ISSN:0193-7197    

DOI:10.1002/vnl.730130202

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY

摘要:

AbstractCompression‐molded sheets of plasticized poly(vinyl chloride) (PVC) were prepared to investigate plasticizer migration phenomena into paraffin oil environment. Interest is focused on prior sample history: Specimens from sheets of different dioctyl phthalate (DOP) contents are maintained in the liquid medium until the plasticizer concentration drops to a predetermined value. Then they are switched into “fresh” paraffin oil, at the same immersion temperature, to compare long‐term migration behavior with that of new sheets of this predetermined plasticizer content, i.e., excluding the prior desorption cycle. The results obtained reveal restriction of the migration activity for the two‐stages

ISSN:0193-7197    

DOI:10.1002/vnl.730130203

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY

摘要:

AbstractRecently, cadmium‐containing additives for plastics have been designated as undesirable environmentally. Prior to this adverse characterization of cadmium derivatives most flexible vinyl in the United States involving severe stabilizer demand during processing or service utilized metal blends based on cadmium salts. As a result many vinyl formulators have been forced to find suitable alternatives. Replacement of a stabilizer composed of specific levels of barium/cadmium salts in flexible vinyl with another containing the same levels of barium/zinc has been found to give dramatically reduced performance in heat stability tests. Results of this study has shown that satisfactory replacement of barium/cadmium/zinc or barium/cadmium systems in flexible vinyl is possible with barium/zinc stabilizers. This replacement appears to depend on higher barium‐to‐zinc ratios than those utilized in barium/cadmium analogs, use of special ligands that compensate for the smaller sized zinc cation; and prevention of their destruction by inadvertent addition of compet

ISSN:0193-7197    

DOI:10.1002/vnl.730130204

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY

摘要:

AbstractMany varied articles for the health care industry are produced by extrusion and injection molding processes using poly(vinyl‐chloride). Until recently, a mixture of 12% ethylene oxide/88% dichlorodifluormethane (Freon 12) was used to sterilize PVC based components and sets by chemical fumigation. In 1978 EPA reported ethylene oxide to be carcinogenic and mutagenic and established a 50 ppm exposure which was later lowered to 1 ppm. Likewise, Freon 12 came under regulation and is currently being taxed. These developments resulted in an industry need to be furnished with a viable replacement for ethylene oxide sterilization. Gamma irradiation was selected for this purpose as an economical and effective method. This study shows that a rigid PVC compound can be commercially produced that satisfies the critical balance of properties required for the medical device market and also can be sterilized by gamma irradiation without adversely affecting critical propertie

ISSN:0193-7197    

DOI:10.1002/vnl.730130205

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY

摘要:

AbstractThis discussion of the past regulatory trends and current developments for the vinyl industry will provide an overview of the regulatory world that producers and fabricators of poly(vinyl‐chloride) face today, with some projections of what the future may hold. By considering past regulatory trends and current developments, projecting future developments can be more than mere speculation. Because environmental issues are very complex and challenging, the overview begins and concentrates there. The focus will also discuss OSHA regulations, pending actions of EPA, California's Proposition 65, and Consumer Product Safety Commission's regulation of phthalates. The overview will conclude with an analysis of projected specific regulatory actions including: reducing VCC emissions, additional restrictions on land disposal, demands that vinyl products demonstrate that they fit the general solution to the solid waste crisis, and coping with state and local regulations that pose conflicting or unreasonable requirement

ISSN:0193-7197    

DOI:10.1002/vnl.730130206

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY

摘要:

AbstractDespite industry protests to the contrary, in September, 1989, few people believed that PVC bottles were recyclable in the same sense that PET soft drink bottles and HDPE milk bottles were. At that time, however, OxyChem announced its post‐consumer recycling initiative, offering to buy bottles back from anywhere in the United States. By paying prices comparable to that of PET ($0.06–$0.10/1b) and paying the freight from the recycler's dock, recycled PVC has begun to appear. Collection is handled by existing waste haulers and recyclers as an addon to their overall program. Promotional materials were generated to aid in visual separation of PVC from other plastics; in addition, automated sortation is being engineered by two laboratories with financial assistance from the Vinyl Institute. In general, PVC is reprocessed in the same fashion as other plastics: it must be ground, washed, and pulverized or repelletized. Care must be taken to minimize heat history and in some cases to boost stability and lubricity before pelletization. Material is resold into permanent, semi‐permanent and packaging applica

