DEVELOPMENT OF WASTE-BASED-THERMOPLASTIC COMPOSITE HEAT INSULATORS

The main scope of this research is to develop polymer-filler thermal insulators utilizing natural and industrial local waste such as date pit powder (DPP), devulcanized tire rubber (DVR), and buffing dust (BD). Recycling and reuse of these local wastes as fillers in insulation materials has significant benefits for the UAE environment. An objective of this work was to study the effect of the combination of these local wastes with polystyrene (PS) on the physical, mechanical, and thermal properties of the developed thermal insulators. PS was used as a matrix, mixed in different proportions with the waste fillers. Each mixture was then exposed to heat and pressure in a hot press to form a solid sample. The formed composites were tested to evaluate their physical (water absorption and bulk density), mechanical (compression strength, compression modulus, tensile strength, tensile modulus, flexural strength, and flexural modulus), and thermal properties (thermal conductivity and thermogravimetric analysis (TGA)). The results established that DPP, DVR, and BD were suitable as fillers in thermal insulation materials. Use of DPP and DVR waste in ratios ranging from 0 wt. % to 30 wt. % affected thermal conductivity minimally and resulted in an acceptable reduction in mechanical properties. Replacing 50 wt. % of PS by DPP increased the thermal conductivity by only 9.1%. Adding 10 wt. % of BD to the PS reduced thermal conductivity by 13.29 %, with negligible effect on the mechanical properties. Similarly, low DVR rubber content led to a slight reduction in thermal conductivity (4 %). However, higher proportions of DVR and BD content had a negative effect on the thermal and mechanical properties. Prior treatment of the waste fillers with NaOH, enhanced mechanical performance in composites prepared from the treated fillers. Scanning electron microscopy (SEM) was used to investigate the microstructure of the prepared composites. In addition, the waste fillers were analyzed by infrared spectroscopy (FTIR) to identify the main functional groups in the fillers. To study the effect of the chemical treatment on the main functional groups, these fillers were analyzed by FTIR after the treatment. Although the addition of the three types of waste reduced mechanical strength, all prepared composites with a waste filler concentration below 30 wt. % displayed good mechanical properties, compared with available commercial thermal insulators. Moreover, replacing one-third of the thickness of a building wall with DPP-polystyrene, DVR-PS, and BD-PS composites reduced the heat transfer coefficient by 85 %, 87.8 %, and 83 %, respectively. Therefore, recycling of the local wastes DPP, BD, and DVR as filler materials in thermal insulators presents an opportunity for significant benefit to the UAE economy

Testing of aluminium composite panels in a cone calorimeter : a new specimen preparation method

Fire testing data consistency and repeatability are essential for regulatory scrutiny, product development, and fire modelling of the lightweight cladding system. Lightweight composite claddings such as aluminium composite panels (ACPs) have been challenging to assess in terms of combustibility and flammability due to their sandwiched composite structures, which led to inconsistent data during bench-scale fire testing and fire risk assessment. This study aims to improve the test data consistency of reaction-to-fire properties such as time to ignition (tign), peak heat release rate (pHRR), time to peak heat release rate (tpHRR), total heat release (THR), which are the critical parameters for fire assessment and regulatory screening of the ACP claddings used in buildings. Therefore, a modified test approach is proposed in this study to facilitate the proper combustion process with the formation of a steady fuel gas/air mixture during the testing of cladding panel. The test data repeatability, standard deviation (SD) and relative standard deviation percentage (RSD%) of reaction-to-fire properties have been improved significantly with the modified test approach compared with the existing test approach

Utilization of devulcanized waste rubber tire in development of heat insulation composite

This study aims to investigate the possibility of recycling devulcanized rubber tires for their use as fillers for thermoplastic thermal insulators. A devulcanized rubber tire was ground into powder and then mixed with polystyrene in different proportions (0–50 wt%) using a melt extruder. The mixture was then transferred to a hot press for fabricating the final sample. The effect of devulcanized rubber tire content on the physical, thermal, and mechanical properties of devulcanized rubber tire–polystyrene composites was investigated. Thermal conductivity measurements were verified using series and parallel conduction models and the Hashin and Shtrikman model. Composites with less than 40 wt% devulcanized rubber tire content exhibited superior properties, with thermal conductivity ranging from 0.0502 to 0.07084 W/(m⋅K), density from 462.8 to 482.32 kg/m3, compressive strength from 11.66 to 7.47 MPa, and flexural strength from 40.4 to 19.26 MPa. Moreover, alkaline treatment of the devulcanized rubber tire further improved the mechanical properties and thermal stability of the composite. The results are supported by characterization techniques such as scanning electron microscopy, thermogravimetric analysis, and Fourier-transform infrared spectroscopy. The chemical treatment was found to enhance the coherence between treated devulcanized rubber tire and polystyrene. The novel devulcanized rubber tire–polystyrene composite can be used as an alternative insulation material because of its superior properties compared with those of conventional insulation materials. Furthermore, the environmental and economic implications of using devulcanized rubber tire–polystyrene composites as a new insulation material are discussed herein

