SPE Library

In the current research, hybrid laminates having veneer facesheets and natural fibre composite cores were fabricated to investigate their fire and mechanical properties and to observe a suitable combination. Wool and flax fibres were selected for fibre reinforcement. Ammonium polyphosphate (APP) was used as the primary flame retardant for all the composites. The mechanical performance of the flax fibre reinforced fire retardant polypropylene (flax-FRPP) and fire retardant wool-polypropylene (FR-wool-PP) hybrid layered panels were further studied and compared to plywood made similarly. The results showed that hybrid laminates have better fire properties and the hybrid layered veneer composites can have significant structural applications if proper bonding between the composite and the veneer layers can be achieved. The tensile properties showed a reduction in Young’s modulus and ultimate tensile strength, though the wool-veneer hybrid laminates outperformed the flax-veneer ones. Moreover, the impact test showed that the wool-veneer hybrid laminates had the best resistance when compared to all the veneer-based samples tested. The results point towards the possibility of manufacturing a superior fire-resistant hybrid veneer composite laminate.

The present study aims to design a comonomer based resin matrix with a prolonged gel time while maintaining low viscosity and minimal curing time to ensure its processability with high filler contents in fabricating polymer concrete composites (PCC) for bases of tool machines. In this work, a copolymerization route was adopted to optimize the processability of a commercially available epoxy vinyl ester. Comonomer resin systems were prepared from addition of Methyl methacrylate (MMA) as a reactive diluent into the commercial epoxy vinyl ester resin (VE) which was premixed with styrene (ST) diluent (48 wt. %). Compositions of comonomer resin systems were varied systematically to achieve an optimum mixture design. The viscosity and gel time of comonomer resin systems were measured by a digital Brookfield viscometer. The influence of MMA on the curing behavior, elastic modulus and glass transition temperatures of comonomer resin systems have been investigated by differential scanning calorimeter (DSC) and dynamic mechanical analyses (DMA) respectively. The obtained optimum comonomer resin system was 40wt% VE resin, 23wt% MMA and 37wt% ST. This formulation exhibited 80% lower viscosity and about 45% longer gel time as compared to the viscosity and gel time of commercial VE resin system with just half the styrene monomer content, thereby not only ensuring its processing with high filler contents, but also reducing the volatile organic compounds associated with the large-scale manufacturing of PCC products. Also, this composition showed the shortest curing time and 60% higher flexural strength (53.6 MPa) compared to that of the commercial VE resin system (17.3MPa).

The incorporation of technical lignin, a multifunctional natural polymer, into rigid polyurethane foam (RPUF) for the enhancement of thermal insulation performance has gained increasing interest in academia and industry. However, the structural complexity of technical lignin hinders its dispersion in the polyols commonly used for the preparation of RPUF. Poor dispersion of technical lignin in polyols inhibits the chemical reactions and limits the potential improvement in the thermal and mechanical properties of RPUF. Herein we report enhanced dispersion of unmodified kraft lignin, at a loading of 3 wt % in a mixture of glycerol and an aromatic polyester polyol (20:80) for the preparation of RPUF. It has improved the insulation property by 30% while retaining its mechanical performance compared to the control RPUF without lignin. Such a level of improvement, to the best of our knowledge, has not been reported in RPUF using chemically unmodified lignin to date. This is attributed to the enhanced dispersion of the kraft lignin in the polyol blend causing changes in the cell morphology of the resultant RPUF, as supported by microscopic and rheological analysis. To this end, the insights into the influence of kraft lignin on the polyol-precursor on the properties of the RPUF are discussed.

The preparation and characterization of a multilayer film reservoir with clay/essential oil (EO) composites was described. The goal is to analyze the potential use of these reservoirs with clay/EOs composites as aroma-controlled release for various applications such as pesticide or attractant for pest control as well as antimicrobial control. Two types of clays were analyzed, porous halloysite (HNT) and octadecyl modified montmorillonite (MMT) nanoclay; as well as two types of essential oils, orange (OO) and thyme oil (TO). The DRX results confirmed that MMT clay presented higher thyme oil adsorption and better interactions than orange oil. Clay/EO composites encapsulated in multilayer film showed a prolongated aroma release during longer times. Polyamide (PA) barrier layer thickness has an effect on the liberation of the volatile compounds through the multilayer film.

ASTM D-2863 is a small-scale fire performance classification test, part of ASTM C-578 standard for polystyrene rigid thermal insulations, with a binary pass/fail outcome at a given oxygen concentration level. When applied to foams, the test is highly variable and is easy to manipulate, putting its accuracy as a test method into question. In this work, macro-imaging was used to closely monitor the foam – flame interaction to gain a better understanding of variability levers. For example, one of the levers is duration of flame application to a sample. Our imaging studies indicate that the pass / fail boundary oxygen level is strongly correlated with the flame application duration.

In this paper, a decorative material was first applied onto the light weight reinforced thermoplastic (LWRT) composite core mat during the core manufacturing, and then followed by a consolidation process through the calender rolls. This method is defined as an in-line lamination process with a finished A-surface panel in comparison with conventional off-line decorative materials lamination process, in which the decorative layer is applied in a separate process from core manufacture. Decorative layers with two patterns, namely woodgrain and marble, have been studied. The adhesion performance between the decorative skin material and LWRT composite substrate has been evaluated by 180° peel adhesion test following ASTM standard D903. The separation between the decorative layer and the substrate was difficult to initiate, which demonstrates an outstanding adhesion between the two components. A stylus method quantitatively confirmed the decorative surface is smooth and able to cover the core’s texture. Flatwise tensile test results by ASTM standard C297 method showed the decorative panels could not be delaminated, indicating strong bonding between decorative skin material and core mat. Materials produced with the woodgrain pattern were tested to have better flexural strength and stiffness than the sample made with marble decorative pattern material. In addition, flame retardancy results showed the laminated decorative panels can meet ASTM E84 requirement of Class C and above. The decorative material with custom design provides the decorative A-surface with an appearance of wood, stone, textile or other natural materials as desired, opening a window for the LWRT composite to be used inside an RV such as the interior layer of sidewall and ceiling.