ISSN:0193-7197    

DOI:10.1002/vnl.730130207

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY

摘要:

AbstractOn March 29, 1990, EPA promulgated the Toxicity Characteristic (TC) greatly expanding the amount of waste considered hazardous. The rule became effective six months later on September 25, 1990. Under the TC, wastes are evaluated using the Toxicity Characteristic Leaching Procedure (TCLP) to determine if the waste is hazardous. Regulatory levels were established for an additional 25 organic compounds expanding the TC constituents list to 39 substances. The regulatory level for vinyl chloride was set at 0.2 mg/1, a sufficiently high level to assure that most PVC wastes will not be hazardous because of VCM.

ISSN:0193-7197    

DOI:10.1002/vnl.730130208

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY

摘要:

AbstractPlasticizers have been used for centuries to improve the processability and flexibility of a variety of materials. At the dawn of civilization water was used to plasticize clay for the production of pottery and clay tablets and the Ark was reputedly waterproofed with pitch plasticized with oil. Today the most common plasticizers are phthalates, adipates, and similar esters the majority of which are used to produce flexible PVC products. The widespread use of plasticizers in these applications over the last forty years has resulted in their toxicology being extensively researched and understood. As a consequence of these investigations many official bodies and legislative authorities have concluded that plasticizers pose no significant hazard to man or the environment. Plasticizers will, therefore, continue to be used to enhance all our lives through the production of a wide variety of PVC items ranging from medical components to waterproof clothing and floor coverings.

ISSN:0193-7197    

DOI:10.1002/vnl.730130209

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY

摘要:

AbstractPVC fibers, fastened to a needle frame, were crosslinked by 2‐dibutylamino‐4, 6‐dimercapto‐1,3,5‐trizine in the presence of tetra‐n‐butylammonium bromide and alkali in water at 96°C. Solvent resistance, characterized by the gel fraction of THF, improves markedly. Mechanical properties of the fibers investigated by tensile tests at 20°C show that both the modulus and tensile strength at break increase, while elongation at break decreases over 40% gel content. Creep tests indicate that the resistance to heat deformation improves by crosslinking. The heat distortion temperature increases by 12°C at 75% gel content. Results of dynamic tests show that theTgof PVC fibers determined by a peak in the loss modulus (E'') increases from 40% gel content. Dynamic modulus (E') increases by 74% at 23°C and theTgby 37°C in the case of crosslinked PVC fibers having a 92% gel content. The shrinkage of PVC fibers in hot water at 94°C for 30 min decreases more than 50% over 75–80% gel content indicating the improved resistanc

ISSN:0193-7197    

DOI:10.1002/vnl.730130210

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY

摘要:

AbstractSubstitution reactions are an appropriate way to attach chemical functions to polymer chains for improving properties and to diversify the application of polymer materials. The stereoselective substitution of chlorine atoms affords a useful way to plasticize polyvinychloride (PVC) by attaching appropriate plasticizing functions (ester group) such as isooctylthiosalicylate. Thus, the substitution of chlorine atoms of PVC by reactant bearing plasticizing groups was carried out in a continuous mixing apparatus such as a twin screw extruder. This continuous chemical engineering process taking place in the extruder is studied as the function of the residence time distribution (RTD) measured by a UV method. This function combined with the kinetics of the chemical reaction allows to define a new function G as the distribution of the extent of conversion by analogy with the RTD function.

ISSN:0193-7197    

DOI:10.1002/vnl.730130211

出版商:Society of Plastics Engineers    

年代:1991

数据来源: WILEY