Study on Larch Bark and Polystyrene Composite Insulation Materials
The three major problems facing the world today are population expansion, environmental pollution, and energy shortages. Among them, energy shortage is the primary issue. Nowadays, China's building heating energy consumption accounts for about 27.6% of the total energy consumption, and there is a trend of continued growth. This energy consumption is long-term. Therefore, vigorously developing green energy-saving buildings, developing new types of thermal insulation materials, and reducing residential energy consumption are one of the main tasks for achieving sustainable development. Throughout the development of the construction industry at home and abroad, thermal insulation has always been the most effective way to achieve building energy efficiency. With the vigorous promotion of energy-saving buildings in China, the variety and quantity of thermal insulation materials are increasing rapidly. At present, the commonly used insulation material in China is polystyrene foam board benzene board), the material can be processed into different sizes, easy to use, and low thermal conductivity (0.042W/nrK). Especially after the 50% energy saving design standard for building energy conservation was issued, the use of benzene board increased sharply, which resulted in the low price of polystyrene beads, was fragile, was difficult to reuse, and caused serious environmental pollution. Larch is one of the most abundant tree species in China. The tree-making and plywood factories have a large amount of bark left every year. Most of them are thrown away or burned, except for a small amount used to make silicone or adhesive fillings. . Because of the low thermal conductivity of the cork layer in the bark, its thermal insulation is better than wood. This article is to study the larch bark through shavings, flaking and a series of processes, processing into a flat, slender scrap, and then through the adhesive, additives and other materials composite sound insulation board. Through the research on the ratio of polystyrene and larch bark, the amount of adhesives added and the density, the superior manufacturing process was selected to provide basis for the further development and application of the product and provide a new one for the comprehensive utilization of larch timber. Test materials and equipment 1.1 Instrument and equipment thermal conductivity measuring instrument DPR-1, microcomputer multi-channel sampling instrument BES-C, multi-functional material testing machine DS20/20, press and mixer, etc., are provided by Heilongjiang Provincial Forest Industry Research Institute. Test material 1 Cooked polystyrene foam particles and adhesive (Urea formaldehyde resin, solids content 63%). 2 Larch bark. Using a chipper to process the bark into pieces, and then using a double drum flaking machine to obtain 5-40 mesh larch bark, dried to a moisture content of 3%-5%, and then sealed in a plastic bag. . The cumulative percentage of larch bark for various screening values. The orthogonal test scheme is shown in Table 2. Table 2 Orthogonal Experimental Design and Test Results Test ABC Thermal Conductivity Compressive Strength 2.2 Slab Preparation % Scratch Sieving Score/Larch Bark Cumulative Percentage According to Orthogonal Experimental Design Plan Press plate. First put the polystyrene and larch bark into the mixer, rotate a certain number of times until the larch bark and polystyrene particles are mixed uniformly, then spray the adhesive and evenly distribute the adhesive to the bark and polystyrene. Particle surface. The sizing mixture was placed in a self-made mold and paved by hand into loose boards of 403 mm > 406 mm. The plastic film was then placed on the surface of the board and pre-pressed at room temperature with a cold pressing pressure of 0.1 MPa and time. 5min, pressure relief, stuck with clamps, pressure preservation health, until the slab completely cured. Three plates were repeatedly pressed under each test condition, of which two were used for physical and mechanical properties tests and the other was used for other purposes. The thickness of the plate is controlled by a gauge. The final thickness of the composite board is 50mm and 20mm. Padding a pressure a health a polystyrene foam particles test method 2.1 Orthogonal experimental design test using orthogonal test design, the impact of various factors affecting the product specifications after the test analysis, the choice of L9 34) orthogonal table. This experiment used three factors and three levels. The changes of each factor are shown in Table 1. Each factor has three levels. Namely: Table 1 Factor Level Table Horizontal Factor 2.3 Thermal Conductivity Test Specimen The thermal conductivity is measured by the heat pulse method. Compress the composite material according to the above method, place it at room temperature for 2 days, and process it into 200mm200mmX50mm and 200mm>500mmX20mm two kinds of specimens, put it into a drying oven and dry it, and confirm that the weight measurement reaches a constant weight interval of 6 hours and the difference of two weighings reaches the specimen. After 0.1% of the mass, it is placed in a dry box and cooled to room temperature, and then weighed. Measure the density of the test pieces, see Table 2. Determination of the steady-state thermal resistance and related properties of GB/T10295 thermal insulation materials and GB/T 8813 rigid foam plastic compression