聚丙烯酸丁酯／蓖麻油聚氨酯SEN的研究（Ⅱ）：全SEN

聚丙烯酸丁酯(PnBA)/蓖麻油聚氨酯(COPU)半SEN(Semi-Simultaneous Elastomer Net-work)中,PnBA为线形分子,两组分间只能形成“蛇笼式”的互穿和缠结.这种缠结在外力作用下易脱开,组分间相容性虽较简单混合有所改善,但不甚显著,在某些组分比之下,力学性能也较差.全SEN中两组分均为交联结构,会产生一部分环套式的永久性缠结.只要不发生化学键断裂,这种网间缠结便不能脱开,它将对全SEN的形态、性能及组分间相容性产生较大的影响.     

PPO-PDMS-PHS_n三元多嵌段共聚物的形态结构和性能

利用DMA,TEM和SAXS对以聚苯醚(PPO)为硬段、聚对羟基苯乙烯(PHS)为半硬段和聚二甲基硅氧烷(PDMS)为软段的三元多嵌段共聚物(?)PPO-PDMS-PHS(?)_n的形态结构和性能进行了研究.结果表明,(?)PPO-PDMS-PHS(?)_n以三种嵌段相容相为连续相,PPO与PHS的相容相和PDMS相为两种分散相,其tanδ随温度变化曲线在-100℃至200℃一直是一很高的平台,并具有优异的力学性能,较好地解决了含有机硅类嵌段共聚物强度低的弱点,同时又保留了嵌段共聚物微相分离的特性.     

高浓度不相容聚合物共混体系相形态与流变性能研究

通过光学显微镜观测和流变实验研究了应力弛豫过程中高浓度不相容聚合物共混体系相形态演变与流变性能的关系,发现随体系浓度增大,共混体系内液滴弛豫变慢,同时体系应力弛豫过程变慢,这与高浓度体系中液滴之间相互作用有关.结合有效介质思想提出适用于较高浓度共混体系的形态张量模型,较好地预测了共混体系的相形态与应力弛豫行为.     

高分子复杂体系的结构与流变行为

流变学测试对非均相体系的结构变化具有敏感响应,被认为是表征多相/多组分聚合物体系结构与性能极为有效的方法.本文主要依据作者及其合作者的工作,对近年来围绕非均相体系形态结构与流变响应所开展研究的最新结果进行了总结和评述,涉及LCST型高分子共混体系的相形态与黏弹松弛、嵌段共聚物的微结构与线性/非线性黏弹行为、聚烯烃剪切诱导结晶时间尺度与流变响应、填充聚合物体系的结构性能和流变行为.对多相/多组分高分子共混体系形态结构演变的特征流变响应的充分认识,将有助于优化非均相体系的形态结构与最终力学性能.     

滑石粉及混炼顺序对PA6/PP/MAPP合金相形态及力学性能的影响

通过挤出和注射成型制备了滑石粉(Talc)填充的尼龙6/聚丙烯/马来酸酐接枝聚丙烯(PA6/PP/MAPP)合金, 研究了Talc和混炼顺序(一步法和PA6母料法)对合金相形态和力学性能的影响. 场发射扫描电镜(FESEM)分析结果表明, 添加Talc后注射样条中心部分的PP相由球状转变为沿流动方向取向的有分支的条状结构, 且用PA6母料法制样比用一步法制样的相形态更为精细. 溶解PA6相后对PP相进行热重分析(TGA), 确定了Talc在PA6相和PP相中的分布比例, Talc选择性分布于PA6相中. PA6母料法中Talc的分散好于一步法. 研究了材料的拉伸、 弯曲、 冲击、 热变形温度和动态力学性能, Talc的添加能够明显提高材料的刚性, 且母料法样品的性能优于一步法样品.     

用新型的半固相方法合成掺钴尖晶石材料LiCo_xMn_(2-x)O_4及其性能研究

用一种新型的半固相法合成得到LiCo_xMn_(2-x)O_4材料,通过X射线衍射技术 和充放电实验对材料的结构及循环性能进行了研究。与传统的固相合成法相比,这 种半固相法显示了产物颗粒尺寸均匀,电化学性能良好的特点。通过对结构,组成 与电化学性能关系的探讨,对不同半固相法合成路线的选择及适当的优化,可得到 电化学性能良好的掺钴尖晶石材料,其中LiCo_(0.016)Mn_(1.984)O_4在室温下的 初始容量为118 mA·h/g,循环25周后,容量仍能保持在113 mA·h/g左右。通过这 种新型合成方法得到的掺钴尖晶石材料,在高温下也表现出了令人满意的充入电循 环性能。     

聚丙烯材料聚集态结构的定量表征及其与力学性能的关系

报道了用IAS4图像分析系统研究聚丙烯材料的聚集态结构 ,表明用图像分析仪可定量表征结晶型聚合物材料球晶和第二相颗粒在基体中的形态 .通过材料聚集态结构的定量测定 ,对材料性能的变化可作出满意的解释 ,是研究结晶型高聚物结构与性能关系的有效手段     

