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 uPVC window profile waste

Methods of recycling unplasticized polyvinyl chloride (uPVC) window frame waste were investigated. The quality of untreated granular waste was compared to that of waste treated by a range of contaminant removal processes including melt filtration and dissolution. Processability of each recyclate was evaluated by using a highly instrumented single screw extruder that enabled melt viscosity and process variation to be monitored in real time. Product quality measurements such as mechanical properties and surface defects were made on extruded strip, and the nature of the stabilizers present was determined. The mechanical properties of recyclates were found to be comparable to or better than those of virgin material in all cases and conformed to industry standards for window profile. Contaminant removal stages significantly reduced the amount of large surface defects detected in extrudate. Processability was comparable to that of virgin compounds, but melt viscosity varied among different batches of recyclate, depending on the source and composition of the original PVC formulation. J. VINYL ADDIT. TECHNOL., 11:119–126, 2005. © 2005 Society of Plastics Engineers     

Low‐temperature UV irradiation induced the color change kinetics and the corresponding structure development of PVC film

The low‐temperature ultraviolet (UV) irradiation equipment, developed in our Lab, was used to study the photo‐aging of poly (vinyl chloride) (PVC) films at low temperature. The color change kinetics and corresponding structure development of PVC film during low‐temperature UV aging were studied through L*a*b* coordinates Commission International d' Eclau‐age (CIE 1976 color space) and Ultraviolet spectrophotometer (UV–vis) and Fourier transform infrared spectroscopy (FTIR). It was found that the yellowness difference (?b*) and color difference (?E*) of the PVC film increased almost linearly with the aging time. Their values had a slower change at lower temperature. The kinetic study showed that the relationship between the velocity of coloration of the PVC film and the temperature agreed well with Arrhenius equation at low temperature. The activation energy of coloration of the PVC film was calculated. The FTIR spectra indicated that photo‐dehydrochloration, resulting in the generation of conjugated carbon–carbon double bonds, was the main reaction for PVC during photo‐aging at low temperature. Meanwhile, the photo‐oxidation was also obvious and could not be neglected. It clearly confirmed that the absorption peaks of conjugated carbon–carbon double bond increased and shifted to longer wavelength during photo‐aging in the UV‐abs analysis. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Crystallization and chemi‐crystallization of recycled photodegraded polyethylenes

Test bars (3 mm thick) made from a high‐density polyethylene (HDPE), a low‐density polyethylene (LDPE), and a linear low‐density polyethylene (LLDPE) were injection‐molded from virgin polymer and from blends containing recycled photodegraded polymer of the same kind. The molded bars were then subjected to ultraviolet (UV) exposure. Crystallinity measurements were made at different depths from the exposed surface using differential scanning calorimetry. The effects caused by processing and photodegradation were separated by comparing thermograms obtained in the initial DSC run and in a reheating run, respectively. Chemi‐crystallization was produced by UV exposure. The results are interpreted in terms of molecular scission and photo‐initiated molecular defects. Scission accounts for the observed chemi‐crystallization, whereas the molecular defects inhibit crystallization and eventually limit chemi‐crystallization. After remelting, crystallization of the photodegraded materials is influenced both by the molecular mass distribution and by the defect content of the material. The changes in crystallization behavior caused by photodegradation are different for the three polyethylenes. The results obtained using blends that included photodegraded recyclate were consistent with this material acting as a pro‐degradent. The recyclability of the materials is discussed. POLYM. ENG. SCI., 45:588–595, 2005. © 2005 Society of Plastics Engineers     

Real‐time monitoring of laser photochemical reactions of polyvinylchloride

The formation of conjugated double bonds in polyvinylchloride (PVC) films by ultraviolet (UV) irradiation is analyzed using an in situ laser‐monitoring technique we have developed to measure changes in transmittance of thin UV‐irradiated PVC films. Conjugated polyenes of different lengths are produced by laser irradiation at 193 and 248‐nm wavelengths. This technique promises to have broader applications in the study of polymer reaction mechanisms and kinetics. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 59–63, 2000     

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     

Study on lanthanum‐pentaerythritol alkoxide as a thermal stabilizer for rigid polyvinyl chloride

