Aging of surface properties of ultra high modulus polyethylene fibers treated with He/O2 atmospheric pressure plasma jet

doi:10.1016/j.surfcoat.2007.09.043

Surface and Coatings Technology

Volume 202, Issue 12, 15 March 2008, Pages 2670-2676

https://doi.org/10.1016/j.surfcoat.2007.09.043 Get rights and content

Abstract

To investigate the relationship between aging of the treatment effect and the gas composition of atmospheric pressure plasma treatment, ultra high modulus polyethylene (UHMPE) fibers were selected as a model fiber to study the aging behavior of fiber surface treated by atmospheric pressure plasma jet (APPJ) with pure helium, helium + 1% oxygen, and helium + 2% oxygen. Atomic force microscopy showed increased surface roughness, while X-ray photoelectron spectroscopy revealed increased oxygen contents after the plasma treatments. The plasma treated fibers had lower contact angles and higher interfacial shear strengths to epoxy than those of the control fiber. Adding 1% of O₂ to helium increased effectiveness of the plasma in polymer surface modification and suppressed aging after the treatment, while adding 2% of O₂ had a negative effect on the APPJ modification results and accelerated aging. In addition, no significant difference in single fiber tensile strength was observed between the control and the plasma treated fibers.

Introduction

Plasma treatments have been used for decades in modifying the surface of polymeric materials. It is regarded as an environmentally friendly process since no chemicals are involved and also as a effective way to modify the bondability and wettability of polymer surface by introducing polar groups or increasing surface roughness without affecting the bulk properties [1], [2], [3].

Most of plasma treatments have been performed under low pressure or high vacuum which would be expensive for many products with relatively low profit margin such as textiles. Therefore, much attention has been paid to plasmas operating at atmospheric pressure due to possible advantages of eliminating an expensive vacuum system, on-line processing capabilities, high efficiency, and the scalability to a larger area [4], [5], [6]. Typical atmospheric pressure plasma systems are arc plasma torches, corona discharges and dielectric barrier discharges (DBD) [7], [8]. In recent years, an atmospheric pressure plasma jet (APPJ) is invented to produce the homogeneous plasmas at low temperature. It consists of an inner electrode, which is coupled to a 13.56 MHz radio frequency power source, and a grounded outer electrode. Typically a small fraction of reactive gases, e.g., oxygen or nitrogen is added to helium feed gas in order to generate chemically active species [9].

One of the problems that hinder the application of plasmas in surface modification of polymeric materials is potential aging of the treatment effects. After plasma treatments, the polymer surfaces show a gradual hydrophobic recovery over the time and the surface free energy simultaneously decreases to the original value [10], [11], [12], [13], [14]. It has been suggested that the hydrophobic recovery is mainly due to two mechanisms: one is the reorientation of polar chemical groups on the treated surface towards the bulk of the material, and the other is the diffusion of portions of non-modified macromolecules to the surface [15], [16], [17].

Limited number of papers has recently been published regarding the application of APPJ technology to polymer surface modification [5], [18], [19]. However, little has been reported about aging of the treatment effects of APPJ and its correlation with treatment conditions. It has been suggested that aging behavior of a fiber can be influenced by many factors among which plasma treatment gas composition could play an important role [20], [21], [22], [23]. In this study, the ultra high modulus polyethylene (UHMPE) fibers were selected as a model fiber to investigate the aging behavior of fiber surface treated by APPJ with pure helium, and helium mixed with oxygen at two levels. UHMPE fiber is a fiber with high tensile strength and modulus, low specific density but poor wettability and bondability to resins [1], [2]. The surface morphology, the adhesion between the fiber and epoxy, the surface chemical composition and the water contact angle were measured at 0, 7, 14, 21 and 40 days after the plasma treatment using atomic force microscopy, micro-bond tests, X-ray photoelectron spectroscopy and sessile drop method.

Section snippets

Materials

The UHMPE fiber tow with an average single fiber diameter of 28 μm supplied by Ningbo Dacheng Chemical Fibers Company (Zhejiang, China) was soaked in acetone for 10 min and then dried in a vacuum oven to remove residual acetone. The cleaned fiber tow was wound onto glass frames to facilitate the subsequent plasma treatment. The matrix was epoxy resin prepared with DER 311 (bisphenol-A type epoxy) and DER 732 (polyglycol di-epoxide) and the curing agent was DEH 26 all supplied by Dow Chemical.

Plasma treatment

Surface morphology

The surface average roughness (R_a) and root mean square roughness (R_ms) are shown in Table 1. After the plasma treatment, all samples showed an increased surface roughness. This is the result from the etching effect of the plasma treatments. According to the literatures [26], [27], the main species in the plasma which are responsible for the etching effect are positive ions and photons, with ability of breaking primary chemical bonds and inducing cross-linking. The samples treated with pure

Discussion

From the above results, it can be concluded that the amount of oxygen added to the carrier gas helium has a significant influence on the APPJ treatment and the aging effect.

