Polypropylene (PP) composites with cellulose nanofibril (CNF), lignocellulose nanofibril (LCNF) or bleached kraft wood pulp (BWKP) cellulose microfibril compatibilized by maleic anhydride grafted polypropylene were produced by different approaches. Samples containing 10–30 wt% filler were prepared by mixing cellulose aqueous suspensions and PP through solid‐state shear pulverization. The flakes obtained were compounded by twin‐screw melt extrusion (MSE) followed by injection molding (IM) into standard specimens. Reference samples with 30 wt% CNF or LCNF were prepared through a standard procedure, which involved freeze‐drying of nanofibrils aqueous suspensions before MSE and IM, whereas a sample with 30 wt% BWKP was prepared directly by MSE and IM. Injection‐molded specimens were characterized by scanning electron microscopy, differential scanning calorimetry, thermogravimetry, and tensile and notched impact tests. The thermal behavior of the PP matrix in the composites was not significantly affected by the filler type and content and processing route as well. CNF and LCNF reinforced PP composites showed inferior mechanical properties, due to the formation of nanofibrils agglomerates in the PP matrix, regardless of the processing route adopted. Highly filled (30 wt%) BWKP composites presented superior mechanical properties with significant increase in the modulus, tensile strength, and impact strength due to the formation of well‐dispersed microfibrils bundles in the PP matrix. A comparative analysis showed that the composites developed in this study present similar or even superior mechanical performance for given filler content to other natural fiber reinforced PP composites reported in the literature.

中文翻译：

---

固态剪切粉碎处理的纤维素纳米/微原纤增强聚丙烯复合材料的表征

用不同的方法制备了由马来酸酐接枝聚丙烯增容的纤维素纳米原纤维（CNF），木质纤维素纳米原纤维（LCNF）或漂白牛皮纸浆（BWKP）纤维素微原纤维制成的聚丙烯（PP）复合材料。通过固态剪切粉碎将纤维素水悬浮液和PP混合，可以制备出含10–30 wt％填料的样品。将获得的薄片通过双螺杆熔融挤出（MSE）进行复合，然后注塑（IM）成为标准样品。通过标准程序制备具有30 wt％CNF或LCNF的参考样品，该方法涉及在MSE和IM前冷冻干燥纳米原纤维的水悬浮液，而由MSE和IM直接制备具有30 wt％BWKP的样品。通过扫描电子显微镜对注塑成型的样品进行表征，差示扫描量热法，热重法以及拉伸和缺口冲击试验。复合材料中PP基体的热行为也不受填料类型，含量和加工路线的显着影响。CNF和LCNF增强的PP复合材料显示出较差的机械性能，这是由于PP基体中形成了纳米原纤维团聚物，而与所采用的加工方法无关。高填充（30 wt％）的BWKP复合材料具有优异的机械性能，并且由于在PP基体中形成了分散良好的微纤维束，模量，拉伸强度和冲击强度显着提高。