Formulating technology for rigid cellular PVC sheet

Rigid vinyl can be considered as a highly versatile thermoplastic, finding its way into many different applications. Vinyl's capacity for innovation is virtually limitless, thanks in part to advances in formulation additives, which have enlarged vinyl's processing and end-use performance capabilities. The importance of formulating is particularly evident in rigid cellular PVC, which can be extruded into a variety of shapes, such as profile, pipe, and sheet, all made with less PVC than their solid counterparts. The sheet application can be especially challenging, and it has been made the subject of this paper. The various types of extrusion processes, formulations, and uses for rigid cellular PVC sheet that are found in North America and Europe are compared. The effect of certain types of formulation ingredients on sheet density, surface, and impact strength is described. Reference is made to coextrusion of solid/cellular PVC layers as an economically feasible approach to handling industrial regrind PVC.     

Evaluating recyclability of fly ash reinforced polyvinyl chloride foams

Using fly ash as a reinforcing filler can be very cost effective; however, the recycling of postconsumer products containing fly ash is of a considerable concern. In this study, the recycling of processed polyvinyl chloride (PVC) foam reinforced with fly ash was investigated by evaluating the effect of regrind content (up to 40 wt%) and fly ash content (up to 20 wt%) on the physical, mechanical, microstructural, and processing properties of the composites. Experimental results show an increase in the foam density with increasing regrind and fly ash contents. The melt viscosity increased with increasing the regrind concentration; however, it dropped with increasing the fly ash content. The tensile strength increased with increasing the regrind content, indicating a good degree of gelation in the composites. Meanwhile, the charpy impact strength of the composites decreased due to the high rigidity of fly ash particles. Dynamic mechanical analysis show that the storage modulus improved with both the addition and increasing the amount of regrind, which confirmed good stress transformation between the polymer foam matrix and the fly ash particles. The polymer matrix morphology, as was determined by scanning electron microscopy (SEM), confirmed uniform foam structure even with the addition of 40 wt% regrind in the virgin PVC. J. VINYL ADDIT. TECHNOL., 24:154–161, 2018. © 2016 Society of Plastics Engineers     

Compatibility study of recycled poly(vinyl chloride)/styrene‐acrylonitrile blends

The aim of the present study is to analyze the compatibility between recycled Poly(vinyl chloride) (PVC) and styrene‐acrylonitrile copolymer (SAN). With this objective recycled PVC coming from credit cards have been blended with both virgin and recycled SAN with the aim of increase the benefits of recycled PVC. The compatibility of the components will be crucial for the final properties of the material. Furthermore, the recycled nature of some of the components will determine the compatibilization capability of the blend. The degradation level in the recycled materials was determined using Fourier transform infrared spectroscopy (FTIR). The compatibility between the PVC and the SAN was studied using differential scanning calorimetry and dynamic mechanical analysis. A greater compatibility was observed in mixtures of PVC and virgin SAN than in mixtures of PVC and recycled SAN. Finally, a morphological study of the fracture surface under cryogenic conditions was carried out using scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Study on thermal,mechanical and morphological properties of recycled poly(vinyl chloride)/fly ash composites

The present study deals with the development of composite materials utilizing recycled poly(vinyl chloride) (r‐PVC) recovered from waste electrical and electronic materials and waste fly ash obtained from thermal power plants. The effect of the incorporation of fly ash on the mechanical, thermal and morphological properties of the r‐PVC matrix was studied. The primary characterization of r‐PVC and fly ash was done employing FTIR, EDX, particle size analysis and XRD analysis. Subsequently, fly ash with a particle size of approximately 9.29 μm was incorporated within the r‐PVC matrix. Composite sheets were prepared using a melt blending process followed by compression moulding. The mechanical test revealed an increase in the tensile strength and elongation at break of the r‐PVC/fly ash composite up to 30 wt% loading of fly ash beyond which there was a decrease in the tensile strength. The impact strength, however, decreased with increasing fly ash content in the r‐PVC matrix. The morphological properties of the composites showed a good distribution of the filler within the recycled matrix. The thermal properties of r‐PVC also improved with the incorporation of fly ash which was revealed from DSC and TGA studies. The water absorption test showed an increase in water uptake with the addition of fly ash in the r‐PVC matrix. © 2020 Society of Chemical Industry     

