Abstract

Objective In deep-sea and polar resource extraction， cementing materials are frequently subjected to extreme environmental conditions， including low temperatures， high hydrostatic pressures， and repeated low-amplitude dynamic loads. These harsh conditions significantly compromise the mechanical integrity of conventional cement systems， particularly in terms of toughness. Toughness， the capacity of a material to absorb energy and deform plastically without fracturing， is a critical mechanical property for maintaining wellbore integrity over long service periods. Cement sheaths with low toughness are highly susceptible to cracking， especially under abrupt stress fluctuations or impact loading， potentially leading to fluid migration， well leakage， or structural failure. Therefore， improving the toughness of cement under such extreme conditions is an urgent and essential goal. This study aims to explore a novel toughening approach by incorporating physically modified polyvinylidene fluoride （PVDF） powder into cement paste and investigating its effects on mechanical performance， particularly toughness， under low-temperature conditions.

Methods To address this issue， we employed low-temperature plasma treatment to physically modify PVDF powder， producing a material referred to as PVDF-G. This modification process alters the physical characteristics of the PVDF particles， specifically reducing their size and increasing their surface roughness， without introducing any new chemical functional groups. The treatment is intended to enhance the interfacial compatibility between PVDF and the cement matrix by improving the physical anchoring and distribution of the particles. Modified PVDF-G and unmodified PVDF powders were separately added to cement paste at identical dosages. A blank control group without any additives was also prepared for comparison. All specimens were cured at 4 ℃ to simulate polar or deep-sea conditions. Mechanical tests， including uniaxial tensile strength and dynamic impact energy absorption， were conducted to assess the effectiveness of the modification. Particular attention was given to evaluating how the surface morphology and particle size of PVDF influence the toughening performance of the resulting cement composites.

Results and Discussion The results demonstrate a pronounced improvement in the mechanical performance of the cement paste incorporating PVDF-G compared to both the unmodified PVDF group and the blank control. Under low-temperature curing conditions， the cement specimens containing PVDF-G exhibited a maximum tensile strength of 4.31 MPa， which was significantly higher than that of the other two groups. Furthermore， impact resistance was substantially enhanced. Under impact loading， the PVDF-G-modified cement specimens showed an outstanding energy absorption capacity. Within just 0.1 milliseconds of impact duration， the PVDF-G group absorbed approximately 1.5 times more energy than the blank control and twice as much as the unmodified PVDF group. These findings indicate that PVDF-G markedly improves the toughness of cement composites under cold conditions.

Conclusion This study confirms that low-temperature plasma treatment is an effective physical modification technique for enhancing the performance of PVDF powders used in cement-based materials. The improved properties of PVDF-G-including reduced particle size and increased surface roughness-significantly enhance its physical bonding with the cement matrix， leading to higher tensile strength and markedly improved impact resistance under low-temperature conditions. Importantly， these improvements were achieved without introducing new chemical functionalities， highlighting the role of physical interfacial engineering in toughening brittle cement systems. The findings suggest that PVDF-G is a promising additive for developing advanced cement composites suitable for deployment in extreme environments such as deep-sea wells， polar drilling operations， and infrastructure construction in sub-zero climates. This work provides both a theoretical foundation and a practical strategy for improving the durability and reliability of cementitious materials in demanding applications.

Keywords： PVDF powder； low-temperature plasma modification； oil well cement； toughening

Get Citation: MEI Kaiyuan， AN Ran， HUANG Kun， et al. Effect of low-temperature plasma-modified PVDF powder on impact toughness of oil well cement at low temperatures［J］. China Powder Science and Technology， 2026， 32（3）： 1-14.

Received: 2025-03-28 .Revised:2025-07-24,Online: 2025-10-14.

Funding Project:国家自然科学基金项目，编号：42207206。

First Author: 梅开元（1993―），男，副研究员，硕士生导师，研究方向为固井水泥基材料。E-mail： mky0101@swpu.wdu.cn。

DOI：10.13732/j.issn.1008-5548.2026.03.009

CLC No:TE256.5；TB4                            Type Code: A

Serial No:1008-5548（2026）03-0001-14