Structure–property relationships of lightly chemical crosslinked poly(vinyl chloride) thermoplastic elastomer

Chemical crosslinked poly(vinyl chloride) (C‐PVC) was synthesized by vinyl chloride suspension polymerization in the presence of diallyl phthalate (DAP) and plasticized to prepare poly(vinyl chloride) (PVC) thermoplastic elastomer (TPE) materials. The chemical crosslinking and physical crosslinking structure in chemical crosslinked PVC‐TPE were investigated. It showed that the gel fraction and the crosslinking density of gel increased as the feed concentration of DAP increased. C‐PVC prepared by VC/DAP copolymerization was lightly crosslinked as compared with irradiation crosslinked PVC. Physical entanglements would greatly influence the crosslinking density of gel when the gel fraction was high. Chemical crosslinking had little influence on the recrystallization behavior of PVC. A structure model of chemical crosslinked PVC‐TPE was proposed, in which chemical networks acted with physical networks cooperatively. It also showed that chemical crosslinking and physical crosslinking influenced the processability and mechanical properties of chemical crosslinked PVC‐TPE cooperatively. Although the processability of PVC‐TPE deteriorated with chemical crosslinking, the dimension stability and elasticity of PVC‐TPE were improved as the permanent chemical networks were introduced. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 868–874, 2000     

Influences of contents and molecular weights of LDPE on DOP plasticization of PVC

Influences of contents and molecular weights of low‐density polyethylene (LDPE) on dioctyl phthalate (DOP) plasticization in the poly(vinyl chloride) (PVC) plastisol (PVC/DOP/AO = 100/30/6.5) were investigated using DMA and DSC. The plasticization effects of DOP on the PVC plastisol were found to decrease with increasing LDPE content. A negligible plasticization effect of DOP on the PVC plastisol was found when the LDPE content was equal to or higher than 75 parts per 100 parts by weight of LDPE and PVC together. Based on thermal fractionation experiments, a favorable interaction between LDPE and DOP was developed during melt blending of LDPE and the PVC plastisol. The present interaction enabled the incorporation of DOP into LDPE and decreased the plasticization effects of DOP on the PVC plastisol. A further decrease in the plasticization effects of DOP on the PVC plastisol by the presence of LDPE was found with increasing LDPE molecular weights. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2548–2555, 2002     

Meaningful evaluation of plastisol gelation and fusion temperatures by dynamic mechanical analysis

In most PVC plastisol processing operations, gelation and fusion characteristics of the plastisol are critically important. For example, in chemically foamed plastisols, plastisol fusion temperature and blowing agent decomposition temperature must be carefully coordinated. In rotomolded parts, rates of gelation may determine the quality of the finished parts. For plastisol products made by any process, the final fusion temperature determines the processing temperatures required to give the finished product acceptable mechanical properties. For a variety of reasons, the methods commonly used to characterize plastisol gelation and fusion (hot bar test, resin in plasticizer clear point, torque rheometer measurements, etc.) provide comparisons between plastisols but do not provide temperatures that are easily related to actual industrial processes. With dynamic mechanical analysis (DMA), one can characterize, under low shear conditions, the temperatures at which gelation begins, gelation ends, and complete fusion occurs. Additionally, it is possible to record plastisol viscosities (and other dynamic mechanical properties) over the processing temperature range. We used a multiple linear regression program to analyze the DMA data for plastisols heated from 30 to 210°C and containing either 70, 80 or 90 phr of Jayflex dihexyl phthalate (DHP) or Jaylflex di-isodecyl phthalate (DIDP). Further, we determined the plasticizer phr dependence and the reproducibility of gel and fusion temperatures given by data analyzed in this manner. Finally, for comparison, we analyzed the reproducibility of initial and final plastisol gel temperatures and fusion temperatures, which were determined by visually analyzing the DMA data for plastisols containing 70, 80, and 90 phr of Jyflex plasticizers DHP, Jayflex 77, diisononyl phthalate (DINP), and DIDP. Precise characterization of plastisol gelation and fusion behavior will, undoubtedly, facilitate substitution of plastisol ingredients as is often required by those who manufacture and process plastisols.     

