聚丙烯纤维化学接枝改性增强水泥基复合材料的界面结合

以过氧化苯甲酰(BPO)为引发剂,采用二步化学接枝法对聚丙烯纤维进行接枝丙烯酸改性,利用正交分析法研究了引发温度、BPO浓度、接枝温度、接枝时间及丙烯酸(AA)浓度对纤维接枝率的影响,并评价了改性前后纤维与水泥基体的界面结合性能.结果表明:上述因素对纤维接枝率的影响大小为引发温度＞ BPO浓度＞接枝时间＞接枝温度＞AA浓度,最佳反应条件为引发温度90℃,BPO 4.50×10-2 mol/L,接枝时间60 min,接枝温度75℃,AA 1.4 mol/L,此时纤维接枝率达13.12％;经化学接枝改性后,聚丙烯纤维表面亲水性和粗糙度增大,与水泥基体的界面结合得到增强,纤维掺量为0.05％(体积分数)时,聚丙烯纤维增强水泥砂浆的抗开裂性能比增大了26.6％,抗塑性收缩开裂性能显著增强.     

聚丙烯纤维化学接枝改性增强水泥基复合材料的界面结合

以过氧化苯甲酰(BPO)为引发剂, 采用二步化学接枝法对聚丙烯纤维进行接枝丙烯酸改性, 利用正交分析法研究了引发温度、BPO浓度、接枝温度、接枝时间及丙烯酸(AA)浓度对纤维接枝率的影响, 并评价了改性前后纤维与水泥基体的界面结合性能。结果表明: 上述因素对纤维接枝率的影响大小为引发温度>BPO浓度>接枝时间>接枝温度>AA浓度, 最佳反应条件为引发温度90℃, BPO 4.50×10^-2mol/L, 接枝时间60 min, 接枝温度75℃, AA 1.4 mol/L, 此时纤维接枝率达13.12%; 经化学接枝改性后, 聚丙烯纤维表面亲水性和粗糙度增大, 与水泥基体的界面结合得到增强, 纤维掺量为0.05%(体积分数)时, 聚丙烯纤维增强水泥砂浆的抗开裂性能比增大了26.6%, 抗塑性收缩开裂性能显著增强。     

电子束辐照接枝改性PTFE多孔膜

通过高能电子束预辐照接枝丙烯酸（AA）／对苯乙烯磺酸钠（SSS）对PTFE多孔膜进行亲水改性，并研究了单体浓度、辐照剂量等对接枝率，接枝反应对多孔膜表面形貌膜和化学组成以及亲水性的影响。研究结果表明接枝率随混合单体中AA含量增加而增大，而且随辐照剂量的提高而增大，PTFE多孔膜的接枝覆盖层增加膜表面的亲水基团含量，同时对膜的亲水改性效果能保持稳定。     

预光照聚四氟乙烯薄膜表面的无光引发剂气相光接枝聚合

研究了聚四氟乙烯（ＰＴＦＥ）薄膜的非极性表面光接枝改性，以赋予其在面一定的极性，改善表面的亲水性。采用预光照、不加光引发剂，用紫外光直接引发ＰＴＦＥ薄膜表面的丙烯酸接枝。改性后薄膜表面的水接触角由９８°降至６５°，染色程度明显提高。研究了反应条件对接枝结果的影响，并通过ＥＳＣＡ等分析手段，探讨了接枝反应机理。预先照可活化ＰＴＦＥ膜表面，使聚四氟乙烯的Ｃ－Ｆ键断裂产生自由基。光引发剂二苯甲酮不能引发ＰＴＦＥ膜，而能引发丙烯酸，便之一生均聚物，不加二苯甲酮可减小接枝阻力。     

紫外光接枝改性聚丙烯薄膜的研究

以二苯甲酮为光敏剂,通过紫外光辐照引发,将亲水性单体丙烯酸(AA)和甲基丙烯酸(MAA)接枝在聚丙烯薄膜表面。考察了光敏剂浓度、辐照时间以及溶剂类型对接枝率的影响。利用衰减全反射红外光谱和扫描电子显微镜对接枝薄膜的表面化学组成和形貌结构进行表征,通过水接触角和吸水率研究了接枝后薄膜的亲水性。结果表明,在相同条件下,AA的接枝率高于MAA;相比于有机溶剂,在水溶剂中AA的接枝率明显提高;当接枝率达到11.8%时,薄膜表面水接触角由原膜的95°降低到35°,亲水性显著提高。     

聚偏氟乙烯膜表面丙烯酸接枝改性研究

采用自由基接枝聚合反应制备了丙烯酸改性的聚偏氟乙烯膜,研究了单体浓度对接枝率的影响,测定了改性后样品的红外光谱、表面接触角、水通量、蛋白吸附等.结果表明,通过自由基接枝聚合,丙烯酸接枝到膜的表面,明显提高膜的亲水性.接枝后膜的水通量也非常明显下降,特别是在高丙烯酸浓度下.改性的膜的通量对溶液的pH值有明确的响应关系,表明接枝链在水中的溶胀对膜的性能有显著的影响.蛋白吸附实验表明,改性后的膜相比未改性膜有较高的吸附量,而且在酸性情况下,膜的吸附量较大,这主要与丙烯酸和蛋白质之间的相互作用有关.     

