Adhesion of PE modified by capacitively coupled radio frequency plasma-induced graft polymerization of glycidyl methacrylate

A graft polymerization of glycidyl methacrylate (GMA) on the pretreated polyethylene (PE) sheet samples by oxygen capacitively coupled radio frequency (RF) plasma was carried out to improve the adhesive properties of PE. The PE samples were treated with a RF power of 200W for a treatment time of 40s and then exposed to an oxygen atmosphere for a saturation time of 10min. The grafting of the plasma pretreated PE performed in an aqueous GMA solution with the monomer concentration from 20vol.% to 100vol.% at a temperature from 20°C to 90°C for a reaction period up to 50h. The optimum wettability of the graft polymerized PE surface with the concentration of 40vol.% at the temperature of 70°C and for the time of 24h was obtained as the static contact angle decreased from 104.2° for the original PE to 67.6° for the graft polymerized. After the graft polymerization, a strong absorption peak of C―O bonding was shown at 1050cm⁻¹ in Fourier transform infrared spectrum, indicating an introduction of epoxy groups on the graft polymerized surface. Correspondingly, the surface roughness (Ra) increased from 0.137μm for the original PE to 1.660μm for the graft polymerized. The maximal lap adhesive strength of the graft polymerized PE samples lapped using a mixture of epoxy resin and curing agent was achieved to about 160N·cm⁻². The fractured surfaces by tearing of the PE sheet matrix were observed on the tensioned PE samples due to the higher adhesive strength than that of the PE matrix.     

挤淤爆破规律及其振动效应研究

为了研究挤淤爆破规律以及爆破地震波的传播特性,结合连云港连云新城示范区填海造地及基础设施建设项目的挤淤爆破工程实例,对挤淤爆破的全过程进行高速摄影录像和爆破地震波监测与分析。高速摄影再现了挤淤爆破过程中"水—淤泥—围堰"系统相互作用的运动过程,有效解释了挤淤爆破过程中预埋石料与淤泥置换的作用机理。利用实测的爆破地震波数据修正与地形地质条件有关的系数K和衰减系数α,获得了适于挤淤爆破过程中计算质点振动速度随距离衰减的Sadovsk计算公式,为有效预测类似工程中爆破地震波的传播规律特征提供了一种方法参考。挤淤爆破过程中测得的爆破地震波主振频率范围在8~50 Hz之内,说明淤泥介质对爆破地震波不同频率成分的传播具有选择性:高频地震波通过淤泥时产生大幅度的衰减,低频地震波通过淤泥后对建(构)筑物造成破坏。