Natural rubber modified clay nanocomposite pressure sensitive adhesive / Adesivos sensiveis a pressão a base de nanocompositos de borracha e argila

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Pressure sensitive adhesives (PSA) are polymeric adhesives used for mainly in tapes and labels. Usually, there are 3 types of PSA: solvent based, water based and hot melt. Solvent based adhesives have few limitations, like flammability and toxicity, but they are still often used, due to their properties as good adhesion to polar substrates and good bonding with some plastics. The compounds for pressure sensitive adhesives, in general, use fillers due to cost reduction and properties they can give, like dielectric properties, water resistance and tensile strength. On the other side, nanocomposites are showing great advantages on several polymers applications improving thermal resistance, flame retardancy and mechanical properties. Nanocomposites for solvent-based adhesives were prepared by an exfoliation-solution process of natural rubber and organically modified clay compounds. A Design of Experiment (DOE). 22 with replication, was used to verify the influence of compounding factors; concentration and grades of nanoclays.A control adhesive compound was prepared using CaCO3, very common filler for adhesive fonnulations. The PSA were characterized by their adhesive properties (cohesion or shear, adhesion to steel or peel test, tack), gel and flammability. Almost all these properties showed statistical significance at least for one of the compounding factors, grade or concentration of nanociay. The flammability tests showed an improvement on the flame retardancy properties for all the nanoclays adhesives compared to the control compound. TGA analyses showed the same pattern of mass reduction as a function of temperature for all the adhesives. DMTA showed differences between the 2 kinds of nanoclays regarding Tg. XRD analyses did not show any diffraction peak related to the clays, likely due to the diluted samples or even to an exfoliation. SEM analyses showed a slightly lamellar pattern of clays and EDS analyses of the compounds confirmed the presence of Si and Al, elements of the nanoclays

ASSUNTO(S)

nanocompositos argila clay adesivos borracha natural rubber nanocomposites pressure sensitive adhesive

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