摘要:

AbstractDynamic elastic modulus and internal friction of a Portland cement (Type I) mortar system impregnated with an epoxy resin system and with methyl methacrylate were measured in the temperature range of 100 to 450°K by use of a free‐free resonance technique. Dynamic modulus values were found to increase greatly compared to controls, especially at lower (<300°K) temperatures. Above 320°K the dynamic moduli of polymer‐impregnated mortars exhibited a sharp decrease toward control values. Low temperature damping maxima of the composites differed significantly from those of the constituent

ISSN:0032-3888    

DOI:10.1002/pen.760150202

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractA crosslinked polybutadiene containing a cyclic depsipeptide (Valinomycin) has been synthesized in which there is some possibility of threading to produce a catenated structure (polymeric catenane). Unthreaded rings were removed by extraction with toluene. An elemental analysis indicated the yield of threaded rings to be greater than the calculated expected yield. The total amount of threaded Valinomycin present was 0.37 percent. The rings showed no effect on the calorimetric glass transition temperature, but did result in an increase in the tensile modulus.

ISSN:0032-3888    

DOI:10.1002/pen.760150203

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe liquid heat capacities and heats of vaporization of three linear esters of poly(hexamethylene sebacate) with hexylcapped end groups (M(mol. wt.) = 370, 655, and 939) have been determined. The heats of vaporization of the oligomers measured at a mean temperature were corrected to 323.15 to 523.15°K by use of the experimental liquid (melt) heat capacities and the calculated gas heat capacities. The corrected heats of vaporization were fitted to the equation ΔHv= S(T)Mα+I(T), where the temperature dependence of the slope and intercept are represented, respectively, as S(T) =ClnT+KoandI(T) =aT+bo, and α is an exponent. The results indicate (at corresponding molecular weights and constant temperature) that the ratio of the liquid heat capacities of the oligomer ester and the n‐alkane, and similarly the ratio of the heats of vaporization, depend on the number of carboxyl groups in the oligomer ester

ISSN:0032-3888    

DOI:10.1002/pen.760150204

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe mechanical properties of a propylene‐ethylene copolymer resin depend strongly on the mold temperature employed during injection molding. Average spherulite size correlates well with most physical properties; good impact properties are related to small average size, and high heat distortion temperatures to large average size. Tensile specimens have three distinct regions when viewed through crossed polars. The outer region (Region 1) does not contain spherulites, but Regions 2 and 3 do. The largest spherulites are found in Region 3, the center of the specimen. Region 1 has a molecular weight higher than that of the other two region

ISSN:0032-3888    

DOI:10.1002/pen.760150205

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractViscous dissipation causes significant temperature increases in polymers while they are flowing through extruder dies. The development of the temperature field has been studied numerically using the dimensionless parameters Na and Gz. With the annular geometry (parameter: ratio of radii κ) the well known developing temperature fields in capillaries could be compared with the developing temperature fields in an annulus and in a plane slit. The shear dependence of the viscosity is described by a “power law” and the temperature dependence by an exponential function. A simple graphical method is suggested for estimating temperature fields in extruder dies, making use of the fully‐developed temperature field for very long dies as a reference state. For the demonstration of results, a power law exponentn= 0.4 has been

ISSN:0032-3888    

DOI:10.1002/pen.760150206

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractTests have been made for use of a high‐density polyethylene of ultra‐high molecular weight as a gear material. The gears had a diametral pitch of 10 and 30 teeth. They were tested in mesh with a steel gear of the same size in two operating conditions: (1) in still air without lubrication, and (2) in oil with generous lubrication.The effects of speed, temperature, and initial lubrication on the load capacity of the gears were tested and an equation was developed to express the limits of these gears operating without lubrication. In the lubricated conditions, the influence of oil flow and its temperature on the gear teeth temperature were evaluated. The wear of the plastic gear was measured in both operating conditions and wear rate was calculated as a function of the load and gear life. Curves are presented suggesting design limits of the gears in the two operating conditions. There are also recommendations on the center distance setting and the backlash to

ISSN:0032-3888    

DOI:10.1002/pen.760150207

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractAllyl fluoride can be copolymerized with vinyl chloride, vinyl acetate, ethyl acrylate, or SO2using free radical types of initiation. The copolymerization of allyl fluorida with vinyl chloride is comparable to the free radical initiated copolymerization of propylene with vinyl chloride. The allyl fluoride‐vinyl acetate couple tends to form completely random copolymers, the reactivity ratios of the monomers being close to unit

ISSN:0032-3888    

DOI:10.1002/pen.760150208

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe flow behavior of poly (butylene‐terephthalate) (PBT) has been investigated using a capillary extrusion rheometer. The behavior was measured as a function of temperature, moisture content, and residence time of the molten polymer in the rheometer barrel. The temperature and moisture dependence of PBT are compared with polycarbonate. The notched Izod impact strength of injection‐molded PBT is also reported as a function of moisture content and residence time at processing temperatu

ISSN:0032-3888    

DOI:10.1002/pen.760150209

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractThe thermal conductivity of segregated distributions of poly (vinyl chloride)/nickel (PVC/Ni) and poly(vinyl chloride)/copper (PVC/Cu) was measured for volume fractions ranging from 0 to 0.15. The thermal conductivities increased from 0.15 Btu/hr ft °F for unmodified PVC to 2.79 Btu/hr ft °F for PVC/15 percent Cu. While the thermal conductivity increased smoothly with volume loading, the electrical resistivity decreased discontinuously over fifteen orders of magnitude. Using the parallel slab model as a basis, a semi‐empirical model was deduced which described the thermal conductivity as a function of volume loading. With this work, a survey of the thermal, electrical, and mechanical properties of segregated PVC composites is compl

ISSN:0032-3888    

DOI:10.1002/pen.760150210

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY

摘要:

AbstractDuring the last several years there has been considerable interest in the occurrence of structure in certain bulk polymers normally thought to be structurally homogeneous. Specifically, it has been proposed that polymers produced by emulsion polymerization may retain a particle structure in the bulk state. This has been demonstrated by both rheological measurements and by electron microscopy. In this work we show conclusively that at least part of the particle structure observed by electron microscopy for polystyrene is an intrinsic feature of the fracture surface and is in no way related to the history of the sample.

ISSN:0032-3888    

DOI:10.1002/pen.760150211

出版商:Society of Plastics Engineers, Inc.    

年代:1975

数据来源: WILEY