Owen P. Mills

A morphological investigation of thermosets toughened with novel thermoplastics. I. Bismaleimide modified with hyperbranched polyester

The morphology of a bismaleimide (BMI) toughened with a thermoplastic hyperbranched aliphatic polyester (HBP) was studied by scanning electron microscopy (SEM). The effect of thermoplastic architecture, molecular weight, and end group on the size and arrangement of the dispersed phase was investigated and compared with the thermoset fracture toughness. SEM micrographs showed that higher molecular weight HBP formed roughly spherical dispersed domains of up to ∼ 60 μm, which contained BMI inclusions. Lower molecular weight HBP formed spherical dispersed thermoplastic domains, with diameters up to ∼ 10 μm with no BMI inclusions. A low molecular weight linear polyester with a repeat unit structure, which was similar to that of the HBP, was prepared and used as a control. Within error, BMI toughened with the linear control yielded the same fracture toughness as the best values obtained with HBP-modified BMI, but the morphology differed. The linear polyester phase separated into particles with a larger average diameter and also possessed some phase-inverted regions. End group effects were studied by modifying the hydroxy-terminated HBP to unreactive nitrophenyl, phenyl, and acetyl end groups. The nitrophenyl-terminated HBP did not phase separate from the thermoset, whereas the nonpolar phenyl- and acetyl-terminated HBP phase separated to form small (≤1 μm and ∼ 2 μm, respectively) spherical domains. Some comparisons were made to other results with HBP thermoplastics in BMI and epoxy thermosets.

Shape and surface area measurements using scanning electron microscope stereo-pair images of volcanic ash particles

The shape and surface area of fiparticles are traditionally measured using projected or two-dimensional (2D) sections or with nitrogen gas adsorption using the BET (Brunauer, Emmett, and Teller) method. However, 2D sections are incomplete shape descriptors and nitrogen gas adsorption analysis is precluded when the amount of sample is limited, for example, in direct ash cloud sampling. In this study we present a technique for measuring the shape and surface area of individual grains of volcanic ash using scanning electron microscope (SEM) stereo pairs. The application we discuss is the stereoscopic analysis of 25 ash particles in the 4‐130 µm size range from the August 1992 Crater Peak‐Spurr eruption, located 130 km west of Anchorage, Alaska. Surface area data are presented from stereo measurements of glass microspheres in the same size range as validation of the technique’s accuracy. Differences in surface area values between our technique, 2D shape data, and nitrogen gas adsorption are presented and discussed.

Effects of multiple carbon fillers on the electrical and thermal conductivity and tensile and flexural modulus of polycarbonate-based resins

Adding conductive carbon fillers to insulating thermoplastic polymers increases the electrical conductivity of the resulting composite, which could allow them to be used in electrostatic dissipative and semiconductive applications. In this study, three different carbon fillers (carbon black [CB], carbon nanotubes [CNTs], and exfoliated graphite nanoplatelets [GNPs]) were studied via three different combinations of two different fillers (CB/CNT, CB/GNP, and CNT/GNP). These filler combinations were studied via three 32 factorial designs, which considered the following loading levels: CB: 0, 2, 5 wt%; CNT: 0, 1, 5 wt%; and GNP: 0, 2, 5 wt%. These composites were compounded, injection molded, and tested for electrical and thermal conductivity (TC), and tensile and flexural modulus. All of the single fillers caused a statistically significant increase at the 95% confidence level in composite electrical and TC, and tensile and flexural modulus. Many two filler interactions had a statistically significant effect on composite electrical and TC, and tensile and flexural modulus. For example, when CB and CNT are combined into a composite, the composite tensile modulus is higher than what would be expected from the additive effect of each single filler. Five different formulations (four containing two filler combinations) could be used for electrostatic dissipative applications and seven different formulations (six containing two filler combinations) may be used for semiconductive applications.