Lanthanum‐pentaerythritol (La‐PE) alkoxide, a polyol‐based metal alkoxide, had been synthesized and used as a thermal stabilizer for polyvinylchloride (PVC) . Thermogravimetric (TG), differential thermal analysis (DTG), mass spectrum (MS), and Fourier transform infrared (FTIR) spectroscopy were used to confirm the synthesis reaction. The thermal stability of rigid PVC stabilized with La‐PE was tested by means of the Congo Red test, conductivity test, thermal aging test, thermal gravimetric analysis (TGA), and UV‐visible (UV‐vis) spectroscopy. The results showed that addition of La‐PE could significantly prolong static stability time of PVC and increase the apparent activation energy for degradation reaction. The oven aging test showed that La‐PE could improve the initial color of PVC. Moreover, addition of La‐PE could significantly reduce the concentrations of the conjugated double bonds of PVC and reduce weight loss . The possible thermal stability mechanism had also been discussed. Besides having good ability to neutralize hydrochloric acid (HCl), La‐PE could substitute or inactivate the labile chlorine atoms in the PVC chains. J. VINYL ADDIT. TECHNOL., 23:55–61, 2017. © 2015 Society of Plastics Engineers     

Photodegradation of some poly(vinyl chloride) (PVC) blends: PVC/ethylene-vinyl acetate (EVA) copolymers and PVC/butadiene-acrylonitrile (NBR) copolymers

Poly(vinyl chloride) (PVC) and its blends with polybutadiene-acrylonitrile (NBR) (containing 21.7 weight-percent acrylonitrile (AN), a heterogeneous two-phase system; and containing 41.6 weight-percent of AN, a homogeneous one-phase system) and with polyethylene-vinyl acetate (EVA) (containing 45 weight-percent of vinyl acetate (VA), a heterogenous two-phase system; and containing 65 weight-percent VA, a homogeneous one-phase system) were UV-irradiated (at 3500 Å UV-light (solar spectrum)). After UV irradiation the kinetics measurements were made of the formation of hydroperoxy (OOH) and carbonyl (CO) groups and the changes of mechanical properties: tensile strength, elongation to break, and impact energy. As a result of the photooxidative degradation of PVC blends, decreases of mechanical properties were observed. The effects are more severe in PVC/NBR blends, which contain unsaturated bonds (polybutadiene segments) than in the case of PVC/EVA. The phase structure plays an evident role on the UV degradation only of PVC/NBR blends. The photostability of PVC blends can be slightly improved by introducing Tinuvin P or Ni-chelates photostabilizers.     

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     

Blends of poly(vinyl chloride) (PVC)/natural rubber‐g‐(styrene‐co‐methyl methacrylate) for improved impact resistance of PVC

To improve the mechanical properties of poly(vinyl chloride) (PVC), the possibility of combining PVC with elastomers was considered. Modification of natural rubber (NR) by graft copolymerization with methyl methacrylate (MMA) and styrene (St) was carried out by emulsion polymerization by using redox initiator to provide an impact modifier for PVC. The impact resistance, dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM) of St and MMA grafted NR [NR‐g‐(St‐co‐MMA)]/PVC (graft copolymer product contents of 5, 10, and 15%) blends were investigated as a function of the amount of graft copolymer product. It was found that the impact strength of blends was increased with an increase of the graft copolymer product content. DMA studies showed that NR‐g‐(St‐co‐MMA) has partial compatibility with PVC. SEM confirmed a shift from brittle failure to ductility with an increase graft copolymer content in the blends. The mechanical properties showed that NR‐g‐(St‐co‐MMA) interacts well with PVC and can also be used as an impact modifier for PVC. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1666–1672, 2004     

A study of the processing characteristics and mechanical properties of multiple recycled rigid PVC

This study focuses on the ability of U‐PVC to be processed a number of times. Three different types of U‐PVC were investigated: virgin lead‐stabilized material; virgin calcium/zinc‐stabilized material; and reground, 20‐year‐old, post‐consumer windows. Each material was extruded four times, without any addition of any stabilizers. Samples were taken at each stage for rheological and mechanical analysis. J. Vinyl Addit. Technol. 10:174–178, 2004. © 2004 Society of Plastics Engineers.     