SEBS-丙烯酸接枝共聚物的合成与结构分析

以过氧化二苯甲酰(BPO)为引发剂，在甲苯溶液中进行丙烯酸(AA)接枝SEBS树脂。经红外光谱和光电子能谱(ESCA)分析表明，丙烯酸已接枝到SEBS树脂上。研究了反应温度、反应时间、单体浓度、引发剂浓度等因素对单体转化率、接枝聚合物接枝率、单体接枝效率等的影响。根据实验结果，接枝反应的适宜条件：温度为90℃，引发剂用量为聚合物的10％，丙烯酸用量为5mL，时间6h～8h。     

等离子体引发接枝聚合改善聚丙烯表面的亲水性

将等离子体引发接枝技术用于聚丙烯（PP）膜表面接枝丙烯酸。FT—IR证明处理后的膜表面存在有羧基,染色法定量测定了羧基的含量。另外,对修饰后的聚丙烯膜表面进行接触角的测定。结果表明,等离子体引发接枝聚合可明显改善聚丙烯膜表面亲水性,能控制PP膜表面的接枝率大小,可得到不同水接触角的PP膜,进而能人为调节PP膜的表面亲水性。     

溶聚丁苯橡胶接枝丙烯酸的改性研究

为提高溶聚丁苯橡胶(SSBR)与极性物质的相容性,以丙烯酸(AA)为极性单体对SSBR进行接枝改性。研究了AA用量、引发剂(BPO)用量、反应温度和应时间对接枝聚合物接枝率和凝胶率的影响。通过优化制备条件,在实验范围内SSBR-g-AA接枝率最高为1.26%,凝胶率为0.78%。并对接枝产物进行了红外、热重和接触角的分析表征。     

连续化功能中空纤维膜的制备方法EI北大核心CSCD

文中旨在介绍一种可产业化的中空纤维膜表面功能化方法。通过连续化紫外光辐照接枝法,将亲水性单体丙烯酸(AA)接枝到膜表面,形成亲水接枝层。膜的亲水性受接枝密度的影响,可方便地通过调整卷绕速度、单体浓度和光敏剂浓度等工艺参数来获得合适的接枝密度。随着接枝密度的增大,膜的水接触角降低,纯水通量显著增大,表明亲水性得到了提高。抗污染性实验结果显示,随着接枝密度从0增大到3.54 mmol/m2,膜的总污染系数从0.647下降到0.377,不可逆污染系数从0.5减小到0.097,纯水通量恢复率从49.98%增加到90.30%,部分不可逆污染可转变为可逆污染,从而通过水力反清洗的方法除去,表明经过连续紫外辐照接枝亲水改性后,膜的抗污染性得到了显著的提高。     

Modification in Surface Chemistry of the Polyetrafluoroethylene Through Chemical Graft Copolymerization for Potential Oil Contamination Control

In the present study, an attempt has been made to design an oleophobic surface through chemical graft copolymerization of methyl methacrylate (MMA) onto polytetrafluroethylene (PTFE) film. The PTFE films were grafted with MMA resulting in PTFE-g-MMA grafts using benzoyl peroxide (BPO) as initiator in aqueous media. Optimum conditions pertaining to maximum percentage of grafting were evaluated by varying time, temperature, initiator, and monomer concentration. The maximum graft yield 9.47% was obtained at [BPO] = 0.03 M, [MMA] = 10%V/V, [reaction temperature] = 50°C and [reaction time] = 120 min. Methyl iodide was used to measure the contact angle, which revealed the oleophobic nature of grafted PTFE-g-MMA film. Maximum contact angle 95.5° of PTFE-g-MMA film was observed at optimum grafting conditions. The surface morphology of PTFE-g-MMA films was studied by Field emission scanning electron microscopy (FE-SEM) and x-ray diffraction (XRD) analysis confirmed the change in structure of PTFE after MMA grafting.     

