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Henry Rogers
Henry Rogers

Additives For Polyolefins: Getting The Most Out Of Polypropylene, Polyethylene And TPO



This book focuses on the polyolefin additives that are currently important in the plastics industry, alongside new additives of increasing interest, such as nanofillers and environmentally sustainable materials. As much as possible, each chapter emphasizes the performance of the additives in the polymer, and the value each relevant additive brings to polypropylene or polyethylene. Where possible, similar additives are compared by capability and relative cost.




Additives for Polyolefins: Getting the Most out of Polypropylene, Polyethylene and TPO



The last but not the least-important issue concerns speed. POs, which are so often used in high-volume commodity applications, are being processed with faster, computer-controlled equipment and tooling. Competition is driving this need for speed. A simple example is a molder who requires a PP margarine tub to be molded at a certain cycle time on a high-speed injection molding press; if it is not, the molder cannot be competitive and profitable at the same time, and the job cannot be considered a winner. With processing machines getting faster all the time, PO formulations include additives that help processors reach their productivity goals using processing aids, nucleating agents, and other additives.


It follows, therefore, that under solar exposure most of theseadditives are considerably degraded and consumed, and it is importantto mention that the depletion of these additives (with the exceptionof adipate) follows an exponential behavior, inside the experimentalerror. Thus, the time dependence of these processes can be expressedby an exponential function of the type


The values of apparent concentrationfor the diverse additiveswere determined from the individual peak areas in the total ion chromatogramof each additive in relation to the area obtained for the internalstandard, 8OCB. Absolute concentrations may be somewhat differentsince variations in response factors among the studied substancesare expected. Anyway, the most relevant issue is the relative changeof the different additives with degradation time, and that shall remainunaffected by considering or not the response factors.


The studied compounds cannot always be found in the mass spectrometersoftware libraries (especially when the peaks correspond to degradationproducts identified from high-molecular-weight additives). In suchcases, the assignment is made by comparing the expected fragmentationpath from the most probable degradation products with that observedin the chromatogram.


This book focuses on the polyolefin additives that are currently important in the plastics industry, alongside new additives of increasing interest, such as nanofillers and environmentally sustainable materials. As much as possible, each chapter emphasizes the performance of the additives in the polymer, and the value each relevant additive brings to polypropylene or polyethylene. Where possible, similar additives are compared by capability and relative cost. With major sections for each additive function, this book provides a highly practical guide for engineers and scientists creating and using polyolefin compounds, who will find in this book a wealth of detail and practical guidance. This unique resource will enable them to make practical decisions about the use of the various additives, fillers, and reinforcements specific to this family of materials. ABOUT THE AUTHOR Michael Tolinski is a freelance writer and a lecturer at the University of Michigan's College of Engineering. He is a frequent contributor to Plastics Engineering and Manufacturing Engineering. Structured to make it easy for the reader to find solutions for specific property requirements Contains a number of short case studies about companies that have used or developed a particular additive to achieve a desired result Covers environmental resistance, mechanical property enhancement, appearance enhancement, processing aids, and other modifications of form and function.


The application of paint to polypropylene and thermoplastic polyolefin (TPO) is difficult because of the poor adhesion of most coatings to plastics. Eastman chlorinated polyolefins (CPOs) are widely used as adhesion promoters for coatings and inks on polyolefin plastics such as untreated polyethylene, polypropylene, or TPO. Our chlorinated polyolefins serve as adhesion promoters in at least three ways:


Unreacted monomers in MPs released by polycarbonate, polystyrene and PVC mesoplastics are carcinogenic, mutagenic, and a reproductive hazard. MPs containing additives and dyes, such as PVC, pose increased inflammation than additive-free ones. Literature suggests that some MPs, such as PE, PVC, and PS, have higher capacities to release initially adsorbed PCBs and PAHs than other PM in the atmosphere. In other polymers such as PA and PU, these toxic compounds are almost bonded irreversibly through hydrogen bonding and therefore rarely released into the environment (Liu et al., 2019c). This poses a significant danger due to the high carcinogenic and mutagenic potentials of PCBs and PAHs.


Polyolefins are the most widely used commercial polymers. These materials, such as polyethylene and polypropylene, are used extensively, due to their low cost, versatile mechanical properties, low density, and excellent solvent resistance. These materials are found in applications as diverse as food packaging, garbage bags, beverage containers, and ultra-high strength fibers. Thermoplastic polyolefins (TPO) are a family of polyolefin blends consisting of impact modified polypropylene and other polyolefins (i.e.. ethylene-propylene rubber and ethylene-butene rubber) as the dispersed phase. These types of materials are widely used for the fabrication of automobile parts.


