摘要:

AbstractThere are occasions and causes why and wherefore in all things.—Henry V, V.i.

ISSN:0193-7197    

DOI:10.1002/vnl.730140102

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractCurrent designs put automotive instrument panels and other interior trim parts under severe heat and light stress. Vinyl by itself can easily be formulated to pass the most rigorous oven aging and light stability tests. With a semirigid polyurethane foam backing, as is currently used in these applications, even the most stable vinyls fail to pass proposed new specifications. This study deals with the mechanism of what occurs in the polyurethane backed vinyl to cause this instability.

ISSN:0193-7197    

DOI:10.1002/vnl.730140103

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractAn important characteristic of a resin is the speed with which the polymer can be processed with the plasticizer in the plant, or its dryblending characteristics. The dryblending behavior of the polymer is dependent upon its microstructure and macrostructure. It is well known that some degree of porosity is required in order to obtain good dryblending properties; however, there are also other factors which affect the dryblending. Another factor, which is defined as the Swelling Index, is identified, and the use of this to help characterize dryblending behavior of different resins is discussed.

ISSN:0193-7197    

DOI:10.1002/vnl.730140104

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractIn the absence of mixed metal carboxylates, triaryl phosphites react rapidly with a model allylic compound for degrading vinyl, cinnamyl chloride, to yield phosphonium salts. On heating, these appear to yield allylidene phosphoranes by 1,1 elimination of HCl, with subsequent rearrangement to diphenyl phosphonates. With aryl alkyl phosphites, the phosphonium chloride intermediate undergoes rapid Arbusov rearrangement to the diphenyl phosphonate, eliminating alkyl chloride (or corresponding olefin). In the presence of zinc or cadmium carboxylates, Arbusov rearrangement is intercepted and chloride is transferred instead to the metal, forming the alkyl ester. The observed reaction paths appear to yield insight into the question of which phosphites are optimum for particular metal carboxylate blends and ratios in vinyl stabilizers, and into the related topic of which types of other additives are inappropriate.

ISSN:0193-7197    

DOI:10.1002/vnl.730140105

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractLead stabilized uPVC potable water pipe was successfully formulated and produced to comply with the health effects criteria established by the National Sanitation Foundation (NSF). The maximum allowable level (MAL) of lead extraction, from products that come in contact with drinking water, is specified in the new NSF Standard Number 61 as 5.0 µg/L (or, 5 parts per billion, ppb). Samples of uPVC pipe stabilized with 0.3 phr (parts per hundred parts of resin) of tribasic lead sulfate stabilizer were tested in accordance with the procedures of NSF Standard Number 61, and the extraction results were all below 2 ppb lead at both pH 5 and pH 10. Continued, daily extractions showed that the amount of lead released into drinking water fell below quantitation levels within one week, in agreement with previous findings reported in the scientific literature. Thus, lead stabilized uPVC potable water pipe has been shown to be safe and in compliance with established health effects criteria

ISSN:0193-7197    

DOI:10.1002/vnl.730140106

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractPVC profile extrusion compounds have a unique morphology. While other polymers gradually decrease in extrusion die swell with increasing length/thickness (L/D) ratio, PVC profile extrusion compounds have a low die swell, quite independent of the die's L/D ratio in the range of 5 to 20. The fact that the die land length can be changed without changing the extrudate swell is an important consideration, which makes die design and balancing dies simpler and easier for PVC profile extrusion compounds. While other polymers substantially increase extrudate swell with increased shear rate, the swell of the PVC profile compounds is not much affected by shear or extrusion rate. This unique behavior allows wider processing latitude in profile extrusion and faster extrusion rates than with other polymers. Another unique factor in the rheology of PVC profile extrusion compounds is that extrusion die swell increases with increasing melt temperature, while other polymers have decreasing die swell with increasing melt temperature. The unusual rheology of PVC profile extrusion compounds is attributed to its unique melt morphology, where the melt flow units are 1 um bundles and molecules that have low surface to surface interaction and entanglement at low processing temperatures but increased melting and increased entanglement at higher processing temperatures. Other polymers, unlike PVC, have melt flow at the molecular level.

ISSN:0193-7197    

DOI:10.1002/vnl.730140107

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractAssessing the degradation of electrical cable insulation is an important feature in extending plant life. The older generating stations are extensively wired with PVC insulated cables, and procedures have been developed to assess degradation using micro specimens in a manner that does not destroy the function of the cable. Material degradation of accelerated aged specimens was systematically monitored by measuring melting or glass transition temperatures (Tg), gel content, infrared peroxide absorbance, relative hardness, and plasticizer loss. The shift in theTgor the characteristic melting peak predicted the maximum exposure temperature of the PVC. The peroxide absorbance and gel content measurements were sensitive indicators of degradation. The relative hardness as measured by thermo‐mechanical analyzer (TMA) penetration distance and plasticizer content decreased as the material aged. The results obtained on micro specimens were related to the ultimate elongation values, which have been the traditional measure of degradatio

ISSN:0193-7197    

DOI:10.1002/vnl.730140108

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractBecause PVC mixes very slowly with plasticizer, analogs of PVC were used to obtain heats of mixing via direct calorimetry. Initial studies were done with DBP, DOP, and DOS plasticizers and chloroform, 1,3‐dichloropropane, and 2,4‐dichloropentane as the analogs. Simultaneous calculations for the enthalpy of mixing were done using the UNIFAC‐FV model. Both the propane and the pentane derivatives behaved according to the predictions of UNIFAC. Both experiments and calculations suggested that 1,3‐dichloropropane is a better model for PVC than 2,4‐dichlo

ISSN:0193-7197    

DOI:10.1002/vnl.730140109

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractPoly(vinylchloride) compositions containing 0–24 v% of copper and 0–48 v% of aluminium powders were prepared and their d.c. electrical conduction and ultrasound wave propagation at 2, 3, 6, 9 MHz were studied. Segregated network formation by the filler as evident by photomicrograph. DTA and X‐ray diffraction, drastically reduces the electrical resistivity in these composites. The limiting resistivity of PVC/Cu composite is 31.62 ohm‐cm and that of PVC/Al composites is 1258 ohm‐cm. Ultrasound wave propagation through these composites having segregated network of fillers shows that absorption at 9 MHz is more in copper filled PVC than in aluminium filled PVC. Dispersion at 9 MHz is more in aluminium filled composites than in copper filled composites. Other parameters, such as excess absorption, relative velocity, relative modulus were evaluated. No definite correlation exists between electrical conduction due to segregated network formation and ultrasound wave pr

ISSN:0193-7197    

DOI:10.1002/vnl.730140110

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY

摘要:

AbstractThe effects of temperature in twin screw extrusion of a window profile compound have been studied. Compounds were made with and without an acrylic impact modifier. Fusion levels of the extruded profiles were rated from values of the rubbery plateau modulus at temperatures near 110°C. Impact strength was measured at room temperature using notched tensile specimens at 1 m/s jaw separation rate. The impact strength of these materials does not increase with fusion level once an adequate degree of gelation has been achieved. The impact‐modified compound shows a dramatic improvement in impact strength when the melt temperature was increased from 319°F to 343°F. A further increase to 365°F had no effect. The compound without impact modifier exhibited no improvements in impact strength over the whole extrusion temperature range. Conflicting reports in the literature on effects of fusion level on impact strength of PVC articles probably reflect different interactions between extrusion conditions and compound compos

ISSN:0193-7197    

DOI:10.1002/vnl.730140111

出版商:Society of Plastics Engineers    

年代:1992

数据来源: WILEY