| FAQs; • What are composites?: Are combinations of two or more materials with different, often complementary properties. • Composites Advantages: Are light, stiff and strong, and they allow both large and small series production at a greatly reduced energy cost. Are very durable and extend the lifetime of articles. • Thermosetting: Before being cured (or cross-linked) during the composite production process, they are very liquid, and hence easy to impregnate intro the fibrous performs. Is not possible to remould again after first figure. Stable under temperature and pressure variations. Example: STRUCT-CORE. Most common techniques used: hand lay-up, spray-up, resin injection (RTM, VARI,..), compression moulding, and autoclave. • Thermoplastic: Less resistance when temperature increases. Are more viscous than thermosetting and hence require different processing techniques. With heat can be remould several times, keeping always new form. Easy to recycle than thermosetting (not when cross-linked). Example: PVC. Mainly open mould techniques are used. • AO - MO Comparison: Does not exist a real equivalence between both categories: O Category AO-A1,..: Referred to Fire Resistant Classes adopted by IMO (International Maritime Organization). Indicates the capacity of the material to block the propagation of the fire and insulate one area from the other. AO Class means poor level of resistance. Category MO-M1,..: Means Flammability grade in AFNOR standard an gives the level of flammability of one material. Flammability indicates how fast a material is able to propagate flames. According AFNOR the lowest flammability is MO, the highest is M5. • Classification IMO (A,B,C): Adopted by IMO (International Maritime Organization) referred to performance of different vessel parts (not to the components like foam). If one marine door is B class approved means all the door fulfil B class requirements. Just A and B class are accepted and certified for naval construction. • Shear Elongation: used as indicator of foam's toughness and ability to absorb energy without failing. Majorvalues Indicates higherfatigue resistance. • Stability in relation to Organic Solvents: Styrene is the most aggressive solvent we could find inside resins. Don't exist in the Certification process an official method to measure the stability of a core material in relation to organic solvents. According to the results of our lab tests, organic solvents don't affect STRUCT-CORE. If necessary do not hesitate to ask for a specific test. • Compressive Modulus: Official method for a sandwich's core material homologation is ASTM D1621 (last edition: 2OOO) or ISO 844, known as Cross Head-Motion. In the ASTM D1621/2OOO those two methods are said to be equivalent. ASTM D1621 specifies that the Cross Head-Motion device should be used to measure deflections. Another way exists and it corresponds to the old method ASTM D1621B called Strain Measurement (measured mechanically with extensometer). Official values (Cross Head-Motion) are approximately half of the Strain Measurement value. For example ifyou have a value of 54 MPa with ASTM D1621/2OOO, probably you would reach a value of 1O5 MPa fulfilling the old non official method ASTM D1621B or any method that is equivalent to it. DIN 53421 methods is not accepted. High values of remanent deformation in compression avoids deformation. • ISO 1926: dTensile strength?: This module is not required by Lloyd's Register in the certification process. The manufacturer could measure it using any official standard available like: ISO 1926 or ASTM D1623 (both equivalent). |