Disclosed herein are methods for designing composite materials with improved toughness.

Glass compositions suitable for fiber forming having low levels of Li.sub.2O and glass fibers having high-modulus are disclosed. The glass composition may include SiO.sub.2 from about 59 to about 63 weight percent, Al.sub.2O.sub.3 from about 13.7 to about 16 weight percent, CaO from about 14 to about 16.5 weight percent, MgO from about 6 to about 8.5 weight percent, Fe.sub.2O.sub.3 less than 1 weight percent, and TiO.sub.2 less than 1 weight percent. In some cases, the composition may be substantially free of Li.sub.2O. In some cases, the composition may include Li.sub.2O up to 0.5 weight percent. In some cases, RE.sub.2O.sub.3 may be present in the composition in an amount up to 1.5 weight percent. The glass compositions can be used to form glass fibers which can be incorporated into a variety of other fiber glass products (e.g., strands, rovings, fabrics, etc.) and incorporated into various composites.

A molded product having both small specific gravity and high stiffness and also suffering few sink marks is described along with a method for the production thereof, where the molded product includes a porous body (A) integrated with an injection molded body (B), the porous body (A) having an apparent density of 0.05 to 0.8 g/cm.sup.3, the average thickness (tA) of the porous body (A) and the average thickness (tB) of the injection molded body (B) satisfying the relation tA≥3×tB, and the injection molded body (B) covering at least one face of the porous body (A).

A belt with a tensile cord embedded in an elastomeric body, having an adhesive composition impregnating the cord and coating the fibers. The adhesive composition is the reaction product of a polyisocyanate and a polyol, or a polyurethane prepolymer derived therefrom, and a polyamine curative and optionally additional polyol, and with optionally added plasticizer. At least one of the polyisocyanate, the prepolymer, and the polyamine are blocked with a blocking agent. The belt body may be of cast polyurethane, vulcanized rubber, or thermoplastic elastomer. The cord may have an adhesive overcoat.

Diphthalonitrile compounds of formula I:

##STR00001##

in free or salt or solvate form, wherein: Ar.sup.1 is a C.sub.6-C.sub.10-aryl group; Ar.sup.2 is a C.sub.6-C.sub.10-aryl group; R.sup.1 and R.sup.2 are independently C.sub.3-C.sub.10-alkyl; T is a C.sub.6-C.sub.10-aryl group; and n is 0, 1, 2, 3, 4 or 5, or a mixture thereof; Cured diphthalonitrile thermosets are provided by curing resin blends of such compounds.

Provided is a glass direct roving that can achieve good productivity for long glass fiber-reinforced thermoplastic resin pellets, and achieve excellent spinning productivity and good strength of glass fiber-reinforced resin molded articles produced by using long glass fiber-reinforced thermoplastic resin pellets in combination. The glass direct roving includes a plurality of glass filaments bundled together, wherein the filament diameter of the glass filaments, D, is in the range of 17.5 to 21.5 μm, the number of the glass filaments bundled, F, is in the range of 3000 to 7000, the mass of the glass direct roving is in the range of 2450 to 4000 tex, the ignition loss of the glass direct roving, L, is in the range of 0.03 to 0.90%, and the D, F, and L satisfy the following formula (1): $\begin{array}{cc}1050\le \left(D^4\times F^{1/4}\right)/\left(1000\times L^{1/6}\right)\le 1640.& \left(1\right)\end{array}$

A method for producing a prepreg, includes the steps of (1) an opening step of opening glass fiber bundles to form plural glass fiber filaments, and (2) a step of aligning the plural glass fiber filaments formed in the previous opening step, on a thermosetting resin composition-coated surface of a carrier material so as to make the filaments run nearly parallel to each other in one direction thereon to form a prepreg. A method for producing a laminate, includes a step of preparing two or more prepregs formed in the previous step (2), laminating them in such a manner that, in at least one pair of prepregs, the running direction of the plural glass fiber filaments in one prepreg differs from the running direction of the plural glass fiber filaments in the other prepreg, and heating and pressing them.

A method for producing a prepreg, includes the steps of (1) an opening step of opening glass fiber bundles to form plural glass fiber filaments, and (2) a step of aligning the plural glass fiber filaments formed in the previous opening step, on a thermosetting resin composition-coated surface of a carrier material so as to make the filaments run nearly parallel to each other in one direction thereon to form a prepreg. A method for producing a laminate, includes a step of preparing two or more prepregs formed in the previous step (2), laminating them in such a manner that, in at least one pair of prepregs, the running direction of the plural glass fiber filaments in one prepreg differs from the running direction of the plural glass fiber filaments in the other prepreg, and heating and pressing them.

A thermoplastic composite material includes a thermoplastic polymer matrix component, a microparticle component, a nanoparticle component, and a compatibilizing agent component, at least a portion of the microparticle component and/or nanoparticle component is a natural fiber.

A barium titanate fiber is useful as a filler for a polymer composite piezoelectric body, a polymer composite piezoelectric body has high piezoelectric properties, and a piezoelectric element utilizes the polymer composite piezoelectric body. In the barium titanate fiber, the molar ratio of barium atoms to titanium atoms (Ba/Ti ratio) falls within the range of 1.01 to 1.04. The polymer composite piezoelectric body includes a resin composition containing the barium titanate fiber and a polymer. The piezoelectric element including an electrically conductive layer on one surface or both surfaces of the polymer composite piezoelectric body.