ISSN:0193-7197    

DOI:10.1002/vnl.730100202

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe strain‐induced crystallization (SIC) behavior of vinylidene chloride/vinyl chloride (VDC/VC) copolymer is reported as a function of the uniaxial extension ratio and the temperature of the rubbery amorphous specimen. The copolymer studied was an 88/12 wt/wt VDC/VC copolymer with a weight average molecular weight of 100,000 containing liquid additives that function as processing aids. It was found that SIC is initiated at an extension ratio of approximately 3.5, independent of the stress and stretching temperature. The growth rate of the crystalline phase increases sharply with extension ratio above 3.5. The crystalline phase growth rate at a given extension ratio also increases sharply with temperature between 15°C and 35°C. The implications of film temperature control during bubble expansion on the blown film process are discus

ISSN:0193-7197    

DOI:10.1002/vnl.730100203

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractSpecimens of amorphous VDC/VC tube taken immediately after the water quench bath on the blown film process were stretched uniaxially and biaxially using a T. M. Long film stretcher. The stress and temperature responses were monitored. The crystalline content as a function of time was calculated based on an energy balance and the observed temperature response. It was found that SIC kinetics shows a similar dependence on extension ratio (ER) for the uniaxial and biaxial cases. The crystallization rate increases rapidly when an extension ratio of 3.5 is first reached in either the machine direction (MD) or transverse direction (TD). However, significantly greater engineering and true stress values are reached for biaxial stretching than for uniaxial stretching. This is due to the greater molecular alignment in the plane of the specimen versus the thickness direction and to the lesser specimen thickness for the biaxial case. The copolymer studied was an 88/12 wt/wt VDC/VC copolymer with a weight average molecular weight of 100,000 containing liquid additives that function as processing aids.

ISSN:0193-7197    

DOI:10.1002/vnl.730100204

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractA general theory of diffusion of large molecules in rubbery amorphous polymers is of interest for the scientific understanding and with regard to material design and process optimization. A broadly applicable model would be useful in developing controlled transport of plasticizers and other additives through polymeric substances. A diffusion model is presented which has been developed for large molecular penetrants above theTgof the amorphous polymer allowing for required increase in redistribution of the free volume of the polymer structure, as well as the penetrant size and shape. Applicability of the model is demonstrated by comparing theoretically developed diffusion curves for DNOP and DNDP in PVC vs. their weight fractions at 82°C and 91°C. These theoretically derived plots are compared with experimental D vs.w1curves for these systems generated at lower temperatur

ISSN:0193-7197    

DOI:10.1002/vnl.730100205

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractFlory‐Huggins interaction parameters, χ, have been determined as a function of plasticizer composition for poly(vinyl chloride) in various binary mixtures of phthalate ester plasticizers using a method involving the micro‐determination of the temperature at which PVC particles in excess plasticizer appear to melt. An optimum composition at which χ goes through a minimum was found to exist for some of the systems. A good correlation between the apparent melting temperaturetmand χ for the neat plasticizers with PVC was also estab

ISSN:0193-7197    

DOI:10.1002/vnl.730100206

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe applicability of a modified version of UNIFAC group contribution method, UNIFAC‐FV, is explored for use in predicting liquid‐liquid equilibrium behavior of plasticizer/PVC systems. A Fortran program for the UNIFAC‐FV model has been written to calculate the activities and changes in the Gibbs free energy for multicomponent systems. By this means, the interaction parameter X for a polymer‐solvent system is defined using the well known Flory‐Huggins equation. The concentration dependent Gibbs free energy of mixing is used as a criterion for the relative compatibility of the PVC‐plasticizer system. The method indicates that, for the plasticizers examined, DOS is the least compatible and DBP is the most compatible with PVC. This confirms the results of the glass transition width measured by dynamic mechanical analysis previous

ISSN:0193-7197    

DOI:10.1002/vnl.730100207

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe conventional test method for evaluating the potential of a material to produce smoke in a real fire is the NBS Smoke Density Chamber. However there are major problems with this approach. These include foremost the fact that its results do not correlate with those of real fires. Furthermore, materials that melt and drip are able to achieve a favorable, but misleading, evaluation because a significant fraction of the sample escapes the burning process. Another problem is that the test takes no account of the role the rate or extent of material burning plays in controlling the smoke density in a real fire situation. The physical problems are solved by material smoke production evaluation techniques based on measurements from the Cone Calorimeter rate of heat release apparatus, which has been developed by the National Bureau of Standards. A smoke parameter has been developed, calculated from cone calorimeter measurements, which reflects the smoke hazard of a real fire. The smoke evolution characteristics for a series of rigid thermoplastic materials have been measured using the cone calorimeter and the smoke parameter concept. The results demonstrate that due to its tendency to resist ignition and to burn very slowly, PVC would produce very little smoke in a real fire situation. Of the 15 materials tested, the expected real fire smoke performance characteristics of PVC were superior to those of all other materials except one.

ISSN:0193-7197    

DOI:10.1002/vnl.730100208

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractAmong the most feared toxic chemicals known to man is 2,3,7,8‐tetrachlorodibenzodioxin (TCDD). PVC is a source of chlorine in waste and therefore it has been contended that its means of disposal should not be incineration. It is argued that the chlorine content of non‐PVC sources is in excess of that needed for dioxin production and therefore exclusion of PVC from municipal waste will have little effect upon harmful emissions. This investigation presents evidence substantiating this conc

ISSN:0193-7197    

DOI:10.1002/vnl.730100209

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractFlexible and semi‐rigid PVC formulations with high oxygen indexes and low smoke densities, as measured by the NBS Smoke Test (ASTM E662‐83) in both flaming and non‐flaming modes have been identified. The feasibility of a significant reduction of HCl emission from PVC compounds has been demonstrated in concept, and appears to be achievable when accompanied by increased oxygen index and/or significant reductions in rate of heat release and in smoke density, when measured in both the non‐flaming and flaming modes. PVC compounds, including those incorporating the kind of improvements outlined here for experimental prototypes, may be expected to compete in the future in both performance and price compared to other plastics ma

ISSN:0193-7197    

DOI:10.1002/vnl.730100210

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY

摘要:

AbstractThe shear level was increased during twin screw extrusion of PVC at different melt temperatures by inserting a hole plate in front of the screw tips. The variation of shear level did not significantly affect the capillary pressure in capillary viscometry at 135°C. However, the falling weight impact strength was markedly influenced. In internal water pressure tests at 60°C premature failure was obtained for pipes extruded at 198°C at the highest shear lev

ISSN:0193-7197    

DOI:10.1002/vnl.730100211

出版商:Society of Plastics Engineers    

年代:1988

数据来源: WILEY