乙烯-乙酸乙烯酯共聚物/氢化丁腈橡胶共混物的相态结构和低温性能研究

采用熔融共混法制备乙烯-乙酸乙烯酯共聚物(EVM)/氢化丁腈橡胶(HNBR)共混物,研究其硫化特性、相态结构、动态力学性能、物理性能和低温拉伸性能。结果表明:当EVM/HNBR共混比为70/30时,EVM形成连续相,HNBR形成分散相;随着HNBR用量的增大,HNBR相态由分散相向连续相转变。HNBR的加入可以提高EVM的耐低温性能,当EVM/HNBR共混比为30/70时,共混物-40℃下的低温拉断伸长率可达300%左右。差示扫描量热分析表明,随着HNBR用量的增大,共混物玻璃化温度降低。     

PP/EPDM/玻璃微珠三元复合材料的仪表冲击分析

考察了室温下ＰＰ／ＥＰＤＭ／玻璃微珠三元复合材料的冲击过程。在不同玻璃微珠含量和填料表面处理等条件下,研究了裂纹扩展力、冲击断裂时间、冲击断裂功等参量的变化规律和相互关系。研究结果表明,随着玻璃微珠体积分数的增大,试样的惯性功呈线性形式增大;采用马来酸酐接枝ＥＰＤＭ,有利于改善其应力分布,提高材料的冲击韧性。     

PP/PP-g-PA6/PA6的相容性和低温冲击性能

利用自制的聚丙烯(PP)和3-异丙烯基-α,α-二甲基苄基异氰酸酯(TMI)的接枝物PP-g-TMI为起始剂,在催化剂己内酰胺钠存在下,TMI中异氰酸官能团引发己内酰胺开环阴离子聚合,合成了PP与尼龙6(PA6)接枝聚合物PP-g-PA6。以PP-g-PA6为相容剂研究了PP和PA6共混体系的相容性和低温冲击强度。结果表明,在体系中PA6质量分数为20%的情况下,加入质量分数2%的PP-g-PA6,分散相粒径可以减小到2μm左右。-20℃低温冲击强度试验结果表明,加入质量分数2%的PP-g-PA6可以使共混体系的冲击强度从纯PP的0.85 kJ/m2提高到2.00 kJ/m2。     

The Improvement of Compatibility in Glass Fiber Reinforced PA6/PP Blends

Abstract

Rheological properties (melt flow index and melt stability), mechanical properties (tensile strength, flexural strength and impact) of polyamide (PA6) polypropylene (PP) blends were investigated. Influence of potential compatibilizors: 4,4′-diphenyhnethane carbodiimide (OCDI), 4,4′-diphenylmethane bismaleimide (BMI) and 2,2′-(1,4-pheaylene)-bisoxazoline (OX) on mechanical properties and thermostability of initial and glass reinforced polymer blends was also investigated too. We tried to study the structure of glass fiber reinforced composites by mercury intrusion porosimitry. The influence of compatibilizors on molecular weight of PA6 was studied by GPC, on chemical structure of blends was investigated by NMR and IR-spectroscopy. Addition of OCDI and OX (chain extenders) preserves the product formation as the react with the active and carbonyl groups of PA6. BMI has lower reactivity. Grafting of BMI to PP chains improves compatibility in PA6/PP blend and increases PP adhesion to glass fiber.     

Effect of SBS Content on Low Temperature Impact Strength,Morphology and Rheology of PP-cp/SBS Blends

Izod impact strength of PP impact copolymer/Styrene-Butadiene-Styrene blends were evaluated at varied sub-zero temperatures and demonstrated 12 times enhancement in impact strength of 40% SBS containing blend over pure PP-cp at ?40°C. SBS content played a vital role in morphology development as it changes from droplet morphology to elongated ellipsoid to a seemingly networked structure leading towards different fracture mechanisms. Rheological properties of blends evaluated on capillary rheometer showed pseudoplastic behavior at varied shear rates (50 ? 10⁴ s^?1) at 220°C and good agreement between experimental shear viscosity and theoretical values as per log additivity principle at high shear rates.     

