Toughening of aromatic diamine-cured epoxy resins by modification with hybrid modifiers composed of N-phenylmaleimide–styrene copolymers and N-phenylmaleimide–styrene–p-hydroxystyrene terpolymers

Hybrid modifiers composed of N-phenylmaleimide–styrene copolymers (PMS), and N-phenylmaleimide–styrene–p-hydroxystyrene terpolymers (PMSH) containing pendent p-hydroxyphenyl groups as functionalities, were used to improve the toughness of bisphenol-A diglycidyl ether epoxy resin cured with p,p′-diaminodiphenyl sulphone. The hybrid modifiers were effective in toughening the epoxy resin. When using the modifier composed of 10 wt% PMS (M?_w 313000) and 2.5 wt% PMSH (2.5 mol% p-hydroxystyrene units, M?_w 316000), the fracture toughness (K_IC) for the modified resins increased 100% with no deterioration in the flexural properties and the glass transition temperature. The improvement in toughness of the epoxy resins was attained because of the co-continuous phase structure and the improvement in interfacial adhesion. The toughening mechanism is discussed in terms of the morphological characteristics of the modified epoxy resin systems.     

4,4′-二碘二苯基砜的合成、谱学表征及其晶体结构

以氯磺酸和碘代苯为原料,经氯磺化反应合成了4,4′-二碘二苯基砜。最佳反应条件为:于-20～-15℃将碘代苯滴入氯磺酸的氯仿溶液,n(碘代苯):n(氯磺酸)=1:3,50℃反应2h,冷却反应液后用碎冰洗涤、无水MgSO4干燥,脱除溶剂,粗产物经苯重结晶,收率82.6%,熔点207～208℃。并通过熔点、元素分析、UV、IR、1HNMR及X射线单晶衍射对产物进行了谱学表征和晶体结构分析。该晶体属于单斜晶系,C2/c空间群,晶胞参数:a=21.612(4)nm,b=4.9550(10)nm,c=14.449(3)nm,α=90.00°,β=117.27(3)°,γ=90.00°,V=1.3754(5)nm3,Dx=2.270g/cm3,Z=4,F(000)=872,μ=4.712mm-1,S=1.078,R=0.0370,wR=0.0897。     

聚砜低聚物改性PPES流变性能的研究

通过熔融挤出制备了不同比例的二氮杂萘联苯聚醚砜(PPES)和聚砜低聚物(O-PSU)的共混物,并用毛细管流变仪对该共混物的流变性能进行了研究。结果表明,共混物熔体在所测定的温度和剪切速率范围内呈现出典型的假塑性流体特性;共混体系的表观粘度随O-PSU用量的增加、温度的升高和剪切速率的增加而降低;O-PSU的加入明显地改善了PPES的熔融加工性能。     

新型含杂萘联苯聚醚砜类嵌段共聚物的合成与性能研究

采用连续缩聚法合成氯端基聚醚砜齐聚物,然后与杂萘联苯构成的类双酚合成的羟端基齐聚物进行缩聚反应,合成了新型PPES-PES嵌段共聚物.用IR、DSC、TGA、X-WAXD等方法对聚合物进行了表征,并研究了聚合物的溶解性能.结果表明该嵌段共聚物具有较高的玻璃化转变温度,较好的热稳定性和良好的溶解性能,为非结晶型聚合物,并可浇铸得到透明、韧性高的薄膜.实验还发现聚醚砜组分含量变化对共聚物的热性能影响很大,对杂萘联苯聚醚砜改性效果明显.     

The effect of stress ageing on deformation in thin films of polystyrene and poly(ether sulphone)

Step-strain ridges are known to form when glassy polymers are subjected to a stepwise series of strain increments. For relatively short times between increments (ageing times) and at relatively low temperatures, these step-strain ridges (studied here in crazes in polystyrene and in deformation zones in poly(ether sulphone)) become more marked as the interval t_i between successive strain increments is increased. This is related to the phenomenon of stress ageing, as suggested by the approximate logarithmic dependence of the ridge height δ on t_i. However, at high temperatures, and or low molecular weight and relatively long t_i, δ may begin to decrease with t_i. This is argued to be a result of the onset of disentanglement in the aged material.     

