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iupiacelemalloy

Basic Properties


Basic Properties

Iupiace is a polymer alloy made by modifying PPE with high impact polystyrene (HIPS), nylon-6 or nylon-66. Iupiace provides well-balanced mechanical, electrical and thermal properties. In addition, Iupiace boasts relatively lower density than other engineering plastics. These enable Iupiace to respond to the needs of customers for compactness, superior performance and flame retardance.

Lemalloy is a polymer alloy made by modifying PPE with high-impact polystyrene (HIPS), polyamide-6, or polyamide-66. Lemalloy provides well-balanced mechanical, electrical, and thermal properties. In addition, Lemalloy boasts the lowest specific gravity among engineering plastics. Equipped with the above features, Lemalloy meets market requirements for compactness, high performance, and flame retardance.

Special features:

  • Usability in a wide range of temperatures (-40 to 160)
  • Higher rigidity, impact strength and fatigue resistance
  • Excellent insulation properties, low dielectric constant and low dielectric dissipation factor
  • Excellent dimensional stability with low water absorption
  • Flame retardance and excellent self-extinguishing properties
  • Low density
  • Low shrinkage rate, ensuring quality precision parts
  • Good mold release, easy flow properties and a wide range of stock temperatures

Special features:

  • Stable rigidity, impact strength and fatigue resistance through a wide range of temperatures
  • Excellent insulation properties, low dielectric constant and low dielectric dissipation factor
  • Excellent dimensional stability with low water absorption
  • Excellent heat stability
  • Low specific gravity
  • Excellent moldability and low shrinkage rate for quality precision parts
  • Excellent processability; good mold release, easy flow properties and a wide range of stock temperatures

About “modification” in m-PPE resin

Polyphenylene ether (PPE) resin is a macromolecule made mainly from 2,6-xylenol as monomer, and this amorphous resin is characterized by high thermal resistance because the glass-transition temperature (Tg) exceeds 200℃ as pure PPE itself. It has the following macromolecular structure:

However, since the molten flowability of the pure PPE itself is extremely poor, this resin is widely used as polymer alloy materials (“Alloy” stands for mixed metal, then it represents a material made by blending different resins). One of the resins used for alloying with PPE is Polystyrene (PS) resin, freely compatible with PPE. The materials based on this polymer alloy method are generally referred to as modified Polyphenylene ether resin (modified PPE resin or m-PPE resin, where “m” stands for “modified”).
Through the modification of PPE resin, m-PPE resin becomes one of the widely-used engineering plastics with the following characteristics: its specific gravity is the lowest among engineering plastics (1.06, for example, for a PS resin-based alloy material), PPE/PS alloy materials exhibit widely variable Tg (an indicator of thermal deformation temperature) and molten flowability as the function of the PPE/PS composition, high dimension stability, superior electric properties (such as electrical breakdown strength, low-dielectric constant, and low-dielectric tangent), self-extinguishing and easy to add flame retardant properties, superior long-term durability (creep/fatigue resistance), and water/alkali/acid resistance.

On the other hand, there are also limitations in use due to physicochemical properties unique to the chemical structure of the aromatic ether structure in PPE resin, such as inferior oil/solvent resistance (soluble in benzene, toluene, and chloroform) and light resistance (it derives from photoabsorption property ranging from visible short wavelength region to ultraviolet region, and it needs to be colored black for outdoor use).

[Explanation] About the characteristics of crystalline and amorphous resins

(1) Macromolecule crystallization

Crystallization of macromolecule (in this document, linear polymer molecule is set forth as a premise for explaining the principle) refers to a phenomenon in which parts of chainlike polymeric molecule gather together to make up flux which are partially arranged in one direction under certain given conditions, for example, under the cooling conditions in the molten state during injection molding or the concentrating conditions in the solution state (Refer to Figure 2), although it refers to a phenomenon in which small molecules and ions are arranged systematically to make up a crystal in the case of molecular crystals (Example: sugar) and ionic crystals (Example: salt) (Refer to Figure 1). In addition, when macromolecules crystalize, amorphous regions with varying molecular conformation other than such crystalline region normally exist together.


[Figure 1] A schematic diagram showing molecular and ionic crystals (simple cubic lattice, as an example);
blue represents molecules or ions and grey represents crystal lattices (hypothetical concept).
The same crystal lattices continue systematically in the directions of X, Y, and Z axes.

[Figure 2] A schematic diagram of a crystalline resin;
blue represents crystalline regions and grey represents amorphous regions. In the crystalline regions, macromolecular chains form fluxes in the same direction.
In the amorphous regions, macromolecular chains locate indeterminately.

The both crystallizations have a common feature that molecules, ions and polymeric repeating units (monomer units) seek to employ the most stable conformation thermodynamically, using intermolecular forces or ionic binding as driving forces. However, the macromolecule case is essentially different from the ones of low molecular or ionic crystals because of the less freedom of macromolecular mobility than monomers (low molecules) before polymerization; i.e., monomer units are bundled each other within a polymeric chain. This reduction of molecular mobility unique to macromolecules is the cause of remaining amorphous regions. Furthermore, the proportion of crystalline region (“crystallinity”) and the sizes of respective crystalline regions (“crystal size or crystallite size”) are largely dependent on the molding conditions.

Macromolecular chains are basically amorphous when in the molten or solution state, but they crystallize as cooled or concentrated because the effect of intermolecular force (attractive force) becomes evident. However, macromolecules have one more characteristic that their viscosity increases significantly as cooled or concentrated in the molten or solution states, respectively, compared to low molecule systems. Due to this viscosity increase effect, it actually happens that macromolecules become solidified before they crystallize well. Therefore, in general, the crystallinity can be increased by taking a longer time for macromolecular chains to relocate them through slow cooling or slow concentration. It can be understood that so-called amorphous resins such as polycarbonate resin (PC resin) and polyphenylene ether resin (PPE resin) tend to solidify in an amorphous state in the molding process, because they crystallize slowly.