Processability,rheology, and thermal,mechanical, and morphological properties of postconsumer poly(vinyl chloride) bottles and cables

The processability, rheology, and thermal, mechanical, and morphological properties of three different commercial poly(vinyl chloride) (PVC) compounds blended with postconsumer PVC bottles and PVC cables were examined with respect to the recycled PVC content. The addition of PVC bottle recyclates [recycled bottles (RBs)] into virgin PVC bottle (VB) and virgin PVC pipe (VP) compounds caused a progressive reduction in the average torque. No thermal degradation or color change in the RB‐blended PVC compounds used was detected through carbonyl and polyene indices from IR analysis. The rheological properties for VP compounds were more sensitive to RB addition than those of VB compounds. The extrudate swell ratio did not change with the RB content. The decomposition temperature for the VB and VP compounds increased at 60–80% RB, whereas the glass‐transition temperature was unaffected by the RB loading. The 20 and 80 wt % RB loadings were recommended for the VB and VP compounds, respectively, for the optimum impact strength, the blends showing ductile fracture with a continuous phase. At the optimum impact and tensile properties, introducing RB recyclates into the VB compounds gave better results than the VP compounds. The hardness and density of the VB and VP compounds did not change with the RB content. The RB property change was comparatively faster than that of recycled PVC pipes. Adding the PVC cable recyclate [recycled cable (RC)] to virgin PVC cable (VC) had no obvious effect on the torque value of the RC/VC blends. The decomposition temperatures of the RC/VC blends stabilized at 20–60% RC and tended to decrease at 80% RC. The ultimate tensile stress was improved by the addition of the RC compounds, whereas the hardness and density of the VC compounds were unaffected by the RC content. It was concluded that the optimum concentrations of PVC recyclates to be added to virgin PVC compounds were different from one property to another and also depended on the type of virgin PVC grade used. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2738–2748, 2003     

Recycling of commingled plastics by cellulosic reinforcement

In this article, a model study was conducted on the effect of combining cellulose on the properties of virgin and/or recycled commingled plastics with a simulated waste‐plastics fraction composed of high‐density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), and poly(vinyl chloride) (PVC) (PE/PP/PS/PVC = 7/1/1/1 by weight ratio). The compatibilizing effect of maleic anhydride‐grafted styrene–ethylene/butylene–styrene block copolymer (SEBS‐g‐MAH) for the cellulose‐reinforced commingled blends was also investigated. Commingled blends were prepared in a table kneader internal mixer. Mechanical properties were measured by using a universal testing machine. Thermal stability was measured by a thermogravimetric analyzer. It was found that the addition of more than 12.5% cellulose into the commingled blends was effective to enhance the mechanical properties of the virgin and recycled blends. The thermal stability as well as the mechanical properties of the commingled blends were much improved by the reactive blending of cellulose with the commingled blends by peroxide and maleic anhydride. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1531–1538, 1999     

Evaluation and optimization of the mechanical properties of highly filled PVC/(wood flour) composites by using experimental design

In this study, PVC/(wood flour) (WF) composites were prepared by using a counterrotating twin‐screw extruder, and the effects on the mechanical properties of concentration and particle size of the WF, type and amount of coupling agent, K value of PVC, feed rate of extruder, and die temperature were investigated. Optimization of various formulation parameters based on the Taguchi method demonstrated that the wood content and wood particle size were the most important parameters. Flexural modulus increased upon increasing WF loading up to 50 wt%. Also, flexural strength and modulus increased with particle size because of the higher aspect ratio and better quality of mixing. Use of coupling agents had a minor effect that was attributed to the moderately high polarity of PVC causing relatively good compatibility between WF particles and the PVC matrix. The optimum level of WF calculated by considering the contribution factor was 50 wt%. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Recyclability of a glass fiber poly(butylene terephthalate) composite

The recyclability of a fiber-reinforced poly(butylene terephthalate) (PET) composite has been studied. After treatment with a suitable silane, processed regrind composites are successfully recycled, with mechanical properties as good as a comparable, commercial composite. The three processing techniques investigated are injection molding, extrusion compression molding and compression molding. As expected, processing technique and processing parameters are important in determining the mechanical properties of the molded regrind. Our results show that injection- and extrusion-compression-molded regrind composites have good fiber bundle dispersion and fiber alignment, resulting in tensile properties better than the compression-molded samples. On the other hand, compression-molded samples, which show random fiber orientation and low fiber bundle dispersion, have lower tensile properties, but better impact strength than injection- and extrusioncompression-molded composites.     