A rheological study of the ageing of emulsion and microsuspension-based PVC plastisols

A PVC plastisol is a homogeneous dispersion of PVC resin in a liquid continuous phase consisting basically of a plasticizer and a thermal stabilizer; the PVC resin being usually a fine powder is polymerized by emulsion or microsuspension processes. Plastisol rheology is affected by many aspects of the plastisol formulations, such as type and amount of each ingredient, the mixing procedure, temperature, and the effect of PVC resin properties. In this work, the ageing behavior of PVC plastisols with different resin types was studied, with the results showing an unexpected behavior in the elastic modulus, probably originating from plasticizer adsorption at the surface of the PVC particles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Structure and properties of poly(vinyl chloride)‐triallyl cyanurate plastisols

Triallyl cyanurate (TAC) has been used as a reactive plasticizer to promote the high‐temperature creep resistance of poly(vinyl chloride) (PVC) plastisols. The resultant crosslinked structure is characterized using gel content and swell ratio measurements as well as Fourier transform infrared spectroscopy. The crosslinking reaction was initiated using peroxide. The effect on the network structure of using a free radical scavenger in the formulation has also been studied. The gel yield and crosslink density in the gel increase with increasing TAC concentration in the plastisol, while the grafted PVC fraction and the residual unsaturation of TAC behave in the opposite way. Introduction of TAC into the plastisol promotes creep resistance at high temperatures, and the logarithmic creep rate was found to decrease linearly with increasing crosslink density.     

Modification of poly(vinyl chloride). XXXIII. Novel poly(vinyl chloride) foam crosslinked with 6-dibutylamino-1,3,5-triazine-2,4-dithiol

The formulation for producing the PVC foam crosslinked with a novel crosslinking agent such as 6-dibutylamino-1,3,5-triazine-2,4-dithiol (DB) was studied to determine the processing conditions. DB was almost consumed by radical combination with a coexistent blowing agent such as azobisformamide to give a high-density foam with excessively low crosslinking density. Blowing agents such as p-toluenesulfonylhydrazide (TSH) and 4,4′-oxybis(benzenesulfonylhydrazide) (OBSH) gave a crosslinked foam of low density, while a combination of the two crosslinking agents had moderate crosslinking reaction rate. The formulation recommended in the present study consists of PVC Zeon 101EP or Zeon 121 for paste, 100 parts; DOP, 100 parts; DB, 3–5 parts; OBSH or TSH, 10 parts; MgO, 1–3 parts; and RP101 (mixture of Ba, Ca, and Zn stearate), 2 parts, which gave colorless and insoluble foam of apparent density 0.14 under hot pressing at 180°C. The molded foam could be released without extraction of heat from a hot mold for fusion and expansion.     

种子微悬浮聚合法制备微胶囊相变材料

以苯乙烯(St)和二乙烯基苯(DVB)为壁材聚合单体,偶氮二异丁腈(AIBN)为引发剂,羟丙基纤维素(HPC)和碳酸钙(Ca CO3)为复合分散剂,用种子微悬浮聚合法制备交联聚苯乙烯(PS)包覆硬脂酸丁酯微胶囊。用扫描电子显微镜(SEM)、差示扫描热量仪(DSC)、粒度分析仪和热重分析仪(TG)表征了微胶囊的形貌和性能,考察了聚合方法、交联剂和分散剂对微胶囊形貌结构和性能的影响。结果表明,种子微悬浮聚合法制备的微胶囊呈粒径分布均匀、规整的球形结构,与常规悬浮聚合法制备的微胶囊相比,相变潜热提高了41.6%,包覆率提高15.1%;随着DVB用量的增加,壁材的交联度增大,微胶囊密封性和热稳定性提高;采用复合分散剂且m(HPC)∶m(CaCO_3)=2.2∶1时,微胶囊相变潜热提高了26.8%。     

阻燃型NBR改性PVC软质泡沫塑料的研制

在以聚氯乙烯（ PVC）为主体材料、加入丁腈橡胶（ NBR）共混改性、用化学交联模压一步法制备改性 PVC泡沫塑料的基础上,选用阻燃型增塑剂氯化石蜡（ CP）、阻燃剂 Sb2O3进行阻燃型 NBR改性 PVC软质泡沫塑料的制备研究。结果表明,当用 PVC 100份 (质量份,下同 )、 NBR 60份、邻苯二甲酸二辛酯 30份、 CP 30份、 Sb2O3 8份、偶氮二甲酰胺 4.0份、 N,N′－二亚硝基五次甲基四胺 4.0份、过氧化二异丙苯 1.0份及适量稳定剂时,可使 NBR改性 PVC软质泡沫塑料的氧指数达到 27.0％,综合力学性能较好。电镜分析表明,阻燃型 NBR改性 PVC软质泡沫塑料的泡孔分布均匀性不如非阻燃型同类产品的好。     

Preparation of crosslinked and thermostable paste poly(vinyl chloride)

The grafting of a mercaptoalkyltrialkoxysilane onto an activated poly(vinyl chloride) (PVC) paste resin with subsequent hydrolytic crosslinking has been studied. The resins were prepared by copolymerization of vinyl chloride monomer and glycidylmethacrylate (GMA). The grafting of a mercaptosilane was carried out during gelation of the plastisol. In this step the formation of a chemical network was avoided. By steaming at 120°C for 30 min the grafted samples crosslinked. The gel yield increased with increasing fraction of GMA and up to a given level with the fraction of the mercaptosilane. When using a resin of PVC homopolymer no crosslinking occurred. The silane grafted and crosslinked samples were found to have satisfactory thermal stability. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:849–853, 1998     