(2) The properties of the crystalline region of macromolecules

Since the crystalline region has a dense structure based on strong intermolecular force, they generally show a higher thermal softening temperature and elastic modulus as well as lower coefficient of linear thermal expansion (CLTE) and water absorption rate (that is, a reduction in dimension change due to temperature and humidity) than those of the amorphous region. Of these, thermal softening temperature roughly corresponds to, in the amorphous region, the glass transition temperature (Tg) which correlates with the rigidity of monomer unit structure (the lowness of mobility or flexibility of molecular structure); but in the crystal region corresponds to the melting point (hereinafter quote as “Tm”) which is higher than Tg.

Therefore, in resin molded articles, the increase of the crystallinity moves above physical properties generally to the preferred direction. However, since the crystalline regions dispersed in the amorphous region function as a stress concentration point induced by external force due to a difference in elastic modulus, the toughness of resin molded articles generally decreases as the crystallinity increases and moves in the direction of embrittlement. If the crystallinity is the same, toughness can be improved by reducing the crystalline size.

(3) The properties of the amorphous regions of macromolecules

The amorphous region in resin molded articles functions as a matrix (continuous phase) containing the crystalline regions (hard and difficult to be thermally-softened) as “fillers” (reinforcing materials to be filled). Although the thermal properties of the amorphous region are dominated by the aforementioned Tg, for the mechanical properties it is important to understand mechanism of the amorphous region exhibiting toughness (durability).

At temperatures lower than Tg, the amorphous region subjected to external force (e.g., tensile, flexural, compressive and torsional stresses, as well as gravity force causing self-weight deformation) causes reversible (elastic) deformation first. This phenomenon is relatively small deformation which can be restored by eliminating the external force, and can also be observed in hard and brittle materials such as inorganic glass. However, the toughness of the amorphous region, in terms of a molecular discussion, depends on how far irreversible (plastic) deformation is allowed after the elastic deformation limit. The nature of the plastic deformation is a process of viscous flow, that is, a process in which macromolecular chains tangled with each other dissipate the energy of external force as heat by moving irreversibly to change their arrangement (conformation) gradually and the entire material deforms while bearing breakage.

A trigger which leads plastic deformation to breakage is occurrence of micro-crack (cleavage) and micro-void. Assuming an ideal amorphous region, that is a case where stress concentration factors such as foreign matter and inhomogeneous structure (e.g., crystalline regions, fluctuation of density in amorphous) do not exist, micro-cracks/voids are considered to be caused by (1) macromolecular chain ends, (2) unbinding of macromolecular chain entanglements, and (3) breakage of macromolecular chains, which could be the cause of very tiny voids in the molecular dimension can be generated in the macroscopic deformation. Among these three factors, (1) and (2) are reduced as the molecular weight increases, because the smaller the number of molecular ends per unit weight becomes and the more difficult the entangled chains become unbound, the larger (the longer) the molecular weight becomes (It can be estimated from an example that the longer the boiled noodles are, the more difficult to unbind the entanglements involved in the entire noodle). That is, larger molecular weight is better for toughness.

Concerning the above (3) Breakage of macromolecular chains which is also associated with the perspective of entanglement as described in the above (2), the hardness of the macromolecular chain (the rigidity of monomer unit structure) is one of the factors. That is, if macromolecular chains are flexible, they can follow the entire deformation without eliminating the molecular entanglements. However, if they are rigid, they cannot follow the deformation due to low mobility and stress is concentrated in the entangled points. As a result, it is considered that breakage of macromolecular chains tends to occur. It can be said that the rigidity of macromolecular chains is the cause of complicated behaviors which contradict each other in a practical way. That is, the higher rigidity increases the elastic modulus of amorphous regions and also increases the aforementioned Tg (increases the thermal softening temperature) but reduces melt flowability (increases the molten viscosity to deteriorate the moldability) as thermal properties. On the other hand, if the molecular weight is decreased to increase the melt flowability, the toughness is reduced as described above.

(4) Crystalline and amorphous resins

Basically, linear polymer molecules have the capability to crystallize under certain cooling or concentration conditions. However, “crystalline resins” generally refer to resins which undergo crystallization so that practically preferred physical property balance is shown under common injection or extrusion molding conditions. On the other hand, “amorphous resins” refer to resins which almost do not crystallize under such common molding conditions.

Engineering plastic materials as “crystalline resin” including Polyamide (PA) resin, Polyacetal (or Polyoxymethylene, POM) resin, Polybutylene terephthalate (PBT) resin, Polyethylene terephthalate (PET) resin, and Polyphenylenesulfide (PPS) resins, etc. are characterized by superior molten flowability and chemical resistance, as well as a profound reinforcing effect (an effect of improving elastic modulus, strength, and heat resistance) by compounding fillers such as glass fiber.

The ones as “amorphous resin” including Polycarbonate (PC) resin, modified Polyphenylene ether (m-PPE) resin, and Polyalylate (PAR) resin, etc. are characterized by transparency, anisotropy, and small molding shrinkage.

Product Info.

  • ポリカーボネート樹脂(PC樹脂)ユーピロンノバレックスザンター
  • ポリブチレン テレフタレート樹脂 (PBT樹脂) ノバデュラン
  • ポリアセタール樹脂(POM樹脂)ユピタール
  • 変性ポリフェニレン エーテル樹脂(m-PPE樹脂)ユピエースレマロイ
  • 高性能ポリアミド樹脂(PA樹脂)レニー
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