The excited species of helium have relatively long lifetime (1 ms to 1 s) known as metastable species at a high excitation energy of 19.8 eV to 20.6 eV, while oxygen molecules have ionization potential of 13.6 eV. Therefore, when a metastable helium atom collides with an oxygen molecule, the oxygen can be ionized because its

Conclusions

In this study, UHMPE fibers were selected as a model fiber to investigate the aging behavior of fiber surface treated by APPJ with pure helium, and helium mixed with oxygen at two levels. The treated fibers showed an increase in surface roughness from the AFM images and those treated with pure helium had the largest surface roughness. During the aging, the contact angle increased while the amount of the oxygen-containing polar functional groups on the fiber surfaces and the IFSS for the treated

Acknowledgements

This study was sponsored by the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT0526) and Shanghai Pujiang Program (No. 06PJ14011). We would like to thank Ningbo Dacheng Company for providing UHMPE fibers.

References (36)

J. Behnisch et al.
Surf. Coat. Techol.
(1993)
R.A. Lawton et al.
Colloid. Surface. A
(2005)
E. Occhiello et al.
Polymer
(1992)
C.X. Wang et al.
Surf. Coat. Techol.
(2007)
Y. Ren et al.
Appl. Surf. Sci.
(2007)
U. Konig et al.
Colloids Surf., B Biointerfaces
(2002)
B.J. Carroll
J. Colloid Interface. Sci.
(1976)
G. Hancock
Surf. Coat. Technol.
(1995)
N. De Geyter
Surf. Coat. Technol.
(2007)
Y. Qiu et al.
Adv. Compos. Lett.
(2001)

Y. Qiu et al.

J. Adhes. Sci. Technol.

(2002)

Y. Qiu et al.

J. Adhes. Sci. Technol.

(2002)

Z.S. Cai et al.

J. Appl. Polym. Sci.

(2006)

L. Liu et al.

J. Appl. Polym. Sci.

(2006)

S.R. Matthews et al.

J. Appl. Polym. Sci.

(2004)

J.Y. Jeong et al.

J. Vac. Sci. Technol. A

(1999)

J.Y. Jeong et al.

Plasma Sources Sci. Technol.

(1998)

J. Park et al.

Appl. Phys. Lett.

(2000)

Cited by (102)