网间交联型增韧环氧树脂/蓖麻油聚氨酯互穿网络聚合物的动态力学性能和形态结构

以增韧环氧树脂(TEP)和蓖麻油聚氨酯[PU(CO)]形成的互穿网络聚合物(IPN),两网络间具有一定数量的交联点,在一定组成下,该IPN的tanδ-T曲线半峰宽达100℃,tanδ最大值接近1,阻尼性能良好。形态研究表明,该IPN既有增韧环氧树脂本身的两相结构,又有IPN的两相结构。     

TPU共混增韧POM的研究

通过机械共混的方法制备了聚甲醛(POM)和热塑性聚氨酯弹性体(TPU)复合材料.考察了不同硬度TPU及其含量对共混材料韧性的影响.结果表明,TPU硬度的变化对共混材料的力学性能起着非常重要的作用,硬度为65HA的TPU对POM的增韧效果较好,对POM的相形态和结晶性能影响更为显著.     

硫化镉晶体结构形态对乙醇光催化脱氢活性的影响

有关醇类水溶液光催化贮能脱氢反应研究大多集中在提高半导体TiO₂和CdS表面修饰组分的光催化活性^[1～3]及考察TiO₂半导体晶体结构与光催化性能的关系上^[4,5],CdS半导体晶体结构形态对光催化性能的影响尚未见报道.本文在这方面进行了一些有益的研究.     

Electrochemical corrosion resistance performance of sustainable resource-based nanoconducting polymer composites in alkaline medium

The corrosion resistance performance of poly (otoluidine) (POT)-dispersed castor oil-polyurethane, (COPU) nanocomposite coatings, POT/COPU, with three different compositions (i.e. 0.25, 0.5 and 1.0 wt%) in alkaline medium is studied. The coatings are applied on mild steel specimens by brushing. Corrosion resistance behaviour of these coatings is investigated using potentiodynamic polarization measurements, electrochemical impedance spectroscopy (EIS) and by weight loss. The morphological behaviour of corroded and uncorroded coated specimens is investigated by scanning electron microscopy (SEM). It is interesting to report that the presence of conducting polymer nanoparticles in POT/COPU coatings suppresses the saponification of COPU in an alkaline environment. These investigations show that the dispersion of POT in COPU remarkably improves the corrosion resistance performance of COPU in alkaline media. POT/COPU (1.0 wt%) coatings have potential as anticorrosive-coating materials in alkaline media at higher pH. These coatings have a higher resistance to alkaline medium in comparison to other compositions.     

蓖麻油聚氨酯／乙烯类聚合物交联共聚物的动态力学性能

本文研究了蓖麻油聚氨酯(COPU)/聚甲基丙烯酸丁酯(PBMA)交联共聚物(简称ABCP)的动态力学性能,并将其与COPU/PBMA,IPN的动态力学性能作了比较。发现在ABCP中两组份的阻尼峰互相叠加,形成半相容体系,而在IPN中阻尼峰有个宽的平台。透射电镜照片表明,IPN具有更大的相区结构。这些结果证明,化学交联比物理缠结具有更大的强迫互容性。通过对COPU/乙烯类聚合物(VP)交联共聚物相容性的研究,可知COPU/PBMA,COPU/PST和COPU/PMMA交联共聚物,在动态力学性能上是半相容体系,而COPU/PMA和COPU/PBA交联共聚物是互容体系。     

Separation and characterization of functional poly(n-butyl acrylate) by critical liquid chromatography

The separation of functional poly(n-butyl acrylate) (PnBA) polymers based on the number of end-groups under critical liquid chromatography (LC) conditions has been studied using a bare-silica column. The (near-) critical solvent compositions for non-, mono-, and difunctional (telechelic) carboxyl-PnBAs were determined in normal-phase LC, using mixtures of acetonitrile, acetic (or formic) acid, and dichloromethane of varying composition. Some formic or acetic acid had to be added to the mobile phase to elute PnBA polymers with carboxyl end-groups. The critical solvent compositions obtained were not exactly the same for non-, mono-, and difunctional PnBA polymers. These were unusual experimental observation, but they were in agreement with theoretic predictions. Nevertheless, low-molecular-mass PnBA samples were successfully separated according to the carboxyl functionality at (near-) critical conditions. With the aid of mass spectrometry (MS), the (near-) critical separation of low-molecular-mass PnBA polymers was confirmed to be mainly based on the carboxyl functionality. Calibration curves for evaporative light-scattering detection (ELSD) were used for quantitative analysis of carboxyl-functional PnBA polymers. The results proved that nearly ideal functionalities (average number of carboxyl end-groups per molecule up to 1.99) were achieved for telechelic PnBAs prepared by one-step reversible addition-fragmentation chain-transfer (RAFT) polymerization of PnBA.     