苯乙烯类塑料耐老化性能研究

对纯聚苯乙烯(PS)、高抗冲聚苯乙烯(HIPS)、PS/(苯乙烯/丁二烯/苯乙烯)共聚物(SBS)共混物、添加助剂的PS和HIPS等5组试样进行紫外光加速老化。表征了5组试样老化前后的力学性能、特性粘度、分子链结构的变化。研究表明,紫外光加速老化使材料的力学性能降低,表层发生龟裂;表层的溶液粘度下降较明显,距厚度大于0.4mm时其粘度下降缓慢;傅立叶变换红外光谱谱图中在1720cm-1处出现明显的吸收峰,表明有CO生成;纯HIPS、添加助剂的HIPS和PS/SBS共混物在910、966cm-1处的吸收峰强度明显减弱,表明发生了烯烃碳碳双键的断裂,添加助剂的HIPS老化后的透过率保持率最高。     

Mechanochemical improvement of the flame‐retardant and mechanical properties of zinc borate and zinc borate–aluminum trihydrate‐filled poly(vinyl chloride)

In this study, the effect of the high‐energy mechanical milling of a mixture of poly(vinyl chloride) (PVC) with zinc borate (ZB) or ZB–aluminum trihydrate (ATH), a mixture of ZB and ATH, on the flame‐retardant and mechanical properties of ZB and ZB–ATH filled PVC was examined. The high‐energy mechanical milling of PVC/ZB and the PVC/ZB–ATH mixture produced chemical bonding between PVC and ZB or ZB–ATH, increasing the interfacial interaction of PVC/ZB and PVC/ZB–ATH blends, which resulted in a great increase in the limiting oxygen index, the impact and yield strengths, and the elongation at break of PVC/ZB and PVC/ZB–ATH blends. The results from ultraviolet spectroscopy and gas chromatography–mass spectroscopy show that mechanochemical modification of ZB and ZB–ATH much more effectively suppressed the release of aromatic compounds in PVC/ZB and PVC/ZB–ATH blends during burning. Mechanochemical modification provided an excellent route for the improvement of the flame‐retardant and mechanical properties of flame‐retardant‐additive‐filled PVC. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 753–762, 2003     

马来酸酐对PVC／CaCO3力学性能的影响

在PVC加工过程中，通过共混，使马来酸酐（MAH）中的双键与PVC降解形成的共轭双键发生Diels—Alder加成反应，MAH接枝到PVC分子链上，改善了PVC与CaCO3的相容性，提高了PVC与CaCO3的粘接力，从而提高了PVC／CaCO3的力学强度。     

马来酸酐对PVC/CaCO_3力学性能的影响

在PVC加工过程中,通过共混,使马来酸酐(MAH)中的双键与PVC降解形成的共轭双键发生Diels-Alder加成反应,MAH接枝到PVC分子链上,改善了PVC与CaCO3的相容性,提高了PVC与CaCO3的粘接力,从而提高了PVC/CaCO3的力学强度。     

Synergistic effect of hindered amine light stabilizers/ultraviolet absorbers on the polyvinyl chloride/powder nitrile rubber blends during photodegradation

The photostability of hindered amine light stabilizer (HALS) and ultraviolet absorber (UVA) on the blends of plasticized poly (vinyl chloride) (PVC) and powder nitrile rubber (NBR) has been studied with a Xenon Test Chamber. The digital photos, color differences, attenuated total refection‐Fourier transform infrared (ATR‐FTIR) spectra and mechanical properties of the blends have been determined. HALS combined with UVA effectively protects PVC/NBR blends from yellowing and restrains the decrease of elongation at break of the blends. The synergistic phenomenon is ascribed to the different photostable mechanisms of HALS and UVA at different photo aging stages. The color of PVC/NBR control sample quickly changes into yellow at the first 400 h of irradiation, due to the polyenes structures that induced by the double bonds of butadiene in NBR. From 400 to 800 h, crosslinking dominates and the amount of polyenes decreases, resulting into the decrease of color change. At the early stage of irradiation, chain‐scission of polymer takes the predominant place, and the tensile strength decreases. But during the latter stage, crosslinking takes the predominant place and the tensile strength increases slightly. HALS and UVA have a little effect on the maintaining of elongation at break of PVC/NBR blends. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers     

