Wu Bo, Zheng Xian, Ren Yanwei, Yu Hailong, Leng Haiqiang, Wang Yubo, Jiang Huanfeng
School of Chemistry and Chemical Engineering, South China University of Technology 381 Wushan Road Guangzhou 510641 China
Guangdong Winner New Materials Technology Co., Ltd. Foshan 528521 China.
RSC Adv. 2024 Apr 10;14(16):11584-11593. doi: 10.1039/d3ra08484a. eCollection 2024 Apr 3.
It is challenging to naturally produce large amounts of β-crystals by directly adding a commercial β-nucleating agent (β-NA) into polypropylene random copolymer (PPR) at present. In this work, a novel rare earth β-NA WBN-28 was directly introduced into PPR to prepare β-PPR with high β-crystal conversion. The results of differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) indicated that it is an efficient β-NA for PPR. The β-conversion rate (β-CR) could surpass 85% when the nucleating agent content was mere 0.05%. With the further increment of nucleating agent, the β-CR increased gradually, which could reach 89.5% and 86.9% respectively calculated by DSC and WAXD when the addition amount was 0.4%. The incredible high β-CR delayed the βα-recrystallization in isothermal crystallization. The fusion peak of α-crystal was unobserved below the isothermal crystallization temperature of 122 °C when the addition amount was more than 0.2%. Furthermore, there was a highly ordered structure in WBN-28 with the periodicity of 12.89 Å, which was approximately twice of the unit cell parameter in the direction of β-PP, indicating a high lattice matching rate between them. Intuitively observed by polarizing optical microscope (POM), the crystal grains of the blends with β-NA were more refined and finally crystallized in a plate-like shape. The forming process of the plate-like β crystalline regions were proposed by scanning electron microscope (SEM) and POM.
目前，通过直接向聚丙烯无规共聚物（PPR）中添加商业β成核剂（β-NA）来大量自然生成β晶体具有挑战性。在这项工作中，一种新型稀土β-NA WBN-28被直接引入PPR中以制备具有高β晶体转化率的β-PPR。差示扫描量热法（DSC）和广角X射线衍射（WAXD）结果表明，它是一种用于PPR的高效β-NA。当成核剂含量仅为0.05%时，β转化率（β-CR）可超过85%。随着成核剂的进一步增加，β-CR逐渐增加，当添加量为0.4%时，通过DSC和WAXD计算的β-CR分别可达89.5%和86.9%。令人难以置信的高β-CR延迟了等温结晶过程中的βα重结晶。当添加量超过0.2%时，在122℃的等温结晶温度以下未观察到α晶体的熔融峰。此外，WBN-28中存在高度有序的结构，其周期为12.89 Å，约为β-PP 方向晶胞参数的两倍，表明它们之间具有高晶格匹配率。通过偏光显微镜（POM）直观观察到，含有β-NA的共混物的晶粒更细化，最终结晶成板状。通过扫描电子显微镜（SEM）和POM提出了板状β晶区的形成过程。
