Fiber Surface Modification by Particle Coating

Abstract

Functionalities like anti-static, anti-bacterial, anti-odor, soil-resistance, biocompatibility etc. are function of fiber surface properties independent of characteristics of the fiber bulk. Development of processes for imparting these functionalities to the textile substrates is of prime importance.

Current research is one such effort to develop a 'single step' process to dry-coat meltblown webs with functional nano particles. Driven by the ecological and economic advantages, electrostatic spraying technique was integrated with meltblow process to impart ultraviolet shielding properties by coating titanium dioxide to the meltblown web. Various process parameters like carrying air pressure, electrostatic charging voltage, spraying distance etc. were studied to maximize the amount of particle coating for least amount of particle loss in the environment. It was found that particle loading percentage increased linearly with carrying air pressures. Final weight loading of 90-94wt% was achieved for 0.8 bars of carrying air pressures. Electrostatic charging voltage played critical role in capturing the charged particles that were not deposited on to the meltblown web. Point of spray of particles in the web was of critical importance to ensure good bonding of particles.

Motivated by the objective to control the heavy loss of particles while spraying, particle filled polymer was also spun in various bicomponent configuration. Bicomponent sheath-core, side-by-side and biconstituent web with particle filled polymer as one of the component were meltblown. Highest particle loading of 0.7wt% was achieved for the biconstituent webs.

All the samples made were characterized for ultraviolet transmission testing, mechanical properties like tensile stress and strain % at failure and bending length. Thermo gravimetric analysis and differential scanning calorimetry was also done for the bicomponent samples to study the effect of particle loading on thermal decomposition temperature and crystallinity. Samples made by electrostatic spraying showed the excellent ultraviolet protection factor while the samples made by bicomponent spinning had improved thermal stability along with ultraviolet rays blocking characteristics.