新型无卤阻燃聚丙烯材料结晶性能

将多聚磷酸铵(APP)、季戊四醇(PER)、三聚氰胺(MEL)及有机化蒙脱土(OMMT)于160℃下预混,制备了新型膨胀型阻燃剂(IFR).以PP为基材,IFR为阻燃剂,聚苯乙烯-丁二烯-苯乙烯(SBS)为增韧剂,马来酸酐接枝聚丙烯(PP-g-MAH)为增容剂,通过熔融挤出制备了新型阻燃PP(FRPP).通过XRD、P...     

PET/PP共混合金结晶动力学研究

用GJY-3光学解偏振仪测定了PET、PP与PET/PP合金的结晶速度,并且在不同的结晶温度下比较了它们结晶速度的快慢。最后通过Avrami方程对PET/PP(3:1)合金进行了结晶动力学的研究。结果表明,其Avrmi指数为3。     

NBR/PP TPV中PP的非等温结晶行为研究

通过不同方法制备了3种不同NBR/PP热塑性硫化胶(TPV),用差示扫描量热法研究TPV中PP的非等温结晶动力学,并分别利用Ozawa方程和莫志深方法对3种TPV中PP的非等温结晶行为进行解析。结果表明:TPV中NBR对PP的结晶起成核剂的作用,可提高PP的结晶速率,原位反应增容制备的TPV中PP的结晶速率最大;莫志深方法能很好地描述PP的非等温结晶过程。     

胆甾液晶弹性体的合成及液晶性能研究

以胆甾液晶单体和向列液晶交联剂与含氢聚硅氧烷接枝聚合制备了一系列弹性体.通过红外光谱(FT-IR)、核磁氢谱(1 H-NMR)确定了液晶单体及弹性体的化学结构.通过差热扫描量热仪(DSC)、偏光显微镜(POM)以及X-射线衍射研究了其介晶性质及液晶相行为.结果表明,弹性体的玻璃化转变温度随着向列液晶交联剂的加入先降低后升高.随着向列液晶交联剂的加入,系列弹性体的X-射线衍射峰弥散,且最大反射波长略微变长,说明液晶分子间的有序性受到干扰.     

单体接枝PP包覆纳米CaCO3对PP结晶动力学的影响

采用不同单体接枝聚丙烯(PP)包覆纳米CaCO3与PP复合制备PP/纳米CaCO3复合材料,用差示扫描量热法研究了复合材料中PP的等温和非等温结晶动力学。研究结果表明,不同单体接枝PP包覆纳米CaCO3填充PP复合材料中PP的结晶温度取决于单体类型。PP复合材料的结晶速率高低顺序依次为马来酸酐,丙烯酸丁酯,丙烯酸(或苯乙烯),PP。结晶速率快的复合材料具有低的结晶活化能。     

侧链聚硅氧烷液晶弹性体的合成与性能研究

综述了国内侧链聚硅氧烷液晶弹性体的研究情况,并对不同类型的侧链聚硅氧烷液晶弹性体的分子结构、结构与性能之间的关系进行了总结。     

石墨烯/聚丙烯复合材料的等温结晶动力学研究

采用差示扫描量热仪(DSC)研究了石墨烯(RGO)/聚丙烯(PP)复合材料的等温结晶行为。结果表明:对于纯PP和RGO/PP复合材料,结晶温度(Tc)的提高将导致结晶速率(G1/2)变慢、绝对结晶度(Xc)提高;PP和RGO/PP复合材料的等温结晶在相当大的范围内符合Avrami方程;同纯PP相比,RGO/PP复合材料的G1/2相对增加,而结晶活化能相对减小,这意味着RGO对PP起到了外加成核剂的作用,促进了PP的结晶。     