Traditional, state-of-the-art and renewable thermal building insulation materials: An overview

© 2019 Elsevier Ltd Energy saving has become a strategic goal in the whole world, that will lead to protect the environment and conserve natural resources. The energy consumption in buildings for heating and cooling is considered as one of the major sources of energy consumption in a lot of countries. Therefore, there is an ongoing search for finding the proper alternatives to preserve energy and minimize energy losses. Subsequently, heat insulators, part of building materials, are steadily getting their importance as a means of saving energy. Although, a lot of insulation materials are used commercially, this part of building construction still faces different difficulties and challenges such as the cost, thermal and mechanical properties, health problems, etc. Current insulation materials used in construction industry are generally polymer based materials such as polystyrene and polyurethane foam. Although these materials have a high performance in thermal insulation, but the environmental impacts in their production processes are significant. Consequently, the researchers find that there is a necessity to develop and come up with insulating materials that possess excellent properties and at the same time, they have less environmental impacts, and are relatively cheap. In this review paper, the researches carried out in the formulation and development of different kinds of thermal insulation in the last decades are presented. The focus was placed on researches utilized of renewable resources and wastes in thermal insulations development. In addition, the light was shed on the composites materials which was developed as a construction material with high thermal insulation capacity

Ultrasensitive and low temperature gas sensor based on electrospun organic-inorganic nanofibers

Organic-inorganic hybrid material is one of the most promising materials for high performance gas sensors due to its improved properties like high sensitivity, selectivity, fast response time, flexibility and low power consumption. This work presents ultrasensitive, selective and low operating temperature H2S gas sensor. It is based on metal-oxide nanoparticles (NPs) embedded in organic semiconductor polymeric nanofibrous (NFs) membrane containing an ionic liquid (IL). In this context, high surface area Tungsten(VI) oxide- Polyvinyl alcohol (WO3-PVA) nanofibrous composite sensor material with average diameter of 130 ± 20 nm were synthesized with controlled morphology and interconnectivity through an electrospinning technique. The obtained WO3 NPs-containing PVA nanofibrous sensing material was evaluated for its ability as a potential sensor for H2S gas at different operating temperatures and gas concentrations. Results demonstrated that the fabricated sensor is ultrasensitive and selective for H2S gas and exhibit an excellent reproducibility, and long-term stability. Furthermore, the sensor showed adequate response in a humid environment. It was also shown that nanofibers' membrane porosity and thickness control the sensing performance. The optimum operating temperature of 40°C with a detection threshold as low as 100 ppb with a response time of 16.37 ± 1.42 s were achieved. This combined high sensitivity, fast response time and low operating temperature (low-power consumption) provides clear evidence of the sensor's potential to outperform existing devices, which could pave the way for a commercial exploitation

Flame behaviour, fire hazard and fire testing approach for lightweight composite claddings : a review

Purpose – The purpose of this study is to review and summarise the existing available literature on lightweight cladding systems to provide detailed information on fire behaviour (ignitibility, heat release rate and smoke toxicity) and various test method protocols. Additionally, the paper discusses the challenges and provides updated knowledge and recommendation on selective-fire mechanisms such as rapid-fire spread, air cavity and fire re-entry behaviours due to dripping and melting of lightweight composite claddings. Design/methodology/approach – A comprehensive literature review on fire behaviour, fire hazard and testing methods of lightweight composite claddings has been conducted in this research. In summarising all possible fire hazards, particular attention is given to the potential impact of toxicity of lightweight cladding fires. In addition, various criteria for fire performance evaluation of lightweight composite claddings are also highlighted. These evaluations are generally categorised as small-, intermediate- and large-scale test methods. Findings – The major challenges of lightweight claddings are rapid fire spread, smoke production and toxicity and inconsistency in fire testing. Originality/value – The review highlights the current challenges in cladding fire, smoke toxicity, testing system and regulation to provide some research recommendations to address the identified challenges