Polypropylene/styrene‐ethylene‐butylene‐styrene thermoplastic elastomer nanocomposite films

Nanocomposite (polypropylene/styrene‐ethylene‐butylene‐styrene/organoclay) films were sheet‐extruded with differing clay concentrations. Blends were compounded using a high shear single screw reciprocating kneader. Results demonstrated that higher clay content increased the Shore A hardness of the films but induced a significant improvement in both O₂ and CO₂ barrier performance. J. VINYL ADDIT. TECHNOL., 13:46–52, 2007. © 2007 Society of Plastics Engineers.     

Thermal and structural effects of poly(vinyl chloride)/(wood flour) compound gelation in the Brabender mixer

The processing of two unplasticized compounds of poly(vinyl chloride) (PVC) with and without wood flour (WF) was performed in a Brabender mixing chamber, at various chamber temperatures between 130 and 200°C and at a shear rate of 12.61 s^?1. The test was carried out up to the time corresponding to the equilibrium state of the torque, and the variations of torque and real melt temperature as functions of time were analyzed. It was found that the addition of WF led to fusion at lower chamber temperature and that during gelation, stronger self‐heating effects occurred in the WF‐filled PVC compound. Various characteristics of the real temperature gelation curves of PVC with and without the WF filler were observed and are discussed. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

Effect of precipitated calcium carbonate on the mechanical properties of poly(vinyl chloride)

This study examines the effect of various grades of precipitated and ground calcium carbonate on the tensile strength and Charpy impact energy of extruded PVC profile. The results confirm that ultra‐fine precipitated calcium carbonate (pcc) can give rise to large improvements in single notch impact strengths. Control values of 9 kJ/m^?2 were increased to 79 kJ/m^?2 through the addition of ultra‐fine pcc. The results have been interpreted in terms of the particle size, shape, and coating of the calcium carbonate grades and the effect on the gelation characteristics of the PVC formulations. J. VINYL ADDIT. TECHNOL., 13:98–102, 2007. © 2007 Society of Plastics Engineers.     

Optimization of plastisol processes by dynamic mechanical analysis

Dynamic mechanical analysis (DMA) can be a particularly useful tool for studying PVC plastisol manufacturing processes. DMA temperature sweeps are uniquely able to characterize plastisol gelation and fusion behavior under low shear stress conditions that are similar to conditions found in many commercial plastisol processing operations. Dynamic mechanical analysis is also well‐suited for studying plastisol melt viscosities at low shear rates such as might be encountered in a flexible PVC foaming process or rotomolding process. Likewise, DMA rate sweeps or strain sweeps can give insights into self‐association and flow properties in a plastisol which ordinary viscometers cannot provide. J. VINYL ADDIT. TECHNOL., 13:151–154, 2007. © 2007 Society of Plastics Engineers     

The melting temperature (or not melting) of poly(vinyl chloride)

The best answer to what is the melting temperature of PVC is its previous processing temperature. That temperature is where secondary crystallites, created by gelation, melt and allow the primary particle flow units to flow again independently. In the case of powder compounds being processed for the first time, the question of melting is less relevant. The PVC, out of the polymerizer, contains crystallites that are not completely meltable. The issue is how easily the grains of PVC disperse to primary particle flow units. This property depends on polymerization conditions and the type of processing equipment. The temperature achieved affects the amount of fusion (gelation). J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.     

A brief overview of theories of PVC plasticization and methods used to evaluate PVC‐plasticizer interaction

This paper reviews the most widely used models for explaining how plasticizers render PVC flexible. These models include the gel, lubricity, and free volume theories; kinetic theories; and mathematical models which predict on the basis of plasticizer structure how much a plasticizer will lower the polymer glass transition in a flexible PVC compound. Since plasticization results from interactions between plasticizer and polymer, methods which have been used to study either the strength or the permanence (or both) of those interactions are also briefly discussed. Tools which have often been used to study plasticizer‐PVC interactions include infrared and nuclear magnetic resonance spectroscopy, compression and humid‐aging tests, dynamic mechanical analysis, torque rheometer tests, plasticizer‐resin clear point temperature measurements, plastisol gelation/fusion by hot stage measurements, and others. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Nanoscopic characterization of a plastisol gelation and fusion process utilizing scanning electron microscopy and atomic force microscopy

Understanding the physical properties associated with the gelation and fusion of a PVC plastisol will help to improve process efficiency. Plastisol gelation and fusion were characterized by using both scanning electron microscopy (SEM) and atomic force microscopy (AFM) and were compared with the tensile properties developed at various temperatures. Both SEM and AFM showed good agreement during the early stages of gelation. However, AFM continued to show particle boundaries during the latter stages of gelation and fusion that provided a more nearly accurate comparison with the resulting tensile properties. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.     

