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Free Chain Polymerization (Addition Polymerization)
Published in Charles E. Carraher, Carraher's Polymer Chemistry, 2017
Many flat sheet signs are made of PVC. Films are also formed from PVC. Many of these signs and films are simply referred to as vinyl. These films and sheets form many of our commercial signs and markings on vehicles. Unplasticized or rigid PVC is used in the construction industry as a siding simply known as vinyl siding. It is also used to repair window frames and sills and fascia and widely used in the construction of plastic gutters, downpipes, and drainpipes.
Exterior Enclosure Components
Published in Kathleen Hess-Kosa, Building Materials, 2017
Vinyl siding, also referred to as PVC siding, is a thermoplastic polymer that is comprised of ethylene and chlorine. When unstabilized and exposed to intense radiant heat, PVC emissions of “regulated, toxic/irritating” hydrogen chloride gas and detectable organic compounds occur. The chlorine component renders PVC fire resistant, but vinyl will burn—slowly, releasing irritating/toxic chlorine gas.
Thermal resistance of ventilated air-spaces behind external claddings; definitions and challenges (ASHRAE 1759-RP)
Published in Science and Technology for the Built Environment, 2021
Mohammad Rahiminejad, Dolaana Khovalyg
Verification and validation are important components of any model development. To validate the analytical solution, computed temperatures of surfaces were compared with the results of two hot-box tests referenced in the work statement of 1759-RP (Meyer et al. 2019; EXOVA Test Report 2011). The testing by Meyer et al. (2019) considered brick cladding with a 0.07 m/s forced ventilation airflow behind the brick veneer. EXOVA tested vinyl siding with a conventional hot-box test using a mixing fan airflow applied to an exterior side of the assembly. In contrast to the test performed by Meyer et al. (2019), no forced ventilation air-flow behind the siding was applied. Thus, the airflow behind the vinyl siding only occurs as a result of mixing fan-induced airflow over the surface of the vinyl siding.
Measuring the effective thermal resistance of ventilated air-spaces behind common wall assemblies: Theoretical uncertainty analysis and recommendations for the hot box method modifications (ASHRAE 1759-RP)
Published in Science and Technology for the Built Environment, 2022
Mohammad Rahiminejad, Dolaana Khovalyg
There are a few studies in the literature that attempted to use the hot box test method to examine the thermal performance of the wall structure incorporating a ventilated cavity. In the report provided by DuPont Building Innovations (ASTM 1363-05 test report 2009), a computational model is validated using the experimental measurements of different wall structures with a ventilated air-space behind the brick cladding. The impact of the emissivity of the weather resistance barriers in wall cavities on the thermal performance of the wall assembly is analyzed by changing the size of the air cavity, the airflow rate in the air gap, and the type of weather-resistant barrier. The thermal transmittance and the thermal resistance of the entire wall structure are determined in general accordance with the standardized hot box method. The results reveal that the overall R-value is increased when the airflow is applied in the cavity. A similar wall structure to the aforementioned test is employed by Meyer et al. (2019), and the thermal benefit of low-emissive barriers adjacent to the ventilated air-space behind different cladding types is evaluated. The tests show that the presence of the air cavity behind the external cladding is essential to achieve the thermal benefits of a low-emissivity surface. It is concluded that the thermal performance of the air-space depends on the emissivity of the adjacent cavity surfaces, the size of the air gap, and the airflow applied in the cavity. In another test report provided by EXOVA (EXOVA Test Report 2011), the conventional hot box test method is used to evaluate the thermal performance properties of a wall structure with vinyl siding incorporating a narrow cavity behind the external cladding. The thermal resistance contribution of a low-emissive material is determined by varying the configuration of the wall assembly and using a mixing fan airflow applied to the exterior side of the structure. In contrast to the test performed by Meyer et al. (2019), no forced ventilation airflow behind the siding was applied. Thus, the airflow behind the vinyl siding only occurs as a result of mixing fan-induced airflow over the surface of the vinyl siding. The results showed that the thermal resistance of the entire wall structure increases if the emissivity of the cavity surface is decreased.