Leószilárdite, the first Na,Mg-containing uranyl carbonate from the Markey Mine, San Juan County, Utah, USA

Abstract Leószilárdite (IMA2015-128), Na6Mg(UO2)2(CO3)6·6H2O, was found in the Markey Mine, Red Canyon, White Canyon District, San Juan County, Utah, USA, in areas with abundant andersonite, natrozippeite, gypsum, anhydrite, and probable hydromagnesite along with other secondary uranium minerals bayleyite, čejkaite and johannite. The new mineral occurs as aggregates of pale yellow bladed crystals flattened on {001} and elongated along [010], individually reaching up to 0.2 mmlong. More commonly it occurs as pale yellow pearlescent masses to 2 mmconsisting of very small plates. Leószilárdite fluoresces green under both longwave and shortwave ultraviolet light, and is translucent with a white streak, hardness of 2 (Mohs), and brittle tenacity with uneven fracture. The new mineral is readily soluble in room temperature H2O. Crystals have perfect cleavage along {001}, and exhibit the forms {110}, {001}, {100}, {101} and {101}. Optically, leószilárdite is biaxial (-), α = 1.504(1), β = 1.597(1), γ = 1.628(1) (white light); 2V (meas.) = 57(1)°, 2V (calc.) = 57.1°; dispersion r > v, slight. Pleochroism: X = colourless, Y and Z = light yellow; X < Y ≈ Z. The average of six wavelength dispersive spectroscopic analyses provided Na2O 14.54, MgO 3.05, UO3 47.95, CO2 22.13, H2O 9.51, total 97.18 wt.%. The empirical formula is Na5.60Mg0.90U2O28C6H12.60, based on 28 O apfu. Leószilárdite is monoclinic, C2/m, a = 11.6093(21), b = 6.7843(13), c = 15.1058(28) Å, β = 91.378(3)°, V = 1189.4(4) Å3 and Z = 2. The crystal structure (R1 = 0.0387 for 1394 reflections with Iobs > 4σI ), consists of uranyl tricarbonate anion clusters [(UO2)(CO3)3]4- held together in part by irregular chains of NaO5(H2O) polyhedra sub parallel to [010]. Individual uranyl tricarbonate clusters are also linked together by three-octahedron units consisting of two Na-centred octahedra that share the opposite faces of a Mg-centred octahedron at the centre (Na-Mg-Na), and have the composition Na2MgO12(H2O)4. The name of the new mineral honours the Hungarian-American physicist, inventor and biologist Dr. Leó Szilárd (1898-1964).

Collector's Note: A New Find of Manganese-rich Pumpellyite from the Manganese Mine, Copper Harbor, Keweenaw County, Michigan

Originally the mineral was described under the name ‘lotrite’ from the southern Carpathian Mountains (Murgoci 1901). Charles H. Palache, who in 1920 made the first systematic study of the secondary minerals in the altered [Michigan] copper lodes for the Calumet and Hecla Copper Mining Company, noted a green mineral which he believed to be a new mineral closely related to the zoisite-epidote family. Unaware of Murgoci’s earlier work, he submitted a manuscript to Calumet and Hecla describing the ‘new’ mineral, proposing to call it ‘kearsargeite.’ B. S. Butler didn’t like the name, and Palache changed the manuscript by crossing out ‘kearsargeite’ and penciling in ‘pumpellyite,’ in honor of Raphael Pumpelly.

Tensile and conductivity properties of epoxy composites containing carbon black and graphene nanoplatelets

