curing of the System Cycloaliphatic Diepoxide‐Epoxidized Natural Rubber‐Glycidyl Methacrylate in Presence of Cationic Initiators

Electron beam curing of the system cycloaliphatic diepoxide‐epoxidized natural rubber‐glycidyl methacrylate containing a cationic initiator was carried out. Storage modulus, glass transition temperature and pendulum hardness were measured as function of EB dose, photoinitiator concentration, content of epoxidized natural rubber, post cure temperature and post cure time. At electron beam doses larger than 100 kGy a highly cross‐linked polymer network is generated which shows a two phase morphology. Microscale elastomeric domains are incorporated into a continuous epoxy resin phase. Dynamical mechanical analysis and pendulum hardness measurement show that an increase of the ENR ratio leads to a more elastic polymer network. Post curing results in increased glass transition temperatures. This EB cured polymer system is believed to provide both toughness and favorable viscoelastic properties to be used as component of EB curable composites.     

The effect of flow on the physical properties of polyurethane/carbon nanotubes nanocomposites: Repercussions on their use as electrically conductive Hot‐Melt adhesives

The properties of multiwall carbon nanotubes (MWCNT)/polyurethane (PUR) nanocomposites after being submitted to flow, i.e., in conditions similar to their application as electrically conductive adhesives (ECA), are investigated. A decrease of the elastic modulus is observed after flow is stopped, compatible with a rearrangement of the MWCNT/PUR network during flow. The implications of the viscoelastic results on probe‐tack data are elucidated and a slightly higher energy of adhesion is observed for sheared samples. Dynamic viscoelastic measurements reveal that crystallization of PUR is fastened with MWCNTs, shortening the solidification process for samples submitted to flow or not. Electrical conductivity results show that the 4 wt% MWCNT/PUR nanocomposite can be submitted to flow and give, on cooling to room temperature, values of the electrical conductivity between 10⁻² and 10⁻¹ Siemens /m. 2 wt% MWCNT/PUR sample presents a shear induced semiconductor to insulator transition and a temperature‐induced isolator to semiconductor transition. We conclude that MWCNT/PUR nanocomposites are good candidates to develop Hot Melt ECAs, since they display satisfactory viscosity, tack, crystallization (linked to permanent adhesion), and electrical conductivity. POLYM. COMPOS., 36:704–712, 2015. © 2014 Society of Plastics Engineers     

Comparison of two high temperature treatment methods on preparing electrically conductive polysulfide/Ag composites for aerospace sealant applications

High electrical conductivity of aircraft fuel tank sealant is vital to prevent charge accumulation during operation. In this work, we prepare highly conductive polysulfide (PS)/Ag composite (10⁶ S m⁻¹) via two thermal treatment methods-namely post cure annealing and high temperature (HT) curing, where the room temperature (RT) cured sample was previously found insulative. The HT cure samples resulted in a milder hardness increase compared to the RT cure-annealed ones. Through various chemical and thermal analyses, a strong coordination of the sulfide components on Ag surfaces is found blocking the electron tunneling pathways at RT, which turns out to be weakened at HT. Post cure annealing causes the decomposition of the coordinated segments and provides intimate contact of Ag particles to support conductivity. HT cure on the other hand prevents the Ag/S coordination in the first place, therefore producing highly conductive PS/Ag composite with softness well maintained which makes it the preferred method for conductive sealant applications.     

Electrical behavior of polyurethane derived from polyols synthesized with glycerol,phthalic anhydride,and oleic acid

The direct current (DC) and alternating current (AC) conductivity of polyurethane (PUR) derived from polyols synthesized with glycerol, phthalic anhydride, and oleic acid were investigated in this article. The PUR was prepared by varying the oleic acid content in polyol (28, 40, and 65%) and the NCO/OH ratio of the PUR was varied to 1.2, 1.4, and 1.6. The electrical conduction studied by measuring the dependence of current on the applied field and temperature. Electrical conductivity in PUR was expressed by Arrhenius relations and the activation energies were calculated. Moreover, hyperbolic sine function was used to determine the conduction mechanism in PUR. It's presumed that the conduction mechanism was assisted by ions for the PUR which were contributed by oleic acid due to dissociation of protons and highly polar urethane groups in PUR. Furthermore, the dielectric behaviors of the material have been measured at room temperature in the frequency range of 100 Hz to 40 MHz. The frequency‐dependent conductivity of PUR materials has been analyzed using a Jonscher's power law expression and the plot exhibits the typical behavior of ionic materials, i.e., the DC plateau and the frequency dependent region. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Low‐temperature photopolymerization and post‐cure characteristics of acrylates

Near‐infrared spectroscopy was used to investigate the post‐cure characteristics of acrylates polymerized from ? 75 °C up to room temperature. The results obtained showed that the double bond conversion increased with increasing initiator concentration. Post‐cure was much more striking for samples cured at lower temperatures. The chemical structure of monomer and photoinitiator had a great effect on the post‐cure process. The greater the functionality, the lower the final double bond conversion and the more distinct the post‐cure effect. Copyright © 2006 Society of Chemical Industry Society of Chemical Industry     

基于两种双硫键自修复聚氨酯制备及性能

以异佛尔酮二异氰酸酯(IPDI)和双(2–羟基乙基)二硫醚(DTBO)为硬段,聚四氢呋喃(PTMG)为软段,β–巯基乙醇(ME)为封端剂,制备巯基封端且含双硫键的聚氨酯(PUR)预聚物,利用巯基易氧化的特点,用H2O2/NaI进行氧化,合成分子链内和分子链端均含有双硫键的自修复交联PUR。采用傅立叶变换红外光谱仪、差示扫描量热仪、热重/差热综合热分析仪和电子拉力试验机等手段,研究了PUR的结构及PTMG与ME的物质的量之比对PUR热性能、力学性能和自修复性能的影响。结果表明,合成的系列交联PUR都具有一定的自修复能力和良好的热性能,当DTBO和PTMG物质的量分数分别为总二元醇的40%和60%时,PUR的拉伸强度达到最大值,为2.6 MPa,在60℃热处理8 h条件的自修复率为80.8%,且该试样经三次自修复后,自修复率仍可达到50.0%。     

RIM用接枝共聚PUR／PS弹性体—A组份的研究

本文研究了接枝共聚PUR/PS弹性体反应注射成型中A组分中主成份改性聚酯二醇的合成及A组分的配制.考察了不同配方下的A中各组分相容性及粘度与所含苯乙烯量的关系以及A组分的贮存稳定性.本方法获得的A组分在常温下是稳定的溶体,粘度小.适用于室温下的反应注射成型。简化了传统的加热型聚氨酯反应注射成型工艺,并具有优良的脱模性能。所得弹性体的物理机械性能基本与低模量聚氨酯弹性体相当。