Influence of Curing Condition on the Adhesive Strength of EVA Modified Mortar to Tile

The reducing water effectiveness of EVA latex and powder was observed. Adhesive strength of EVA modified mortar to tile under different curing condition was studied. And the adhesive strengths of mortars modified by EVA latex and by EVA powder were compared. The results show that the reducing water effectiveness is improved by 36.12% and 21.55%, respectively, when the content of EVA latex and powder are 8% and 4%. EVA latex and powder can improve the adhesive strength of modified mortar to tile under the standard curing, high temperature curing, and freeze-thaw circle curing.EVA latex can improve the water resistance obviously, besides improve the adhesive strengths of standard curing and high temperature curing, comparing with EVA powder.

Effect of Different Organic Modifiers on the Tensile Properties of PVC/EVA/Montmorillonite Composites

Poly (vinyl chloride)/ethylene-vinyl acetate/montmorillonite (PVC/EVA/OMMT) composites were prepared by melt blending method. Two kinds of montmorillonites were organically modified by trimethyloctadecyl ammonium and dimethyl bis (hydrogenated tallow) ammonium, respectively. The morphology and tensile properties of the resultant composites were discussed in terms of the modifier type and OMMT content. The PVC/EVA/OMMT composites have intercalated structure, which is independent of the polarity of the modifiers, while the tensile properties show strong dependence on the modifier type. The OMMT modified by polar modifier gives higher tensile ductile and strength of PVC/EVA/OMMT composites.

EVA改性EPS混凝土微观结构及性能研究

为了改善聚苯乙烯(EPS)轻集料混凝土中EPS颗粒与水泥砂浆界面的黏结性能,提高EPS轻集料混凝土的力学性能,采用乙烯-醋酸乙烯酯(EVA)乳液对EPS颗粒表面进行改性,并对改性前后EPS轻集料混凝土的力学性能作了对比试验,结合扫描电镜、X射线衍射和红外光谱,分析了EVA乳液对EPS轻集料混凝土性能的影响机理.结果表明:EVA改性改善了EPS轻集料混凝土的微观结构,使其内部孔洞数量减少,孔洞尺寸趋于减小;使水泥水化更为充分,水化产物组成得以优化,EPS轻集料混凝土的180 d抗压强度和抗折强度得到提高.

EVA改性砂浆早龄期收缩应力/应变规律

采用自行设计的试验装置对可再分散醋酸乙烯-乙烯共聚物乳胶粉改性水泥砂浆(EVA改性砂浆)早龄期收缩应力/应变变化规律进行了初步研究,用X射线衍射对其水化产物钙矾石(AFt)、氢氧化钙(CH)和水化铝酸钙(C_4AH_(13))进行了表征,分析了收缩应力、应变变化与EVA掺量(质量分数)、水化产物的关系.结果表明:EVA可使改性砂浆早龄期收缩应力的增长速率变缓、最大收缩应变减小,且EVA掺量为15%时效果最明显;EVA既能抑制C_4AH_(13)的生成和转化,也能抑制AFt和CH的生成,并延缓水泥砂浆水化进程;在水化3h内,EVA改性砂浆的收缩应力变化只受AFt生成量的影响,而其收缩应变变化同时受CH和AFt生成量的影响,且与CH的相关性更大.

EVA改性丙纶的流变性能

报道了用EVA对丙纶物理改性的实验研究,论述了这种改性丙纶的流变性能。由于引入极性基团,破坏了丙纶的高规整性导致的高度结晶,并且通过部分溶出改性剂生成微孔,从而大大改善了丙纶纤维的吸湿性能和导电性能。共混体系的粘度对温度和压力都有明显的依赖性,改性剂EVA的加入量不同影响了共混体系的粘度,在纺丝过程中值得注意。

改性乙烯醋酸乙烯酯共聚物对水泥浆性能的影响

针对水泥环脆性较高,在固井后的施工作业中其完整性易遭受破坏的问题,将用太古油改性的EVA(乙烯醋酸乙烯酯共聚物)作为增韧材料加入油井水泥中,研究了其对油井水泥浆体系常规性能和力学性能的影响,分析了其对水泥石力学特性的影响机理。结果表明,改性EVA与水泥浆的相容性较好,其对浆体的流动性、失水量影响较小,水泥浆稠化时间随改性EVA掺量增加而延长;改性EVA对水泥石抗压强度影响较小,但能提高水泥石的抗折强度和韧性,当改性EVA加量为3%时,水泥石75℃养护3 d的抗折强度提高4.4%,压折比减小28.0%,掺量为4%时,水泥石弹性模量降低39.5%。改性EVA水解产物和水泥水化产物相结合,生成的晶体和脱水聚合物使水泥石内部结构更加致密,减小或消除了水泥石内应力集中,阻止了裂缝扩展,改善了水泥石的力学特性。

改性PVC热熔胶的制备与性能

采用PVC-U缠绕管相同的原料PVC为基料,加入EVA、TPU、CPE、PET、石油树脂对其进行改性研究,制备了PVC改性环保型热熔胶。探索材料种类与用量对热熔胶性能与形态的影响规律。当PVC/TPU/PET/C5石油树脂四混体系中,PET:C5石油树脂为4:6时得到的产品综合性能最好,拉伸强度13.44MPa,断裂伸长率365%,剪切强度4.25MPa。

孕二烯酮宫内节育器的研制

目的:采用乙烯-醋酸乙烯共聚物(EVA)改性的甲基乙烯基聚硅氧烷(硅橡胶)作为控释材料制备孕二烯酮宫内节育器(Ges-IUD)。方法:以十八烷基键合硅胶为填充剂,甲醇:水(65:35)为流动相,流速为1ml/min,检测波长为240nm,采用高效液相(HPLC)分析法进行体外药物释放试验及测定药物在控释膜中的通透率。结果:本品药物释放符合零级动力学,其释药速度与释药管管壁厚度的倒数成线性关系,表明本品释药过程符合膜控制释药的特性。结论:体积分数20%的EVA改性硅橡胶可制备缓释放Ges的IUD。