Room temperature and low temperature toughness improvement in SAN/ASA blends by blending with CPE,HNBR, and BR

Styrene‐acrylonitrile copolymer (SAN)/acrylonitrile‐styrene‐acrylate terpolymer (ASA) blends (75/25, wt/wt) was toughened by blending with impact modifiers including chlorinated polyethylene (CPE), hydrogenated nitrile butadiene rubber (HNBR), and butadiene rubber (BR) and the impact property was tested at four temperatures (–30, ?15, 0, and 25 °C). The combination of CPE and HNBR was imported to toughen the SAN/ASA blends, indicating that CPE and HNBR had similar toughening effect at room temperature but HNBR exhibited a better performance at low temperature. When a little HNBR was substituted by BR, the impact strength improved dramatically with the total content of impact modifiers keeping at 30 phr. After 15 phr CPE, 10 phr HNBR and 5 phr BR were employed into blends together, the impact strength reached to a peak of 14 kJ/m² at ?30 °C while the impact strength of the blends individually toughened by 30 phr CPE or 30 phr HNBR was 5 or 12 kJ/m², respectively. The toughening mechanism showed that the low glass‐transition temperature (–108 °C) of BR and the compatibilization between BR and matrix accounted for the improvement of toughness. Simultaneously, scanning electron microscopy, dynamic mechanical analysis, flexural and tensile properties, heat distortion temperature, and Fourier transform infrared spectroscopy were measured. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45364.     

Gamma Radiation Effects on the Glass Transition Temperature and Mechanical Properties of PMMA/soot nanocomposites

Summary Poly(methyl methacrylate) (PMMA) was produced via free radical polymerization. Polymer samples were sonicated and melt compounded to form 1%, 0.5%, and 0.25% PMMA/soot samples. Soot containing unpurified carbon nanotubes was provided by NASA Ames Research Center. The composites were compression molded and exposed to ionizing radiation in air from a Cesium-137 source. The PMMA/soot samples were characterized before and after exposure to radiation. Differential Scanning Calorimetry (DSC) was used to determine glass transition temperatures. Mechanical properties of composites were characterized via Dynamic Mechanical Analysis (DMA) and microhardness measurements. The glass transition temperatures from this study, when compared to similar studies conducted by Harmon et. al on purified single-wall and multi-wall carbon nanotube composites indicate that soot composites possess lower radiation resistance.     

ILs-MPEG对PLA玻璃化转变温度和热稳定性的影响

利用链长不同的含聚乙二醇单甲醚侧链的咪唑基离子液体( ILs-MPEG)改性聚乳酸(PLA),通过熔融共混法制备PLA/ILs-MPEG共混物试样.采用扫描电子显微镜观察了ILs-MPEG在PLA基体中的分散情况,应用差示扫描量热仪和热重分析仪,分别研究了ILs-MPEG对PLA的增塑作用与热稳定性的影响.结果表明,ILs-MPEG可较为均匀地分散在PLA基体中,但随着其侧链长度增加,分散性下降.ILs-MPEG能促使PLA的玻璃化转变温度(Tg)明显降低,表现出显著的增塑作用,同时PLA热稳定性随ILs-MPEG侧链长度增加均呈先增加后减小的趋势.其中,ILs-MPEG800能有效降低PLA的Tg,但对PLA的热稳定性影响最小.     

The Importance of Crosslinking and Glass Transition Temperature for the Mechanical Strength of Nanofibers Obtained by Green Electrospinning

Crosslinked particles containing butyl acrylate, methyl methacrylate, and allyl methacrylate are prepared by free‐radical emulsion polymerization. The glass transition temperatures of the polymers are varied by the crosslinking densities in the latex particles. Aqueous acrylate dispersions with polymers of different glass transition temperatures are electrospun with PVA as the matrix polymer. The effects of crosslinking density and T_g on the structure and mechanical properties of the fibers are studied. Crosslinking of unreacted allyl groups is induced by UV irradiation to stabilize the fibers by interparticle crosslinking. Both the ability to undergo interparticle crosslinking and the E modulus depend on the merging of the particles during the electrospinning process.

