ISSN:0193-7197    

DOI:10.1002/vnl.730060402

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractA dynamic model for the continuous emulsion polymerization of vinyl chloride (VCM) in a train of stirred tank reactors has been developed. This model can predict monomer conversion, polymer particle size distribution (PSD), molecular weight distribution and long and short chain branching frequencies under non‐steady reactor operation during startup, reactor switching and during unstable operation when conversion and polymer and polymer particle properties oscillate with time. The model has been used to design a flexible reactor train configuration which operates in a stable mode and can produce latexes with a wide range of properties including a bimodal polymer particle size distributio

ISSN:0193-7197    

DOI:10.1002/vnl.730060403

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThe microstructure of suspension PVC primary particles has been revealed by scanning electron microscopy. The primary particles are composed of agglutinated domains which resemble linked sausage and in some cases are branched. Use of highly polished thin sections and special ion etching techniques appears responsible for revealing these microstructural features not previously reported by other investigators.

ISSN:0193-7197    

DOI:10.1002/vnl.730060404

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractIn this study, natural, delaminated and silane‐treated micas were screened to give fractions passing 60 to 325 screen mesh sizes. The micas were used as fillers (to 80 wt. percent) in plasticized PVC compounds, their dispersion behavior and their effects on mechanical properties of compounds being noted, and compared with the performance of similarly compounded PVC with CaCO3fillers. The fusion and dispersion performance of these solids was contrasted strongly. While fusion time and maximum torque in Brabender mixing responded only weakly to the presence of CaCO3, in the presence of ≳40 wt. percent mica both of these parameters increased sharply. The elastic modulus of filled compounds indicated little reinforcement by CaCO3, while mica raised the modulus as much as 150 percent, suggesting significant bonding at the filler‐matrix interface. This bonding appeared unable to withstand shear strain, elongations at rupture of mica‐filled compounds falling catastrophically when compared with CaCO3‐filled controls. The tested micas appear of questionable value as substitutes for inexpensive commodity fillers. As expected, at given loading, finer‐particle micas gave increased values of the elastic modulus, but particle size did not strongly affect ultimate mechanical properties. Torque maxima and equilibria in mixing correlated well with particle size. Silane‐treated micas produced compounds with properties only mildly different from those using untreated versions. Thus, in PVC (and possibly in other chloride‐group containing polymers) interfacial conditions seem only mildly influenced by conventional coup

ISSN:0193-7197    

DOI:10.1002/vnl.730060405

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper compares the performance of Estertin mercaptide, alkyltin mercaptide, barium/cadmium carboxylate, inorganic lead, and organotin carboxylate PVC heat stabilizers for exterior PVC profile applications. These stabilizers were all evaluated for heat stability performance, exterior and accelerated weatherability, and lubrication and processability. Since their lubrication characteristics vary greatly, several formulation modifications were employed including European and U.S. types. While all stabilizers could be processed acceptably into exterior rigid profiles, with the possible exception of the tin carboxylate, the Estertin mercaptide and the alkyltin mercaptide exhibited fewer processing difficulties. The barium/cadmium carboxylate provided the best weatherability at low titanium dioxide loadings. At high titanium dioxide loadings, only small differences could be detected between all types of stabilizers evaluated.

ISSN:0193-7197    

DOI:10.1002/vnl.730060406

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractEnvironmental stress cracking (ESC) (failure caused by crack and craze formation at a stress less than the yield stress) reduces the service life of many plastic products. This paper is concerned with ESC of rigid PVC products which are in contact with a plasticized PVC material. The ESC affect (as measured by elongation to break) is reduced at faster strain rates and by higher plasticizer viscosity, which suggests a mechanism requiring flow of plasticizer into a growing craze. Well fused (gelled) PVC made at a higher melt temperature slowed but did not eliminate environmental stress cracking. Rubber impact modifier added to the rigid PVC had no effect on ESC. Environmental stress cracking can be avoided by using flexible PVC that has a non‐migrating plasticizer or by designing the product so that rigid PVC is not stressed while in contact with plasticized PV

ISSN:0193-7197    

DOI:10.1002/vnl.730060407

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThere are technical, as well as economical, advantages to employ light‐stable polyvinyl chloride heat stabilizers for rigid weatherable applications. The desirable stabilizer systems should also be less or non‐toxic, without sulfur staining problem, with acceptable odor, with stable and competitive economics. Our research effort has been targeted towards worldwide applicability. Our earliest effort was to search for an active metal from the periodic table! Considerations were given to the fate of the metal chlorides formed in the PVC resin. Preliminary compounds were synthesized for screening. Subsequently, organic ligands were designed to control and to activate the molecule in the stabilization of polyvinyl chloride. Co‐additives, mostly conventional, were added to form stabilizer packages. Accelerated indoor light‐stability tests demonstrated the desired light‐stability against current stabilizer systems. Preliminary outdoor weathering data further supported the conclusion. The primary stabilizer has the following general structure:\documentclass{article}\pagestyle{empty}\begin{document}$${\rm (controlling ligand)}-{\rm (divalent metal)}-{\rm (activating ligand)}$$\end{document}The chemistry and stabilization mechanism will be discussed. The above patent pending technical innovation is revealed as a contribution of our research effort to the Vinyl Industry. The eventual product commercialization will be of interest to all, especially those involved in the rigid weatherable app

ISSN:0193-7197    

DOI:10.1002/vnl.730060408

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

摘要:

AbstractThere are many known methods for determining the particle size distribution of PVC dispersion resins. Most of these methods require that the resin be in an aqueous medium. PVC dispersion resins are used primarily in a plasticizer medium. The shearing action that takes place when the resin is mixed in plasticizer and the subsequent solvating action of the plasticizer affect the particle size distribution of the dispersion resin. It is advantageous to be able to determine the particle size distribution of the plasticized resin since it can affect various properties such as rheology, gloss and foam quality. It is the purpose of this paper to show that a fast zonal sedimentation technique can be used to analyze the less than 20 μ particle size fraction of a dispersion resin after it has been mixed in a plasticizer system. This can be accomplished in less than 90 minutes. This technique can be used to relate particular dispersion resin properties to the particle size distribution of the resin. The method can also be used as a quality control test

ISSN:0193-7197    

DOI:10.1002/vnl.730060409

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY

ISSN:0193-7197    

DOI:10.1002/vnl.730060401

出版商:Society of Plastics Engineers, Inc.    

年代:1984

数据来源: WILEY