The effects of plasticizers on the properties of poly(vinyl chloride) foams

The effects of plasticizers on poly(vinyl chloride) (PVC) plastisol mixtures were investigated. The investigations were carried out by determining the density of the PVC foam obtained by gelling the plastisol, as well as its elasticity and degree of expansion. Two series of experiments using different types of PVC were performed, using eight plasticizers, individually or as mixtures. Two-component plasticizer mixtures showed better properties than single-component plasticizers, and mixtures of di-iso-heptyl phthalate (DiHP) and butyl benzyl phthalate (BBP) proved to be the most appropriate. The effect of plasticizer amount also was investigated, and of the three parameters studied, the foam density, which steadily increased with plasticizer amount, was the critical one. It was also shown that in order to obtain consistent results, the foam expansion had to be precisely timed and the temperature carefully chosen.     

Rheometric study of the gelation and fusion processes of poly(vinyl chloride‐co‐vinyl acetate) plastisols with different commercial plasticizers

Evolution of the complex viscosity of pastes of PVC‐VA (vinyl chloride‐vinyl acetate copolymer) plasticized with different commercial plasticizers has been studied. Knowledge of the rheological behavior of the formulations allows for better understanding of the gelation and fusion processes. Twenty commercial plasticizers of different types and with different functional groups have been studied and are grouped into five families: phthalate esters with linear chains, phthalate esters with branched chains, adipates (normal and polymeric), citrates, and rest of the plasticizers (carboxylates, alkylsulfonates, and pentaerythritol ester derivatives). Interesting relationships among the observed rheologies and the nature and molecular weight of the plasticizer have been observed. The evolution of the complex viscosity with temperature—at the temperatures where the blowing agents normally used in PVC plastisol foaming processes generate the main amount of gas—has been newly discussed with regard to the chemical structure and molecular weight of all of the plasticizers used. It was found that several different dynamic processes must be synchronized in order to understand the relationships among the chemical structure, plasticization, plasticizer compatibility, rheological properties, and foaming process of such materials. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

粉末NBR和交联剂在PVC／HDPE中的增容－交联作用

用抽提、示差扫描量热仪、扫描电镜和拉伸试验等方法，研究了粉末丁睛橡胶（Ｐ－ＮＢＲ）与以过氧化二异丙苯、三烯丙基异氰尿酸酯和ＭｇＯ组成的交联体系对ＰＶＣ／ＨＤＰＥ（５０／５０）共混物的增容－交联协同作用。单独加交联剂时主要发生ＨＤＰＥ的自交联，并使共混物形成半互穿网络结构，从而提高其力学性能；如再加入Ｐ－ＮＢＲ，则可明显促进两组分的相互分散，使交联剂聚集在两相的界面，ＰＶＣ和ＨＤＰＥ间产生大量互交联，从而显著提高共混物的力学性能。     

Characterization of resol resins modified by the addition of PVC plastisols

Plastisols, which are a blend of poly(vinyl chloride) resin and a plasticizer (DEHP), were used as a toughening agent of a resol resin in order to improve the mechanical properties. It was not possible to formulate resol blends by adding more than 10 % of plastisol owing to a lack of apparent homogeneity in the systems, which also showed many air bubbles. The relationship between dynamic mechanical, mechanical and thermal properties and the amount of plastisol added was studied. It was determined from the infrared spectroscopy and dynamic mechanical results that the resol–plastisol blends seem to be formed by a reaction between the phenol and PVC giving a higher crosslinked structure. An improvement in the thermal resistance of the blends at lower temperatures was observed with an increase in the percentage of plastisol. Flexural analysis showed the elastic behaviour of the systems. However, it was not possible to observe the effect of the plasticizer (DEHP) owing to the low quantity of plastisol that was added to the resol. Copyright © 2004 Society of Chemical Industry     

Effect of molecular weight on the surface morphology of crosslinked polymer particles in the RITP-dispersion polymerization

The RITP (reverse iodine transfer polymerization)-dispersion polymerization of methyl methacrylate (MMA) was conducted and the molecular weight and SEM images of them were investigated to propose the mechanism of the formation of surface morphology in crosslinked polymers. The morphology of the crosslinked particles varied depending on the sorts and contents of the crosslinking agents and iodine. As the iodine content increased under the same content of the crosslinking agent, the average molecular weight of the polymers [uncrosslinked portion of the polymers] decreased and the surface roughness simultaneously reduced. On the other hand, as the contents of the crosslinking agent increased, the molecular weight of polymers reduced and the surface morphology changed from smooth to rough in the absence of iodine. On the other hand, was the molecular weight was barely changed and the solubility increased upon iodine. Thus the mechanism of the formation of crosslinked polymers in the RITP-dispersion polymerization was proposed as the following; when crosslinking agent and iodine were simultaneously involved, the low molecular weight of polymers were first formed due to the effect of iodine and then the crosslinking was taking place, resulting in that iodine was a critical factor in controlling the molecular weight, particle size, solubility and the surface morphology in the crosslinked polymer particles.     

