Mechanical properties laminate constructions

Polyurethane rigid foam is an excellent insulation material, particularly well suited for applications requiring high mechanical properties. In the form of laminated boards, they are applied on roofs, ventilated facades, ventilated double walls, masonry construction, single-wall masonry interior walls, floors and ceilings and for floor heating systems. 

Table 6.5 Mechanical properties of various laminate constructions...

CEN/TC 124 Timber Structures , SN EN 408 2003 Timber structures — construction timber and glued laminated timber — Determination of some physical and mechanical properties, SIA Schweizerischer Ingenieur- und Architektenverein Zurich, Switzerland (2003). 

An epoxy prepreg will provide a composite with higher mechanical properties than a comparable epoxy hand lay-up resin and with less voids (0-2%) compared with 5-8% voids in a wet laminate. However, the prepreg does require to be stored under refrigeration, requires a well constructed mold and must be cured at 70°C or above. 

LMP, the construction and applications of which have been described elsewhere is some detail (1-3). In the present work, LMP treatments have been performed on substrates of aromatic polyamides, notably du Pont "Kevlar". The excellent mechanical properties of Kevlar fibers and of structures based on this fiber have been well documented, as have some of their shortcomings (4, 5). Our concern is with the apparent difficulty of bonding Kevlar with adhesives of the epoxy and triazine type. A comparison study was carried out for bond strengths in laminates based on control Kevlar multifilament cloth and for similar structures using Kevlar subjected to plasma treatments. The results of that study are reported here, along with complementary data on the various effects of plasma treatment. 

PF foam technology has progressed in recent years so that slabstock and laminated boards can now be produced using continuous technologies. PF cannot match the versatility of foam/facing combinations developed by PU and PIR, but it offers to the construction industry a useful combination of physical, mechanical and fire properties. 

Flame retarded polyesters cured, as prepregs, at 135 - 163 C for vacuum-bag or low pressure press cure. Suitable for laminate or sandwich panel construction in aircraft and other secondary structural applications requiring good mechanical performance, low flammability and excellent electrical properties. 

The ceramic reinforcement tows have high filament counts (500-2000) and are woven with large units cells, several millimeters in size. In a tube configuration, the composites can have a 1-D filament wound, 2-D laminate, or 3-D (weave or braid) construction depending on what tensile, shear, and hoop stresses are considered. The fiber architecture in the tubes can be geometrically tailored for highly anisotropic or uniform isotropic mechanical and thermal properties. ... 

---