COPU／PMMA AB交联聚合物的性能

AB交联聚合物(ABCP)是由聚合物A链与化学组成不同的聚合物B链交联构成。它的网络结构不同于IPN。IPN是由两个独立的网络构成,而在ABCP中仅存在一个聚合物网络。目前人们对它远不及对IPN了解得多。 本文选用蓖麻油为原料,与甲基丙烯酸甲酯共聚,合成了一种ABCP。研究了它的力学性能,转变与松弛,相容性及形态结构与组成及交联密度的关系。     

蓖麻油聚氨酯/甲基丙烯酸甲酯交联共聚物的合成与表征

<正> AB交联共聚物(ABCP)和互穿网络聚合物(IPN)都属交联网状聚合物,只是前者形成一个网络,后者构成两个独立网络(图1),因此两者的性能有明显差别,特别是相容性。目前对ABCP的研究主要是聚酯,聚醚体系,本工作选用便宜的蓖麻油聚氨酯(COPU)和MMA为原料,合成ABCP,得到具有阻尼性能的材料。     

Friction and damage in the scratching of poly(n‐butyl acrylate) films

Scratch testing was performed on poly(n‐butyl acrylate) (PnBA) films with a sapphire indenter with a spherical tip (76 μm in radius). For uncrosslinked PnBA film, the surface of which is sticky, the horizontal or scratching force decreases with decreasing normal load and has a residual value (～ 6 mN) as the normal load approaches zero. The relation between the scratching force and normal load can be understood by finite element computation based on the Johnson–Kendall–Roberts theory under the assumption that the scratching force is proportional to the contact area, which depends on the normal load. With increasing driving speed, the scratching force shows a power relation with speed indicating a rate process. For crosslinked PnBA film, which behaves as an elastomer, the horizontal force approaches zero at zero normal load. Below a critical normal load, which depends on the thickness of the film, the crosslinked film recovers elastically after being scratched. Above the critical load, the film is damaged and, depending on its thickness, shows two distinct damage mechanisms. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 585–592, 2002; DOI 10.1002/polb.10117     

核／壳结构增韧剂对环氧树脂的抗冲改性

核／壳结构增韧剂对环氧树脂的抗冲改性张明耀，张会轩，杨海东，冯之榴（吉林工学院化学工程系长春１３００１２）（中国科学院长春应用化学研究所长春）关键词核／壳结构，增韧剂，环氧树脂，共混核／壳结构增韧剂是用分步乳液聚合技术制造的一种复合乳胶粒子，其核为橡...     

Mechanical properties,surface morphology and failure mode of γ-ray irradiated blends of polypropylene and ethylene-vinyl acetate rubber

The effect of ⁶⁰Co γ-radiation on the mechanical properties, surface morphology and failure characteristics of blends of polypropylene [PP] and ethylene-vinyl acetate rubber [EVA] has been studied with specific reference to the effect of blend ratio, dynamic crosslinking of the rubber phase and absorbed radiation doses. Samples were subjected to radiation in the dose range of 1 to 100 Mrad in air at room temperature at the rate of 0·321 Mrad/h. Both chain scission and crosslinking occur simultaneously in the blend samples. PP and blends containing higher proportions of PP (≥50%) undergo predominant chain scission at lower doses (≤50 Mrad), which causes a drastic drop in tensile strength, followed by a levelling out at higher doses of 100 Mrad. EVA undergoes crosslinking at lower doses resulting in an increase in tensile strength in the dose range 1 to 10 Mrad followed by a decrease in the range 10–25 Mrad. Further increase in radiation dose has little effect on tensile strength. The effect of radiation on stress-strain behaviour, elongation at break, energy at rupture and hardness was also studied. The morphology of the irradiated surfaces after an absorbed dose of 100 Mrad has been examined by scanning electron microscopy (SEM). In order to understand the effect of γ-radiation on the failure mechanism, tensile failure surfaces of both unirradiated and irradiated samples have also been examined by SEM.     

1:1 alternating copolymer of acrylonitrile and vinyl acetate

Copolymerization of the acrylonitrile-zinc chloride complex with excess vinyl acetate has been investigated. Alternating 1:1 copolymers of acrylonitrile and vinyl acetate of high molecular weights have been successfully prepared. The alternating structure has been ascertained by means of high-resolution nuclear magnetic resonance spectroscopy. The copolymer is amorphous (T_g = 85°C) and has shown thermal and oxidative stability better than those of polyacrylonitrile. The copolymer is soluble in acetone as well as in more powerful solvents such as dimethylformamide, dimethyl sulfoxide, nitromethane, and N-methylpyrrolidone. The copolymer has been processed into films and fibers from its acetone solutions. Films show tensile properties similar to those of cellulose acetate under ambient conditions; they suffer drastic loss in tensile properties at above 50°C and retain their good tensile properties at subzero temperatures (determined as low as ?40°C). Fibers show tensile properties comparable to those of modacrylic fibers under ambient conditions but suffer marked loss in stiffness at 40°C in water and 60°C in air. The fibers also retain their good properties at subzero temperatures (measured down to ?60°C).