• Laser surface induced roughening of polymeric materials and the effects on Wettability characteristics

      Waugh, David G.; Lawrence, Jonathan; Shukla, Pratik; University of Chester (2015-01-15)
      It has been thoroughly demonstrated previously that lasers hold the ability to modulate surface properties of polymers with the result being utilization of such lasers in both research and industry. With increased applications of wettability techniques within industries there is greater need of predicting related characteristics, post laser processing, since such work evaluates the effectiveness of these surface treatments. This paper details the use of a Synrad CO2 laser marking system to surface roughen polymeric materials, namely: nylon 6,6; nylon 12, polytetrafluoroethylene (PTFE) and polyethylene (PE). These laser-modified surfaces have been analyzed using 3D surface profilometry to ascertain the surface roughness with the wettability characteristics obtained using a wettability goniometer. From the surface roughness results, for each of the samples, generic wettability characteristics arising from laser surface roughening is discussed.
    • Laser Surface Treatment of a Polymeric Biomaterial: Wettability Characteristics and Osteoblast Cell Response Modulation

      Waugh, David G.; Lawrence, Jonathan; University of Chester (Old City Publishing, 2014)
      Biotechnology has the potential to improve people's quality of life and holds the key to-many unmet clinical needs. In the UK alone the biotechnology market is worth £4.5 billion and estimates of future growth ranks from 10 to 15%. This growth can only be driven by the increased use of inexpensive and easy to manufacture polymeric biomaterials. Although polymer science is a rapidly developing area of research, it remains that one of the most intractable problems encountered in biotechnology is that the performance of polymeric biomaterials depends both upon the bulk and surface properties. In this book the authors describe Their work using lasers to modify the wettability characteristics of nylon 6,6 (as wetting often is the primary factor dictating the adhesion and bonding potential of materials) as a route to enhancing the area in terms of in vitro osteoblast cell response. What is more, modifying wettability characteristics in this way is shown to be a highly attractive means of estimating the biofunctionality of a polymer. The book demonstrates and explains how the generation of a biomimetic polymers and is surface using laser beams provides an in vitro platform on which to deposit and grow cells for either the development of implants or to reconstitute functional tissue. The correlative trends and generic characteristics which are identified are in the book between the laser treatment, wettability characteristics and osteoblast cell response of the nylon 6,6 provide a means to estimate the osteoblast cell response in vivo. The book shows clearly that laser surface modification of polymeric materials has tremendous potential for application within the field of regenerative medicine.
    • Modifications of surface properties of beta Ti by laser gas diffusion nitriding

      Ng, Chi-Ho; Lawrence, Jonathan; Waugh, David G.; Chan, Chi-Wai; Man, Hau-Chung; University of Chester (Laser Institute of America, 2015-10)
      β -type Ti-alloy is a promising biomedical implant material as it has a low Young’s modulus but is also known to have inferior surface hardness. Various surface treatments can be applied to enhance the surface hardness. Physical vapour deposition (PVD) and chemical vapour deposition (CVD) are two examples of this but these techniques have limitations such as poor interfacial adhesion and high distortion. Laser surface treatment is a relatively new surface modification method to enhance the surface hardness but its application is still not accepted by the industry. The major problem of this process involves surface melting which results in higher surface roughness after the laser surface treatment. This paper will report the results achieved by a 100 W CW fiber laser for laser surface treatment without the surface being melted. Laser processing parameters were carefully selected so that the surface could be treated without surface melting and thus the surface finish of the component could be maintained. The surface and microstructural characteristics of the treated samples were examined using X-ray diffractometry (XRD), optical microscopy (OM), 3-D surface profile & contact angle measurements and nano-indentation test.
    • Modulating the wettability characteristics and bioactivity of polymeric materials using laser surface treatment

      Waugh, David G.; Lawrence, Jonathan; Shukla, Pratik; University of Chester (Laser Institute of America, 2015-10)
      It has been thoroughly demonstrated previously that lasers hold the ability to modulate surface properties of materials with the result being utilization of such lasers in both research and industry. What is more, these laser surface treatments have been shown to affect the adhesion characteristics and bio-functionality of those materials. This paper details the use of a Synrad CO2 laser marking system to surface treat nylon 6,6 and polytetrafluoroethylene (PTFE). The laser-modified surfaces were analyzed using 3D surface profilometry to ascertain an increase in surface roughness when compared to the as-received samples. The wettability characteristics were determined using the sessile drop method and showed variations in contact angle for both the nylon 6,6 and PTFE. For the PTFE it was shown that the laser surface treatment gave rise to a more hydrophobic surface with contact angles of up to 150° being achieved. For the nylon 6,6, it was observed that the contact angle was modulated approximately ±10° for different samples which could be attributed to a likely mixed state wetting regime. The effects of the laser surface treatment on osteoblast cell and stem cell growth is discussed showing an overall enhancement of biomimetic properties, especially for the nylon 6,6. This work investigates the potential governing parameters which drives the wettability/adhesion characteristics and bioactivity of the laser surface treated polymeric materials.