Window Profiles Research Articles

The influence of acrylic impact modifiers on the weld strength of extruded rigid PVC

AbstractThe weld strength of a PVC window profile is a function of complicated interactions among many contributing variables. Major determinats of weld strength include the PVC formulation, profile processing conditions, and welding parameters. Impact modifiers enhance weld strength due to their well‐known effects on PVC mechanical properties. For modifiers having similar impact efficiency, the contribution to improved weld strength is maximized through optimization of the PVC viscosity and blend morphology at the weld line.

The Monolithic Double-Crystal Spectrometer: Theory and Design Principles

The monolithic double-crystal spectrometer (MDCS) is a perfect-crystal device allowing X-ray spectroscopic measurements on an absolute energy scale with an accuracy of better than 1 in 106. This paper presents a detailed analysis of its properties using the dynamical theory of X-ray propagation in perfect crystals. The transmitted wavelength, the transmission window profile, the energy dispersion and the integrated intensity of the transmitted radiation and their dependence on the scanning angle of rotation are derived. The polarization mixing is shown to have a subtle yet important effect on the transmission of the MDCS. An example of a specific MDCS, designed for measuring the Cu Kβ emission spectra, is discussed in detail. The results of the study highlight the advantages and limitations of this device and yield tools for optimizing the MDCS for a wide class of X-ray spectroscopic measurements and for correcting the inevitable, although minimal, distortions introduced by the finite instrumental window of the device.

Modeling of single‐screw extruders with mixing pins: The case of PVC

AbstractA computer model is proposed to simulate the flow of molten polymer in the melt conveying zone of extruders provided with mixing pins. This model is based on the calculation of down‐channel velocities within cross sections perpendicular to the flow. A Lagrangian reference frame (i.e. that of the barrel sliding on top of the channel) is used to describe the flow in a convenient manner, the mixing pins being represented as a set of virtual boundary conditions (geometric constraints). The proposed method is compared to a full 3D finite element flow simulation with Newtonian and non‐Newtonian fluids showing a good agreement in term of the pressure drop calculation. Numerical tests are also carried out in the case of a rigid PVC compound used for window profile extrusion. The adequacy found between the predictions and experimental measurements obtained on an industrial extruder confirms the performance of the proposed model.

A numerical model for single screw extrusion with poly(vinyl chloride) (PVC) resins

AbstractA computer model has been developed to simulate the behavior of molten polymer in the melt conveying zone of extruders. This model, based on a hybrid finite difference/finite element resolution of the equations of change governing momentum and heat transfer, allows the prediction of the pressure profile while accounting for wall end effects as well as the solid bed velocity. Simulation results are compared with analytical and finite difference method results found in the literature. A fairly good agreement is obtained in the case of low density polyethylene. Numerical tests are also carried out with rigid poly(vinyl chloride) compound used for window profile extrusion. The good agreement found between the predictions and experimental measurements obtained on an industrial extruder confirms the performance of the proposed model.

A novel impact modifier system for vinyl siding and profile substrate

AbstractThe use of a newly developed ABS impact modifier in coextruded vinyl siding and window profile substrate is discussed. Considerations of toughness at room and low temperature, output, reduced lubricant levels, and weatherability of the finished siding are reviewed. Actual outdoor weathering results are presented, along with long‐term heat aging tests, showing the modifier to have good property retention characteristics.

Stabilizer systems in PVC window profiles

Statistical procedures are presented for estimating change from thematic maps available for the same region at two times. Estimators for the joint distribution of the true proportions of classes at both times are given for a simple random sampling scheme and a stratified sampling scheme. Estimators are derived for the true marginal distributions of the proportions of each class at time 1, time 2, and the difference between times 1 and 2 along with variance estimates.

Dauerhaftigkeit von lamellierten Holzfensterprofilen

Components of window frames, produced by laminating profiles of 3 softwood lamellae using PVAc glues, were exposed to «differential climate» conditions for 18 months and to laboratory accelerated aging methods (water soaking; application of water soaking, heating and freezing cycles). After 18 months exposure, 78% of window profiles exhibited delamination on the weather-exposed surfaces. The glue bond strength was not significantly impaired during natural exposure, as long as the delamination had not occured. On the other hand, both laboratory accelerated aging methods substantially reduced the glue bond strength.

Effects of compounding and extrusion variables on degree of fusion and impact strength of PVC window profile

AbstractThe effects of temperature in twin screw extrusion of a window profile compound have been studied. Compounds were made with and without an acrylic impact modifier. Fusion levels of the extruded profiles were rated from values of the rubbery plateau modulus at temperatures near 110°C. Impact strength was measured at room temperature using notched tensile specimens at 1 m/s jaw separation rate. The impact strength of these materials does not increase with fusion level once an adequate degree of gelation has been achieved. The impact‐modified compound shows a dramatic improvement in impact strength when the melt temperature was increased from 319°F to 343°F. A further increase to 365°F had no effect. The compound without impact modifier exhibited no improvements in impact strength over the whole extrusion temperature range. Conflicting reports in the literature on effects of fusion level on impact strength of PVC articles probably reflect different interactions between extrusion conditions and compound composition.

Barium/cadmium for the stabilization of rigid vinyl for exterior applications

AbstractThe highly developed synergistic Ba/Cd stabilizer system for rigid vinyl use in exterior applications is the result of long lasting efforts in this field. By itself, cadmium carboxylate is ineffective because developing cadmium chloride acts as a strong Lewis acid and accelerates the decomposition of PVC. Barium carboxylate converts cadmium chloride formed back into the cadmium carboxylate. Addition of a chelating agent decidedly improves the stability of PVC. A certain ratio of Ba/Cd stabilizer must be retained; best ratio is 6 to 1. The addition of epoxidized soybean oil further improves both heat and light stability of these systems. More than 20 years performance of these formulations has been applied successfully. Increased stability of colored window profiles is effected with the addition of 0.5 parts of a UV absorber. Recommended pigmentations for masstone colored and tinted shades are provided in addition to formulations for white titanium dioxide pigmented profiles.

The all‐acrylic weatherable impact modifier for PVC

AbstractRigid poly (vinyl chloride), PVC, is finding increasing use in outdoor applications as a replacement for conventional materials such as wood, aluminum, steel, and other materials. Formulating PVC for outdoor applications requires special attention to several essential properties in order to achieve the high‐quality standards needed over a long period of time. One area that needs modification in a rigid PVC formulation for outdoor applications is toughness. Impact modifiers used to improve the toughness of PVC in outdoor use are CPE, EVA copolymers, and acrylates.The all‐acrylic weatherable impact modifier is designed especially to modify PVC for outdoor use and ease of processability. We will review its key performance features with special emphasis on the processing advantages of the all‐acrylic impact modifier. The study of the influence of processing conditions on the physical performance of weatherable PVC compounds in a Ba/Cd stabilized window profile shows an acrylic modifier to give consistently high toughness over a wide temperature range and shearing friction.