Adding conductive fillers to an insulating polymer matrix produces composites with unique properties. Varying amounts of carbon black (0.33, 0.67, and 1 wt%) and graphene nanoplatelets (5, 10, 15, and 20 wt%) were added to epoxy. In addition, a few carbon black/graphene nanoplatelet/epoxy formulations were also fabricated. The conductivity and tensile properties were determined and analyzed. The single filler composites containing 5 and 10 wt% graphene nanoplatelet and 0.33 wt% carbon black could be used for electrically insulating applications. Composites containing 15 and 20 wt% graphene nanoplatelet could be used for static dissipative applications. The following composites could be used for semi-conductive applications: 0.67 wt% carbon black/epoxy, 1 wt% carbon black/epoxy, 0.33 wt% carbon black/5 wt% graphene nanoplatelet/epoxy, and 0.33 wt% carbon black/10 wt% graphene nanoplatelet/epoxy. At the 95% confidence level, the combination of 0.33 wt% carbon black with 5 wt% graphene nanoplatelet caused the composite electrical resistivity (1/electrical conductivity) to significantly decrease from ∼1015 ohm-cm to ∼104 ohm-cm. It is likely that the highly branched, high surface area carbon black is forming an electrically conductive network with graphene nanoplatelets. Concerning single filler composites, adding ≤1 wt% carbon black did not significantly lower the composite tensile strain; however, adding graphene nanoplatelet did decrease tensile strain and increase modulus. One possible application for the 10 wt% graphene nanoplatelet/epoxy composite is in Polymer Core Composite Conductors for power transmission lines, which need to be electrically insulating, have improved thermal conductivity (increased from 0.2 to 0.3 W/m-K), increased tensile modulus (increased from 2.7 to 3.3 GPa), and good tensile strength (70 MPa) and strain (3.3%).

Leesite, K(H2O)2[(UO2)4O2(OH)5]·3H2O, a new K-bearing schoepite-family mineral from the Jomac mine, San Juan County, Utah, U.S.A.

Abstract Leesite (IMA2016-064), K(H2O)2[(UO2)4O2(OH)5]·3H2O, is a new uranyl-oxide hydroxyl-hydrate found underground in the Jomac mine, Brown’s Rim, White Canyon mining district, San Juan County, Utah. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses provided the empirical formula K0.67Na0.004Ca0.012U4O20H15.31, based on 4 U and 20 O apfu. Sheets in the crystal structure of leesite adopt the fourmarierite anion topology, and so belong to the schoepite family of related structures that differ in the interlayer composition and arrangement, and charge of the sheet. Leesite may form as one of the principal components of “gummite” mixtures formed during the alteration of uraninite, and the unit cell of leesite resembles the previously described, but poorly understood mineral, paraschoepite. Uptake of dangerous radionuclides (90Sr, 135Cs, 137Cs, 237Np, 238Pu) into the structure of leesite and other members of the family has important implications for the safe disposal of nuclear waste.

Secondary Lead Minerals from the Copps Mine, Gogebic County, Michigan

CULLEN LAUGHLIN-YURS 513 Iron Street Norway, Michigan 49870 kc9pjm@gmail.com TRAVIS A. OLDS Materials Science of Actinides Energy Frontier Research Center 301 Stinson-Remick Hall University of Notre Dame South Bend, Indiana 46556 tolds@nd.edu DANIEL R. FOUNTAIN 167 East Buffalo Road Negaunee, Michigan 49866 dfountain906@gmail.com OWEN P. MILLS Applied Chemical and Morphological Analysis Laboratory Michigan Technological University 1400 Townsend Drive Houghton, Michigan 49931 opmills@mtu.edu Figure 1. Entrance to an adit on the Copps mine property. The white material is snow. Shawn Carlson photo (2015).

A New Occurrence of Callaghanite from Michigan's Copper Country

T mineralogy of Michigan’s world-class native copper district has been well studied, from the academic and economic viewpoints as well as collectible specimen mineralogy. In addition to native copper, the principal ore mineral, the district is home to forty-two copper species and is the type locality for three: anthonyite, calumetite, and the newly approved centennialite (Crichton and Müller 2014). However, the cessation of copper mining in the district in 1995 (closure date of the White Pine copper mine) coupled with the surprising rate at which old mine dumps are being Michigan’s Copper Country CULLEN LAUGHLIN-YURS 513 Iron Street Norway, Michigan 49870 kc9pjm@gmail.com