Influence of additional thermal stabilizers on the reprocessing of postconsumer poly(vinyl chloride) bottles

The addition of heat stabilizers is essential for preventing the degradation of poly(vinyl chloride) (PVC) during its processing. The heat stabilizers consumed in the first run have to be made up before the reprocessing of recycled PVC. In this study, solvent‐cast films, which were prepared from granulated postconsumer PVC bottles mixed with plasticizers and thermal stabilizers, were used. The films were subjected to various heat treatments. No considerable structural change upon heat treatments at 140–160°C was found in IR and differential scanning calorimetry analyses. Polyene formation observed through ultraviolet analysis was not severe, indicating that the added stabilizers worked well in preventing degradation. The weight loss during the heat treatments was attributed partly to the decomposition of PVC and the evaporation of volatile components and mainly to the removal of the solvent upon heating. Although this study was conducted with water bottles that were to be recycled, it may be equally well applied to other similarly formulated PVC‐based materials, such as packaging films. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3994–3999, 2003     

The development of poly(vinyl chloride) extrusions for a 14,000‐ton self‐supporting structure for the detection of neutrinos

The NOvA Neutrino Experiment has built a one‐of‐a‐kind self‐supporting plastic structure, potentially the largest ever built. The poly(vinyl chloride) (PVC) structure serves as a neutrino detector and is composed of 28 individual blocks that measure 15.5 m (51 feet) high by 15.5 m (51 feet) wide by 2.1 m (7 feet) deep. The primary parts in the detector construction are 15.5‐m (51‐foot), 16‐cell PVC extrusions. These extrusions form the basis of the detector modules, which are laminated together in a crossed pattern to form the individual blocks and then filled with (mineral oil)–based liquid scintillator. The self‐supporting nature of the detector places important structural requirements on both the PVC formulation and the extrusions. Block assembly requirements impose narrow geometric tolerances. Because of the method of detecting neutrinos, the extrusions must possess exceptionally high reflectivity over a particular wavelength range. This requirement places additional restrictions on the components of the PVC formulation. Altogether, the PVC extrusions have to maintain important reflectivity characteristics, provide structural support to the detector, and meet relatively tight geometric requirements for assembly. In order to meet these constraints, a custom PVC formulation had to be created and extruded. We describe the purpose and requirements of the NOvA detector leading to the production of our unique PVC extrusion, summarize the research and development process, and discuss the lessons learned. J. VINYL ADDIT. TECHNOL., 22:368–376, 2016. © 2014 Society of Plastics Engineers     

Highly filled polyolefin plastomer formulations for possible PVC replacement in flooring

Calcium carbonate highly filled composites of a polyolefin plastomer (POP), and its blends with postconsumer linear low‐density or high‐density polyethylene (PC‐LLDPE or PC‐HDPE) were prepared and evaluated. The mechanical properties of compounded POP and its blends were compared with those of a PVC–calcium carbonate formulation used for flooring applications. Tensile and impact properties of calcium carbonate‐filled POP composites compare very favorably to the PVC‐based formulation at filler loadings as high as 200 phr. Moreover, postconsumer LLDPE or HDPE can replace at least 50% of the POP in these composites without affecting their main properties. DSC analyses indicate that the synergism occurring in mechanical properties for some of the blend compositions, may be related to the ability of the individual polymers to cocrystallize in the respective blends. This article presents the results of a preliminary study. Continued research is expected to contribute toward a complete characterization of the compounded POP/postconsumer PE blends to establish if they can replace plasticized PVC compounds in some or all flooring applications. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1156–1168, 1999     

Processing and mechanical properties of recycled PVC and of homopolymer blends with virgin PVC

Mechanical and processing properties of recycled polyvinylchloride (PVC, from bottles and pipes) were compared with those of virgin pipe grade PVC. Blends of recycled and pipe grade PVC were also prepared and characterized. It was found that the particle size and the restabilization of the recycled PVC are the two main points to be considered for obtaining virgin/recycled PVC blends with uniform and good mechanical properties. In general, recycled PVC not only does not significantly reduce the modulus and tensile strength, but also improves the impact strength and processing behavior of pipe grade virgin PVC. Only the thermomechanical resistance is slightly lowered. The latter points hold, of course, only when the recycled PVC contains both reinforcing and modifier agents. © 1996 John Wiley & Sons, Inc.     

