Full
XIE Qingbin (2001-), female, Master candidate. E-mail: qbin_xie@163.com
Outline
Low-density polyethylene (LDPE) is limited in its high-end applications due to insufficient mechanical and thermal properties. Using silicate minerals as fillers is an effective strategy, as they possess high modulus, thermal stability, and abundance. Anorthite (An), as a framework silicate mineral, is a highly promising candidate material. However, its hydrophilic surface is incompatible with the hydrophobic LDPE, thus hindering the performance. Silane coupling agent (i.e., KH570) can improve interfacial bonding, but its role in the An/LDPE system remains unclear. In this study, the effect of KH570-modified An on the LDPE performance was investigated, offering some insights into the development of high-performance LDPE composites and the efficient utilization of An resources.
The silane coupling agent KH570 was used to modify An. KH570 was hydrolyzed in an ethanol-water solution (7∶3 v/v) and reacted with An at 80 ℃ for 6 h. After centrifugation, washing, and drying, modified anorthite (K-An) was obtained. K-An/LDPE composites (in a mass ratio of 95 ∶ 5) were fabricated via melt blending with a twin-screw extruder (130-180 ℃) followed by hot pressing. The modification mechanism was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The morphology and dispersion were characterized by scanning electron microscopy (SEM). The surface wettability was determined by contact angle measurement. The mechanical properties were determined by tensile testing (ISO 527-1), and the thermal stability was determined by thermogravimetric analysis/derivative thermogravimetry (TG/DTG).
KH570 effectively modifies the chemical properties of the surface of An without altering its crystal structure or morphology. The FT-IR and XPS spectra confirm the formation of covalent bonds, enhancing the hydrophobicity of the An surface and improving its dispersibility in LDPE. The mesoporous structure remains stable, and the distribution of small pores is improved, indicating a regulatory effect on the pore characteristics. The K-An/LDPE composite material exhibits excellent tensile strength, elongation, and thermal stability due to the rigidity of An, intense interfacial bonding, and thermal barrier effects, highlighting its potential as an LDPE reinforcing filler.
KH570 could react with -OH groups on the surface of An to form stable bonds, reducing surface polarity, while preserving its crystal morphology, thereby lowering the interfacial energy difference with LDPE and enhancing compatibility. As a result, K-An/LDPE composites modified with KH570 showed enhanced tensile strength, elongation at break, tensile modulus and thermal residue, which could be increased by 38.01%, 104.39%, 48.32%, and 15.05%, respectively. This was attributed to the rigidity and thermal stability of the An framework, intense interfacial bonding, and a uniform thermal barrier network.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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