SCE-SiO_2/PES-MBAE复合材料微观形貌及性能

为研究增韧双马来酰亚胺方法及其对性能的影响,首先利用超临界乙醇处理纳米SiO2(SCE-SiO2),改善其表面活性;然后以4,4’-二氨基二苯甲烷双马来酰亚胺(MBMI)、3,3’-二烯丙基双酚A(BBA)、双酚A双烯丙基醚(BBE)为原料合成了MBMI-BBA-BBE(MBAE)复合材料基体,并利用原位聚合法和溶胶-凝胶法将SCESiO2和聚醚砜(PES)加入MBAE基体中制备了SCE-SiO2/PES-MBAE多相复合材料;最后采用SEM观察了SCESiO2/PES-MBAE复合材料断面形貌。SCE-SiO2的FTIR分析结果表明:在3 434cm-1处的Si—OH的吸收峰消失,出现了3 310cm-1处的乙醇分子间—OH的吸收峰、2 984cm-1处的甲基和亚甲基的吸收峰,证明纳米粒子可能以某种形式结合了乙醇分子,改善了表面性能。PES以"蜂窝"状分散相的形式存在于基体中,断裂方式由脆性断裂向韧性断裂转变,SCE-SiO2和PES对材料均有增韧作用,PES的增韧效果更明显,二者之间具有协同作用,当SCE-SiO2含量为2wt%、PES含量为4wt%时,多相复合材料的冲击强度和弯曲强度分别为15.02kJ/m2和130.47MPa,较MBAE树脂分别提高了57.3%和35.8%。介电性能测试表明:SCE-SiO2和PES的引入均会导致SCE-SiO2/PES-MBAE复合材料的介电常数和损耗略有上升,但二者之间的协同作用可以抑制PES组分所带来的负面影响。     

Physical characterization of suspension-crosslinked polystyrene particles and their sulphonated products: 2. Ionic networks

Strong cationic resins have been prepared from isoporous polystyrene networks in bead form with H₂SO₄ and HSO₃Cl as sulphonating agents. The effect of the reaction time of H₂SO₄ sulphonation on ion exchange capacity has been examined. The polymer-solvent interaction parameter, X, with aqueous electrolyte solutions has been calculated after minimization of electrostatic repulsions. The average molecular weight per crosslinked unit, $\text{M}\text{?}{}_{\mathrm{<mtext>c</mtext>}}$ has been measured after sulphonation and an estimation of formation of sulphone-type crosslinks has been attempted. The average size of the network structure, r_c, has been calculated as a function of the ionic strength of aqueous electrolyte solutions for networks of different molecular weight per crosslinked unit, $\text{M}\text{?}{}_{\mathrm{<mtext>c</mtext>}}$. The ion exchange capacity of the prepared resins has been measured.     

Copolymerization of Bis(4-methacryloymethylphenyl) sulphone with styrene

Bis(4-methacrloylmethylphenyl) sulphone (BMMPhSu) was prepared by the reaction of bis(4-chloromethylphenyl)sulphone with potassium salt of methacrylic acid. The structure of this new compund was determined by element analysis, IR, 1 H-NMR and 13 C-NMR analyses. Besides, the fundamental physical properties of bis(4-methacryloylmethylphenyl)sulphone such as the melting point and solubility in common as well as vinyl solvents: styrene, methyl methacrylate, butyl acrylate, acrylonitrile, and divinylbenzene were determined. Using 8 different hardening systems (polymerization initiators) copolymerization of this compound with styrene was carried out. Combinations of the following compounds: benzoyl peroxide, methyl ethyl ketone hydroxyperoxide, N,N-dimethylaniline, cobalt naphthenate, and aromatic amine adduct were used for hardening (polymerization initiation). An infludence of BMMPhSu concentration on gelation times with the use of three hardening systems was studied. Finally two hardening systems were chosen and using them copolymerizations of 20 and 25% of BMMPhSu with styrene were carried out. The obtained copolymers were tested for mechanical properties: tensile strength, Young's modulus, elongation at break hardness by Shore's and Brinnell's methods. Their thermal properties were also determined.     

A microstructural study of polystyrene—polyether sulphone polymer blends

Polystyrene (PS)-polyether sulphone (PES) polymer blend thin films were prepared for investigation in a scanning transmission electron microscope. The microstructures of PS-PES films (prepared by drawing from solutions at temperatures above ambient) of three different compositions were characterized: (1) 75 wt% PS-25 wt% PES, (2) 50 wt% PS-50 wt% PES, and (3) 25 wt% PS-75 wt% PES. For films prepared at ～ 40°C all three compositions exhibited microstructures consisting of spherical inclusions, ranging from ～0.2μm to ～ 1.2μm in diameter. The microscope used here was equipped with an energy-dispersive X-ray spectrometer, and this was employed to determine the chemical content of the inclusions and the matrix material. From X-ray analysis, it was found that films (1) and (2) consisted entirely of PES-rich inclusions, while film (3) contained both PS-rich and PES-rich inclusions. In addition, these analyses revealed that films (2) and (3) possessed a ‘mixed’ PS-PES matrix phase. At the other temperatures for film preparation some significant differences in morphology were observed, reflecting the different rates of solvent evaporation.     

交联透明质酸钠凝胶的制备工艺研究

以细菌发酵透明质酸(HA)为原料,在室温条件下采用二乙烯基砜(DVS)交联剂制备DVS-HA凝胶,为去除未反应的交联剂进行多方案实验,通过气相色谱法检测凝胶中残留交联剂含量,以期获得较优工艺方案,为进一步开发HA临床应用产品奠定了基础.