Prediction of mechanical properties of recycled fiberglass reinforced polyamide 66

An experimental study of the mechanical performance of in-plant recycled fiberglass reinforced polyamide 66 is reported. The fiber length distributions were used to investigate and to predict the influence of process induced fiber shortening on the short term performance of recycled samples compared to that of virgin samples. The results indicate that fiber shortening has a strong influence on strength. Applying a modified Kelly-Tyson model to the fiber length distribution gave excellent agreement with measured strength. There was no need to vary interface or matrix properties in the theoretical analysis. The effect of reprocessing on these factors does not appear to influence strength within the bounds of the model. The decrease in strength during a continuous in-plant recycling process is small at a 30 wt% regrind level. Indeed, below 50 wt% regrind, the strength remains within design limits. The impact strength of dry unnotched samples indicated that the resistance is related to the reciprocal fiber length.     

Preparation of intercalated Mg‐Al layered double hydroxides and its application in PVC thermal stability

The Mg‐Al oxide precursor prepared by the calcination of Mg‐Al‐carbonated layered double hydroxide (LDH) at 500 K for 4 h is used as the host material, 2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonic acid (BP) is used as the guest material, BP‐intercalated LDH (LDH‐BP) is prepared by ion‐exchange method. The structure of LDH‐BP is characterized by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), and thermogravimetry and differential thermal analysis (TG‐DTA). The thermal stability of PVC/BP, PVC/LDH, PVC/LDH‐BP composites, as well as pure PVC is investigated by conventional Congo Red test and dynamic thermal stability analysis in both the open and closed processing environments. According to XRD and FTIR, BP anions have been intercalated into interlayer galleries of LDH. TG‐DTA results show that the layer‐anionic interaction results in the improvement of the thermal stability of BP. Congo Red tests indicate that the addition of BP catalyzes the thermal degradation of PVC. A little amount of LDH (such as 1 phr) makes PVC more stable, but excessive addition accelerates the thermal degradation of PVC. The addition of LDH‐BP markedly improves the static thermal stability of PVC. The results of dynamic thermal stability tests in both the open and closed processing environments are consistent with that of Congo Red tests. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Improvement in the heat resistance of poly(vinyl chloride) profile with styrenic polymers

The styrenic polymers poly(α‐methylstyrene‐acrylonitrile) (α‐MSAN) and poly(acrylonitrile‐butadiene‐styrene) (ABS) and (three types) were used to improve the heat resistance of poly(vinyl chloride) (PVC). The glass transition temperature (T_g) and miscibility were analyzed by dynamic mechanical thermal analysis (DMTA). Effects of composition on heat distortion temperature (HDT) were investigated with the different styrenic polymers. Other physical properties such as mechanical properties and melt flow rate (MFR) were also determined. Morphology was observed by scanning electron microscopy (SEM) in order to support the mechanical property results. The PVC was miscible with α‐MSAN but partially miscible with the ABS series, and α‐MSAN was much more effective in enhancing the T_g and HDT of rigid PVC than the ABS series as for mechanical properties, the addition of α‐MSAN could improve the tensile strength, bending strength, and bending modulus but decrease the impact strength of the materials compared with the addition of the ABS series. Improvement in processability was observed in the MFR results with the addition of the styrenic polymers. On the basis of all the properties, the formulation with an α‐MSAN content of 30 phr (parts per hundred parts of resin) was superior for heat‐resistant PVC profile. The HDT of PVC could be increased from 76.9°C to 85.4°C (measured under the maximum bending stress of 0.45 MPa) and combined with good mechanical properties and processability by the addition of 30 phr of α‐MSAN. Also, a heat‐resistant PVC profile was successfully fabricated. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Stabilizations of molecular structures and mechanical properties of PVC and wood/PVC composites by Tinuvin and TiO2 stabilizers