MAH—g—PP孚L液对PP／GF复合材料界面的影响

利用自制的MAH—g—PP乳液和KH-550溶液组合进行玻纤的表面处理。考察了MAH—g—PP乳液和KH-550溶液处理对PP／GF界面粘结的影响,研究了MAH—g—PP乳液处理玻纤表面的适宜温度和时间,探讨了MAH—g—PP乳液对PP／GF的偶联机理。结果表面：玻纤表面经MAH—g—PP乳液和KH-550溶液处理后,在PP／GF界面上形成了牢固的化学键连接,出现了明显的横晶层;MAH—g—PP乳液处理玻纤表面的适宜温度和时间为105℃、1h;MAH—g—PP乳液对PP／GF的偶联机理为乳液中的羧基与玻纤表面KH-550的氨基发生化学键合。     

Application of blocked isocyanate in preparation of polyurethane(urea) elastomers

High-performance casting polyurethane elastomers (CPUe) were successfully synthesized by the reaction of polyurethane prepolymer (PUP) blocked by methyl ethyl ketone oxime (MEKO) with diamine chain extenders. The effects of blocking agent were systematically studied on the structures, thermal stabilities, mechanical properties, and processability of polyurethane. The addition of MEKO significantly improved the tensile strength and toughness. The maximum tensile strength was 35.6 MPa, and the maximum elongation at break was 1065%. The high strength and toughness were attributed to the fact that under mild reaction conditions, the reaction tended to extend the molecular chains, which indicated that the formation of long chains was conducive to the extension and self-reinforcement of chain segments. Crystallization and strong hydrogen bonds between molecules also led to low loss factor. This deblocking polymerization strategy solves the gel problem in the polymerization process, and provides a new idea for the preparation of CPU.     

Synthesis and properties of liquid crystalline polyurethane elastomers

Novel type of mesogenic chain extenders used in this study are N,N′‐bis(4‐hydroxyphenyl)‐3,4,3′,4′‐biphenyldicarboxyimide (BPDI) and N,N′‐bis[4‐(6‐hydroxyhexyloxy) phenyl]‐3,4,3′,4′‐biphenyldicarboxyimide (BHDI). BHDI has a flexible spacer of 6‐methylene units but BPDI does not. The liquid crystalline polyurethane elastomers were synthesized from BPDI or BHDI as a mesogenic chain extender, 4,4′‐diphenylmethane diisocyanate, and poly(oxytetramethylene)glycol (MW 1000) as a soft segment. Polyurethane based on BHDI exhibited two melting transitions. However, any melting behavior was not shown in the BPDI‐based polyurethanes because of higher melting temperature than decomposition temperature. The composition of polyurethanes was varied as a means of manipulating liquid crystalline behavior and physical properties. The BHDI‐based polyurethanes containing above 50 wt % of hard segment content exhibited nematic liquid crystal behaviors. As the hard segment content of the BHDI‐based polyurethanes increased, the glass transition temperature (T_g), strength, modulus, and the amount of hydrogen bonding increased. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 577–585, 2000     

Morphology and crystallization behavior of the PP/PET nanocomposites

Nanocomposites containing polypropylene (PP), PET, and montmorillonite were prepared in a twin‐screw extruder. X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, polarized optical microscopy, and differential scanning calorimetry were used to characterize the samples. Intercalated and exfoliated morphology were observed in the nanocomposites. The PET domains usually presented spherical shapes and they were the start point to PP crystallization. The average diameter and number of PET domains was evaluated. The influence of addition of PP‐MA as compatibilizer on PP/PET was investigated. The interconnected morphology was observed in the nanocomposite containing PP‐MA. The clay located predominantly in the interphase and in the PET phase. The crystallization process was monitored and the PET crystallization rate was slower in the nanocomposites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of a series of smectic liquid crystalline elastomers