U‐PVC gelation level assessment,part 1: Comparison of different techniques

Several different gelation assessment methods such as differential scanning calorimetry, capillary rheometry, solvent absorption, wide angle x‐ray scattering, transmission electron microscopy, and atomic force microscopy were applied to a typical PVC window profile formulation subjected to various thermomechanical histories. Shear applied during the process could be decomposed into two components: (i) a thermal component corresponding to the self‐heating that was generated and (ii) a “mechanical” component associated with a “pure” shearing action deprived of any thermal aspect. Shear sensitivity of the above‐mentioned gelation assessment techniques was evaluated by considering both aspects. Gelation levels established by differential scanning calorimetry and capillary rheometry were especially compared, thus allowing a comparison of the two physical aspects evidenced by each technique, i.e., crystallite melting and macromolecular network development. It appeared that as soon as the PVC particulate structure had been fragmented into micronic entities (primary particles) the gelation process was governed mainly by the thermal aspect, i.e., crystallite melting. J. VINYL. ADDIT. TECHNOL. 12:98–107, 2006. © 2006 Society of Plastics Engineers.     

Considerations affecting landfill biodegradability of PVC

The combination of tin carboxylate heat stabilizer and a dimethylaminopropyl methacrylamide‐titanate adduct enables anaerobic landfill decomposition of plasticized poly(vinyl chloride) (PVC). Through a mechanism as yet not understood, the above combination directs decomposition under anaerobic conditions to chain scission, thus lowering molecular weight to the point of vulnerability to microorganisms. J. VINYL ADDIT. TECHNOL., 13:133–135, 2007. © 2007 Society of Plastics Engineers     

Lubrication mechanism of poly(vinyl chloride) compounds: Changes upon PVC fusion (gelation)

Poly(vinyl chloride) (PVC) compounds perform best with adequate metal lubrication and polymer‐to‐polymer lubrication of PVC primary particle flow units. Much of the mechanism for the lubrication of PVC has been elucidated over the years. One point has not been completely understood, which is the “lubricant failure” at higher processing temperatures where the compound is known to become less ductile. This result is contrary to what might be expected with better PVC fusion (gelation). This article discusses the mechanism involved, which is lubricant inversion, where the lubricant goes from the continuous phase, as a surfactant coating all the PVC primary particle flow units at lower melt temperatures, to become the discontinuous phase at higher melt temperatures. J. VINYL. ADDIT. TECHNOL., 11:57–62, 2005. © 2005 Society of Plastics Engineers     

Lubrication,single screw extrusion rates,and plasticizer structure in flexible PVC compounds

It is well‐established that changes in plasticizer structure affect (among other things) the melting temperatures, melt viscosities, and lubrication of flexible PVC compounds. In turn, these properties affect the extrudability of the compounds. The current study looks at the effects of plasticizer structure on lubrication, melt viscosities, extrusion rates, stock temperatures, and shear rates of PVC compounds in a single screw extrusion process. J. VINYL ADDIT. TECHNOL., 13:22–25, 2007. © 2007 Society of Plastics Engineers.     

Polypropylene/polysulfone compatibilized blends

Polypropylene and polysulfone have not been previously blended because of viscosity and processing temperature differences. These blends, which showed structure‐property improvements with the addition of functional polyolefins, were made into environmentally friendly membranes. J. VINYL ADDIT. TECHNOL., 13:143–146, 2007. © 2007 Society of Plastics Engineers     

Use of nonpolar processing aids to improve the efficiencies of extruded polyolefins

The addition of nonpolar processing aids has been shown to widen the processing window for manufacturers of polyolefin film and other extruded products. Opportunities exist to run lines stably at faster speeds with power savings. The benefits of using a nonpolar processing aid in blown film are discussed. J. VINYL ADDIT. TECHNOL., 13:155–158, 2007. © 2007 Society of Plastics Engineers     

One step forward to a sustainable green solution for extruded foam PVC building products

This paper is dedicated to the development of a robust and cost‐effective formulation to maximize the use of recycled poly(vinyl chloride) (PVC) back into its virgin compounds. This study concludes that a balanced stabilizer and lubricant formulation will overcome the detrimental effects of repeated heat history on the recycled/regrind PVC. The developed formulation using up to 70% of recycled/regrind PVC has been successfully implemented in the extrusion process for manufacturing high‐quality foam PVC profiles for the building industry. As a result, this study takes a huge step forward toward a green and sustainable solution for PVC applications. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

UV light resistance of biocides for PVC/wood fiber composites

Several of the biocides most commonly used in PVC compositions were exposed to UV‐A radiation for periods up to 2000 hr in order to determine the effects on their ability to protect various wood fibers from colonization by bacteria and fungi. Three species of bacteria and three fungi, all known to metabolize cellulose, were used. The ability of these species to exist by predation on their competitors also was studied. J. VINYL. ADDIT. TECHNOL. 12:124–126, 2006. © 2006 Society of Plastics Engineers     