A tool for biomedical application: Synthesis and modification of polyhydroxyalkanoates
2023, Sustainable Chemistry and Pharmacy
In light of the many uses for different biodegradable and biocompatible polymers; polyhydroxyalkanoate (PHAs) are a kind of hydrophobic, biodegradable, and biocompatible bioplastic that can be used to create a variety of artificial implants as well as novel micro/nanoporous carriers for targeted therapy. Author concentrated on the possible uses of PHAs in biomedical disciplines like tissue engineering, wound healing, and drug delivery in the current analysis by examining how various bacteria amass PHAs using waste carbon sources. The review study also covered the extraction and purification of PHAs with regard to the molecular structure and molecular weight. Separate descriptions were given for various PHA degrading methods.
Aurora Borealis in dentistry: The applications of cold plasma in biomedicine
2022, Materials Today Bio
Citation Excerpt :
In their study, Ye et al. found that non-thermal plasma therapy caused post-surface aging. After being treated with plasma, the fiber posts were exposed to air for 1 h or more, and the bond strength improved [82]. Non-thermal plasma treatment of posts has thus shown significant advantages in terms of strength and retention.
Plasma is regularly alluded to as the fourth form of matter. Its bounty presence in nature along with its potential antibacterial properties has made it a widely utilized disinfectant in clinical sciences. Thermal plasma and non-thermal (or cold atmospheric) plasma (NTP) are two types of plasma. Atoms and heavy particles are both available at the same temperature in thermal plasma. Cold atmospheric plasma (CAP) is intended to be non-thermal since its electrons are hotter than the heavier particles at ambient temperature. Direct barrier discharge (DBD), atmospheric plasma pressure jet (APPJ), etc. methods can be used to produce plasma, however, all follow a basic concept in their generation. This review focuses on the anticipated uses of cold atmospheric plasma in dentistry, such as its effectiveness in sterilizing dental instruments by eradicating bacteria, its advantage in dental cavity decontamination over conventional methods, root canal disinfection, its effects on tooth whitening, the benefits of plasma treatment on the success of dental implant placement, and so forth. Moreover, the limitations and probable solutions has also been anticipated. These conceivable outcomes thus have proclaimed the improvement of more up-to-date gadgets, for example, the plasma needle and plasma pen, which are efficient in treating the small areas like root canal bleaching, biofilm disruption, requiring treatment in dentistry.
About the deterioration of polyethylene exposed to plasma discharges: A comparison between two models
2021, Applied Surface Science
The present work is devoted to the modelling of the deterioration process of polyethylene exposed to reactive plasma. In particular, we present the comparison between two different models. The first one, already presented in the literature, considers the $H$ -abstractions due to the $OH \cdot$ and $O \cdot$ radicals, and some successive reactions, involving mainly other gaseous species. The second model, in addition to the first model reactions, is enriched by including the effects (both $H$ -abstractions and chemisorptions) due to the collisions of a series of plasma ions with the surface. These collisions have been reproduced by ab initio molecular dynamics simulations. The performance of both models has been tested by implementing them in a code for simulation of surface chemical reactions induced by a plasma discharge. The related results are then compared with some experimental data.
The first model is able to well reproduce the experimentally detected oxidation of the polyethylene surface exposed to plasma discharges. The second model, including also the decisive effects of the $NO \cdot$ radical on an already oxidized surface, is able to explain the presence of nitrogen on the sample surface.
Hydrophobic functionalization of cellulosic substrate by tetrafluoroethane dielectric barrier discharge plasma at atmospheric pressure
2021, Carbohydrate Polymers
Hydrophobic functionalization of cellulosic fabric (viscose) was carried out using helium/tetrafluoroethane (He/TFE) plasma, a commercially available fluorocarbon gas, at the atmospheric pressure. By selecting suitable plasma parameters, He/TFE plasma was produced and maintained in glow state so that the various fragments of TFE in plasma zone could react covalently with the cellulose. After the plasma treatment, the highly hydrophilic cellulosic fabric turned into superhydrophobic fabric with a water absorbency time of >> 60 min, a water contact angle of 153° and a water rolling angle of 5°. The functionalization was found to be wash durable to 25 laundry cycles. From the analyses of species present in plasma zone by optical emission spectroscopy (OES), gas-chromatography-mass spectrometry (GC–MS), and the chemical nature of the functionalized substrate by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS), a possible mechanism involved in the reaction of TFE fragments with cellulose macromolecule was arrived at. Further, it could be inferred that the modification took place only at the surface of the fibres at the nanometre level. The study postulates that it is possible to elucidate reactions undergoing in plasma zone and to control them to achieve desirable modification of substrates.
Tailoring surface properties of polyethylene terephthalate by atmospheric pressure plasma jet for grafting biomaterials
2020, Thin Solid Films
Tailoring surface hydrophilicity on polyethylene terephthalate (PET) by a radio frequency (RF) atmospheric pressure plasma jet (APPJ) for grafting biomaterials was investigated in this study. Two thermally responsive biomaterials of hydrophilic non-ionic surfactant of polyoxyethylene polymer and hydroxypropyl cellulose were used, while hydroxyethylmethacrylate (HEMA) was applied as the carrier for drug release. As applying the RF power in an APPJ system, PET substrates represented a tendency from an originally hydrophobic surface to a hydrophilic one, while apparent damaged areas were observed as the RF power exceeded 200 W. APPJ-induced polar functional groups onto PET surface without serious etching were most likely to improve the surface hydrophilicity for further grafting biomaterials. The grafted polyoxyethylene polymer on APPJ-treated PET substrates exhibited a surface change from opaque into transparent as the ambient temperature exceeded lower critical solution temperature of 37°C, while hydroxypropyl cellulose displayed a change from transparent into milky white as the temperature over 55°C. For the drug release behavior of aspirin on APPJ-treated PET substrates, the cumulative release rate of aspirin entrapped substrate for 3 h was 22%. Our results suggest that tailoring surface hydrophilicity of PET substrates without surface etching by 100W-APPJ process possessed a higher surface energy with a higher polar interaction, resulting in a good bonding with the grafted biomaterials.
Mechanism of oxygen and argon low pressure plasma etching on polyethylene (UHMWPE)
2019, Surface and Coatings Technology
Different preferential sites for etching are observed for low pressure argon and oxygen plasma on ultra-high molecular weight polyethylene. Atomic force microscopy analysis showed an organized pattern after 1 min of oxygen plasma treatment. Roughness decreases after 3 min and then after 5 min increases again, when surface is completely damaged. A different etching pattern is observed after argon plasma treatment, where nanometric pits are formed with size increasing with treatment time. Infrared spectroscopy shows that, by analyzing the relative intensity of the different peaks, the different etching mechanisms are explained where oxygen plasma reduces coupling between parallel chains in the crystalline short axis direction and argon plasma suppresses hydrogen and induces surface reorientation of functional groups.

View all citing articles on Scopus

View full text

Aging of surface properties of ultra high modulus polyethylene fibers treated with He/O2 atmospheric pressure plasma jet

Abstract

Introduction

Section snippets

Materials

Plasma treatment

Surface morphology

Discussion

Conclusions

Acknowledgements

Surf. Coat. Techol.

Colloid. Surface. A

Polymer

Surf. Coat. Techol.

Appl. Surf. Sci.

Colloids Surf., B Biointerfaces

J. Colloid Interface. Sci.

Surf. Coat. Technol.

Surf. Coat. Technol.

Adv. Compos. Lett.

J. Adhes. Sci. Technol.

J. Adhes. Sci. Technol.

J. Appl. Polym. Sci.

J. Appl. Polym. Sci.

J. Appl. Polym. Sci.

J. Vac. Sci. Technol. A

Plasma Sources Sci. Technol.

Appl. Phys. Lett.

Aging of surface properties of ultra high modulus polyethylene fibers treated with He/O₂ atmospheric pressure plasma jet