A series of new smectic and cholesteric liquid crystalline elastomers was prepared by graft polymerization of mesogenic monomer with the chiral and nonmesogenic crosslinking agent using polymethylhydrosiloxane as backbone. The chemical structures of the monomers and polymers obtained were confirmed by Fourier transform infrared (FTIR), proton nuclear magnetic resonance spectra (¹H‐NMR). The mesomorphic properties were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X‐ray diffraction measurements (XRD). M₁ showed smectic (S_B, S_C, S_A) and nematic phases during the heating and the cooling cycles. Polymer P₀ and elastomer P₁ exhibited smectic B phase, elastomers P₂–P₅ showed smectic A phase, P₆ and P₇ showed cholesteric phase, and P₈ displayed stress‐induced birefringence. The elastomers containing less than 15 mol % M₂ displayed elasticity and reversible phase transition with wide mesophase temperature ranges. Experimental results demonstrated that the glass transition temperatures decreased first and then increased; melting temperatures and the isotropization temperatures and the mesophase temperature ranges decreased with increasing content of crosslinking unit. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 498–506, 2005     

聚丙烯/超高相对分子质量聚乙烯共混物的结晶动力学及发泡性能研究

采用差示扫描量热仪（DSC）对含有不同含量超高分子量聚乙烯（UHMWPE）的聚丙烯进行测试和表征,采用Ozawa方法、莫志深方法和Kissinger方法分析了该体系的非等温结晶动力学。利用自行研制的超临界流体挤出发泡实验装置,对含有UHMWPE的PP进行了超临界二氧化碳挤出发泡实验研究。结果表明：超高分子量聚乙烯的加入降低了PP的结晶活化能,含有UHMWPE的PP在较高的温度下开始结晶,且由于超高分子量聚乙烯大分子链的存在,与聚丙烯分子链发生缠结,阻碍聚丙烯分子链排入晶格,降低了结晶速率,结晶温区拓宽,有利于聚丙烯挤出发泡成型;加入UHMWPE后,PP的发泡效果明显改善,泡孔平均直径减小,泡孔尺寸分布更加均匀,PE-UHMW的含量为5份时,表观密度达到0.038g/cm-3。     

Thermoplastic rubber/PP elastomers toward extremely low thermal expansion

Fine regulation of the microstructure of rubber/polypropylene (PP) alloys could remarkably reduce the coefficient of linear thermal expansion (CLTE) while retaining the mechanical properties similar to those of thermoplastic elastomers. Rubber/PP elastomers with different morphologies were successfully prepared by controlling the appropriate rubber type, viscosity ratio, and processing method. The CLTE of the polymer alloy parallel to the microlayer directions was considerably reduced when the rubber domains were deformed into microlayers and co‐continuous with plastic domains. The thickness of the PP layers played a crucial role on CLTE reduction. The CLTE considerably decreased with reduced thickness of the PP layer. The sample with a co‐continuous microlayer structure exhibited good flexibility, high elongation, low hardness, and permanent deformation. Thus, low‐thermal‐expansion elastomer materials may have wide applications. Stress relaxation and strain recovery of the ethylene–propylene–diene terpolymer/PP (70/30 wt %) blend were investigated to further clarify the influence of co‐continuous microlayer structure on mechanical properties. Anisotropic mechanical properties were consistent with the morphology. Results of the stress relaxation behavior test would provide further support to the mechanism of the low thermal expansion of blends with co‐continuous microlayer structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43902.     

Synthesis and characterization of side‐chain liquid‐crystalline elastomers containing cholesterol

A series of new smectic and cholesteric liquid‐crystalline elastomers were prepared by graft polymerization of mesogenic monomer with the chiral and nonmesogenic crosslinking agent using polymethylhydrosiloxane as backbone. The chemical structures of the monomers and polymers obtained were confirmed by Fourier transform infrared and proton nuclear magnetic resonance spectra. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. M₁ showed cholesteric phase during the heating and the cooling cycle. Polymer P₁, elastomers P₂ and P₃ exhibited smectic phase, elastomers P₄? P₆ showed chiral smectic C phase, P₇ showed cholesteric phase, and P₈ displayed stress‐induced birefringence. The elastomers containing less than 15 mol % M₂ displayed elasticity and reversible phase transition with wide mesophase temperature ranges. Experimental results demonstrated that the glass transition temperatures, the isotropization temperatures, and the mesophase temperature ranges decreased with increasing content of the crosslinking unit. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 383–390, 2005     