Optimization of fusion behavior of the nanocomposites based on poly(vinyl chloride)/poly(epichlorohydrin‐co‐ethylene oxide)/organoclay

In this work, poly(vinyl chloride)/poly(epichlorohydrin‐co‐ethylene oxide) (PVC/ECO)/organoclay nanocomposites were prepared via melt processing and their fusion behaviors were comprehensively investigated. In this way, response surface methodology was employed to study the main and interactive effects of three parameters (Cloisite 30B content, ECO content, and rotor speed) on fusion of the PVC matrix. The results showed that ECO rubber has a negative influence on the fusion process, while optimal levels of other parameters are appropriate. Furthermore, the interactive plots revealed significant mutual effects of the parameters. Also, optimized levels of the parameters for achieving the best response were obtained by using contour plots. Since additives in PVC compounds have considerable effects on the fusion phenomenon, the results of the present study could be important from industrial point of view. J. VINYL ADDIT. TECHNOL., 25:98–105, 2019. © 2018 Society of Plastics Engineers     

Processability of PVC plastisols containing a polyhydroxybutyrate‐polyhydroxyvalerate copolymer

Plastisols based on polyvinyl chloride (PVC) can be processed by different techniques; their processability markedly depends on their flow properties and gelation/fusion processes. Classically, PVC has been the only polymer present in plastisol formulations. The present work explored the possibility of adding polyhydroxyalkanoates (PHAs), a type of biopolymer that, according to previous work, exhibits a good miscibility with PVC processed by other techniques (internal mixer and compression molding). The influence of PHA particles on flow properties, gelation‐fusion processes, tensile strength, hardness, and processability by rotomolding was evaluated. Although the biopolymer markedly increased the viscosity of PVC plastisols and caused a decrease in tensile strength in processed specimens, formulations including 20% by weight of biopolymer presented a good thickness distribution in rotomolded items, an elongation at break of around 300%, and an ultimate tensile strength of around 6–7 MPa. J. VINYL ADDIT. TECHNOL.,, 2012. © 2012 Society of Plastics Engineers     

Processing of precipitated nongranular PVC in the brabender measuring mixer

The structure and properties of processed poly(vinyl chloride) (PVC) depend on temperature, shear rate, operations time, and morphology of the PVC grains. The aim of our research was the preparation of a nongranular PVC and the examination of its processing during kneading in a Brabender plastographometer in comparison with the processing of commercial PVC. It was stated that grains of virgin PVC‐S61, a commercial suspension resin, cause a self‐heating of the compound during kneading in such a way that point X of the plastograms occurs at a temperature 15°C lower than that of precipitated PVC (i.e., PVC without grains). As a result of self‐heating, time of compound processing needed to reach point depends largely on the grain morphology of the PVC. The less compact structure, the smaller bulk density, and the greater absorption of plasticizer, result in a longer processing time. Homogeneous, loosely packed particles of powder and the crystalline structure of precipitated PVC are different from PVC‐S61 morphology and cause a high degree of gelation and low melt flow rate values for compounds processed at 175°C and higher. J. VINYL ADDIT. TECHNOL., 18:147–152, 2012. © 2012 Society of Plastics Engineers     

The effects of maleated polybutadiene‐grafted polypropylene (MAPB‐g‐PP) content on the properties of wood flour/polypropylene composites

This research investigated the effects of a compatibilizer of maleated polybutadiene‐grafted polypropylene (MAPB‐g‐PP) on the properties of wood‐flour/polypropylene composites through the analysis of mechanical properties, water absorption, thermogravimetry, differential scanning calorimetry, and scanning electronic microscopy. The results demonstrate that the mechanical properties of composites were significantly increased; the thermal stability and water absorption were improved. The crystallization temperature and crystallinity were decreased. These improvements have been attributed to the strong interfacial interaction of MAPB‐g‐PP with both wood and polypropylene. J. VINYL ADDIT. TECHNOL., 26:17–23, 2020. © 2019 Society of Plastics Engineers     

Effects of processing on the structure of PVC/montmorillonite composites. I. Melt and solution processes

The effects of processing conditions on the structure of poly(vinyl chloride) (PVC)/clay composites were investigated. Dry‐blending conditions were shown to affect composite structure in compression‐molded samples. PVC/(Cloisite Na) nanocomposites could not be prepared by melt compounding. Partially exfoliated and intercalated PVC/(Cloisite 30B) nanocomposites could be prepared by melt compounding. The effects of the grain structure of PVC resin and the PVC fusion mechanism on nanocomposite formation were considered. The particulate structure of the PVC resin was found to restrict the distribution ofclay, which could be improved by increasing the processing temperature. Almost fully exfoliated PVC/(Cloisite 30B) nanocomposites were prepared from solutions in tetrahydrofuran, and the plasticizer migration resistance of these composites was substantially improved. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers