海藻酸钠/PDMS互穿聚合物网络体系的制备及其对提高纸张阻隔性能的研究

Paper products made of cellulose fibers are widely used in packaging industry. Paper is a porous and hydrophilic medium. As the result, paper can hardly meet the demand of high barrier properties of the packaging materials which are especially for water and oil repellent properties. It is necessary to develop new biodegradable and multi-functional products with high barrier properties because the conventional treatments have limitations including the high energy consuming, low efficiency, non-biodegradable and unhealthy for people and the environments, etc. .Interpenetrating polymer networks (IPNS) including biodegradable sodium alginate and hydroxyl-terminated polydimethylsiloxane (PDMS) are prepared and applied in the surface treatment of paper to enhance the barrier properties of paper products in this application. The preparation techniques, stability and the influencing factors of IPNS, as well as the effects of the water and oil barrier properties of the paper with IPNS treatment will be investigated. In detail, the arrangement of SA-PDMS system on the paper surface, the water or oil resistant efficiency, water vapor transmission rate and oil penetration will be discussed in this work. Moreover, the LCSM will be used to characterize the spreading and penetration of the dyed oil on the surface and inside of the treated paper, in order to investigate the mechanisms for the barrier effects on SA-PDMS treated paper products. In the long run, it is hoped that this work could provide clues for the further study on developing new paper-based environmentally-friendly packaging materials.

由纤维素纤维为原材料抄造而成的纸张具有亲水性、多孔性结构, 对液体有良好渗透性，难以满足高阻隔性包装材料的需求。提高阻隔性能的传统处理方法存在能耗过高、难降解及对人与环境不安全等局限性。因此，发展新型可降解、对环境友好并赋予纸张抗水抗油等阻隔性能的食品包装材料十分必要。.本研究拟以可降解天然产物海藻酸钠和羟基封端的聚二甲基硅氧烷PDMS为主要材料，制备互穿网络聚合物体系SA-PDMS并将其作用于纸张表面。通过对SA-PDMS制备方法、影响因素和结构的研究，制备出稳定的互穿网络聚合物体系。将SA-PDMS作用于纸张表面，通过对SA-PDMS膜表面抵抗水滴油滴的能力和SA-PDMS处理后纸张的水蒸气透过率（WVTR）、油脂渗透率等的研究，验证SA-PDMS对植物纤维材料的阻隔性能。利用染色油脂在纸张涂层表面的铺展渗透以及在涂层内部、纸张内部纤维间的渗透等方式研究SA-PDMS涂层的抗水抗油机制

天然纤维素是自然界非常丰富的资源，可降解，可再生，环境友好，然而作为纸制品主要原料，由于其自身的亲水性特质，存在低阻隔性的缺点，需要对纸张性能做一些改进。.本项目合成的互穿网络聚合物（IPN），同时具备可降解天然产物海藻酸钠-氯化钙和羟基封端的聚二甲基硅氧烷PDMS-正硅酸甲酯TMOS 水解体系两个独立的体系，制备互穿网络聚合物体系（简称SA-PDMS IPN）并将其作用于纸张表面处理，同时能满足纸张抗水性能与抗油性能。通过对IPN制备方法、影响因素和结构的研究，制备出稳定的互穿网络聚合物体系。主要研究了SA-PDMS IPN的制备及条件调控，并将SA-PDMS IPN作用于纸张表面，研究处理后纸张的水蒸气透过率（WVTR）、油脂渗透等，验证SA-PDMS IPN对植物纤维材料的阻隔性能。在研过程也制备了一种半互穿网络体系（SA-PDMS semi-IPN），其与SA-PDMS IPN的异同是，都保留了抗水体系PDMS-TMOS 水解体系，抗油体系单独采用海藻酸钠SA。.结果发现（1）在制备PDMS-TMOS水解体系时，采用DBTL催化体系优于NaOH催化体系效果，NaOH催化体系下，产物在pH为7.2时接触角最高，可达近100°；DBTL催化体系下，显示接触角超过100°，而且经过60s测试的时间，几乎没有变化，显示很好的抗水性，且TMOS:DBTL=1:0.02（摩尔比）时接触角最佳。（2）SEM扫描结果显示SA-PDMSIPN具备规律的蜂窝状结构，且在结构内具有颗粒状物质。（3）IPN涂布后滤纸测水蒸气透过率结果显示，在50%RH，23℃测试条件下，与未涂布纸张相比降低了86%；在90%RH，35.8℃条件下，与未涂布纸张相比降低了78%，取得了很好的水蒸气阻隔性能。IPN涂在纸张抗油性能，测得KIT No.最高可达9级。且IPN涂布纸张的水接触角达到了120°。（4）对SA-PDMS semi-IPN体系，处理纸张的KIT抗油实验结果显示最佳抗油级别可达10级。在RH90%，35℃和RH50%，23℃测试条件下，WVTR相比未经涂布的纸张，可分别降低72%和63%，显示了低WVTR值或高水蒸气阻隔能力，且处理后纸张水接触角超过110°。目前制备的SA-PDMS IPN与semi-IPN体系,其涂布纸张均具有很好的抗水抗油效果且无毒，绿绿色环保,很有应用前景。