Light-emitting diodes （LEDs） have advantages in small size, light weight and, energy saving. They are usedfor portable device, backlight sources for TVs, light sources for illumination by practical application of white LEDs. Polyamide （PA） resin molding compounds are mainly used from the viewpoint of initial reflectivityand mechanical toughness for the LED reflectors. However, there is a problem that the light emissionintensity and luminance of the LED are lowered. The reason may be discoloration of PA in the reflector dueto heat and light, discoloration of impurities and low molecular weight oligomers in the resins, oxidation ofadditives （antioxidant, plasticizer, oligomer, etc.） by heat and light. PA resins are unavoidable in the formationof pyrrole ring compounds in thermal degradation （in the presence of oxygen ） and in the formation ofcompounds having aldehyde and amino groups in photodegradation. It is known that they form conjugateddouble bonds to absorb visible light, resulting in color change. It is said that PA resins containing amide grouphave fundamental issue, because higher heat resistance and light resistance are emphasized by increasing thebrightness of LEDs in the future.Therefore, we focus on thermosetting polyester （UP）, which is characterized by （Ⅰ） free from amidegroup, （Ⅱ） achievement with outdoor paint, （Ⅲ）high degree of freedom of combining polyhydric alcoholand polybasic acid. We have developed UP molding compounds having high reflectivity and high whiteness.We have reported that the light fastness of materials is improved by incorporating cyclohexyl ring into thebackbone of UP. In this manuscript, we report on the modeling of light source distance dependency of materialdeterioration, trial for manufacturing and evaluation of small actual model package, which is the current trendusing the developed UP materials.The developed UP molding materials have found overwhelming performance and high reliability byevaluation of side view type PKG compared with PA molding materials.

This paper describes the efficient and powerful synthetic method of monodisperse oligoamide hard segment,and its application to multiblock copolymer synthesis. The SOCl2 with amide solvent activation reagent fordicarboxylic acid compounds was utilized for the controlled synthesis of the monodisperse oligoamide. Thesynthesis of well-defined oligoamide was confirmed by GPC, NMR, and MALDI TOF-MS spectroscopy. Theobtained hard segment was polymerized with PPO or PEG having amine functionalities at the both ends,affording the corresponding multiblock copolymers. The thermoplastic elastomeric properties were studied,and the shape memory effect was found on PEG-based materials. These polymer films also showed goodmoisture responsive behavior within just 10 s upon exposing only one of its surfaces to humid air.

Structural acrylic adhesives have been special interest because those adhesives are cured at roomtemperature and can be bonded to oily substrates. To use those adhesives widely for structural bonding, it isnecessary to clarify the methodology for predicting strengths of bonding structures with those adhesives.In this study static strengths of lap joints with an acrylic adhesive were estimated based on cohesive zonemodel. At first, by using Arcan type adhesively bonded specimens, the traction-separation laws of the acrylicadhesive under mode 1 and 2 loadings were determined by means of simultaneous recording the J-integral andthe opening displacements in the directions normal and tangential to the adhesive layer, respectively.Then, the tensile shear tests of single lap joints with the acrylic adhesive were conducted. Theexperimentally obtained strengths of these joints were compared with simulated ones by using FEM packageABAQUS, wherein the cohesive laws were simplified to trapezoidal shape based on the above tractionseparationlaws. As a result, the experimental strengths of these joints well agreed with simulated ones.