Manufacture of flame retardant foaming board from waste papers reinforced with phenol-formaldehyde resin.
A new flame retardant and waterproof porous fiberboard was manufactured from waste newspapers by using a foaming agent and a reinforcing phenol-formaldehyde resin. To find the optimum conditions for forming fiberboard with high mechanical properties as well as flame retardant and waterproof characteristics, a series of experiments were performed with varying weight percentages of resin (w). The results indicate that the best quality of the fiberboard was obtained for w approximately 11%.
Mechanical behavior of a syntactic foam: experiments and modeling
This paper reports the results of a research activity concerning the mechanical behavior of a syntactic foam employed as core material for sandwich composite panels. Following a purely phenomenological approach, experimental and numerical results are presented and compared at the macroscopic scale. The main features observed in the uniaxial, biaxial and Three Point Bending (TPB) tests are highlighted. A bimodulus constitutive model of the Drucker-Prager type is chosen for modeling biaxial stress states with diffused damage. An alternative discrete crack approach is devised for the computer simulation of the (TPB) three point bending tests: the best matching is achieved for a rectangular Dugdale-type cohesive law. Though not proposing novel experimental or numerical methodologies, the present engineering approach should interest readers generally involved in computational composite mechanics and, specifically, in modeling particulate composites of the type considered here.
Influence of filler addition, storage medium and evaluation time on biaxial flexure strength and modulus of adhesive systems
Abstract Objective. This study evaluated the effects of filler addition, storage medium and time on biaxial flexural strength and flexural modulus of six adhesive systems. Materials and methods. The adhesives were either unfilled resins: Single Bond, Prime&Bond 2.1 and One-Step; or filled resins: Single Bond Plus, Prime&Bond NT and One-Step Plus. Resin discs of each product (0.5 mm thick × 6.0 mm diameter) were prepared using silicon molds (n = 10). The discs were stored dry, in water, mineral oil or ethanol for 1 week or 3 months before biaxial flexural testing. Data were statistically analyzed by 3-way ANOVA and Tukey's post-hoc test (α = 0.05). The specimens were tested in a universal testing machine at 1.27 mm/min until failure occurred. Results. In general, the storage in ethanol led to significantly lower flexural strength and flexural modulus values than the other storage conditions for all adhesives in both storage periods. Filler addition increased flexural strength and flexural modulus for Prime&Bond NT, when it was stored dry or in water for 1 week. For Single Bond Plus, the filler addition resulted in higher flexural modulus, when it was stored for 1 week in oil and in ethanol. No significant differences in flexural modulus were observed between One-Step and One-Step Plus in any storage medium. Conclusions. Results suggested that filler addition does not necessarily have to increase the flexural strength and flexural modulus. Ethanol and oil storages tended to yield opposite effects.