Grafting of poly(ethylene glycol) monoacrylates on polycarbonateurethane by UV initiated polymerization for improving hemocompatibility

Poly(ethylene glycol) monoacrylates (PEGMAs) with a molecular weight between 400 and 1,000 g mol^?1 were grafted by ultraviolet initiated photopolymerization on the surface of polycarbonateurethane (PCU) for increasing its hydrophilicity and improving its hemocompatibility. The surface-grafted PCU films were characterized by Fourier transformation infrared spectroscopy, X-ray photoelectron spectroscopy, water contact angle, scanning electron microscopy (SEM) and atomic force microscopy measurements. The surface properties of the modified films were studied in dry and wetted state. Blood compatibility of the surfaces was evaluated by platelet adhesion tests and adhered platelets were determined by SEM. The results showed that the hydrophilicity of the films had been increased significantly by grafting PEGMAs, and platelets adhesion onto the film surface was obviously suppressed. Furthermore, the molecular weight of PEGMAs had a great effect on the hydrophilicity and hemocompatibility of the PCU films after surface modification and increased with increasing molecular weight of PEGMAs.     

Surface modification of natural rubber latex films via grafting of poly(ethylene glycol) for reduction in protein adsorption and platelet adhesion

Natural rubber (NR) latex films with surface grafted poly(ethylene glycol) (PEG) chains were prepared by UV-induced graft copolymerization of methoxy poly(ethylene glycol) monomethacrylate (PEGMA) onto the plasma-pretreated NR latex films. PEGMA macromononers of different molecular weights were used. The UV-induced graft copolymerization of PEGMA onto the plasma-pretreated NR latex films was also explored with PEGMA of different macromonomer concentrations and with different UV graft copolymerization time. The surface microstructures and compositions of the PEG-modified NR latex films were characterized by contact angle, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) measurements. In general, higher macromonomer concentration and longer UV graft copolymerization time led to a higher graft yield. Water contact angle measurements revealed that the hydrophilicity of the NR latex film surface was greatly enhanced by the grafting of the PEG chains. The NR surface with a high density of grafted PEG was very effective in reducing protein adsorption and platelet adhesion. A lower graft concentration of the high-molecular-weight PEG was more effective than a high graft concentration of the low-molecular-weight PEG in reducing protein adsorption and platelet adhesion. © 2001 Kluwer Academic Publishers     

聚丙烯微孔膜表面的臭氧处理接枝改性

采用臭氧处理聚丙烯微孔膜,在其表面引入过氧化物,然后通过过氧化物的分解引发丙烯酸单体在微孔膜表面接枝。研究了臭氧处理条件、接枝反应条件对聚丙烯微孔膜的接枝率、亲水性及溶胀性的影响。研究结果表明,丙烯酸接枝微孔膜与水的接触角随接枝率的增加而逐渐下降,吸水率随接枝率的增加而呈线性增加趋势,表现出良好的亲水性与溶胀性。     

α-甲基丙烯酸接枝ABS树脂的研究

以过氧化二苯甲酰（BPO）为引发剂,在1,2－二氯乙烷溶液中进行了α－甲基丙烯酸接枝ABS树脂,经红外光谱分析表明,α－甲基丙烯酸已接枝到ABS树脂上,研究了单体浓度,引发剂浓度,反应时间和反应温度对接枝聚合物接枝率,凝胶率等的影响。根据实验结果,推测终止反应主要为接枝链间的偶合终止。     

PP粉表面固相接枝及其表征

以过氧化苯甲酰（ＢＰＯ）、过氧化二异丙苯（ＤＣＰ）为引发剂,用固相接枝法在聚丙烯（ＰＰ）粉表面接枝马来酸酐（ＭＡＨ）。研究了引发剂浓度、单体浓度、反应温度及时间等因素对接枝率的影响,并采用Ｘ射线光电子能谱（ＸＰＳ）与广角Ｘ射线衍射（ＷＡＸＤ）对ＭＡＨ－ｇ－ＰＰ的接枝效果和晶态结构进行了表征。     

聚丙烯悬浮法接枝HEMA的研究

研究了聚丙烯悬浮法接枝丙基丙烯酸β－羟乙酯（ＨＥＭＡ），考察了反应温度，反应时间，ＨＥＭＡ及过氧化苯甲酰（ＢＰＯ）的浓度对ＨＥＭＡ接枝率的影响，同时，用红外光谱，扫描电镜对接枝物进行了定性表征。     

乙烯基三乙氧基硅烷原位乳液接枝丁苯橡胶的制备及性能

采用原位乳液接枝法,制备乙烯基三乙氧基硅烷(VTES)接枝的丁苯橡胶。分别用凝胶含量和红外光谱(FTIR)研究了接枝产物的形成机理。考察了VTES的接枝效率和橡胶中的硅含量,并比较了接枝产物机械性能和热性能的变化。结果表明,VTES的接枝效率高达87%,接枝丁苯橡胶的拉伸强度提高了30.3%,耐热温度提高了5.16℃左右。