     

硫化体系和混炼工艺对胶料玻璃化温度的影响研究

研究不同硫化体系和混炼工艺对胶料玻璃化温度（Tg）的影响。结果表明：随着硫化剂用量的增大,多硫键和双硫键比例减小,单硫键比例增大,胶料的Tg明显上升;混炼时间较短时,胶料的Tg随混炼时间延长而下降;随着混炼时间的进一步延长,胶料的Tg有上升的趋势。     

（PE—HD／PE—LD）—g—GMA增容PC／PE—UHMW共混物的冲击性能与断面形态

采用反应挤出方法，制备了缺口冲击性能良好的(PE-HD／PE-LD)-g-GMA(甲基丙烯酸缩水甘油脂)增容PC／PE-UHMW共混物。当增容剂(PE-HD／PE-LD)-g-GMA用量为6份时，共混物的冲击强度达到最大值66kJ／m^2，比未增容PC／PE-UHMW提高了28．5kJ／m^2。冲击断面的SEM分析表明，增容剂的加入产生了反应性的增容效果，提高了两相之间的界面粘结力，促进了相的分散，对基体的剪切屈服形变有利，冲击性能得以改善。     

PPO/EP复合材料的玻璃化转变温度及其测试方法

介绍了玻璃化转变温度(Tg)的内涵及其主要测试方法;以聚苯醚/环氧树脂(PPO/EP)为研究对象,分别采用DSC法和DMA法测定其Tg值,并讨论了两种测试方法的异同。结果表明:两种测试方法的测试条件、测试精度及影响测试结果的因素是不同的。在给出某一种高聚物的Tg时须注明测试方法和条件。     

HAN-TEAN-H_2O 三元体系的玻璃化转变温度的依数性和微观结构的推测

用ＤＳＣ研究了九种不同ＴＥＡＮ／ＨＡＮ比率下ＨＡＮ－ＴＥＡＮ－Ｈ２Ｏ三元体系的玻璃化转变温度Ｔｇ与Ｈ２Ｏ含量的关系;根据Ｔｇ的变化规律初步推测了该三元体系的分子结构;讨论了ＴＥＡＮ的含量对玻璃化转变温度的影响,并把该三元体系与二元体系ＨＡＮ－Ｈ２Ｏ进行了对比。     

聚马来酸二丁酯虚拟玻璃化温度的测定及其在乳液体系中的应用

在乳液共聚合的基础上计算了聚马来酸二丁酯(PDBM)的虚拟玻璃化温度,并研究了它在醋丙、苯丙和纯丙乳液体系中的应用。结果表明,聚马来酸二丁酯的玻璃化温度为-15.36℃,该单体在涂料、粘合剂方面可以部分代替丙烯酸丁酯,降低产品的成本。     

SAN共聚物中AN含量对PVC/ABS/DOP共混物结构与性能的影响

采用半连续乳液聚合技术将聚苯乙烯(St)和丙烯腈(AN)接枝到聚丁二烯(PB)乳胶粒子上,通过改变共聚单体的投料比(St/AN)合成了一系列不同AN含量的丙烯腈-丁二烯-苯乙烯共聚物(ABS)接枝共聚物,将其与聚氯乙烯(PVC)和增塑剂邻苯二甲酸二辛酯(DOP)熔融共混制得PVC/ABS/DOP(40/40/20)共混物。研究了共混物的热挺型性、微观形态结构和动态力学性能。结果发现,该共混物为双相连续结构,随着接枝SAN共聚物中AN含量的增加,由于DOP小分子与SAN共聚物的相互作用逐渐减弱,导致了SAN相的Tg和共混物的储能模量不断提高,改善了共混物的热挺型性,阐明了PVC/ABS/DOP共混物热挺型性的科学本质。     