Preparation of novel reactive plastisol based on poly(vinyl chloride) and multifunctional acryl esters

Poly(vinyl chloride) (PVC) powder was mixed with various polyfunctional acryl monomers as plasticizers to prepare acrylate‐modified plastisols. This class of plastisol was hardened into the B stage without reaction and then cured into a harder material through crosslinking of the acrylate. The best formulation was attained after evaluation of various acrylates, PVC grades, and peroxides. Several difunctional acrylates with solubility parameters similar to that of PVC could be most conveniently used as the plasticizer. A sheet molding compound was obtained by the combination of the resultant plastisols with glass fiber by compression molding using conventional machines. It was cured into a PVC‐based fiber reinforced plastic with high performance. This class of acrylate‐modified plastisol is called reactive plastisol. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1794–1801, 2000     

Some effects of irradiation on properties of filled PVC compounds

Compounds based on poly(vinyl chloride) (PVC), and containing CaCO₃ filler and trifunctional acrylic crosslinking agent have been crosslinked by exposure to γ-rays at dosages to 70 kGy. The crosslinking agent was found to be essential for crosslinking to proceed, only minor sensitivity to the irradiation having been found in compounds omitting the chemical. The presence of filler somewhat inhibits crosslink effectiveness, as measured by solvent uptake data. Elastic moduli and elongations at rupture respond to crosslinking processes, the latter being particularly sensitive to the effects of irradiation. The presence of filler was found to raise modulus, while ductilities of compounds were greater than expected, owing to adhesion at polymer/filler interfaces. Favorable acid/base interaction forces appear responsible for the effect. The reduced sensitivity of filled PVC compounds to γ-ray exposure is attributed to polymer immobilization, the consequence of strong interfacial bonding with the filler.     

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     

混合法PVC糊树脂聚合反应机制研究

介绍了混合法PVC糊树脂的聚合工艺特点和配方设计理论基础,详述了混合法聚合工艺中VCM乳液聚合和微悬浮聚合的机制。     

Surface protection of poly(vinyl chloride) by photografting of epoxy–acrylate coatings

UV-curable epoxy–acrylate coatings were used to protect poly(vinyl chloride) against superficial degradation. With α-hydroxy–acetophenone photoinitiators, the crosslinking polymerization develops in the ms time scale; 50% degree conversion is reached after irradiation times of 2.5 ms in a nitrogen atmosphere and 17 ms in air. The adhesion of the coating on to the PVC substrate can be greatly improved by inducing a photochemical grafting process. The best results are obtained by incorporating the photoinitiator into the top layer of the PVC sheet. Highly crosslinked epoxy–acrylate coatings are very stable toward UV radiations and chemical agents like organic solvents and strong acids. By their light-screening effect they provide an excellent protection against photodegradation for light-sensitive polymeric materials.     

Feasibility study of water as thinner for polyvinyl chloride plastisol

In the traditional formula of polyvinyl chloride (PVC) gloves, the diluent of PVC plastisol is usually organic solvent, which causes serious environmental pollution during the molding process. The aim of this study was to develop a low viscosity PVC plastisol emulsion (PDE) using water as a thinner by blending PVC emulsion (PVCE) with diisononyl phthalate (DINP) emulsion. DINP emulsion (DINPE) was prepared by a compound emulsifier of polyoxyethylene octyl phenol ether-10 and sorbitan monooleate. The effects of compound emulsifier concentration on the stability and microstructure of DINPE were investigated. The results showed that the optimal compound emulsifier concentration of DINPE was 10 wt%. In addition, the PDE obtained by blending exhibited a relatively uniform unimodal droplet size distribution. The steady state data revealed that the emulsions were shear-thinning pseudoplastic liquid. The effect of solid content and temperature on the apparent viscosity of PDE were also evaluated. The mechanical spectra obtained suggested the presence of weak gel structure in the PDE. The mechanical test results showed that the tensile strength and elongation at break of PVC film obtained by PDE were 12.62 MPa and 310.31%, respectively. This study demonstrated that water was effective in reducing the viscosity of PVC plastisol, which would promote the application of water thinner in glove production.