SPRINGFIELD — Organizers of the 2015 Western Mass. Business Expo, presented by Comcast Business, have extended the deadline for submitting proposals for educational seminars to be presented at the annual show. Proposals will now be accepted until July 31.This year’s event, set for Nov. 4 at the MassMutual Center, is expected to attract more than 2,000 business professionals. The show will feature a number of seminars to be presented during the course of the day. Presentations should be 45 minutes in length, be interactive, and give business owners and managers insight and actionable ideas to take back to their office or plant. Proposals may be sent to email@example.com.