高低温两段式蓄热室在玻璃熔窑中的应用

针对目前玻璃工业存在的生产成本高、污染严重、能耗高、产业结构不合理等问题,分析采用高低温两段式蓄热室对传统玻璃熔窑进行节能改造,使烟气温度降N200℃以下,预热空气温度达到1300℃以上,在同等条件下可节能10％以上,具有热效率高、加热均匀、保护环境、减少投资等优点,具有较好的推广和应用前景。     

Relationship Between Structure and Glass Transition Temperature in Low-silica Calcium Aluminosilicate Glasses: the Origin of the Anomaly at Low Silica Content

The anomalous behavior of the glass transition temperature ( T _g) in low silica calcium aluminosilicate glasses has been related to the structural modifications observed by neutron and X-ray diffraction. The diffraction data indicate that Al and Si are in tetrahedral sites and that Ca atoms are in distorted octahedral sites. By subtracting the correlation functions for glasses at constant SiO₂ or constant Al₂O₃ content, we have shown that Si and Al atoms are introduced in a different way within the glass structure. Si is present in various Q ⁿ sites, while Al resides in Q³ and Q⁴ sites for glasses with high CaO content and enters fully polymerized Q⁴ sites with increasing SiO₂ or Al₂O₃ content. The higher proportion of Al in Q³ positions at high CaO content yields a depolymerization of the network. The lower connectivity will contribute to a decrease of the viscosity, which may be at the origin of the decrease of T _g for glasses at low silica content.     

Some Effects of Structure,Composition and Cure on the Water Absorption and Glass Transition Temperature of Amine-cured Epoxies

The effect of structure, composition, and cure on the water absorption and T_g of amine-cured epoxies was investigated. Water absorption is considered to depend on the polar group concentration and type, and on the amount of free volume in the polymer network. The contribution of polar groups in terms of their hydrogen bonding capabilities is reflected by the effect of meta (with respect to the diglycidylamino group) chloro, bromo, and methyl substituents on the water absorption of bis[N,N-bis(2,3-epoxypropyl)-4-aminophenyl]methane cured with 4,4′-diaminodiphenylsulphone. The observed water absorptions are in line with the expected electronic effects of the substituents on the basicity of the amine group. Substituents in the ortho position adversely affect the hydrogen bonding capability of the amine group and limit the extent of reaction by steric interference. Examination of four O-glycidyl systems (Epon 825, Epon 1153/114, Epon 1031, and Dow XD-7342) cured with 4,4′-diaminodiphenylsulphone has revealed quite a good linear relationship between the equilibrium water absorption and T_g for a particular hardener concentration irrespective of the epoxy compound employed. Networks ranged from those of low T_g (110°C) and water absorption (1.3%) to those of high values (300°C and 6.1%) for these parameters. Differences in slope for low (50-65%) and high (100%) stoichiometric amounts of hardener are attributed to differences in the relative importance of OH/epoxy and NH₂ or NH/epoxy reactions. The theoretical polar group concentrations and polar group type are much the same for these different systems and thus, free volume is considered to be a function of T_g and to play an important part in determining the level of water absorption.     

超薄玻璃自动定位九点落球冲击强度试验与仿真

随着手机技术的不断进步,对手机用盖板超薄玻璃的强度要求也越来越高,落球冲击试验是超薄玻璃重要的标准指标之一,但落球冲击试验定位精度很难保证.采用高精度模组自动定位的方法进行试验机设计,从根本上改变传统人工定位的模式,通过三坐标运动自动定位到指定九点,并提出防二次冲击的新方案.规范了试验的过程及要求,并对冲击试验过程进行有限元仿真.使落球冲击试验效率大幅度提升,并且定位精度完全满足试验标准的要求.     

马来酸二丁酯虚拟玻璃化温度的测定及其在涂料粘合剂中的应用

通过实验计算出马来酸二丁酯的虚拟玻璃化温度,并研究了它在醋丙、苯丙乳液体系中的应用。结果表明:马来酸二丁酯在涂料、粘合剂方面可以全部或部分代替丙烯酸丁酯,对降低相关产品的成本具有重要意义。