Mechanical and Physical Properties of Glass Wool-Rigid Polyurethane Foam Composites

Al-Nahrain University, College of Engineering Journal (NUCEJ) Vol.18 No.1, 2015 pp.41 - 49 Mechanical and Physical Properties of Glass Wool-Rigid Polyurethane Foam Composites Ismail Ibrahim Marhoon* Aseel Kais Rasheed Material Engineering Department/ College of Ministry of science and technology / Renewable Engineering/Al-Mustansiriya Energy Directorate University/Baghdad *E-mail: [email protected] Abstract foams are obtained by the reaction of isocyanate This research is devoted to the preparation of with polyols, which, depending on the foam polymer matrix composite materials by formulation, regulate the properties of the forming in place method, where the composite material. Their foaming is possible due to the foam material was prepared from the rigid in situ generation of a foaming agent during the polyurethane foam (PU) as a matrix reinforced by exothermal polymerization reaction, leading to glass wool insulator with weight fractions (2%, crosslinked foams with changeable cellular 4%, 6%, 8% and 10%) .Several mechanical and structures[5]. Depending on the amount, physical tests were done and these include impact, proportions and characteristics of the components, flexural, compression, hardness, density, water it is possible to obtain three categories of absorption and thermal conductivity. The result polyurethanes foams which are flexible shows that the values of mechanical and physical polyurethanes, semi rigid polyurethanes and rigid properties in general are increased with the polyurethanes with different densities and cellular increase of glass wool weight fraction content. structures, and thus adjustable properties [5, 6]. The values of flexural strength decrease with the Besides, given that both basic components are increase of weight fraction of glass wool fiber liquid at room temperature, it is relatively after 8% wt. easy to incorporate fillers and reinforcements further, extending the applicability of these Keywords- Rigid polyurethane foam, Glass lightweight materials [7]. wool, foam composite, density, thermal Glass wool insulation is felt materials made of conductor, flexural strength, hardness, impact glass with binder by heating and solidifying. It strength, water absorption, polyol-isocyanate. has good flexibility, affordable price and it is easy to install. Features of fiber glass wool are nature 1. Introduction products, acoustical absorption, high thermal In a country like Iraq, where large seasonal resistance with low thermal conductivity variations in temperatures occur, thermal (Working temperature at about 450 ºC), fire safe insulation is quite important. Though designing materials and environmental friendly materials [8- the building for obtaining thermal and sound 12]. Typical final nominal fiber diameters range insulation characteristics involves additional from 4 µm to 15 µm. and softening point is 675 expenditure, it is well compensated by the ºC [13]. comfortable and healthy environment obtained. Composite polymer foams are materials of a The polyurethanes (PU) foams are widely used polymer phase with voids and an additional solid as insulating and core materials for furniture, or hollow phase distributed throughout the cooling and freezing systems, in house building, polymer, while Foams or cellular materials are ship building, piping, tanks, etc.[1,2]. The use of materials that have a regular arrangement of cells rigid foams is a result of their low heat conduction and solid struts. Thus, the term composite foam coefficient, low density, low water absorption and excludes conventional, single-phase foams made relatively good mechanical strength [3]. The PU by expanding polymers such as (polystyrene, foams have been applied also as core materials of polyurethane, or polypropylene), also excluded sandwich constructions with steel plates, in are structures with single-phase core materials building the industrial houses carrying freezers and covered with a solid skin because the second and cold stores, where they have to fulfill both phase, the skin, is not dispersed throughout the insulating and mechanical requirements. In polymer phase [14]. addition, polyurethane products, for the most part, Composite foams can be classified as follows: are self-supporting, which makes them useful as syntactic foam, particle reinforced foam and fiber- construction insulation panels and as structural reinforced foam. The additional solid components elements in construction applications [3, 4]. PU are combined to enhance certain properties 14 NUCEJ Vol.18 No.1. 2015 Marhoon, Rasheed pp.41 - 49 important to the function of the composite foam Thereafter, part-B (MDI) was added to the part such as strength, stiffness, electrical or mixture and mixed at a similar speed for another thermal conductivity [14, 15]. 