Sulphonation reaction in styrenic membranes is a common method used to graft ionic groups needed to enhance proton conductivity in polymeric electrolytes (PEM). A synthesized copolymer of styrene and acrylic acid (94/6 % mol) was partially crosslinked using a trifunctional monomer, trimethylolpropane trimethacrylate (TMPTMA) (0.01% mol), like a crosslinking agent. The obtained material was subjected to different sulphonation reactions in order to prepare several PEM membranes. The sulphonation reactions used sulphuric acid (H2SO4, 98%) at 50, 75 and 100 %molar ratio considering amount of styrene rings, during 1 and 2 hours of reaction time. Fouriertransformed infrared spectroscopy (FTIR) spectra were obtained to identify specific chemical groups in these materials. Thermogravimetric analysis (TGA) and Dynamic Mechanical Analysis (DMA) were used to evaluate the thermal stability and mechanical effects after sulphonation reactions. Water absorption and its effect on proton conductivity by means of Electrochemical Impedance Spectroscopy (EIS) were also evaluated. FTIR spectra show characteristic bands corresponding to sulphone groups within macromolecular structure. Sulphonating agent concentration and/or sulphonation time induce higher glass transition temperatures and no changes in thermal stability when comparing with the no sulphonated material. Latter condition also allows higher water absorption and an enhancement in proton conductivity.

Flexographic photopolymer plates have a wide range of commercial applications despite the fact that recycling of such materials is difficult. In consequence, there is a large bulk of leftover material around the world. In this research, the photopolymer plate waste products, identified as styrene-butadiene rubber (SBR)/ polyester are blended into common polypropylene (PP) and ethylenevinylacetate (EVA) resins at different loading percentages. PP and EVA are used as the polymer matrix and the recovered styrene-butadiene rubber (SBR) material as the filler. Evaluation of the mechanical, spectroscopic, thermal and chemical properties, as well as morphology, is done by means of scanning electron microscopy (SEM).Mechanical results show that elongation strongly depends on the matrix polymer: the greater the amount of solidsheet photopolymer (SSP), the smaller the elongation. No specific interactions were detected; however, thermal degradation and transitions were displaced, suggesting some miscibility. More homogeneity is seen for EVA blends, with no significant chemical attack detected. It is possible to reuse these recycled materials in blends with PP and EVA resins.

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Alternative copolymers to the well-known Nafion membranes are the styrene/acrylic acid PS/AA) copolymers, which have advantages in cost and availability of raw materials. Previous attempts to improve their mechanical properties involved crosslinking with divinyl benzene, but in this case the use of the tri-functional monomer TMPTMA (trimethylol propane trimethacrylate) is examined. Copolymers with a PS/AA molar ratio of 94/6 were prepared by a free radical polymerization reaction, including TMPTMA at 0.1, 0.01 and 0.001 % mol concentrations. Reactions were followed by percentage yield (gravimetry), Infrared spectroscopy (FTIR) and extent of crosslinking by gel percentage evaluation (soxhlet extraction) with three different solvents (water, tetrahydrofuran and dichloromethane). Thermal transitions were followed by calorimetry (DSC), stability by thermogravimetry (TGA) and mechanical properties by dynamic mechanical analysis (DMA). FTIR spectra show typical bands from the copolymer while the corresponding bands associated with crosslinking are overlapped; however, gel percentage evaluations show a higher level of crosslinking for the 0.1% TMPTMA copolymer and lack of solubility in water. DSC thermograms indicate an increment in the glass transition (Tg) and TGA exhibits a small increment in thermal stability for the crosslinked copolymers. Elastic moduli suggests a rubbery material for TMPTMA crosslinked copolymers while loss modulus confirms a Tg enhancement as observed by DSC. A 0.1 % TMPTMA copolymer does not form a membrane due to its insolubility and infusibility.