5.3 Turning again to Examples 12 and 14 of D2, it is apparent to the skilled reader that the components listed in Table 3 fall into groups, namely the polypropylene matrix components, Ziegler-Natta catalysed EPR additives, metallocene catalysed elastomer additives and further additives. The latter additives are polyethylene and talc, which have no impact improving properties. Thus, it is evident to the person skilled in the art that the impact modification is provided by the two rubbery additives of the composition, namely the EPR (a component which is often used in polypropylene impact modification, eg D13, page 149, last paragraph) and the metallocene catalysed elastomer. Therefore the board agrees with the appellant that Examples 12 and 14 of D2 clearly and unambiguously disclose the impact modification of polypropylene with an ethylene-propylene rubber and a metallocene catalysed ethylene-butene/octane copolymer.


5.8 It follows from the above that Claim 8 of the main request (point II, above), which is directed to the use of the composition of Claim 1 as an impact modifier in compositions comprising polypropylene, would also have been obvious over D2, since Examples 12 and 14 D2 self evidently disclose the use of the EPR and ethylene-co-butene/ethylene-co-octene elastomer as an impact modifier for a polypropylene matrix, the EPR and ethylene-co-butene/ethylene-co-octene elastomer being present in an amount of 30 wt% based on the total weight of the polypropylene, impact modifier and additives.


The invention composition comprises a polymer blend of at least two polymers, one being a crystalline polymer having a melting point above about 110.degree. C., and the other polymer being an amorphous or semi-crystalline polymer having a Tg above about -80.degree. C. and a percent crystallinity between 0 and 20 percent. The crystalline polymer may be selected from a wide variety of such polymers, preferably, but not limited to crystalline polymers such as polypropylene, polybutylene terephthalate, polyethylene, polyethylene terephthalate, nylon, polyphenylene sulfide, polyether ether ketone, and mixtures thereof. More preferably, the crystalline polymer, when making articles such as automotive fascia, is polypropylene, polyethylene, or terephthalate polybutylene. The amorphous or semi-crystalline polymer, having the characteristics described above, may be any such polymer preferably being one such as polycarbonate, natural and synthetic polyisoprene rubbers, ethylene-propylene copolymers (EPM), ethylene-propylene diene rubbers (EPDM), chlorinated rubbers, nitrile rubbers, polystyrene, polyphenylene oxides, methylmethacrylate styrene-butadiene block copolymers, polyether sulfones, polysulfones, polyarylates, other impact modifiers such as styrene-butadiene block copolymer, and mixtures thereof.


60 parts by weight polypropylene, 28 parts by weight ethylene-propylene copolymer, and 7 parts by weight high density polyethylene were mixed and metered into a Buss America kneader extruder operated at 250 rpm, 200.degree. C., and at an output rate of 60 lb./hr. 5 parts by weight Ketjenblack.RTM. (Akzo Chemicals Inc., Akron, Ohio) EC-300J, nominal particle size of 30 nm, pH=9, pore volume=325 cm.sup.3 /100 g, percent volatiles=0.6, and ash content=0.1 was added downstream to the compounded and plasticized polymer blend. The resulting material was pelletized and 4".times.6" plaques were injection molded on a 250 ton Cincinnati Milacron injection molding unit at a mold temperature of 100.degree. F., 430.degree. F. melt temperature, 1000 psi injection pressure, 50 psi back pressure, and 3 second fill rate. Measured injection molded material properties were Izod impact=12.8 ft.lb./in.; Dynatup impact at -30.degree. C.=39.7 joules; and flexural modulus=735 MPa. The measured carbon content by pyrolysis was determined to be 4.7 to 5.3 weight percent. The steady state surface conductivity was measured as 3.3.times.10.sup.-16 S/cm. The internal or core resistivity was measured to be 5.5.times.10.sup.-7 S/cm.


Using polypropylene as the concentrate carrier, a 15 weight percent EC-300J carbon concentrate was prepared on a Haake Rheocord 90 twin screw extruder operated at 75 rpm and barrel temperatures ranging between 200.degree. and 230.degree. C. by adding a dry mixture of polypropylene pellets and dry carbon powder. This material was pelletized after in a continuous fashion after cooling the extruded strand in a water bath. 28 parts by weight polypropylene, 40 parts by weight EC-300J/polypropylene concentrate, 27 parts by weight ethylene-propylene-diene copolymer, and 5 parts by weight polyethylene hand mixed in dry form and introduced to a Farrel type dual blade Banbury mixer. The materials were then blended at 200 rpm for 3 minutes without external mixing reaching a shear induced temperature of 410.degree. F. The molten blend was introduced into a single screw extruder for pelletization. The final pellets were injection molded using a BOY 50 ton injection molding unit. The resulting plaques were evaluated for mechanical and electrical properties. The results were Izod impact=12.24 ft.lb./in.; flexural modulus=780 MPa; and Dynatup impact at -30.degree. C.=35.6 joules. The surface and internal conductivities were measured to be 8.3.times.10.sup.-18 S/cm and 7.7.times.10.sup.-8 S/cm, respectively. 350c69d7ab


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