15 sec. and the mixture was left to produce expanded foam. All composite foams were cured 2. Objective at ambient temperature (25◦C) for 72 hr., and Polyurethane foam is very talented rigid glass wool was added based on weight percentage polymer foam for shock, acoustic and thermal of the overall weight of polyol and MDI resin insulating applications, but it has limitations (w/w %) which were (2, 4, 6, 8,10) %wt. as which exclude its application as a single material. shown in Figure (2). Polyurethane properties are modified by controlling the stages of syntheses or by using 3.3 Foam Composites Measurement fibrous reinforcement additives to overcome some Methods of these limitations. For example, one of the main The specimens were cut according to the limitations of rigid PU foams comes from their standard dimensions for each test. An average of reduced mechanical properties in the case of three different determinations was obtained for all sandwich structures, increasing the risk of experiments except for hardness test, where five possible core crushing, shear or debonding readings were taken from different places of one from the surface skins. The aim of the present sample. The mechanical properties of the foams work is the synthesis of rigid polyurethane foams were conducted parallel to foam rise direction. (PU) modified with short glass fibers in the form Flexure tests are performed with 2.5 kN load at a of (glass wool). The effects of glass wool speed of 2 mm/min. The tests were performed insulation on the foams have been analyzed in according to ASTM D 790-03 [18]. Compression terms of density, thermal conductivity, water strength was determined according to ASTM absorption, mechanical properties (impact, D1621-00 [19]. Impact test was performed compression and flexural ). according to ASTM D4812-99 for unnotched Izod impact test [20]. Density of the foam was 3. Experimental measured according to ASTM D1622-03 [21]. 3.1 Materials Hardness test was performed by using Shore hardness (D) and according to ASTM F1957–99 A two-component polyurethane foam (PU) [22]. Water Absorption test was performed system specifically formulated for the preparation according to ASTM D570-98 [23]. Thermal of medium–high density rigid PU foams ® conductivity was measured using Lee's Disk with (POLYFOAM 55 ) was produced by sample dimensions of 40 mm diameter and 5 mm (POLYBIT), where part-A is a mixture of polyol, thickness. The instrument consists of a heating blowing and curing agents, catalysts and coil and three brass disks. The specimen was stabilizers, with a viscosity of 900 cps at 20 ◦C 3 secured between the brass disks (1, 2) and the and a density of 1.14 g/cm , and part-B is a heating coil was fixed between the brass disks (2, modified diphenylmethane-diisocyanate (MDI), 3). The applied voltage across the terminal of the with a viscosity of 200 cps at 25 ◦C and a density 3 heating coil is 6 V. and the current is 0.2 A. A of 1.24 g/cm . Both components are liquid at heating heater was used to heat the three brass room temperature [16]. Glass wool (URSA ® disks (1, 2, 3) and heat transfer was through the GLASSWOOL ) insulation was produced by specimen from the bass disk (2) to brass disk (1). URSA Uralita group –Turkey, have a density of 3 The temperature of the disks increases gradually 16 kg/m and an individual fiber diameter until it reaches the equilibrium temperature of all between 6.1- 7.7 μm [17]. disks. 3.2 Composite Foam Preparation 4. Results and Discussion Rigid PU-based foams were prepared by 4.1 Physical Properties mixing equal amount 1:1 of part-A (polyol) and 4.1.1 Water Absorption part B (isocyanate (MDI)) components for 15 s Figure (3) show the relationship between water and pouring in a wooden mould (60×90×195 mm) absorption percentage and weight fraction of the as shown in Figure (1). The mould was closed glass wool filler, which were added to the rigid with a lid and the mixture was allowed for PU’s polyurethane foam. Water absorption behavior of synchronized polymerization and foaming. Rigid polymer filled composites at a particular PU reinforced composite foams were prepared by environmental condition is determined by many forming in place method by initially pre-mixing factors, such as processing techniques, matrix glass wool insulation (were dried for 24 hr. at ◦ filler characteristics, composition of the 100 C) with the polyol prior to pouring into the composites, and duration of immersion in water mold with hand mixing for 1 min. after the [24]. The results had revealed that the water mixture was allowed to degas for 2 min. into a absorption percentage increases with increasing wooden mould lined with aluminum foil. 14 NUCEJ Vol.18 No.1. 2015 Marhoon, Rasheed pp.41 - 49 weight fraction of

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