Study of poly(vinyl chloride)/acrylonitrile–styrene–acrylate blends for compatibility,toughness, thermal stability and UV irradiation resistance

A novel rigid poly(vinyl chloride) (PVC)/acrylonitrile–styrene–acrylate (ASA) copolymer blend with good ultraviolet (UV) irradiation resistance and toughness was reported. ASA with good weatherability and toughness was mixed with PVC by conical twin‐screw extruder to improve the UV irradiation resistance and toughness of PVC. The blends were characterized using Fourier‐transform infrared spectra, dynamic mechanical analysis, and scanning electron microscope. Notch Charpy impact test was used to characterize the UV radiation induced changes in toughness. The results showed that ASA was able to toughen PVC with simultaneously improving heat resistance, thermal stabilization, and protecting PVC from irradiation photochemical degradation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2143–2151, 2013     

Insights into the use of zinc–mannitol alkoxide as a novel thermal stabilizer for rigid poly(vinyl chloride)

Zinc–mannitol alkoxide (Zn–Man) was synthesized through alcohol exchange reaction, and investigated by means of Fourier transform infrared spectroscopy and elemental analysis. The thermal stability of Zn–Man for rigid poly(vinyl chloride) (PVC) was evaluated by Congo red testing, conductivity measurements, thermal aging testing, thermogravimetric analysis (TGA), and ultraviolet–visible (UV–vis) spectroscopy test. The experimental results demonstrate that the addition of Zn–Man not only apparently prolonged the static thermal stability time to approximately 96.5 min but also evidently improved the initial color of PVC. More importantly, the color of the PVC sheets stabilized with Zn–Man did not change to black within 180 min; this showed that no zinc‐burning phenomenon occurred. In addition, the results of TGA reveal that Zn–Man raised the initial degradation temperature of PVC to about 273.4°C. UV–vis testing indicated that the presence of Zn–Man decreased the content and shortened the length of the conjugated double bonds of PVC. The possible thermal stability mechanism is discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42038.     

Surface modification strategies for multicomponent polymer systems. III: Effect of diblock copolymer‐modified rutile on the morphology and mechanical properties of LLDPE/PVC blends

Rutile pigment was surface‐modified by the adsorption of various diblock copolymers and used as a component in two‐ and three‐component polymer blends involving the incompatible pair of linear, low‐density polyethylene (LLDPE) and poly(vinyl chloride) (PVC). Stress–strain analyses and electron microscopy show that the copolymer tethered to the rutile surface affects both mechanical and morphological properties of the blends. Inverse gas chromatography was used to evaluate dispersion surface energies and acid–base interaction parameters of the various solids. The mechanical and morphological characteristics of the blends can be rationalized by the concepts of acid–base and dispersion–force interaction. Of the copolymer modifiers used, the diblock based on polyisoprene and poly(4‐vinyl pyridine) (PIP‐P4VP) was best suited for use in LLDPE/PVC blends, ostensibly because of strong acid–base interaction between PVC and P4VP and mechanical interlocking between LLDPE and the PIP moiety. The properties of ternary blends were shown to be dependent on the method used for mixing the components. All mixing procedures used here resulted in time‐dependent variations of mechanical properties, suggesting that none gave rise to equilibrium morphology in the compounds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1891–1901, 2001     

Application of Real Time FTIR and MAS NMR Spectroscopy to the Characterization of UV/EB Cured Epoxidized Natural Rubber Blends

The UV curing of blends consisting of epoxidized natural rubber (ENR), cycloaliphatic diepoxide (ECC) and glycidyl methacrylate (GMA) induced by cationic photoinitiator was studied by real time FTIR. This technique revealed the individual reactivity of epoxy groups and double bonds under UV exposure and thermal postcuring. The epoxy groups of ECC reacted more rapidly compared to those of ENR and GMA. In addition, ¹³C CP MAS NMR showed that acrylic double bonds of GMA are more reactive than isoprenic ones of ENR under EB exposure. It is assumed that only few linkages exist between the diepoxide and the methacrylate interpenetrating network via GMA molecules. The stable embedding of ENR particles via chemical bonds causes toughening of the epoxy matrix while maintaining a desired hardness.