Three different UV stabilizers, 2‐(2H‐benzotriazol‐2‐yl)‐4,6‐ditertpentylphenol (Tinuvin XT833), 2‐(2H‐benzotriazol‐2‐yl)‐p‐cresol (Tinuvin P), or rutile–titanium dioxide (TiO₂) were incorporated into poly(vinyl chloride) (PVC) and wood/PVC (WPVC) composite, and mechanical and physical properties and photostabilities were monitored. The polyene and carbonyl sequences of PVC increased with UV weathering time and with presence of wood flour. The yellowness index increased because of polyene and carbonyl productions, whereas the brightness increased because of the photobleaching of lignin in wood. The photostabilities of PVC and WPVC could be improved through the use of UV stabilizers. Tinuvin P was recommended in this work as the most effective stabilizer for PVC and WPVC composites. The stabilization effect was interfered by presence of wood particles. The mechanical property changes corresponded well to the structural changes under UV for neat PVC. For WPVC composites, the presence of wood particles played more significant effect on the mechanical properties during UV aging than the UV stabilizer. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Mechanical Properties and Morphology of Recycled. Plastic Wastes by Solution Blending

In this study, bottles of mineral water and yogurt as well as Styrofoam bowls were recycled and identified by infrared spectroscopy as poly(vinyl chloride) (PVC), high-impact polystyrene (HIPS), and polystyrene (PS). Solution blending was employed to make polymer blends from these recycled plastics, including PVC/PS, PVC/HIPS/PS blends, and PVC/HIPS blends with or without a com-patibilizer, styrenelp-chlorostyrene (ST-CMS). Thermal behavior from differential scanning calorimetry was used to examine the compatibility of the blends. For the PVC/PS and PVC/HIPS/PS systems, it is found that although the third component (HIPS) may not be good enough as a compatibilizer, the addition of HIPS to the two-component blend (PVC/PS) may enhance the mechanical properties at the specific composition, especially for the blends at the intermediate concentrations. For PVC/HIPS blends with the ST-CMS copolymer as a compatibilizer, all the mechanical properties of the blends except the elongation at break, in general, increased with increasing the concentration of compatibilizer due to the increase of compatibility. The abnormal fracture strain was attributed to the differences in adhesion when various amounts of ST-CMS was added. The results of mechanical properties of the blends were consistent with the morphology from scanning electron microscopy.     

Impact strength of high density microcellular poly(vinyl chloride) foams

The impact strength of microcellular poly(vinyl chloride) (PVC) produced from an industrial formulation was investigated. The solid‐state process with carbon dioxide as the blowing agent was used to prepare the specimens. Processing conditions were explored to produce microcellular PVC with a relative density of 0.6 and higher. These foams were impact tested by using a falling‐weight impact tester. Impact strength of microcellular PVC was found to decrease linearly with relative density. The gas saturation pressure did not significantly affect the impact strength of microcellular PVC foams. Microcellular PVC foams with up to 40% reduction in density possessed a normalized mean failure energy of 3.8 J/mm (0.85 in.‐lb/0.001 in.).     

PVC/wood‐flour composites compatibilized with chlorinated polyethylene

Chlorinated polyethylene has been demonstrated to be an effective compatibilizer for dissimilar materials in various mixed‐polymer or recycled‐polymer systems. In this paper the use of chlorinated polyethylene to compatibilize polymer/natural‐fiber composites is discussed. Examples of applications in PVC/wood‐flour composites are given.     

A study on fusion and rheological behaviors of PVC/SiO2 microcomposites and nanocomposites: The effects of SiO2 particle size

In this study, poly(vinyl chloride) (PVC) and silica (SiO₂) microcomposites and nanocomposites were prepared by melt mixing in a Haake torque rheometer. The fusion and rheological behaviors of PVC/SiO₂ composites were evaluated by means of torque data recorded during processing to investigate the influence of the SiO₂ particle size on these behaviors. It was found that the fusion time and the fusion temperature decreased with the decreasing of SiO₂ particle size, whereas the fusion torque increased with the decreasing of particle size. The PVC/Si‐25‐nm nanocomposite (PVC including the 25 nm of SiO₂) showed the highest apparent viscosity among the PVC/SiO₂ microcomposites and nanocomposites prepared in this study. Scanning electron microscopy results demonstrated that some aggregates, whose sizes about 60–90 nm, were formed when the 25 nm of SiO₂ was used as filler. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers