纤维素/全硫化弹性纳米粒子复合膜的制备与性能

Preparation and Properties of Cellulose/Full-vulcanized Elastomeric Nanoparticles Composite Films

利用碱脲溶剂低温溶解纤维素,在该体系中掺杂一定比例的全硫化羧基丁苯弹性纳米粒子,制备了纤维素/全硫化弹性纳米粒子复合膜.通过透射电镜、扫描电镜、WAXD、固体核磁共振、热分析和力学性能测试等对该复合膜的结构和性能进行了表征.结果表明,全硫化羧基丁苯弹性纳米粒子(CSB ENP)均匀的分散在具有微纳孔洞结构的纤维素基体中.CSB ENP的引入对纤维素再生过程中的结晶性影响不大.纤维素/全硫化弹性纳米粒子复合膜具有良好的透光性,并且热稳定性也有所提高.加入少量的CSB ENP可以增韧纤维素膜,且能保持良好的力学性能.当CSB ENP的含量为5 wt%时复合膜的断裂拉伸强度和断裂伸长率同时得到了提高.

Based on the dissolution of cellulose in aqueous LiOH/urea solvent system at low temperature, a series of cellulose/full-vulcanized carboxylic styrene-butadiene elastomeric nanoparticles （CSB ENP） composite films were successfully prepared for the first time. A certain amount of CSB ENP was introduced by blending the latex with the aqueous LiOH/urea solvent prior to dissolving of native cellulose. Cellulose/CSB ENP composite films with CSB ENP content of 2 wt% - 20 wt% were prepared from the resulting cellulose/CSB ENP complex solutions by coagulating with 5 wt% H2SO4/10 wt% Na2SO4 aqueous solution. Their structure and properties were investigated by TEM, SEM, X-ray diffraction, solid-state NMR, thermogravimetry and tensile testing. The TEM and SEM results indicated that the CSB ENPs with particle size of 50 - 200 nm were embedded uniformly in the matrix of regenerated cellulose film, which possessed homogeneous micro/nanoporous structure. The results from WAXD and solid-state NMR demonstrated that the crystallinity of regenerated cellulose was barely affected by the addition ofCSB ENP and there was no chemical reaction between cellulose and CSB ENP. The cellulose/CSB ENP composite films exhibited a good optical transmittance, suggesting certain miscibility of the two components. The thermal stability of the composite films was improved to some extent compared with that of the pure regenerated cellulose film. The tensile testing results showed that low content of CSB ENP could toughen the regenerated cellulose films probably due to the fact that the highly cross-linking structure of CSB ENP prevented entanglement between the rubber particles. And thus the CSB ENP with a characteristic of small particle size and large specific surface area could disperse in the cellulose matrix in nano scale. Moreover, there existed intermolecular hydrogen-bond interaction between the carboxyl groups of CSB ENP and the hydroxyl groups of cellulose. The composite film with 5 wt% of CSB ENP showed the best tensile strength and elongation at break. When the content of CSB ENP increased, the mechanical property of the composite films decreased gradually. This was possibly caused by the aggregation of excessive elastomeric nano-particles.