Mechanical and thermal properties of uv curable polyurethane acrylate composite coatings

Abstract

ABSTRACT

UV curable coating formulation comprises urethane acrylate resin and nanosilica as filler were synthesized to develop UV curable inorganic organic hybrid composite (PUA). The surface of the nanosilica was chemically modified to improve its chemical interaction within the urethane acrylate matrix. The modification had been undertaken by applying vinyltrymetoxysilane (VTMOS) that acted as a coupling agent to produce organophilic silica shell (SIMA). The shell is linked to the silica via reaction with the surface silanol group of the silica. The disappearance of metoxy groups in VTMOS was demonstrated by FTIR spectrum. The percentage of silica particles in UV curable hybrid formulation were varied on 5%, 10%, 15%, 20% and 25wt% respectively. In this work, the formulation was applied on medium density fiber board (MDF) substrate and subsequent has been irradiated under UV light. Then, the coated MDF were characterized by several testing equipments (TGA, DSC, scratch tester, instron, SEM). From the result, we found that the addition of silica nanoparticles exhibit significant improvement in coating film properties as compared to film without silica nanoparticle includes significant improvement in its modulus and scratch resistance. This make them as promising coating candidate for MDF product.  On the other hand, we also found that an increase of silica particle up to 25 wt%, the viscosity has increased rapidly indicates that it is not suitable for acrylate coating formulation due to disappearance of desired effect known as tixotrophy.

ABSTRAK

Resin uretana akrilat telah disintesis bersama pengisi silika bagi menghasilkan salutan hibrid organik- inorganic (PUA)  dengan menggunakan teknik pematangan sinaran Ultra Lembayung (UV). Permukaan pengisi silika dimodifikasi secara kimia bagi meningkatkan interaksi kimia  diantara matrik uretana akrilat dan partikel silika. Proses modifikasi dilakukan dengan menggunakan viniltrimetoksisilana (VTMOS) sebagai agen pengkupel bagi menghasilkan kerangka  silika organofilik (SIMA). Kerangka SIMA terbentuk dari tindakbalas kumpulan silanol yang terdapat dipermukaan silika bersama kumpulan metoksi dari VTMOS. Kehilangan spektrum kumpulan berfungsi metoksi dari agen pengkupel (VTMOS) dibuktikan melalui analisis FTIR. Bagi tujuan kajian peratus  partikel silika di dalam resin akrilat pematangan sinaran telah divariasikan kepada  5 wt%, 10 wt%, 15 wt%, 20 wt% dan  25 wt%. Dalam kajian ini resin yang diformulasi telah diaplikasikan ke atas permukaan substrat papan serpai (MDF) dan seterusnya  didedahkan di bawah sinaran lampu ultra lembayung (UV). Substrat MDF yang telah disalut  didedahkan di bawah sinara UV kemudiannya dianalisis menggunakan ujian terma (DSC dan TGA), ujian calaran, fleksural dan ujikaji SEM. Hasil ujikaji menunjukkan salutan akrilat berpengisi silika memiliki sifat salutan yang lebih baik berbanding salutan akrilat tanpa pengisi silika. Ini dapat dilihat pada peningkatan mendadak pada  sifat modulus dan kerintangan terhadap calaran. Disamping itu juga dalam kajian ini didapati penambahan partikel silika sehingga 25 wt% akan meningkatkan kelikatan resin akrilat dan seterusnya menurunkan  sifat kebolehaliran bahan salutan di permukaan substrat (tixotrophy).