低硬度POE/PP动态硫化胶的制备与性能研究

采用动态硫化法制备了POE／PP热塑性弹性体，运用正交设计方法系统研究了POE／PP树脂类型及用量比、交联剂类型及用量、助交联剂类型及用量、加工工艺条件等对POE／PP动态硫化胶性能的影响规律。结果表明，POE／PP用量比、加工工艺和捏合温度是影响材料性能的关键因素；当POE／PP用量比为70／30、捏合温度为240℃时，所得低硬度POE／PP共混型热塑性弹性体的性能最佳，其拉伸强度为4．54MPa，断裂伸长率可迭1023%，且加工流动性远优于EPDM／PP型动态硫化胶。     

Melting behavior,nonisothermal crystallization kinetics,and morphology of PP/nylon 11/EPDM‐g‐MAH blends

The melting behavior, nonisothermal crystallization behavior, and morphology of pure polypropylene (PP) and its blends were investigated by differential scanning calorimetry and polarized optical microscopy. The nonisothermal crystallization kinetics was analyzed using the Avrami equation modified by Jeziorny and the equation combining the Avrami and Ozawa method. The surface fold free energy and the effective activation energy for both PP and its blends were obtained by Hoffman‐Lauritzen theory and Vyazovkin's approach, respectively. The results showed that the presence of nylon 11 hindered the mobility of PP chains but accelerated the overall crystallization rate. The POM observation confirmed that the addition of nylon 11 decreased the spherulites size of PP matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of the length of the carbochain on the phase behavior of side‐chain cholesteric liquid‐crystalline elastomers

In this study, we prepared two series of new side‐chain cholesteric liquid‐crystalline elastomers (PI and PII) derived from the same chiral bisolefinic crosslinking units and different nematic liquid‐crystalline monomers. The chemical structures of the monomers and polymers obtained were confirmed by Fourier transform infrared and ¹H‐NMR spectroscopy. The phase behavior properties were investigated by differential scanning calorimetry, thermogravimetric analysis, and polarizing optical microscopy. The effect of the length of the carbochain on the phase behavior of the elastomers was investigated. The polymers of the PI and PII series showed similar properties. Polymer P₁ showed a nematic phase, P₂–P₇ showed a cholesteric phase, and P₄–P₇, with more than 6 mol % of the chiral crosslinking agent, exhibited a selective reflection of light. The elastomers containing less than 15 mol % of the crosslinking units displayed elasticity, a reversible phase transition with wide mesophase temperature ranges, and a high thermal stability. The experimental results demonstrate that the glass‐transition temperatures first decreased and then increased; the isotropization temperatures and the mesophase temperature ranges decreased with increasing content of crosslinking agent. However, because of the different lengths of the carbochain, the glass‐transition temperatures and phase‐transition temperatures of the PI series were higher than those of the PII series, and the PI and PII elastomers had their own special optical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1204–1210, 2005     

New side‐chain nematic liquid crystalline elastomers containing smectic crosslinking units

A series of siloxane‐based liquid crystalline elastomers containing the smectic crosslinking agent M‐1 and nematic monomer M‐2 were synthesized by a one‐step hydrosilication reaction. The chemical structures of the monomers and polymers obtained were confirmed by FTIR spectroscopy. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X‐ray diffraction (XRD) measurements. The influence of the crosslinking unit on the phase behavior was discussed. The experimental results demonstrated that the glass transition temperatures of elastomers had no remarkable change, and isotropization temperatures decrease with increasing the content of the crosslinking agent M‐1. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3755–3760, 2004