test methods. The two physical and mechanical properties of thermal conductivity and compressive strength Conduct the test. Analysis of variance was used to analyze the test results. The thermal conductivity, compressive strength, and density of the composite thermal insulation material using urea-formaldehyde resin as the adhesive are shown in Table 2. From the data in Table 2, it can be seen that each variation factor in the test has various properties. Impact. For the analysis of the mean level difference of the indicators of the level of each factor, see Table 3. The results of the variance analysis of the effect of each factor on various performance indicators are shown in Table 4. The effects of various factors on the performance of thermal insulation materials are discussed separately below. Table 3 Average level difference analysis for each factor level indicator) K value Horizontal thermal conductivity Compressive strength Table 4 Variance analysis Result factor Compressive strength/kPa 3.1 Effect of Larch Bark and Polystyrene ratio on the physical and mechanical properties of the composite When the proportion of polystyrene and larch bark changes within the range of 8:9246:84, the thermal conductivity has a tendency to decrease. This is mainly due to the decrease in the proportion of bark in the proportion of the material, and the content of polystyrene. Relatively increased, the thermal conductivity of the thermal insulation board is reduced, and the thermal insulation effect is enhanced. When the ratio is 8:92, the compressive strength shows an upward trend. When the ratio is from 8:92*15:85, the compressive strength tends to decrease. This is because with the increase of the amount of polystyrene, the amount of bark increases. Relatively reduced, the bark is the main factor that increases the compressive strength, so the compressive strength decreases. 3.2 Effect of sizing on the physical and mechanical properties of composites The amount of sizing directly affects the thermal conductivity and compressive strength of composites. The test results show that as the amount of sizing increases, the thermal conductivity tends to decrease. When the sizing amount increases from 10% to 16%, the thermal conductivity decreases by 5.2%. With the increase of the sizing amount, the compressive strength of the composite insulating material increases, and the sizing amount increases from 10% to 16%. The increase in compressive strength increases the increase in the amount of sizing. The increase in the properties of the composite material mainly increases the cementation point between the larch bark and the polystyrene particles, and enhances the binding strength between the larch bark and the polystyrene particles, thereby increasing the Composite insulation effect. 3.3 The effect of density on the physical and mechanical properties of composites Tests have shown that thermal conductivity increases significantly with increasing density, while compressive strength increases slightly with density. Analysis of variance showed that density had a significant effect on all indicators. This was mainly due to the fact that as the density of composites increased, the contact between the larch bark and the polystyrene foam particles became more tight, the cementation point increased, and the voids decreased, resulting in stress. The better transmission inside the composite material can directly increase the thermal conductivity and compressive strength of the composite material. 3.4 Results Verification of the test Taking into account the requirements for the use of the product and the cost of production, the optimum process parameters are determined first. According to this parameter, the same process is used to compress the sheet and the physical and mechanical properties are tested in the same way. The best process parameters and test verification results are shown in Table 5. Table 5 Best Process Parameters and Validation Test Results Polystyrene Wood Adhesive Density Thermal Conductivity The compression strength verification results show that the thermal conductivity and compressive strength meet the requirements for use. 4 Conclusion Larch bark and polystyrene foam particles composite insulation material and material ratio, sizing amount, density and other factors are closely related to the best process for the preparation of the board: material ratio 1288, sizing 10% , density 0.19g/cm3. Larch bark and polystyrene foam particles composite wall insulation materials in addition to insulation, noise, vibration reduction and ease of construction, but also has a high strength, can expand its scope of use. Due to its high strength, it can be recycled and used to reduce environmental pollution. The material's low thermal conductivity is a very effective building wall insulation material. The larch bark and polystyrene foam particles as raw materials, using adhesives and other composite insulation materials, all indicators have reached the use requirements. In the experiment, density was the main influencing factor, and it had a significant effect on each index. The amount of sizing had a significant influence on the thermal conductivity of the composites, and had a significant effect on the compressive strength; the addition of polystyrene particles to the thermal conductivity of the composites. The coefficient has an effect and has a significant effect on compressive strength.
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